Cytoplasmic expression of fibroblast growth factor receptor-4 in human pituitary adenomas: relation to tumor type, size, proliferation, and invasiveness

Aggressive PitNETs and Potential Target Therapies: A Systematic Review of Molecular and Genetic Pathways

Recently, advances in molecular biology and bioinformatics have allowed a more thorough understanding of tumorigenesis in aggressive PitNETs (pituitary neuroendocrine tumors) through the identification of specific essential genes, crucial molecular pathways, regulators, and effects of the tumoral microenvironment. Target therapies have been developed to cure oncology patients refractory to traditional treatments, introducing the concept of precision medicine. Preliminary data on PitNETs are derived from preclinical studies conducted on cell cultures, animal models, and a few case reports or small case series. This study comprehensively reviews the principal pathways involved in aggressive PitNETs, describing the potential target therapies. A search was conducted on Pubmed, Scopus, and Web of Science for English papers published between 1 January 2004, and 15 June 2023. 254 were selected, and the topics related to aggressive PitNETs were recorded and discussed in detail: epigenetic aspects, membrane proteins and receptors, metalloprotease, molecular pathways, PPRK, and the immune microenvironment. A comprehensive comprehension of the molecular mechanisms linked to PitNETs' aggressiveness and invasiveness is crucial. Despite promising preliminary findings, additional research and clinical trials are necessary to confirm the indications and effectiveness of target therapies for PitNETs.

Analysis of risk factors of pituitary neoplasms invading the sphenoidal sinus

High-resolution computed tomography (HR-CT) can more effectively discern the relationship between pituitary neoplasms (PNs) and neighboring anatomical structures. Moreover, pathological features can facilitate a more accurate determination of the growth pattern of PNs. Consequently, integrating imaging and pathological data might enhance our predictive capability regarding the growth patterns of PNs and aid in the formulation of surgical plans. We compared HR-CT images of 54 patients and 52 volunteers. Using ITK-SNAP software, we segmented and reconstructed the anatomical features of the sphenoidal sinus (SS) and calculated its volume. A comparative analysis of the invasive attributes of the 54 PNs was carried out based on clinical features and pathological data. The average volume of the SS in the volunteer group was 11.05 (8.10) mL, significantly larger than that of the PNs group at 7.45 (4.88) mL (P = .005). The postsellar type was the most common pneumatization type, and a significantly higher proportion in the PNs group exhibited a depressed saddle base (83.3%). A notable male predominance was observed for SS invasion in the PNs group (72.7%), with the Ki-67 antigen and maximum diameter significantly higher (P < .05), showing a positive correlation. The optimal cutoff points for Ki-67 antigen and the maximum diameter of PNs were 3.25% (AUC = 0.754, Sensitivity 54.5%, Specificity 90.6%) and 24.5 mm (AUC = 0.854, Sensitivity 86.4%, Specificity 78.1%), respectively. The type of pneumatization and the morphology of the sellar-floor serve as anatomical foundations for SS invasion. Factors such as the Ki-67 antigen, the maximum diameter of PNs, and high-risk sub-types constitute risk factors for PNs invasion into the SS. These insights are of significant utility for clinicians in crafting treatment strategies for PNs.

The hallmarks of cancer… in pituitary tumors?

Over 20 years ago, Hanahan and Weinberg published a seminal review that addressed the biological processes that underly malignant transformation. This classical review, along with two revisions published in 2011 and 2022, has remain a classic of the oncology literature. Since many of the addressed biological processes may apply to non-malignant tumorigenesis, we evaluated to what extent these hallmarks pertain to the development of pituitary adenomas.Some of the biological processes analyzed in this review include genome instability generated by somatic USP8 and GNAS mutations in Cushing's diseases and acromegaly respectively; non-mutational epigenetic reprograming through changes in methylation; induction of angiogenesis through alterations of VEGF gene expression; promotion of proliferative signals mediated by EGFR; evasion of growth suppression by disrupting cyclin dependent kinase inhibitors; avoidance of immune destruction; and the promotion of inflammation mediated by alteration of gene expression of immune check points. We also elaborate further on the existence of oncogene induced senescence in pituitary tumors. We conclude that a better understanding of these processes can help us dilucidated why pituitary tumors are so resistant to malignant transformation and can potentially contribute to the development of novel anticancer treatments.

The kinome, cyclins and cyclin-dependent kinases of pituitary adenomas, a look into the gene expression profile among tumors from different lineages

Background

Pituitary adenomas (PA) are the second most common intracranial tumors and are classified according to hormone they produce, and the transcription factors they express. The majority of PA occur sporadically, and their molecular pathogenesis is incompletely understood.

