The effect of polymorphisms in the promoter region of the MMP-1 gene on the occurrence and invasiveness of hypophyseal adenoma

Genomics and Epigenomics of Pituitary Tumors: What Do Pathologists Need to Know?

Molecular pathology has advanced our understanding of many tumors and offers opportunities to identify novel therapies. In the pituitary, the field has uncovered several genetic mutations that predispose to pituitary neuroendocrine tumor (PitNET) development, including MEN1, CDKN1B, PRKRIα, AIP, GPR101, and other more rare events; however, these genes are only rarely mutated in sporadic PitNETs. Recurrent genetic events in sporadic PitNETs include GNAS mutations in a subset of somatotroph tumors and ubiquitin-specific peptidase mutations (e.g., USP8, USP48) in some corticotroph tumors; to date, neither of these has resulted in altered management, and instead, the prognosis and management of PitNETs still rely more on cell type and subtype as well as local growth that determines surgical resectability. In contrast, craniopharyngiomas have either CTNNB1 or BRAF^V600E mutations that correlate with adamantinomatous or papillary morphology, respectively; the latter offers the opportunity for targeted therapy. DICER1 mutations are found in patients with pituitary blastoma. Epigenetic changes are implicated in the pathogenesis of the more common sporadic pituitary neoplasms including the majority of PitNETs and tumors of pituicytes.

Association of NM23 polymorphisms and clinicopathological features and recurrence of invasive pituitary adenomas

BACKGROUND

Pituitary adenomas (PAs) are intracranial tumors, deriving from anterior pituitary cells. Previously, expression of non-metastasis-23 (NM23) gene has been shown to correlate with the progression of PAs. In this study, we aim to determine whether there is association between specific NM23 polymorphisms and invasive pituitary adenoma (IPA).

METHODS

Genotypes of rs2302254 and rs16949649 of NM23 were identified in the peripheral venous blood of patients by PCR-RLFP. Next, the correlation between specific genotypes of rs2302254 and rs16949649 and risk of IPA was investigated. Finally, the correlations between NM23 polymorphisms and tumor size, Ki67 LI and recurrence of IPA were analyzed with 3 to 24 months follow-up for the enrolled patients.

RESULTS

We observed that the TT genotype at rs16949649 correlated closely with a high risk of IPA, while CC and CT genotypes reduced the risk of IPA. CC genotype at rs2302254 increased the risk of IPA, while CT and TT genotypes reduced the risk of IPA. T_rs16949649C_rs2302254 haplotype of NM23 was found to be a high-risk haplotype for IPA. TT genotype at rs16949649 and CC genotype at rs2302254 were associated with higher rates of tumors larger than 20 mm, Ki67 LI and tumor recurrence.

CONCLUSION

Taken together, the present study provides evidence that NM23 polymorphisms are closely associated with the incidence and recurrence of IPA. Specifically, TT genotype at rs16949649 and CC genotype at rs2302254 are risk factors of IPA. NM23 polymorphisms could therefore be used as a reference for clinical diagnosis and prognosis of IPA.

The Role of Single-Nucleotide Polymorphisms in Pituitary Adenomas Tumorigenesis

Pituitary adenomas (PAs) are among the most common intracranial neoplasms, but despite their histologically benign nature, these tumors sometimes grow large enough to cause symptoms of mass effect such as vision loss, headaches, or hypopituitarism. When they get this large, surgery will unfortunately not be curative and, other than prolactinomas, medical options are limited, and radiation has variable efficacy in controlling growth. Understanding the genetic perturbations, such as single nucleotide polymorphisms (SNPs), that promote the formation or growth of functional and nonfunctional PAs is important because such genetic insights could improve the diagnosis and subsequent classification of PAs as well as unlock potential therapeutic targets outside contemporary standard of care. While there have been great strides in the research of SNPs as drivers of PA formation and maintenance, a comprehensive discussion of these genetic mutations has not been undertaken. In the present article, and with the goal of providing scientists and clinicians a central review, we sought to summarize the current literature on SNPs and their relationship to PA formation. Across multiple tumor types, such as nonfunctioning PAs, prolactinomas, corticotroph adenomas, somatotroph adenomas, thyrotropic adenomas, and gonadotroph adenomas, SNPs in cell surface receptors implicated in proliferation can be appreciated. Polymorphisms found in tumor suppressors and cell cycle regulators have also been identified, such as p53 SNPs in nonfunctioning PAs or cyclin D1 in prolactinomas. While the translational relevance of SNPs in the formation of PAs is still in the early stages, the use of wide-scale genomic analysis to identify patients at risk for developing PAs could yield therapeutic benefit in the future.

