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Prognostic Biomarkers in Pituitary Tumours: A Systematic Review

Eirini Papadimitriou, Eleftherios Chatzellis, Anastasia Dimitriadi, Gregory A Kaltsas, Stamatios Theocharis, Krystallenia I Alexandraki
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Published Online: Aug 10th 2023 touchREVIEWS in Endocrinology. 2023;19(2):42-53 DOI: http://doi.org/10.17925/EE.2023.19.2.12
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1

Abstract

Overview

Pituitary tumours (PTs) are the second most common intracranial tumour. Although the majority show benign behaviour, they may exert aggressive behaviour and can be resistant to treatment. The aim of this review is to report the recently identified biomarkers that might have possible prognostic value.

Studies evaluating potentially prognostic biomarkers or a therapeutic target in invasive/recurrent PTs compared with either non-invasive or non-recurrent PTs or normal pituitaries are included in this review. In the 28 included studies, more than 911 PTs were evaluated.

A systematic search identified the expression of a number of biomarkers that may be positively correlated with disease recurrence or invasion in PT, grouped according to role: (1) insensitivity to anti-growth signals: minichromosome maintenance protein 7; (2) evasion of the immune system: cyclooxygenase 2, arginase 1, programmed cell death protein 1 (PD-1)/programmed death ligand 2, cluster of differentiation (CD) 80/CD86; (3) sustained angiogenesis: endothelial cell-specific molecule, fibroblast growth factor receptor, matrix metalloproteinase 9, pituitary tumour transforming gene; (4) self-sufficiency in growth signals: epidermal growth factor receptor; and (5) tissue invasion: matrix metalloproteinase 9, fascin protein. Biomarkers with a negative correlation with disease recurrence or invasion include: (1) insensitivity to anti-growth signals: transforming growth factor β1, Smad proteins; (2) sustained angiogenesis: tissue inhibitor of metalloproteinase 1; (3) tissue invasion: Wnt inhibitory factor 1; and (4) miscellaneous: co-expression of glial fibrillary acidic protein and cytokeratin, and oestrogen receptors α36 and α66. PD-1/programmed cell death ligand 1 showed no clear association with invasion or recurrence, while cyclin A, cytotoxic T lymphocyte-associated protein 4, S100 protein, ephrin receptor, galectin-3, neural cell adhesion molecule, protein tyrosine phosphatase 4A3 and steroidogenic factor 1 had no association with invasion or recurrence of PT.

With the aim to develop a more personalized approach to the treatment of PT, and because of the limited number of molecular targets currently studied in the context of recurrent PT and invasion, a better understanding of the most relevant of these biomarkers by well-designed interventional studies will lead to a better understanding of the molecular profile of PT. This should also meet the increased need of treatable molecular targets.

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Article

Pituitary tumours (PTs) are located in the sella turcica, which surrounds the adenohypophysis and neurohypophysis. PTs range from asymptomatic incidentalomas to symptomatic aggressive neoplasms, such as invasive neoplasms or pituitary carcinomas.1 Symptomatic lesions can be characterized either by hormonal overproduction or by dysregulation of hormone secretion, and in invasive lesions by tissue destruction and intracranial mass effects. PTs represent the second most common intracranial tumour, found in a rate of approximately 10–15% of intracranial tumours.2 Ninety per cent of PTs originate from adenohypophysial cells (pituitary adenomas [PAs]),3 and are found at autopsy in approximately 20% of the population, with an increasing prevalence in the USA over the past twenty years.2,4 An incidence of approximately 80 cases out of 100,000 residents of Banbury in Oxfordshire, UK has been reported, corresponding to a fourfold increase in prevalence compared with the previous decade.5 The incidence rate of PT in women is greater than men until the age of 50 years; after the age of 54 years, men have a greater incidence of PT.6 The majority of PTs show slow growth rates and remain within the sella turcica and/or displace the surrounding tissues. However, between 25% and 55% of PTs may show a more aggressive behaviour by infiltrating the surrounding structures, including the sphenoid and/or cavernous sinus, bones and, less frequently, nerves.7–9 They may also present an aggressive behaviour characterised by resistance to treatment, with patients experiencing early and frequent relapses.10

The previous 2004 World Health Organization (WHO) classification indicated that an increased number of mitoses, a Ki-67 labelling index of more than 3%, and extensive nuclear staining for p53 protein are indicators of aggressive behaviour.11 The most recent 2017 WHO classification takes into account tumour size and infiltration of the tumour in the cavernous and sphenoid sinuses, as assessed by magnetic resonance imaging, immunohistochemical type and markers of proliferation (increased mitotic activity and Ki-67).12 In addition, transcription factors such as pituitary-specific positive transcription factor 1 , steroidogenic factor 1 (SF-1) and TPit play a major role in determining tumour subtypes and have become part of the classification criteria.13

The fact that the biological behaviour of PTs cannot be predicted underlines the necessity to discover biomarkers that can predict the aggressive behaviour of PTs. The aim of this review is to report the novel biomarkers that are associated with tumour growth or invasion and might provide a possible prognostic value of tumour behaviour. Such prognostic value may assist clinicians in the determination of appropriate patient management and surveillance.

Material and methods

Protocol

Search strategy and selection of studies

This systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.14 The electronic databases of Medline (Pubmed) were reviewed systematically in August 2022, using appropriate controlled vocabulary and free search terms to identify studies evaluating prognostic biomarkers in PTs. The detailed search strategy vocabulary included the following: “pituitary neoplasms”[MeSH Terms] OR “pituitary neoplasms”[MeSH Terms] OR “pituitary lesions”[Other Term]) AND (“biomarkers”[MeSH Terms] OR “biomarkers, pharmacological”[MeSH Terms] OR “prognostic biomarkers”[Other Term] OR ((“immunohistologic”[All Fields] OR “immunohistological”[All Fields] OR “immunohistologically”[All Fields]) AND “markers”[Other Term]) OR “immunohistochemistry”[MeSH Terms] from 2016 to the present.

Titles, abstracts and full text (when appropriate) of all identified studies were screened for eligibility by three authors (EP, EC, AD). One author (EP) extracted from the studies the following pieces of information in a pre-specified standardized Microsoft Excel spreadsheet: full reference; study identifiers; study design; eligibility; predefined outcomes; details on the outcomes of interest.

The search strategy was validated by KA. When EP raised a discrepancy, KA was consulted. All these steps were validated by a second reviewer (ST). Disagreement was resolved by discussion or adjudication by a third investigator (GK), if necessary.

Criteria for inclusion of studies in the systematic review

Studies fulfilling all of the following criteria were included in the systematic review:

  1. studies published in English with prospective or retrospective design

  2. studies that evaluated PTs of gonadotrophic, corticotrophic, somatotrophic or lactotrophic origins, mixed/plurihormonal adenomas, null-cell adenomas (NCAs) or non-functioning adenomas

  3. studies that assessed biomarkers of a prognostic value by evaluating their presence or absence according to the aggressive behaviour of the PT (e.g. infiltration of surrounding tissues, recurrence)

  4. studies that compared the presence of biomarkers in PTs with healthy pituitary tissue, which have a potential diagnostic value or therapeutic targets for guiding personalized treatment

  5. studies that evaluated gene mutations, proteomic profiling or DNA methylation were excluded from this review.

Study outcomes extracted for the systematic review

The primary outcome extracted from the selected studies was the presence or absence of immunohistochemichal biomarkers in PTs that show potential prognostic value. The secondary outcome extracted from the selected studies was any potential prognostic biomarker that may have gained importance in recent literature.

Results

Search strategy

The search strategy identified 322 references in Medline, which were screened by title and abstract. Of these references, 80 were deemed potentially eligible because they reported studies evaluating biomarkers in PT; 52 of the 80 studies were excluded because either the outcome was not precisely reported or their design did not fulfill the inclusion criteria. In the remaining 28 studies included in the present review, more than 911 PTs were evaluated. The selection process is described in Figure 1.