Methods

Here we performed transcriptome and proteome analysis of tumors derived from POU1F1 (GH-, TSH-, and PRL-tumors, N = 16), NR5A1 (gonadotropes and null cells adenomas, n = 17) and TBX19 (ACTH-tumors, n = 6) lineages as well as from silent ACTH-tumors (n = 3) to determine expression of kinases, cyclins, CDKs and CDK inhibitors.

Results

The expression profiles of genes encoding kinases were distinctive for each of the three PA lineage: NR5A1-derived tumors showed upregulation of ETNK2 and PIK3C2G and alterations in MAPK, ErbB and RAS signaling, POU1F1-derived adenomas showed upregulation of PIP5K1B and NEK10 and alterations in phosphatidylinositol, insulin and phospholipase D signaling pathways and TBX19-derived adenomas showed upregulation of MERTK and STK17B and alterations in VEGFA-VEGFR, EGF-EGFR and Insulin signaling pathways. In contrast, the expression of the different genes encoding cyclins, CDK and CDK inhibitors among NR5A1-, POU1F1- and TBX19-adenomas showed only subtle differences. CDK9 and CDK18 were upregulated in NR5A1-adenomas, whereas CDK4 and CDK7 were upregulated in POUF1-adenomas.

Conclusions

The kinome of PA clusters these lesions into three distinct groups according to the transcription factor that drives their terminal differentiation. And these complexes could be harnessed as molecular therapy targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01206-y.

Tumor Fibroblast Growth Factor Receptor 4 Level Predicts the Efficacy of Lenvatinib in Patients With Advanced Hepatocellular Carcinoma

OBJECTIVES

Biomarkers for optimizing the outcome of treatment with lenvatinib in patients with advanced hepatocellular carcinoma remain to be established despite intensive and comprehensive genomic research. Lenvatinib is characterized by its prominent inhibitory potency for fibroblast growth factor receptor (FGFR) 4 compared with earlier tyrosine kinase inhibitors. Thus, in this study, we focused on simplified quantification of FGFR4 in tumors as a potential predictive indicator.

METHODS

According to The Cancer Genome Atlas data set curation, FGFR4 messenger RNA is broadly overexpressed in hepatocellular carcinoma in the absence of gene alteration. Gene set enrichment analysis revealed that the aggressiveness of the tumor was closely related to the FGFR4 level. To confirm the relationship between the benefits of lenvatinib and tumor addiction to the FGFR4 pathway, we analyzed protein levels in tumors and peripheral blood obtained from 57 prospectively registered patients treated with lenvatinib.

RESULTS

Positive immunohistochemistry (>10% of tumor cells) for FGFR4 in biopsy samples before treatment was associated with a longer progression-free survival (2.5 vs 5.5 months, P = 0.01) and a favorable objective response rate (31% vs 81%, P = 0.006). By contrast, the concentration of soluble FGFR4 in peripheral blood as measured by an enzyme-linked immunosorbent assay was not associated with survival outcomes, because its fluctuations reflect hepatic fibrosis. Additional RNA sequencing analysis using archival surgical specimens (n = 90) suggested that alternative RNA splicing of FGFR4 in cancer may also explain this discrepancy.

DISCUSSION

The tumor FGFR4 level was an independent predictor of response to lenvatinib.

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.

[Genetic basis of Cushing's disease in children and targeted therapeutic future perspectives]

Cushing's disease (CD) is a multisystem disorder of a cortisol excess caused by ACTH -secreting pituitary tumor (corticotropinoma). CD in children is due to somatic or germline mutations with the late onset causing multiple endocrine tumors. If not treated, hypercortisolism leads to severe decrease in quality of life and life-threating conditions. The first-line treatment for CD is pituitary surgery, which might be followed by complications and relapse with necessity of additional surgery or initiations of second-line treatment. Recent studies of molecular basis of corticotropinoma development made it possible to employ medical therapy in CD. Understanding of corticotropinoma etiology and pathogenesis is an important part of education for pediatric endocrinologists since we need to keep in mind possibility of multisystem disorder in case of CD in children and because medical therapy might gain more important role for CD treatment in future.The most actual genetic aspects of corticotroph adenomas growth and the medical treatment opportunities are present in this review.

Exploring the Role of Novel Medical Therapies for Aggressive Pituitary Tumors: A Review of the Literature-"Are We There Yet?"