A PHLDB1 variant associated with the nonfunctional pituitary adenoma

PURPOSE

Previous studies have revealed that PHLDB1 single-nucleotide polymorphisms (SNPs) are associated with glioma risk. Nonetheless, the association between PHLDB1 SNPs and the risk of pituitary adenoma has not been studied. The present study evaluated the association of PHLDB1 SNPs with the risk of pituitary adenomas.

METHODS

We genotyped 27 PHLDB1 tagging and exon SNPs in a case-control study that included 148 patients who got a diagnosis of nonfunctional pituitary adenoma (NFPA) and 375 normal controls within the Korean population. Statistical analyses of the association between PHLDB1 SNPs and the NFPA risk were conducted using logistic regression.

RESULTS

We detected an association between a PHLDB1 SNP and the risk of NFPA in the Korean population. Rs67307131 in intron 2 was significantly associated with NFPA (odds ratio [OR] = 2.15, 95% confidence interval [CI] 1.44-3.20; P = 0.0002 in the dominant model). In the referent analysis, a higher OR and stronger association (lower P value) were observed among patients with the "C/T" genotype (OR = 2.39, 95% CI 1.60-3.58; P = 0.00002). In a functional analysis with a SNP annotation tool, this SNP was predicted to be a CpG site and copy number variant; these properties are associated with susceptibility to diseases.

CONCLUSIONS

Our findings suggest that genetic variation of PHLDB1 may be associated with the risk of NFPA. This is the first report of an association between PHLDB1 variants and NFPA. Further research is needed to confirm the impact of this SNP on NFPA susceptibility.

Molecular Network Basis of Invasive Pituitary Adenoma: A Review

Cases with pituitary adenoma comprise 10-25% of intracranial neoplasm, being the third most common intracranial tumor, most of the adenomas are considered to be benign. About 35% of pituitary adenomas are invasive. This review summarized the known molecular basis of the invasiveness of pituitary adenomas. The study pointed out that hypoxia-inducible factor-1α, pituitary tumor transforming gene, vascular endothelial growth factor, fibroblast growth factor-2, and matrix metalloproteinases (MMPs, mainly MMP-2, and MMP-9) are core molecules responsible for the invasiveness of pituitary adenomas. The reason is that these molecules have the ability to directly or indirectly induce cell proliferation, epithelial-to-mesenchymal transition, angiogenesis, degradation, and remodeling of extracellular matrix. HIF-1α induced by hypoxia or apoplexy inside the adenoma might be the initiating factor of invasive transformation, followed with angiogenesis for overexpressed VEGF, EMT for overexpressed PTTG, degradation of ECM for overexpressed MMPs, creating a suitable microenvironment within the tumor. Together, they form a complex interactive network. More investigations are required to further elucidate the mechanisms underlying the invasiveness of pituitary adenomas.

A Matrix Metalloproteinase-1 Polymorphism, MMP1-1607 (1G>2G), Is Associated with Increased Cancer Risk: A Meta-Analysis Including 21,327 Patients

Although the matrix metalloproteinase-1 (MMP1) polymorphism MMP1-1607 (1G>2G) has been associated with susceptibility to various cancers, these findings are controversial. Therefore, we conducted this meta-analysis to explore the association between MMP1-1607 (1G>2G) and cancer risk. A systematic search of literature through PubMed, Embase, ISI Web of Knowledge, and Google Scholar yielded 77 articles with 21,327 cancer patients and 23,245 controls. The association between the MMP1-1607 (1G>2G) polymorphism and cancer risks was detected in an allele model (2G vs. 1G, overall risk [OR]: 1.174, 95% confidence interval [CI]: 1.107-1.244), a dominant model (2G2G/1G2G vs. 1G1G OR, OR: 1.192, 95% CI: 1.090-1.303), and a recessive model (2G2G vs. 1G2G/1G1G, OR: 1.231, 95% CI: 1.141-1.329). In subgroup analysis, these associations were detected in both Asians and Caucasians. After stratification by cancer types, associations were found in lung, colorectal, nervous system, renal, bladder, and nasopharyngeal cancers. This meta-analysis revealed that MMP1-1607 (1G>2G) polymorphism was significantly associated with elevated risk of cancers.

The role of MMP-1 and FGFR4-R388 gene polymorphisms in pituitary adenoma

Background.