Characteristics of the selected studies

Tissues were obtained from patients who underwent primary surgery for PA. Tumours that presented with pituitary apoplexy, necrosis or fibrosis or patients who took medications (such as cabergoline) were excluded from the studies. Study groups consisted of patients with invasive or recurrent PTs and were compared with patients with either non-invasive or non-recurrent PTs15–29 or normal tissues.15,19,27,30 Of the 28 studies included in this review, 20 described the study groups in detail. PTs were characterized as invasive or non-invasive according to Knosp classification, i.e. they are invasive when Knosp-score was ≥3 and/or the optic chiasm was compressed and non-invasive when Knosp score was 1–2.15–17,22,24–26,28–36 A recurrent tumour was defined as a new confirmed tumour that was diagnosed after complete resection, or the regrowth of a residual tumour after subtotal resection.17,23,24,26–30,33,37 Patients underwent follow-up with magnetic resonance imaging. In the prospective studies, the follow-up of the patients was between 2 and 11 years.

Evaluated biomarkers

The biomarkers are reported in Table 115,17–35,37–45 using the categories proposed by Hanahan and Weinberg.46 They suggest that most of the tumours have acquired the same sets of functional capabilities during their development, albeit there are various mechanistic strategies. According to their study, the hallmarks of cancer were originally six biological capabilities acquired during the multistep development of human tumours; this original hypothesis was established in 2000.46 In 2011, this was increased to eight biological capabilities and two enabling capabilities. The biological capabilities are:

Minichromosome maintenance protein 7

Minichromosome maintenance (MCM) proteins are DNA-binding proteins expressed in the nucleus that are essential for the process of DNA replication. They are up-regulated in gliomas, meningiomas and prostate cancers.47–51 MCM-7 protein is found to be associated with cyclin D1-dependent kinase and may regulate the binding of this protein with the tumour suppressor retinoblastoma protein.52 MCM-7 expression has been found to predict poor clinical outcomes in various types of cancers.53–56

MCM-7 was evaluated in 70 non-functioning PAs (NFPAs), and it was found that MCM-7 expression was higher in the tumour progression group compared with the stable disease group over 6 years of follow-up (p<0.0001).31 The median MCM-7 expression was 7.4% (interquartile range [IQR] 2.4–15.2) in the group with tumour progression and 2.0% (IQR 0.6–5.3) in the stable disease group. The same study found a positive correlation of MCM-7 with Ki-67 and a negative correlation with age. These findings are consistent with a previous study that included 97 patients with both functioning PAs (FPAs) and NFPAs, where it was found that high MCM-7 expression was associated with an increased risk of tumour progression.57

Cyclooxygenase 2 and arginase

Cyclooxygenase 2 (COX-2) is a key enzyme in the synthesis of prostaglandins, and when it is overexpressed, it can reduce the antitumour effect of the immune system by inhibiting the proliferation of B and T lymphocytes.58 Arginase 1 (ARG1) can process L-arginine in the local microenvironment and affect the function of T cells, resulting in immune escape.59,60

COX-2 and ARG1 were evaluated in 25 FPAs, 30 NFPAs and 10 healthy pituitary tissues. There was a significant difference in the expression of COX-2 and ARG1 in PTs compared with healthy tissues (p<0.001).30 There was no significant difference in the expression of COX-2 between FPAs and NFPAs, whereas expression of ARG1 was higher in NFPAs compared with FPAs (p=0.005). Another study investigated the expression of COX-2 in 71 PAs (33 invasive PAs and 38 non-invasive PAs; 30 NFPAs and 41 FPAs) and in 20 healthy pituitary tissues.15 The study found that higher levels of COX-2 were expressed in PTs compared with normal pituitary tissue (p=0.0001). Moreover, the expression of COX-2 was significantly increased in invasive tumours compared with the non-invasive tumours (p=0.04).15 The same study evaluated prostaglandin E2, which has a positive role in cell proliferation, angiogenesis and inflammation, and a higher expression was observed in PTs, NFPAs and invasive PTs compared with normal pituitaries, FPAs and non-invasive PAs, respectively. In contrast to the previous study,30 the expression of COX-2 was significantly elevated in NFPAs compared with FPAs (p=0.001).15

Endothelial cell-specific molecule 1

Endothelial cell-specific molecule 1 (ESM1) is a dermatan sulfate proteoglycan secreted by endothelial cells that are regulated by possible markers of angiogenesis, such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF).61–63 ESM1 is a biomarker associated with tumour progression in various types of tumours, including lung, liver, brain, kidney and gastric tumours. Its overexpression has been associated with poor prognosis,64–67 and there is indirect evidence of it being a poor prognostic biomarker in PT.68 ESM1 was investigated in 94 NCAss (45 invasive NCAs and 49 non-invasive NCAs), and a positive association was observed between ESM1 expression in vascular endothelial tissues and tumour invasion (p=0.002).22 Low expression of ESM1 was observed in 19 invasive NCAs (42.2%) and in 26 non-invasive NCAs (57.8%), whereas high expression was observed in 30 invasive NCAs (61.2%) and in 19 non-invasive NCAs (38.8%) (p=0.065).16

Tyrosine kinase receptors

Epidermal growth factor receptor protein

Epidermal growth factor receptor (EGFR) is a transmembrane glycoprotein belonging to the human epidermal growth factor receptor (HER) family of tyrosine kinase receptors (TKRs), which promote multiple signalling cascades for cellular survival.69 Both neoplastic and normal pituitary tissues express EGFR and phosphorylated EGFR (pEGFR). Overall, NFPAs have higher EGFR and pEGFR expression than FPAs, thus pEGFR expression is more amplified in neoplastic pituitary tissue compared with normal pituitary tissue.70 The expression of pEGFR was investigated in recurrent NFPAs (n=47) and in non-recurrent NFPAs (n=55), and a highly significant difference was reported (p<0.0001). pEGFR positivity was greater in a higher number of recurrent NFPA and the H-scores were also higher in recurrent NFPA compared with non-recurrent (117 ± 6.0 versus 71.2 ± 3.7; p<0.0001).17 The H-score is determined by adding the results of multiplication of the percentage of cells with staining intensity ordinal value (scored from 0 for ‘no signal’ to 3 for ‘strong signal’) with 300 possible values. The study also reported that high expression of pEGFR predicted higher probability of recurrence in NFPA (i.e. hazard ratio [HR] 4.9, confidence interval 2.8–8.8; p<0.0001).

Fibroblast growth factor receptor 4

Fibroblast growth factor receptor 4 (FGFR4) belongs to the TKRs that regulate cellular pathways involved in proliferation, differentiation and survival.71 A prospective study investigated the expression of FGFR4 in 161 PAs, with the patients followed-up for a period of 61 months. The median H-scores for FGFR4 were higher in patients without remission and those with residual lesion compared with those with remission (p<0.05).18 Moreover, PTs with Ki-67 expression ≥3% had higher FGFR4 expression levels than those with <3% expression (p=0.002), and a weak positive correlation between H-score and Ki-67 (p=0.011; r=0.201) was reported.18

Ephrin receptors

Ephrin receptors (EPHs) comprise the largest known subfamily of TKRs. They bind to and interact with EPH-interacting proteins. They have a role in tumour growth, invasion, angiogenesis and metastasis of several neoplasms. Preliminary data indicate a high prevalence of EPH-A4 and a lower expression of EPH-A2 in neuroendocrine neoplasms.72 The expression of EPH-A4, -A5, -B2 and -B5 were evaluated in 18 PTs (seven somatotropic and two corticotropic adenomas, eight non-functioning macro-adenomas and one resistant prolactinoma) by immunohistochemistry.41 The data reported, for the first time, the increased expression of mainly EPH-A4 and, to a lesser extent, EPH-A5, -B2 and -B4 in pituitary lesions. A cytoplasmic (17/18) and nuclear (13/18) pattern of immunostaining for EPH-A4 and a cytoplasmic pattern for EPH-A5, -B2 and -B4 was noted. All corticotropic and somatotropic adenomas were positive for EPH-A4 for both patterns, whereas positivity for EPH-A5 (4/18) and EPH-B2 (1/18) was noted in NFPAs with cytoplasmic pattern. The H-score for EPH-A4 expression ranged from 30–255, whereas for EPH-A5, -B2 and -B4 the range was lower (10–65) (Figure 2).41

Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase 1

Matrix metalloproteinases (MMPs) are capable of degrading all kinds of extracellular matrix proteins that may play an important role in cell proliferation, migration, angiogenesis and apoptosis. MMP-9 may play an important role in angiogenesis and neovascularization and appears to be involved in the remodelling associated with malignant glioma neovascularization.73 MMP-9 and tissue inhibitor of metalloproteinase 1 (TIMP-1) were investigated in 58 invasive PTs and in 50 non-invasive PTs, and it was found that positive expression of MMP-9 in invasive PAs was significantly higher than in non-invasive PTs, whereas positive expression of TIMP-1 was relatively high in non-invasive PTs, with the differences being statistically significant (p<0.05).21 In another study, MMP-9 was evaluated in 27 recurrent adrenocorticotropic hormone (ACTH)-secreting PAs and in 28 non-recurrent ACTH-secreting PTs and in two normal tissues. Recurrent ACTH-secreting PTs were found to express greater levels of MMP-9 and showed a shorter recurrence-free interval.19 No expression of MMP-9 was detected in the two normal pituitary tissues.19 A previous study also reported that MMP-9 may influence the invasiveness and recurrence of PA (Figure 2).74

Pituitary tumour transforming gene

Human pituitary tumour transforming gene (PTTG) is an oncogene that was initially isolated from PT cells. It was identified as a securin, a protein that regulates chromosome separation, that can serve as a marker of malignancy grades in several forms of cancer, particularly endocrine malignancies such as PT.19

PTTG expression was evaluated in 27 recurrent ACTH-secreting PTs, in 28 non-recurrent ACTH-secreting PTs and in two normal tissues.19 PTTG expression was not significantly different between the recurrent group and the non-recurrent group. On the other hand, another study evaluated the expression of PTTG in 11 invasive and 11 non-invasive NFPAs and found significantly higher mRNA expression of PTTG in the invasive group compared with the non-invasive group.22 Similar outcomes were reported by another study, which evaluated PTTG expression in 74 PTs (48 NFPAs and 26 FPAs) and its association with recurrence over a period of 6.0 (± 3.9) years follow-up.37 PTTG nuclear positivity was associated with a higher risk of regrowth or recurrence of the PT (p=0.026), an association which was not statistically significant when total PTTG expression levels were analyzed. Nuclear PTTG positive expression was also positively correlated with tumour volume and suprasellar extension.37  Furthermore, a study evaluating PTTG expression in 38 invasive and 18 non-invasive NFPAs, found a positive rate in more than 50% of the cases, with higher indexes in invasive adenomas.23 The same study reported a statistically significant relationship between PTTG and invasiveness (p=0.022).23 No expression of PTTG was detected in the two normal pituitary tissues.19 In contrast with these findings, there are studies supporting PTTG as a biological marker in PAs75 and other studies supporting the theory that the expression of PTTG was not significantly associated with tumour invasiveness in patients with PA.76

Fascin protein

Fascin is an actin-bundling protein that binds β-catenin and regulates cytoskeletal structures for the maintenance of cell adhesion. Fascin increases the invasiveness of cancer cells since its expression is upregulated in a spectrum of cancers.77 The expression of fascin protein has been assessed in a total of 30 invasive and non-invasive PTs, and higher expression was observed in invasive PTs compared with non-invasive PTs.20

Immune checkpoint molecules

Immune checkpoint molecules are key receptors that inhibit the immune response and prevent its overactivation. Under normal conditions, this mechanism is responsible for maintaining tolerance to its own antigens; however, it can be used by cancer cells to avoid recognition and destruction.78 A number of receptors belonging to the immune checkpoint family have been discovered, including inhibitory immune checkpoints molecules such as programmed cell death ligand 1 (PD-L1), PD-L2, cytotoxic T lymphocyte-associated protein 4 (CTLA-4), CD80, CD86 and stimulatory immune checkpoint molecules such as CD27, CD40, OX40, glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) and CD137 (members of the tumour necrosis factor receptor superfamily), which exert inhibitory or stimulatory effects on immune responses. Their main role is to downregulate the immune system and promote self-tolerance by suppressing T cell inflammatory activity. Consequently, this can prevent autoimmune diseases, but it can also prevent the immune system from killing cancer cells.77 The importance of these molecules has led to the development of immune checkpoint blockade therapy, which has become a major weapon in anti-cancer treatment. PD-L1 is a transmembrane protein and a ligand of programmed cell death protein 1 (PD-1), and plays an important role in maintaining peripheral and central immune tolerance by interacting with PD-1. The expression of PD-L1 by tumour cells or infiltrative immune cells has been confirmed by immunohistochemical staining of various tumour tissues, such as non-small cell lung cancer, melanoma and epithelial ovarian cancer.79

PD-L1 expression has gained attention through many studies.27,30,34,39,40 PD-L1 has been investigated in 73 NFPAs (gonadotroph adenomas, silent corticotroph adenomas, NCAs), and was found to have significantly lower expression in invasive NFPAs than in non-invasive NFPAs (p<0.05), and lower expression in silent corticotroph adenoma and NCA than in gonadotroph NFPA.34 PD-1, PD-L1, PD-L2, CTLA-4, CD80 and CD86 were investigated in 43 recurrent or invasive PAs, 17 PTs without recurrence or non-invasive and in 12 normal pituitaries.27 Significantly higher levels of PD-L2 (p<0.0001), CD80 (p=0.0035) and CD86 (p=0.004) were found in recurrent or invasive PAs, but no significant difference was found in PD-1, PD-L1 and CTLA-4 between recurrent or invasive PTs and normal pituitaries.27  Significantly higher expression of PD-L1 (p=0.02) and PD-L2 (p<0.0001) was found in non-recurrent or non-invasive and normal pituitaries.27 No significant difference was found between PD-1, CTLA-4, CD80 and CD86 expression between non-recurrent or non-invasive PTs and normal pituitaries. The expression of CD86 in recurrent or invasive PTs was significantly higher compared with non-recurrent or non-invasive PTs (p=0.035); however no statistically significant differences were found between PD-1, PD-L1, PD-L2, CLTA-4 and CD80 in these groups.27 No significant difference of PD-1, CTLA-4, CD80 and CD86 was found between functioning PTs (n=21) and non-functioning PTs (n=11);27 similar findings for PD-1 were confirmed by one more study.40 PD-L1 was evaluated in 25 FPAs, 30 NFPAs and 10 healthy tissues and a significant increase in expression of PD-L1 was found, in PTs compared with healthy tissues (p<0.001).30 Interestingly, the levels of immune expression of PD-L1 in PTs ranged from negative staining to highly positive immunostaining, whereas immune expression of PD-L1 in healthy tissues were all negative staining. There was no significant difference in the expression of PD-L1 between FPAs and NFPAs. Other studies reported that PD-1 and PD-L1 showed higher expression in FPAs (p<0.01) compared with NFPAs,35,39 especially in growth hormone secreting adenomas.35

Transforming growth factor 1, Smad proteins and Wnt inhibitory factor 1 protein

Transforming growth factor beta 1 (TGF-β1) is a cytokine that performs many cellular functions, including the control of cell growth, cell proliferation, cell differentiation and apoptosis. It is overexpressed in many human tumours, such as breast, melanoma, renal, prostatic, ovarian, haematological, cervical and brain tumours. TGF-β inhibits cell cycle progression by stopping cells from making the G1/S phase transition.80

Smad proteins are the main signal transducers for receptors of the TGF-β superfamily by regulating cell development and growth. Smad proteins activate TGF-β by downregulating Myc, which is a transcription factor that promotes cell growth. Myc also represses p15 and p21, which are inhibitors of Cdk4 and Cdk2, respectively.81  When there is no TGF-β present, a repressor complex composed of Smad3 and the transcription factors E2F4 and p107 are found in the cytoplasm. However, when the TGF-β signal is present, the complex localizes to the nucleus where it associates with Smad4, and binds to the TGF-β inhibitory element of the Myc promoter to repress its transcription.82 The role of TGF-β and Smad is discussed in the literature in several types of PA.83–85

Wnt inhibitory factor 1 (WIF1) is a lipid-binding protein encoded by the WIF1 gene that binds to Wnt proteins and prevents them from triggering signalling (Wnt pathway off). It has been suggested that aberrant regulation of the Wnt signalling pathway is associated with tumourigenesis.86,87

TGF-β1 and phospho-Smad3 protein were investigated in 13 invasive somatotropinomas and 32 non-invasive somatotropinomas. TGF-β1 protein level was significantly less in the invasive than non-invasive somatotropinomas (p<0.01). Low expression of phosho-Smad3 was also correlated with invasion of somatotropinomas (p<0.01).24

TGF-β1 and WIF1 have been evaluated in 59 NFPAs without recurrence and in 45 NFPAs with recurrence followed for between 6 and 68 months (mean: 38.5 months). The expression of TGF-β1 and WIF1 in the recurrence group was lower than in the non-recurrence group (p<0.001). The same study also reported that NFPAs with low expression of the two proteins are more likely to recur and thus had a shorter time of recurrence (TGF-β1: 52 months; WIF1: 58 months) compared with those with high expression (TGF-β1: 65 months; WIF1: 68 months), but there was no statistically significant difference.26 The results of another study,25 which investigated TGF-β in 19 invasive NFPAs and 23 non-invasive NFPAs were in agreement with the previously mentioned studies.24,26 It is reported that the expression of TGF-β was significantly less in the invasive NFPAs compared with the non-invasive ones (p<0.05) (Figure 3).