Aggressive pituitary tumors account for up to 10% of pituitary tumors and are characterized by resistance to medical treatment and multiple recurrences despite standard therapies, including surgery, radiotherapy, and chemotherapy. They are associated with increased morbidity and mortality, particularly pituitary carcinomas, which have mortality rates of up to 66% at 1 year after diagnosis. Novel targeted therapies under investigation include mammalian target of rapamycin (mTOR), tyrosine kinase, and vascular endothelial growth factor (VEGF) inhibitors. More recently, immune checkpoint inhibitors have been proposed as a potential treatment option for pituitary tumors. An increased understanding of the molecular pathogenesis of aggressive pituitary tumors is required to identify potential biomarkers and therapeutic targets. This review discusses novel approaches to the management of aggressive pituitary tumors and the role of molecular profiling.

Epidemiology and biomarker profile of pituitary adenohypophysial tumors

Recent studies have reported the prevalence of pituitary tumors to be ~1/1000 population. Many are prolactin-producing tumors that are managed medically, however, the epidemiology of surgically resected pituitary adenohypophysial neuroendocrine tumors has not been reported in a large series with detailed characterization. We reviewed 1055 adenohypophysial tumors from 1169 transsphenoidal resections from the pathology files of University Health Network, Toronto, 2001-2016. Tumors were characterized by immunohistochemical localization of transcription factors (Pit-1, ERα, SF-1, Tpit), hormones (adrenocorticotropin, growth hormone, prolactin, β-thyrotropin, β-folliculotropin, β-luteotropin, α-subunit), and other biomarkers (keratins, Ki67, p27, FGFR4). Electron microscopy was used only for unusual lesions. In this cohort, 51.3% of patients were female; the average age was 51 years. Gonadotroph tumors represented 42.5%. Pit-1-lineage-tumors represented 29.9%; these were subclassified as growth-hormone-predominant (somatotroph/mammosomatotroph/mixed; 53%), prolactin-predominant (lactotroph/acidophil-stem-cell; 28%), thyrotrophs (2%), plurihormonal (14%), and not-otherwise-specified (3%). Corticotroph tumors represented 17.1%. Only 4.5% were null cell tumors and 0.5% were unusual plurihormonal tumors. In 5.5% the tumor was not characterized for technical reasons (sample size, fixation, necrosis or other artifact). All corticotroph and plurihormonal tumors were positive for keratins; others tumors showed variable negativity with highest rates in gonadotroph (37.1%) and null cell tumors (28.2%). Tumors with a Ki67 ≥ 3% comprised 60% of this cohort. Global loss of p27 was most frequent in corticotroph neoplasms, specifically those associated with elevated glucocorticoid levels. Corticotroph and lactotroph tumors were more common among females; gonadotroph tumors were more common among males. Younger patients had mainly corticotroph and Pit-1-lineage neoplasms, whereas older patients harbored mainly gonadotroph tumors. This represents one of the largest surgical series of morphologically characterized pituitary tumors reported to date and the first to include the routine use of transcription factors for tumor classification. The data provide the basis for clinicopathologic correlations that are helpful for prognostic and predictive patient management.

Immunohistochemical Biomarkers in Pituitary Pathology

Pituitary pathology is one area of endocrine pathology that is highly dependent on immunohistochemistry. There is a wide range of disorders that occur in and around the sella turcica, and the distinction of tumor-like lesions from neoplasms requires careful evaluation. The diagnosis, prognosis, and predictive features of neoplasms in the sellar region are all dependent on the application and interpretation of biomarkers of cell differentiation, hormonal activity, subcellular morphology, and proliferation. As in hematopathology, the number of biomarkers has increased dramatically and continues to increase. Fortunately, some of the biomarkers provide information that was initially dependent on electron microscopy; therefore, the need for this additional technology has been reduced to only rare unusual tumors. In this review, we provide a simple approach to understanding the importance of the various biomarkers that are used to ensure the correct diagnosis and provide the treating clinicians with tools to guide appropriate patient management and surveillance.

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.