The pathogenesis of pituitary adenoma (PA) is complex and poorly understood. It is thought that PA has a multifactorial aetiology; genetic factors also have an impact on PA development. Since MMP1 and FGFR4 genes play an important role in tumour growth, differentiation and progression, we decided to determine if the frequency of the genotypes of MMP-1 and FGFR4-R388 polymorphisms influence the development of PA.

Materials and methods.

The study enrolled n = 100 patients with PA and n = 200 healthy controls (reference group). The genotyping tests of MMP-1 and FGFR4-R388 were carried out using the real-time polymerase chain reaction (PCR) method.

Results.

The polymorphism in the MMP-1 gene 1G/1G genotype was more frequent in the group of invasive PA than in the control group: 28.6% vs. 16.5%, p = 0.044. The 1G/2G genotype was more frequent in females of the control group compared to PA group females: 50.3% vs. 30.8%, p = 0.011. The polymorphism in the MMP-1 gene 1G/1G genotype was more frequent in the active PA group than in the control group: 28.4% vs. 16.5%, p = 0.044. FGFR4-R388 did not play any predominant role in PA development.

Conclusion.

The MMP-1 gene 1G/1G may play a role in invasive and active PA development.

Ikaros and its interacting partner CtBP target the metalloprotease ADAMTS10 to modulate pituitary cell function

We have previously described the expression and up-regulation of the C-terminal Binding Protein (CtBP) in response to pituitary hypoxia. This co-repressor interacts with the hematopoietic factor Ikaros to target several components implicated in cellular growth and apoptotic pathways. To identify common transcriptional pituitary targets we performed promoter arrays using Ikaros and CtBP chromatin immunoprecipitated (ChIP) DNA from pituitary AtT20 cells. This approach yielded a finite list of gene targets common to both transcription factors. Of these, the metalloprotease ADAMTS10 emerged as a validated target. We show the ability of Ikaros to bind the ADAMTS10 promoter, influence its transfected activity, and induce endogenous gene expression. ADAMTS10 is expressed in primary pituitary cells and is down-regulated in Ikaros null mice. Further, knockdown of ADAMTS10 in AtT20 cells recapitulates the impact of Ikaros deficiency on POMC/ACTH hormone expression. These results uncover a novel role for the metalloprotease ADAMTS10 in the pituitary. Additionally, they position this metalloprotease as a potential functional integrator of the Ikaros-CtBP chromatin remodeling network.

MMP-14 and TGFβ-1 methylation in pituitary adenomas

Pituitary adenoma (PA) is one of the most common abnormalities in the sellar region. Despite the fact that PA is a benign monoclonal neoplasm, it can cause serious complications, including ophthalmological, neurological and endocrinological abnormalities. Currently, the causes that increase the progression of tumors are unknown. Epigenetic silencing of the matrix metalloproteinase-14 (MMP-14) and transforming growth factor beta-1 (TGFβ-1) genes may be associated with the development of PA, since these genes are important in the processes of tumor metastasis and angiogenesis. The purpose of the present study was to determine if the methylation status of the MMP-14 and TGFβ-1 promoters is associated with PA development. In the present study, 120 tissue samples of PA were used. The methylation status of the MMP-14 and TGFβ-1 promoters was investigated by methylation specific-polymerase chain reaction. Statistical analysis was conducted to investigate the associations between the methylation status, age and gender of PA patients, PA tumoral activity, recurrence and invasiveness. The MMP-14 gene was methylated in 30.00% (17/56 functioning and 19/64 non-functioning) of patients with PA, while the TGFβ-1 gene was methylated in 13.33% (9/56 functioning and 7/64 non-functioning) of patients with PA. It was also observed that promoter methylation of MMP-14 correlated with the male gender (58.8 vs. 35.7%, P=0.022), while unmethylated (non-silenced) MMP-14 correlated with the female gender (64.3 vs. 41.7%, P=0.027). Associations between the promoter methylation status of the MMP-14 and TGFβ-1 genes and PA functioning or recurrence were not identified. The present study reveals that silencing of the MMP-14 gene correlates with patients' gender. However, MMP-14 and TGFβ-1 promoter methylation cannot be considered as a prognostic marker in PAs.

Current biomarkers of invasive sporadic pituitary adenomas

Though pituitary adenomas (PA) are considered benign, some of them exhibit invasive behaviors such as recurrence and low rate of total surgical resection. Reliable prognostic biomarkers for invasive PA are highly desired; however they remain to be identified. In this review, we summarize the current controversial findings of biomarkers for invasive sporadic PA, and we discuss the possible reasons for the controversies.