Glial fibrillary acidic protein

Glial fibrillary acidic protein (GFAP) is expressed by several cell types in the central nervous system.88 The co-expression of GFAP and cytokeratin has been investigated in 326 PAs and 13 normal anterior pituitaries.44 Simultaneous co-expression of GFAP and cytokeratin was demonstrated in 26 out of 326 PAs and in all 13 normal pituitaries. Furthermore, PTs with cellular co-expression of GFAP and cytokeratin were associated with a lower recurrence rate (7.7%) compared with adenomas without co-expression (17.8%).44

Oestrogen receptors

The expression of oestrogen receptors (ER), ERα36 and ERα66, have been investigated in 62 prolactinomas, and it was reported that low expression of ERα36 and ERα66 was associated with tumour invasion and increased Ki-67.45 Moreover, low ERα66 expression was associated with dopamine-agonist resistance and enhanced tumour size.

Galectin-3 protein

Galectin-3 is a member of the beta-galactoside-binding protein family that plays an important role in cell–cell adhesion, cell–matrix interactions, macrophage activation, angiogenesis, metastasis and apoptosis. Its expression is suggested to be a predictive biomarker of tumour aggressiveness.89 Galectin-3 expression has been investigated in 12 invasive prolactinomas and 24 non-invasive prolactinomas, and no significant difference was observed; a positive result for galectin-3 was observed in 45.5% of invasive tumours and 54.5% of non-invasive tumours.28 An association was observed between galectin-3 expression and persistence of hyperprolactinaemia.

Cyclin A protein

Cyclin A is a member of the cyclin family that regulates progression through the cell cycle. Overexpression of cyclin A has been linked to astrocytomas’ proliferative state,90 reduced survival in oesophageal cancer,91 early relapse in prostate cancer92 and poorer tumour grade in oral cancers;93 there are limited data for NFPAs. Cyclin A expression was investigated in 15 invasive and in 16 non-invasive NFPAs, and increased expression was found in a minority of NFPAs but does not seem to be related to invasion.29

S100B protein

S100B is expressed in non-endocrine cells of the pituitary, which are also described in pituitary neoplasms, suggesting they might play a role in tumourigenesis-related processes.94–96 The expression of S100B protein was investigated in 54 PTs and in four normal pituitaries, and it is reported that decreased expression was observed in PTs compared with normal pituitaries. Low expression of S100B was associated with a Ki-67 index ≥3, a mitosis count >2/10 per high power fields and a proliferative status, but no association was reported with invasion.32

Neural cell adhesion molecule

Neural cell adhesion molecule (NCAM), also called CD56, is a homophilic-binding glycoprotein expressed on the surface of neurones, glia and skeletal muscle that has been implicated as having a role in cell–cell adhesion.97 NCAM expression was investigated in 16 NFPAs, eight somatotrophinomas and five normal pituitaries, and no significant difference of NCAM expression was observed either between PT and normal pituitary or NFPA and somatotrophinoma.42 There was also no association between NCAM expression and invasion.42

Protein tyrosine phosphatase 4A3

Protein tyrosine phosphatase 4A3 (PTP4A3) is a subclass of the protein tyrosine phosphatase super family and is expressed in a range of epithelial neoplasms. Overexpression of this gene promotes cell growth. PTP4A3 expression was investigated in 34 FPAs and was expressed in more than half of the tumours (19/34); a significant association with the tumour size was observed (p=0.042).43

Steroidogenic factor 1

The SF-1 protein is a transcription factor that is proposed to interact with β-catenin.98 Expression of SF-1 was investigated in 20 recurrent gonadotrophic PTs and 31 non-recurrent PTs, and it was reported that gonadotrophic PT with patchy SF-1 staining is more likely to recur sooner than gonadotrophic PT with diffuse staining (p=0.0007).33

Discussion

Nowadays, invasiveness can be estimated radiologically and surgically, but the need to identify biomarkers that could be useful to everyday clinical management and provide a prognostic value in patients with PT is of great additive importance.

Acknowledging the lack of studies in the literature, the scarcity of the pituitary tissues and the complexity of the mechanisms of tumour growth, we have tried to outline a simple approach to understanding the importance of the various biomarkers that are used to provide prognostic information, and to assist treating clinicians with determining appropriate patient management and surveillance.

This review has shown that the expression of MCM-7, EGFR, MMP-9, PTTG, PD-1/PD-L2 and CD80/86 may be possible prognostic biomarkers for recurrent PTs, and expression of COX, ARG1, ESM1, PD-1/PD-L2, CD80/86, MMP-9, PTTG and fascin protein may be possible prognostic biomarkers for invasive PTs. Notably, PTs with high expression of tyrosine kinase EGFR had 4.9 times higher risk of recurrence (HR 4.9). Moreover, the expression of tyrosine kinase FGFR4 was associated with the proliferative characteristic of PT and could be a marker for more aggressive tumour behaviour. Since tyrosine kinase inhibitors are a therapeutic option, these biomarkers could be of clinical value. Well-designed randomized controlled trials are needed in order to understand their impact on the pathophysiology of PT and, consequently, on recurrence or invasion, before using them in everyday clinical management. From this perspective, the most important biomarkers appear to be MMP-9, PD-1/PD-L2 and CD80/86.

Low expression of other biomarkers, namely TGF-β1, WIF1, and co-expression of the GFAP and cytokeratin, was associated with recurrence of PT; also, low expression of TGF-β1, phospho-Smad, ERα36 and ERα66 was associated with invasion of PT. Higher expression of these biomarkers and TIMP-1 was noted in non-recurrent or non-invasive PTs. With caution, we could hypothesize that the downregulation of the abovementioned biomarkers may be associated with tumour growth.

Expression of additional biomarkers (i.e. EPH, PD-1/PD-L1, CTLA-4, galectin 3, cyclin A, S100 protein, NCA, PTP4A3 and SF-1) did not show a clear association with recurrence or invasion of PT. However, before we reject them as unimportant, additional studies might clarify their role in proliferation, invasion or recurrence, particularly for the druggable molecules such as EPH and PD-1/PD-L1.27,30,41

In aggregate, this review attempts to summarize novel biomarkers, that would predict PT behaviour (i.e. invasiveness, aggressiveness, metastases). Many studies with sufficient number of species, adequate follow-up period and consistent outcomes have drawn attention to MMP-9, MCM-7 and FGFR (tyrosine kinase pathway). Moreover, expression of PTTG (hyperactivation of mammalian target of the rapamycin [mTOR] signalling) has drawn the attention of many researchers. Although studies do not show consistent results, the majority of them have reported an association with either recurrence or tumour growth or suprasellar extension or invasiveness.

Figure 4 depicts the biomarkers that have been investigated in more than 50 pituitary specimens. Some biomarkers were found to be positively correlated with disease recurrence and invasion in PTs, for example, COX-2, ARG1, PD-1/PD-L2, TGF-β1 and CD80/86, all of which have a role in evasion of the immune system; FGFR and PTTG have a role in sustained angiogenesis; and MMP-9 has a role in sustained angiogenesis and tissue invasion.

In the left scale, the biomarkers with positive association with disease recurrence and/or invasion are shown. In the right scale, the biomarkers with negative association with recurrence and/or invasion are shown. In the base of the scale, the biomarkers with no association with disease recurrence and/or invasion are shown. The evaluated biomarkers were sorted according to the evaluation of a minimum of 50 pituitary species for each marker in one or more studies evaluated in the present review.