Trophic and neurotrophic factors in human pituitary adenomas (Review)

The pituitary gland is an organ that functionally connects the hypothalamus with the peripheral organs. The pituitary gland is an important regulator of body homeostasis during development, stress, and other processes. Pituitary adenomas are a group of tumors arising from the pituitary gland: they may be subdivided in functional or non-functional, depending on their hormonal activity. Some trophic and neurotrophic factors seem to play a key role in the development and maintenance of the pituitary function and in the regulation of hypothalamo-pituitary-adrenocortical axis activity. Several lines of evidence suggest that trophic and neurotrophic factors may be involved in pituitary function, thus suggesting a possible role of the trophic and neurotrophic factors in the normal development of pituitary gland and in the progression of pituitary adenomas. Additional studies might be necessary to better explain the biological role of these molecules in the development and progression of this type of tumor. In this review, in light of the available literature, data on the following neurotrophic factors are discussed: ciliary neurotrophic factor (CNTF), transforming growth factors β (TGF‑β), glial cell line-derived neurotrophic factor (GDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), vascular endothelial growth inhibitor (VEGI), fibroblast growth factors (FGFs) and epidermal growth factor (EGF) which influence the proliferation and growth of pituitary adenomas.

Electrochemical sensor for rapid determination of fibroblast growth factor receptor 4 in raw cancer cell lysates

The first electrochemical immunosensor for the determination of fibroblast growth factor receptor 4 (FGFR4) biomarker is reported in this work. The biosensor involves a sandwich configuration with covalent immobilization of a specific capture antibody onto activated carboxylic-modified magnetic microcarriers (HOOC-MBs) and amperometric detection at disposable carbon screen-printed electrodes (SPCEs). The biosensor exhibits a great analytical performance regarding selectivity for the target protein and a low LOD of 48.2 pg mL^-1. The electrochemical platform was successfully applied for the determination of FGFR4 in different cancer cell lysates without any apparent matrix effect after a simple sample dilution and using only 2.5 μg of the raw lysate. Comparison of the results with those provided by a commercial ELISA kit shows competitive advantages by using the developed immunosensor in terms of simplicity, analysis time, and portability and cost-affordability of the required instrumentation for the accurate determination of FGFR4 in cell lysates.

Transcriptome Analysis Showed a Differential Signature between Invasive and Non-invasive Corticotrophinomas

ACTH-dependent hypercortisolism caused by a pituitary adenoma [Cushing's disease (CD)] is the most common cause of endogenous Cushing's syndrome. CD is often associated with several morbidities, including hypertension, diabetes, osteoporosis/bone fractures, secondary infections, and increased cardiovascular mortality. While the majority (≈80%) of the corticotrophinomas visible on pituitary magnetic resonance imaging are microadenomas (MICs, <10 mm of diameter), some tumors are macroadenomas (MACs, ≥10 mm) with increased growth potential and invasiveness, exceptionally exhibiting malignant demeanor. In addition, larger and invasive MACs are associated with a significant increased risk of local complications, such as hypopituitarism and visual defects. Given the clinical and molecular heterogeneity of corticotrophinomas, the aim of this study was to investigate the pattern of genetic differential expression between MIC and MAC, including the invasiveness grade as a criterion for categorizing these tumors. In this study, were included tumor samples from patients with clinical, laboratorial, radiological, and histopathological diagnosis of hypercortisolism due to an ACTH-producing pituitary adenoma. Differential gene expression was studied using an Affymetrix microarray platform in 12 corticotrophinomas, classified as non-invasive MIC (n = 4) and MAC (n = 5), and invasive MAC (n = 3), according to modified Hardy criteria. Somatic mutations in USP8 were also investigated, but none of the patients exhibited USP8 variants. Differential expression analysis demonstrated that non-invasive MIC and MAC have a similar genetic signature, while invasive MACs exhibited a differential expression profile. Among the genes differentially expressed, we highlighted CCND2, ZNF676, DAPK1, and TIMP2, and their differential expression was validated through quantitative real-time PCR in another cohort of 15 non-invasive and 3 invasive cortocotrophinomas. We also identified potential biological pathways associated with growth and invasiveness, TGF-β and G protein signaling pathways, DNA damage response pathway, and pathways associated with focal adhesion. Our study revealed a differential pattern of genetic signature in a subgroup of MAC, supporting a genetic influence on corticotrophinomas in patients with CD.

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.

Gonadotrope Tumors

Gonadotrope tumors arise from the gonadotropes of the adenohypophysis. These cells rarely give rise to hyperplasia, usually only in the setting of long-standing premature gonadal failure. In contrast, gonadotrope tumors represent one of the most frequent types of pituitary tumors. Despite their relatively common occurrence, the pathogenesis of gonadotrope tumors remains unknown. Effective nonsurgical therapies remain out of reach. We review the pituitary gonadotrope from the morphologic and functional perspectives to better understand its involvement as the cell of origin of a frequent type of pituitary tumor.