Emerging Histopathological and Genetic Parameters of Pituitary Adenomas: Clinical Impact and Recommendation for Future WHO Classification

The review assesses immunohistochemical findings of somatostatin receptors and of metalloproteinases in different pituitary adenoma types and the significance of molecular genetic data. Current evidence does not support routine immunohistochemical assessment of somatostatin or dopamine receptor subtype expression on hormone-secreting or nonfunctioning pituitary adenomas. Further prospective studies are needed to define its role for clinical decision making. Until then we suggest to restrict membrane receptor profiling to individual cases or for study purposes. The problems of adenoma expansion and invasion are discussed. Despite partially contradictory publications, proteases clearly play a major role in permission of infiltrative growth of pituitary adenomas. Therefore, detection of at least MMP-2, MMP-9, TIMP-2, and uPA seems to be justified. Molecular characterization is important for familial adenomas, adenomas in MEN, Carney complex, and McCune-Albright syndrome and can gain insight into pathogenesis of sporadic adenomas.

Biomarkers of pituitary carcinomas

Pituitary carcinoma is a rare tumor originating from adenohypophyseal cells. Currently, diverse pathogenetic mechanisms, i.e. de novo versus malignant transformation from pituitary adenoma, remain obscure and require further investigation. During the last two decades, scientific research added new horizons not only in regards to general tumor concepts but also in next generation biomarker armamentarium that sheds light on alternate pathways in carcinogenesis. Areas covered: In this review, the impact of apoptotic and proliferative markers, angiogenesis, telomerase activity, H-ras, HIF-1, HER-2/neu, Rb gene, and microRNAs in pathogenetic mechanisms of pituitary carcinomas were revised. Expert commentary: It is becoming increasingly important for the need of standardization of new biomarkers but also for better comprehension of the diverse pathways in tumorigenesis. This can only be accomplished by tapping into the continuously expanding spectrum of new biomarkers.

Aggressive Pituitary Tumors or Localized Pituitary Carcinomas: Defining Pituitary Tumors

Pituitary tumors are common and exhibit a wide spectrum of hormonal, proliferative and invasive behaviors. Traditional classifications consider them malignant only when they exhibit metastasis. Patients who suffer morbidity and mortality from aggressive tumors classified as "adenomas" are denied support provided to patients with "cancers" and in many jurisdictions, these tumors are considered curiosities that do not warrant reporting in health registries. We propose use of the term "tumor" rather than "adenoma" to align with other neuroendocrine tumors. The features that can serve as diagnostic, prognostic and predictive markers are reviewed. Clinico-pathological and radiographic classifications provide important information and to date, no single biomarker has been able to offer valuable insight to guide the management of patients with pituitary tumors.

Common variants at 10p12.31, 10q21.1 and 13q12.13 are associated with sporadic pituitary adenoma

Pituitary adenoma is one of the most common intracranial neoplasms, and its genetic basis remains largely unknown. To identify genetic susceptibility loci for sporadic pituitary adenoma, we performed a three-stage genome-wide association study (GWAS) in the Han Chinese population. We first analyzed genome-wide SNP data in 771 pituitary adenoma cases and 2,788 controls and then carried forward the promising variants for replication in another 2 independent sets (2,542 cases and 3,620 controls in total). We identified three new susceptibility loci below the genome-wide significance threshold (P < 5 × 10(-8)) in the combined analyses: 10p12.31 (rs2359536, P(meta) = 2.25 × 10(-10) and rs10828088, P(meta) = 6.27 × 10(-10)), 10q21.1 (rs10763170, P(meta) = 6.88 × 10(-10)) and 13q12.13 (rs17083838, P(meta) = 1.89 × 10(-8)). This study is the first GWAS to our knowledge on sporadic pituitary adenoma, and our results provide insight into the genetic basis of this disease.

[Aggressive and resistant-to-treatment pituitary tumors]

Pituitary adenomas define slow growing tumors developing from anterior pituitary. Most often benign, their treatment and subsequent management are based on transphenoidal surgery and/or medical therapy, generally without difficulties in clinical practice. However, 2 clinicopathological situations, more or less intricated, may considerably complicate the management of these tumors and the patient health condition. Firstly, when the tumor is characterized by an usual aggressive behaviour with a possible extension within the cavernous sinus and a high risk of recurence after well- conducted treatment. Otherwise, in some cases of resistant prolactinomas and somatotropinomas, the specific medical treatment may be unsuccessful for controlling the hormonal hypersecretion and/or the tumoral growth, with subsequent complex therapeutic approach. Progress that have been made in the understanding of aggressive as well as in resistant- to- treatment pituitary tumors, both in histopathology and molecular fields, may constitue new tools for improving knowledge on the profile of these atypical tumors and optimizing their management.