ARG1 = arginase 1; COR-PT = corticotroph pituitary tumors; COX-2 = cyclooxygenase 2; CTLA-4 = cytotoxic T-lymphocyte-associated protein 4; EGFR = epidermal growth factor receptor; ER = oestrogen receptor; ESM1 = endothelial cell-specific molecule 1; FGFR4 = fibroblast growth factor receptor 4; GFAP = glial fibrillary acidic protein; MCM-7 = minichromosome maintenance protien 7; MMP-9 = matrix metalloproteinase-9; NCPA = null-cell pituitary adenoma; NFPA = non-functioning pituitary adenoma; PD1 = programmed cell death protein 1; PDL = programmed cell death ligand; PT = pituitary tumour; PTTG = pituitary tumour transforming gene; PRLoma = prolactinoma; SOM = somatotroph adenoma; TGF-β1 = transforming growth factor β1; TIMP-1 = tissue inhibitor of metalloproteinase 1; WIF1 = Wnt inhibitory factor 1.

In NFPA, the biomarkers that were found to be positively correlated with disease recurrence and invasion were: MCM-7 protein that has a role in the insensitivity to anti-growth signals, EGFR that modulates self-sufficiency in growth signals, and PTTG that has a role in sustained angiogenesis. In null-cell PT, ESM1, which has a role in sustained angiogenesis, was positively correlated with invasion. In corticotroph PT, MMP-9 was more highly expressed in recurrent versus non-recurrent PT. On the other hand, a number of other biomarkers may be negatively correlated with disease recurrence and invasion in PT, such as TIMP-1, which has a role in sustained angiogenesis and tissue invasion, and ERα36 and ERα66. In NFPA, TGF-β1, an inhibitor of insensitivity to anti-growth signals, and WIF1, which has role in tissue invasion, were negatively correlated with disease recurrence and invasion. In prolactinomas, the co-expression of GFAP and cytokeratin was negatively correlated with disease recurrence of PT. Finally, no association with recurrence and invasion of PT was found for S100, as opposed to the expression of PD-1/PD-L1 that had no consistent association with recurrence and invasion or with the functionality of PT.

This review highlights the necessity to expand our current knowledge on PT pathogenesis by utilizing molecular and pathological tools. The progress of molecular biology by the use of next-generation sequencing includes genomics, methylomics, transcriptomics, proteomics and glycomics, which can be integrated into the term ‘multiomics’. This progress will lead to a new era of therapeutics by firstly identifying the target (i.e. biomarker) of a tumour, and then targeting the treatment to the identified biomarkers for individualized treatment regimens.99,100 This has already been seen in somatotroph PTs, where the different immunohistochemical profiles may assist with the identification of subgroups of patients that may benefit from similar treatments .100 In addition, it could identify genetic alterations that may have an impact on the outcome of different therapies by targeting specific molecular pathways. An important step in this direction was introduced with the new classification of PTs that included transcription factors.101 A recent seminal study evaluated 134 patients with functioning PTs via multiomics, such as chromosomal alterations, miRNomics (MicroRNA Biology and Computational Analysis), methylomics and RNA transcriptomics.98 According to methylomics, these tumours were classified into three groups, combining the collapsed CpGs and the secretion of the tumours: met1 correlated with somatotrophs, lactotrophs and thyrotrophs; met2 correlated with gonadotrophs; and met3 correlated with corticotrophs. According to miRNomics, these tumours were classified into four groups based on microRNA (miRNA) clusters as prolactin-secreting (miR-1), growth hormone (miR-2), ACTH (miR-3) and follicle-stimulating hormone/luteinising hormone tumours (miR-4). Finally, according to transcriptomics (pangenomic analysis: somatic mutations, chromosomal alterations, miRNome, methylome, transcriptome), these tumours were classified into six clusters: ubiquitin-specific protease 8 wild-type corticotrophs, overt Cushing corticotrophs (t1 cluster) that appeared more aggressive; lactotroph (t2) with higher dopamine receptor 2 expression, silent corticotroph with a gonadotroph signature (t3); gonadotroph and null-cell (t4); sparsely granulated somatotroph with thyrotroph and plurihormonal PIT1-positive (t5); thyrotrophs, somatotrophs and mixed growth hormone-prolactin (t6).98

Conclusion

In this review we have summarized important biomarkers that could provide prognostic information, thus assisting clinicians in a more efficient management and surveillance of these neoplasms. PTs are mostly a benign disease with a long survival. However, treatment complications may alter the quality of life of the patients harbouring these neoplasms, creating an increased need for effective and safe management based on specific molecular tools. A limited number of molecular targets have been studied in the context of PT recurrence and invasion. Further investigation of the most relevant of these biomarkers by well-designed interventional studies will result in a better understanding of the molecular profile of PT. This could meet the increased need of treatable molecular targets, and lead to a more personalized approach to the treatment of PTs.

3

References

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1
Copy DOIDOI Copied
Visit DOI Link

 Asa SLEzzat SAggressive pituitary tumors or localized pituitary carcinomas: Defining pituitary tumorsExpert Rev Endocrinol Metab2016;11:14962DOI: 10.1586/17446651.2016.1153422

2
Copy DOIDOI Copied
Visit DOI Link

 Ostrom QTGittleman HFulop Jet alCBTRUS statistical report: Primary brain and central nervous system tumors diagnosed in the United States in 2008-2012Neuro Oncol. 2015;17 Suppl 4:iv162DOI10.1093/neuonc/nov189

3
Copy DOIDOI Copied
Visit DOI Link

 Alexandraki KIMunayem Khan MChahal HSet alOncogene-induced senescence in pituitary adenomas and carcinomasHormones (Athens)2012;11:297307DOI: 10.14310/horm.2002.1358

4
Copy DOIDOI Copied
Visit DOI Link

 Villwock JAVillwock MDeshaies EGoyal PSignificant increases of pituitary tumors and resections from 1993 to 2011Int Forum Allergy Rhinol2014;4:76770DOI: 10.1002/alr.21356

5
Copy DOIDOI Copied
Visit DOI Link

 Fernandez AKaravitaki NWass JAHPrevalence of pituitary adenomas: A community-based, cross-sectional study in Banbury (Oxfordshire, UK)Clin Endocrinol (Oxf). 2010;72:37782DOI10.1111/j.1365-2265.2009.03667.x

6
Copy DOIDOI Copied
Visit DOI Link

 Gittleman HOstrom QTFarah PDet alDescriptive epidemiology of pituitary tumors in the United States, 2004-2009J Neurosurg2014;121:52735DOI: 10.3171/2014.5.JNS131819

7
Copy DOIDOI Copied
Visit DOI Link

 Dworakowska DGrossman ABAggressive and malignant pituitary tumours: State-of-the-artEndocr Relat Cancer2018;25:R55975DOI10.1530/ERC-18-0228

8
Copy DOIDOI Copied
Visit DOI Link

 Meij BPLopes M-BSEllegala DBet alThe long-term significance of microscopic dural invasion in 354 patients with pituitary adenomas treated with transsphenoidal surgery. J Neurosurg. 2002;96:195208. DOI: 10.3171/jns.2002.96.2.0195

9
Copy DOIDOI Copied
Visit DOI Link

 Hansen TMBatra SLim Met alInvasive adenoma and pituitary carcinoma: A seer database analysisNeurosurg Rev2014;37:27985DOI10.1007/s10143-014-0525-y

10
Copy DOIDOI Copied
Visit DOI Link

 Chatzellis EAlexandraki KIAndroulakis IIKaltsas GAggressive pituitary tumorsNeuroendocrinology2015;101:87104DOI10.1159/000371806

11
Copy DOIDOI Copied
Visit DOI Link

 Al-Shraim MAsa SLThe 2004 World Health Organization classification of pituitary tumors: What is new? Acta Neuropathol2006;111:17DOI10.1007/s00401-005-1093-6.

12
Copy DOIDOI Copied
Visit DOI Link

 Mete OLopes MBOverview of the 2017 WHO classification of pituitary tumors. Endocr Pathol. 2017;28:22843. DOI: 10.1007/s12022-017-9498-z.

13
Copy DOIDOI Copied
Visit DOI Link

 Laws ERPenn DLRepetti CSAdvances and controversies in the classification and grading of pituitary tumorsJ Endocrinol Invest2019;42:12935DOI: 10.1007/s40618-018-0901-5

14
Copy DOIDOI Copied
Visit DOI Link

 Liberati AAltman DGTetzlaff Jet alThe PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: Explanation and elaboration. Ann Intern Med. 2009;151:W6594. DOI: 10.7326/0003-4819-151-4-200908180-00136

15
Copy DOIDOI Copied
Visit DOI Link

 Akbari NGhorbani MSalimi Vet alCyclooxygenase enzyme and PGE2 expression in patients with functional and non-functional pituitary adenomasBMC Endocr Disord. 2020;20:39DOI10.1186/s12902-020-0515-8

16
Copy DOIDOI Copied
Visit DOI Link

 Wang SWu ZWei LZhang JEndothelial cell-specific molecule-1 as an invasiveness marker for pituitary null cell adenomaBMC Endocr Disord. 2019;19:90. DOI: 10.1186/s12902-019-0418-8

17
Copy DOIDOI Copied
Visit DOI Link

 Rai ADas LMukherjee KKet alPhosphorylated EGFR (pEGFR T693) as a novel predictor of recurrence in non-functioning pituitary adenomas. Front Endocrinol (Lausanne). 2021;12:708111. DOI: 10.3389/fendo.2021.708111

18
Copy DOIDOI Copied
Visit DOI Link

 Durcan EKeskin FEOzkaya HMet alFibroblast growth factor receptor-4 expression in pituitary adenomas is associated with aggressive tumor featuresExp Clin Endocrinol Diabetes2022;130:12533DOI10.1055/a-1523-7216

19
Copy DOIDOI Copied
Visit DOI Link

 Liu XFeng MZhang Yet alExpression of matrix metalloproteinase-9, pituitary tumor transforming gene, high mobility group A 2, and Ki-67 in adrenocorticotropic hormone-secreting pituitary tumors and their association with tumor recurrenceWorld Neurosurg2018;113:e21321DOI10.1016/j.wneu.2018.01.214

20
Copy DOIDOI Copied
Visit DOI Link

 You HXu JQin Xet alFascin promotes the invasion of pituitary adenoma through partial dependence on epithelial-mesenchymal transition. J Mol Histol. 2021;52:82338. DOI: 10.1007/s10735-021-09995-9

21
Copy DOIDOI Copied
Visit DOI Link

 Guo HSun ZWei Jet alExpressions of matrix metalloproteinases-9 and tissue inhibitor of metalloproteinase-1 in pituitary adenomas and their relationships with prognosis. Cancer Biother Radiopharm. 2019;34:16. DOI: 10.1089/cbr.2018.2589

22
Copy DOIDOI Copied
Visit DOI Link

 Wang HChen KYang Zet alDiagnosis of invasive nonfunctional pituitary adenomas by serum extracellular vesiclesAnal Chem2019;91:95809DOI: 10.1021/acs.analchem.9b00914

23
Copy DOIDOI Copied
Visit DOI Link

 Trott GOngaratti BRde Oliveira Silva CBet alPTTG overexpression in non-functioning pituitary adenomas: Correlation with invasiveness, female gender and younger age. Ann Diagn Pathol. 2019;41:839. DOI: 10.1016/j.anndiagpath.2019.04.016

24
Copy DOIDOI Copied
Visit DOI Link

 Li ZLi JShan Xet alExpression of transforming growth factor β1, Smad3, and phospho-smad3 in somatotropinomas and their relationship to tumor behavior. World Neurosurg. 2021;153:e207. DOI: 10.1016/j.wneu.2021.05.088

25
Copy DOIDOI Copied
Visit DOI Link

 Gu Y-HFeng Y-GDown-regulation of TGF-β RII expression is correlated with tumor growth and invasion in non-functioning pituitary adenomasJ Clin Neurosci. 2018;47:2648DOI10.1016/j.jocn.2017.07.033

26
Copy DOIDOI Copied
Visit DOI Link

 Zhu HYao XWu Let alAssociation of TGF-β1 and WIF1 expression with 36 paired primary/recurrent nonfunctioning pituitary adenomas: A high-throughput tissue microarrays immunohistochemical study. World Neurosurg. 2018;119:e2331. DOI: 10.1016/j.wneu.2018.06.154

27
Copy DOIDOI Copied
Visit DOI Link

 Xi ZJones PSMikamoto Met alThe upregulation of molecules related to tumor immune escape in human pituitary adenomasFront Endocrinol (Lausanne). 2021;12:726448DOI10.3389/fendo.2021.726448

28
Copy DOIDOI Copied
Visit DOI Link

 Bima CChiloiro SGiampietro Aet alGalectin-3 and estrogen receptor alpha as prognostic markers in prolactinoma: Preliminary results from a pilot study. Front Endocrinol (Lausanne). 2021;12:684055. DOI: 10.3389/fendo.2021.684055

29
Copy DOIDOI Copied
Visit DOI Link

 Lamback EBGuterres ABarbosa MAet alCyclin A in nonfunctioning pituitary adenomas. Endocrine. 2020;70:3807. DOI: 10.1007/s12020-020-02402-5

30
Copy DOIDOI Copied
Visit DOI Link

 Zhao GChen WHe Jet alAnalysis of cyclooxygenase 2, programmed cell death ligand 1, and arginase 1 expression in human pituitary adenomaWorld Neurosurg. 2020;144:e66073DOI10.1016/j.wneu.2020.09.031

31
Copy DOIDOI Copied
Visit DOI Link

 Hallén TOlsson DSHammarstrand Cet alMCM7 as a marker of postsurgical progression in non-functioning pituitary adenomas. Eur J Endocrinol. 2021;184:52131. DOI: 10.1530/EJE-20-1086

32
Copy DOIDOI Copied
Visit DOI Link

 Ilie MDVasiljevic AChanal Met alIntratumoural spatial distribution of S100B + folliculostellate cells is associated with proliferation and expression of FSH and ERα in gonadotroph tumours. Acta Neuropathol Commun. 2022;10:18. DOI: 10.1186/s40478-022-01321-y

33
Copy DOIDOI Copied
Visit DOI Link

 Hickman RABruce JNOtten Met alGonadotroph tumours with a low SF‐1 labelling index are more likely to recur and are associated with enrichment of the PI3K‐AKT pathway. Neuropathology Appl Neurobio. 2021;47:41527. DOI10.1111/nan.12675

34
Copy DOIDOI Copied
Visit DOI Link

 Uraki SAriyasu HDoi Aet alMSH6/2 and PD-L1 expressions are associated with tumor growth and invasiveness in silent pituitary adenoma subtypesInt J Mol Sci2020;21:2831. DOI10.3390/ijms21082831

35
Copy DOIDOI Copied
Visit DOI Link

 Zhou WZhang CZhang Det alComprehensive analysis of the immunological landscape of pituitary adenomas: Implications of immunotherapy for pituitary adenomasJ Neurooncol2020;149:47387DOI10.1007/s11060-020-03636-z

36
Copy DOIDOI Copied
Visit DOI Link

 Knosp ESteiner EKitz KMatula CPituitary adenomas with invasion of the cavernous sinus space: A magnetic resonance imaging classification compared with surgical findings. Neurosurgery. 1993;33:6107. DOI: 10.1227/00006123-199310000-00008.

37
Copy DOIDOI Copied
Visit DOI Link

 Gruppetta MFormosa RFalzon Set alExpression of cell cycle regulators and biomarkers of proliferation and regrowth in human pituitary adenomasPituitary. 2017;20:35871DOI10.1007/s11102-017-0803-0

38
Copy DOIDOI Copied
Visit DOI Link

 Han YLiu DLi LPD-1/PD-L1 pathway: Current researches in cancerAm J Cancer Res2020;10:72742.