The role of mediators of cell invasiveness, motility, and migration in the pathogenesis of silent corticotroph adenomas

Silent corticotroph adenomas (SCAs) represent a distinct subset of clinically non-functioning pituitary adenomas. There are two variants of SCA; type I are densely granulated basophilic tumors and type II are sparsely granulated and chromophobic tumors. SCAs are known to be aggressive than the more common non-functioning gonadotroph adenomas (NFGAs). Cell-matrix interactions play an important role in the pathogenesis of pituitary adenomas. In this study, we compared 19 SCAs and 50 NFGAs with known fibroblast growth factor receptor-4 (FGFR4) status using semi-quantitative immunohistochemistry to localize β1-integrin, osteopontin, and matrix metalloproteinase-1 (MMP-1) as cytoplasmic, membranous, or mixed cytoplasmic-membranous staining to achieve scores of 1-4. Staining for β1-integrin was significantly higher in SCAs (100 %, score 3.3) than in NFGAs (96 %; score 2.6) (p = 0.0482); there was no statistical difference within subgroups of SCA (type II score 3.4; type I score 2.8) (p = 0.2663). Osteopontin immunoreactivity was also higher in SCAs (100 %, score 3.7) than in NFGAs (42 %, score 0.8) (p = 0.0001); there was no statistical difference within subgroups of SCA (type II score 3.6; type I score 3.9) (p = 0.2787). In contrast, MMP-1 immunoreactivity was lower in SCAs (89 %; score 2.5) than in NFGAs (98 %; score 3.6) (p = 0.0005); there was no statistical difference within subgroups of SCA (type II score 2.7; type I score 2.0) (p = 0.30704). The MMP-1 results correlated with FGFR4 expression (NFGA 96 %, type II SCA 71 %, type I SCA 40 %). Our data indicate that the biological aggressivity of SCAs compared with NFGA may be due to high osteopontin expression; in contrast, high MMP-1 is characteristic of NFGAs that also express more FGFR4. Further investigations are warranted to clarify the underlying regulatory mechanisms of these markers. The high osteopontin or FGFR4/MMP-1 expression levels in SCAs and NFGAs, respectively, indicate the potential for therapeutic strategies targeting osteopontin or FGFR4/MMP-1 for inoperable tumors of these types.

The roles of beta-adrenergic receptors in tumorigenesis and the possible use of beta-adrenergic blockers for cancer treatment: possible genetic and cell-signaling mechanisms

Cancer is the leading cause of death in the USA, and the incidence of cancer increases dramatically with age. Beta-adrenergic blockers appear to have a beneficial clinical effect in cancer patients. In this paper, we review the evidence of an association between β-adrenergic blockade and cancer. Genetic studies have provided the opportunity to determine which proteins link β-adrenergic blockade to cancer pathology. In particular, this link involves the major histocompatibility complex class II molecules, the renin-angiotensin system, transcription factor nuclear factor-kappa-light-chain-enhancer of activated B cells, poly(ADP-ribose) polymerase-1, vascular endothelial growth factor, and the reduced form of nicotinamide adenine dinucleotide phosphate oxidase. Beta-adrenergic blockers also exert anticancer effects through non-genomic factors, including matrix metalloproteinase, mitogen-activated protein kinase pathways, prostaglandins, cyclooxygenase-2, oxidative stress, and nitric oxide synthase. In conclusion, β-adrenergic blockade may play a beneficial role in cancer treatment. Additional investigations that examine β-adrenergic blockers as cancer therapeutics are required to further elucidate this role.

Biomarkers of aggressive pituitary adenomas

Pituitary adenomas exhibit a wide range of behaviors. The prediction of aggressive or malignant behavior in pituitary adenomas remains challenging; however, the utility of biomarkers is rapidly evolving. In this review, we discuss potential biomarkers as they relate to aggressive behavior in pituitary adenomas. While detailed histological subtyping remains the best independent predictor of aggressive behavior in the majority of cases, evidence suggests that the additional analyses of FGFR4, MMP, PTTG, Ki-67, p53, and deletions in chromosome 11 may contribute to decisions concerning management of aggressive pituitary adenomas.