39
Copy DOIDOI Copied
Visit DOI Link

 Mei YBi WLAgolia Jet alImmune profiling of pituitary tumors reveals variations in immune infiltration and checkpoint molecule expression. Pituitary. 2021;24:35973. DOI: 10.1007/s11102-020-01114-3

40
Copy DOIDOI Copied
Visit DOI Link

 Suteau VCollin AMenei Pet alExpression of programmed death-ligand 1 (PD-L1) in human pituitary neuroendocrine tumorCancer Immunol Immunother. 2020;69:205361DOI10.1007/s00262-020-02611-x

41
Copy DOIDOI Copied
Visit DOI Link

 Papadimitriou EKyriakopoulos GBarkas Ket alImmunohistochemichal expression of ephrin receptor (EPH) -A4, -A5, -B2 and -B5 in pituitary lesions. EJEA. 2022. DOI10.1530/endoabs.81.EP751

42
Copy DOIDOI Copied
Visit DOI Link

 Marques PBarry SCarlsen Eet alThe expression of neural cell adhesion molecule and the microenvironment of pituitary neuroendocrine tumoursJ Neuroendocrinol. 2021;33:e13052DOI10.1111/jne.13052

43
Copy DOIDOI Copied
Visit DOI Link

 Moyano Crespo GDCecenarro LAPerez Pet alAssociation of PTP4A3 expression and tumour size in functioning pituitary adenoma: A descriptive studyJ Clin Pathol2021;74:1903DOI10.1136/jclinpath-2020-206728

44
Copy DOIDOI Copied
Visit DOI Link

 Wiesnagrotzki NBernreuther CSaeger Wet alCo-expression of intermediate filaments glial fibrillary acidic protein and cytokeratin in pituitary adenoma. Pituitary. 2021;24:627. DOI: 10.1007/s11102-020-01087-3

45
Copy DOIDOI Copied
Visit DOI Link

 Mahboobifard FBidari-Zerehpoosh FDavoudi Zet alExpression patterns of ERα66 and its novel variant isoform ERα36 in lactotroph pituitary adenomas and associations with clinicopathological characteristics. Pituitary. 2020;23:23245. DOI: 10.1007/s11102-020-01029-z

46
Copy DOIDOI Copied
Visit DOI Link

 Hanahan DWeinberg RAHallmarks of cancer: The next generation. Cell. 2011;144:64674. DOI: 10.1016/j.cell.2011.02.013

47
Copy DOIDOI Copied
Visit DOI Link

 Giaginis CVgenopoulou SVielh PTheocharis SMCM proteins as diagnostic and prognostic tumor markers in the clinical setting. Histol Histopathol. 2010;25:35170. DOI: 10.14670/HH-25.351

48
Copy DOIDOI Copied
Visit DOI Link

 Erkan EPStröbel TLewandrowski Get alDepletion of minichromosome maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivoOncogene. 2014;33:477885DOI10.1038/onc.2013.423

49
Copy DOIDOI Copied
Visit DOI Link

 Saydam OSenol OSchaaij-Visser TBMet al. Comparative protein profiling reveals minichromosome maintenance (MCM) proteins as novel potential tumor markers for meningiomas. J Proteome Res. 2010;9:48594. DOI: 10.1021/pr900834h

50
Copy DOIDOI Copied
Visit DOI Link

 Ren BYu GTseng GCet alMCM7 amplification and overexpression are associated with prostate cancer progression. Oncogene. 2006;25:10908DOI: 10.1038/sj.onc.1209134

51
Copy DOIDOI Copied
Visit DOI Link

 Gambichler TShtern MRotterdam Set alMinichromosome maintenance proteins are useful adjuncts to differentiate between benign and malignant melanocytic skin lesions. J Am Acad Dermatol. 2009;60:80813. DOI: 10.1016/j.jaad.2009.01.028

52
Copy DOIDOI Copied
Visit DOI Link

 Sterner JMDew-Knight SMusahl Cet alNegative regulation of DNA replication by the retinoblastoma protein is mediated by its association with MCM7Mol Cell Biol. 1998;18:274857DOI10.1128/MCB.18.5.2748

53
Copy DOIDOI Copied
Visit DOI Link

 Fujioka SShomori KNishihara Ket alExpression of minichromosome maintenance 7 (MCM7) in small lung adenocarcinomas (pT1): Prognostic implicationLung Cancer2009;65:2239DOI10.1016/j.lungcan.2008.11.007

54
Copy DOIDOI Copied
Visit DOI Link

 Toyokawa GMasuda KDaigo Yet alMinichromosome maintenance protein 7 is a potential therapeutic target in human cancer and a novel prognostic marker of non-small cell lung cancerMol Cancer2011;10:65DOI10.1186/1476-4598-10-65

55
Copy DOIDOI Copied
Visit DOI Link

 Fristrup NBirkenkamp-Demtröder KReinert Tet alMulticenter validation of cyclin D1, MCM7, TRIM29, and UBE2C as prognostic protein markers in non-muscle-invasive bladder cancer. Am J Pathol. 2013;182:33949. DOI: 10.1016/j.ajpath.2012.10.017

56
Copy DOIDOI Copied
Visit DOI Link

 Ishibashi YKinugasa TAkagi Yet alMinichromosome maintenance protein 7 is a risk factor for recurrence in patients with Dukes C colorectal cancer. Anticancer Res. 2014;34:456975.

57
Copy DOIDOI Copied
Visit DOI Link

 Coli AAsa SLFadda Get alMinichromosome maintenance protein 7 as prognostic marker of tumor aggressiveness in pituitary adenoma patientsEur J Endocrinol. 2016;174:30714DOI10.1530/EJE-15-0586

58
Copy DOIDOI Copied
Visit DOI Link

 Göbel CBreitenbuecher FKalkavan Het alFunctional expression cloning identifies COX-2 as a suppressor of antigen-specific cancer immunityCell Death Dis. 2014;5:e1568DOI10.1038/cddis.2014.531

59
Copy DOIDOI Copied
Visit DOI Link

 Rodriguez PCHernandez CPMorrow Ket alL arginine deprivation regulates cyclin D3 mRNA stability in human T cells by controlling HuR expressionJ Immunol. 2010;185:5198204DOI10.4049/jimmunol.1001224

60
Copy DOIDOI Copied
Visit DOI Link

 Steggerda SMBennett MKChen Jet alInhibition of arginase by CB-1158 blocks myeloid cell-mediated immune suppression in the tumor microenvironmentJ Immunother Cancer2017;5:101DOI10.1186/s40425-017-0308-4

61
Copy DOIDOI Copied
Visit DOI Link

 Béchard DGentina TDelehedde Met alEndocan is a novel chondroitin sulfate/dermatan sulfate proteoglycan that promotes hepatocyte growth factor/scatter factor mitogenic activity. J Biol Chem. 2001;276:483419. DOI: 10.1074/jbc.M108395200

62
Copy DOIDOI Copied
Visit DOI Link

 Rennel EMellberg SDimberg Aet alEndocan is a VEGF-A and PI3K regulated gene with increased expression in human renal cancerExp Cell Res2007;313:128594DOI: 10.1016/j.yexcr.2007.01.021

63
Copy DOIDOI Copied
Visit DOI Link

 Roudnicky FPoyet CWild Pet alEndocan is upregulated on tumor vessels in invasive bladder cancer where it mediates VEGF-A-induced angiogenesisCancer Res. 2013;73:1097106DOI10.1158/0008-5472.CAN-12-1855

64
Copy DOIDOI Copied
Visit DOI Link

 Grigoriu BDDepontieu FScherpereel Aet alEndocan expression and relationship with survival in human non-small cell lung cancer. Clin Cancer Res. 2006;12:457582. DOI: 10.1158/1078-0432.CCR-06-0185

65
Copy DOIDOI Copied
Visit DOI Link

 Chen L-YLiu XWang S-LQin C-YOver-expression of the Endocan gene in endothelial cells from hepatocellular carcinoma is associated with angiogenesis and tumour invasion. J Int Med Res. 2010;38:498510. DOI: 10.1177/147323001003800213

66
Copy DOIDOI Copied
Visit DOI Link

 Leroy XAubert SZini Let alVascular endocan (ESM-1) is markedly overexpressed in clear cell renal cell carcinoma. Histopathology. 2010;56:1807. DOI: 10.1111/j.1365-2559.2009.03458.x

67
Copy DOIDOI Copied
Visit DOI Link

 Liu NZhang LDu Het alOverexpression of endothelial cell specific molecule-1 (ESM-1) in gastric cancerAnn Surg Oncol2010;17:262839DOI10.1245/s10434-010-1037-9

68
Copy DOIDOI Copied
Visit DOI Link

 Niveiro MAranda FIPeiró Get al. Immunohistochemical analysis of tumor angiogenic factors in human pituitary adenomas. Human Pathology. 2005;36:10905. DOI: 10.1016/j.humpath.2005.07.015

69
Copy DOIDOI Copied
Visit DOI Link

 Navolanic PMSteelman LSMcCubrey JAEGFR family signaling and its association with breast cancer development and resistance to chemotherapy (review). Int J Oncol. 2003;22:23752. DOI: 10.3892/ijo.22.2.237

70
Copy DOIDOI Copied
Visit DOI Link

 LeRiche VKAsa SLEzzat SEpidermal growth factor and its receptor (EGF-R) in human pituitary adenomas: EGF-R correlates with tumor aggressivenessJ Clin Endocrinol Metab1996;81:65662DOI10.1210/jcem.81.2.8636285

71
Copy DOIDOI Copied
Visit DOI Link

 Turner NGrose RFibroblast growth factor signalling: From development to cancerNat Rev Cancer2010;10:11629DOI10.1038/nrc2780

72
Copy DOIDOI Copied
Visit DOI Link

 Alexandraki KAntonopoulou IKaraflou Met al. Immunohistochemical expression of ephrines A2 and A4 receptors in neuroendocrine neoplasms: Preliminary resultsEJEA2019DOI10.1530/endoabs.63.P873

73
Copy DOIDOI Copied
Visit DOI Link

 Forsyth PAWong HLaing TDet alGelatinase-A (MMP-2), gelatinase-b (MMP-9) and membrane type matrix metalloproteinase-1 (MT1-MMP) are involved in different aspects of the pathophysiology of malignant gliomasBr J Cancer1999;79:182835DOI10.1038/sj.bjc.6690291

74
Copy DOIDOI Copied
Visit DOI Link

 Turner HENagy ZEsiri MMet alRole of matrix metalloproteinase 9 in pituitary tumor behaviorJ Clin Endocrinol Metab2000;85:29315DOI: 10.1210/jcem.85.8.6754

75
Copy DOIDOI Copied
Visit DOI Link

 Pei LMelmed SIsolation and characterization of a pituitary tumor-transforming gene (PTTG)Mol Endocrinol1997;11:43341DOI10.1210/mend.11.4.9911

76
Copy DOIDOI Copied
Visit DOI Link

 Wierinckx AAuger CDevauchelle Pet alA diagnostic marker set for invasion, proliferation, and aggressiveness of prolactin pituitary tumors. Endocr Relat Cancer. 2007;14:887900. DOI: 10.1677/ERC-07-0062

77
Copy DOIDOI Copied
Visit DOI Link

 Li ADawson JCForero-Vargas Met alThe actin-bundling protein fascin stabilizes actin in invadopodia and potentiates protrusive invasionCurr Biol2010;20:33945DOI10.1016/j.cub.2009.12.035

78
Copy DOIDOI Copied
Visit DOI Link

 Pardoll DMThe blockade of immune checkpoints in cancer immunotherapyNat Rev Cancer2012;12:25264DOI10.1038/nrc3239

79
Copy DOIDOI Copied
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 Kythreotou ASiddique AMauri FAet alPD-L1J Clin Pathol2018;71:18994DOI10.1136/jclinpath-2017-204853

80
Copy DOIDOI Copied
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 Siegel PMMassagué JCytostatic and apoptotic actions of TGF-β in homeostasis and cancerNat Rev Cancer. 2003;3:80720. DOI: 10.1038/nrc1208

81
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 Warner BJBlain SWSeoane JMassagué JMyc downregulation by transforming growth factor beta required for activation of the p15(Ink4b) G(1) arrest pathwayMol Cell Biol1999;19:591322DOI10.1128/MCB.19.9.5913

82
Copy DOIDOI Copied
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 Chen C-RKang YSiegel PMMassagué JE2F4/5 and p107 as Smad cofactors linking the TGFβ receptor to c-myc repressionCell2002;110:1932DOI: 10.1016/S0092-8674(02)00801-2

83
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 Li ZLiu QLi Cet alThe role of TGF-β/Smad signaling in dopamine agonist-resistant prolactinomasMol Cell Endocrinol. 2015;402:6471. DOI: 10.1016/j.mce.2014.12.024

84
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 Zhenye LChuzhong LYoutu Wet alThe expression of TGF-β1, Smad3, phospho-smad3 and Smad7 is correlated with the development and invasion of nonfunctioning pituitary adenomas. J Transl Med. 2014;12:71. DOI: 10.1186/1479-5876-12-71

85
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 Recouvreux MVCamilletti MARifkin DBDíaz-Torga G. The pituitary TGFβ1 system as a novel target for the treatment of resistant prolactinomas. J Endocrinol. 2016;228:R7383. DOI: 10.1530/JOE-15-0451

86
Copy DOIDOI Copied
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 Amin NVincan EThe Wnt signaling pathways and cell adhesion. Front Biosci (Landmark Ed). 2012;17:784804. DOI: 10.2741/3957

87
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 Gu WLi XWang JMiR-139 regulates the proliferation and invasion of hepatocellular carcinoma through the Wnt/Tcf-4 pathway. Oncol Rep. 2014;31:397404. DOI: 10.3892/or.2013.2831

88
Copy DOIDOI Copied
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 Roessmann UVelasco MESindely SDGambetti PGlial fibrillary acidic protein (GFAP) in ependymal cells during development. An immunocytochemical studyBrain Res. 1980;200:1321. DOI: 10.1016/0006-8993(80)91090-2

89
Copy DOIDOI Copied
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 Righi AMorandi LLeonardi Eet alGalectin-3 expression in pituitary adenomas as a marker of aggressive behaviorHum Pathol2013;44:24009DOI: 10.1016/j.humpath.2013.05.020

90
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 Allan KJordan RCKAng L-Cet alOverexpression of cyclin A and cyclin B1 proteins in astrocytomasArch Pathol Lab Med2000;124:21620DOI10.5858/2000-124-0216-OOCAAC

91
Copy DOIDOI Copied
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 Furihata MIshikawa TInoue Aet alDetermination of the prognostic significance of unscheduled cyclin A overexpression in patients with esophageal squamous cell carcinomaClin Cancer Res1996;2:17815.

92
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 Mashal RDLester SCorless Cet alExpression of cell cycle-regulated proteins in prostate cancer. Cancer Res. 1996;56:415963.

93
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 Kushner JBradley GYoung BJordan RCAberrant expression of cyclin A and cyclin B1 proteins in oral carcinoma. J Oral Pathol Med. 1999;28:7781. DOI: 10.1111/j.1600-0714.1999.tb02000.x

94
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 Nakajima TYamaguchi HTakahashi KS100 protein in folliculostellate cells of the rat pituitary anterior lobeBrain Res1999;191:52331DOI10.1016/0006-8993(80)91300-1

95
Copy DOIDOI Copied
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 Farnoud MRKujas MDerome Pet alInteractions between normal and tumoral tissues at the boundary of human anterior pituitary adenomas. An immunohistochemical study. Virchows Arch1994;424:7582DOI10.1007/BF00197396

96
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 Bresnick ARWeber DJZimmer DBS100 proteins in cancer. Nat Rev Cancer. 2015;15:96109. DOI: 10.1038/nrc3893

97
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 Van Acker HHCapsomidis ASmits ELVan Tendeloo VFCD56 in the immune system: More than a marker for cytotoxicity? Front Immunol2017;8:892DOI: 10.3389/fimmu.2017.00892

98
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 Kennell JAO’Leary EEGummow BMet alT-cell factor 4N (TCF-4N), a novel isoform of mouse TCF-4, synergizes with beta-catenin to coactivate C/EBPalpha and steroidogenic factor 1 transcription factors. Mol Cell Biol. 2003;23:536675. DOI: 10.1128/MCB.23.15.5366-5375.2003

99
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 Neou MVilla CArmignacco Ret alPangenomic classification of pituitary neuroendocrine tumors. Cancer Cell. 2020;37:12334. DOI: 10.1016/j.ccell.2019.11.002

100
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 Alexandraki KIPapadimitriou EMavroeidi Vet alRole of receptor profiling for personalized therapy in a patient with a growth hormone-secreting macroadenoma resistant to first-generation somatostatin analogues. J Pers Med. 2019;9:48. DOI: 10.3390/jpm9040048

101
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 Lopes MBSThe 2017 World Health Organization classification of tumors of the pituitary gland: A summary. Acta Neuropathol. 2017;134:52135. DOI: 10.1007/s00401-017-1769-8