Expression of fibroblast growth factor receptor family members is associated with prognosis in early stage cervical cancer patients

Background

The oncogenic role of the fibroblast growth factor receptor (FGFR) has been recognized in a number of different cancer types. However, the prognostic significance of FGFRs has not been elucidated yet in cervical cancer. In the present study, we investigate the expression of FGFRs and their prognostic value in cervical cancer patients.

Methods

FGFR1, FGFR2, FGFR3, and FGFR4 expression was determined by immunohistochemistry in conjunction with quantitative digital image analysis of 336 formalin-fixed, paraffin-embedded cervical cancer tissues and 61 normal cervical tissues, as well as NCI60 cell microarray. Subsequently, the association between clinicopathological characteristics and patient survival was assessed.

Results

FGFRs proteins were differentially expressed in the NCI60 cell line panel and showed considerable correlation between protein and mRNA expression. The expression of FGFR1, FGFR2, and FGFR4 were higher in cancer tissues than in normal tissues, whereas the expression of FGFR3 was higher in normal tissues. FGFR1 was highly expressed in adeno-/adenosquamous carcinoma (P = 0.020), while FGFR2, FGFR3, and FGFR4 expression were more prominent in squamous cell carcinoma (P < 0.001, P < 0.001, and P = 0.020, respectively). FGFR2 expression was significantly higher in small sized tumors (P = 0.020). Additionally, high FGFR2 and FGFR4 were correlated with negative lymph node metastasis (P = 0.048 and P = 0.040, respectively). FGFR1, FGFR2, and FGFR3 were highly expressed in tumors without parametrial involvement (P = 0.030, P = 0.005, and P = 0.010, respectively). In survival analysis, high expressions of FGFR2, FGFR3, and FGFR4 was associated with longer disease-free survival (P = 0.006, P = 0.035, P = 0.001, respectively) and overall survival (P = 0.003, P = 0.002, P = 0.003, respectively). Notably, the co-expression of all three FGFRs was significantly associated with favorable disease-free survival (P < 0.001) and overall survival (P < 0.001), compared to the negative expressions of the three FGFRs. The prognostic significance persisted in the cox regression analysis.

Conclusions

The frequent expression of members of the FGFR family in cervical cancer suggests they may have prognostic and therapeutic relevance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0874-0) contains supplementary material, which is available to authorized users.

Monomorphous Plurihormonal Pituitary Adenoma of Pit-1 Lineage in a Giant Adolescent with Central Hyperthyroidism

Thyrotropin (TSH)-secreting pituitary adenomas are exceedingly rare at the pediatric age and no cases of co-secretion with other pituitary hormones in these tumors have been described in this age range. We present a case of a monomorphous plurihormonal pituitary adenoma that co-secreted TSH and GH in a pediatric patient. A 13-year-old male presented with increasing height velocity (17.75 cm/year, 9.55SD), weight loss, and visual impairment. Initial biochemical evaluations revealed secondary hyperthyroidism. A giant pituitary tumor compressing the surrounding structures was detected by magnetic resonance, and a transsphenoidal surgery was initially performed. Pathological examinations revealed an atypical, monomorphous plurihormonal Pit-1 lineage tumor with mixed features of silent subtype 3 adenoma and acidophil stem cell adenoma. In the postoperative period, secondary hyperthyroidism recurred with high levels of both GH and IGF1. In addition, due to tumor re-growth, a multimodality treatment plan was undertaken including surgery, somatostatin analogs, and radiotherapy. We report the first pediatric case of a plurihormonal TSH- and GH-secreting pituitary adenoma, further expanding the clinical manifestations of pediatric pituitary tumors. Comprehensive pathological evaluation and close follow-up surveillance are crucial to the prompt delivery of the best therapeutic options in the context of this particularly aggressive pituitary tumor.

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.

Gene and protein expression in pituitary corticotroph adenomas: a systematic review of the literature

OBJECT Functional corticotroph pituitary adenomas (PAs) secrete adrenocorticotropic hormone (ACTH) and are the cause of Cushing's disease, which accounts for 70% of all cases of Cushing's syndrome. Current classification systems for PAs rely primarily on laboratory hormone findings, tumor size and morphology, invasiveness, and immunohistochemical findings. Likewise, drug development for functional ACTH-secreting PAs (ACTH-PAs) is limited and has focused largely on blocking the production or downstream effects of excess cortisol. The authors aimed to summarize the findings from previous studies that explored gene and protein expression of ACTH-PAs to prioritize potential genetic and protein targets for improved molecular diagnosis and treatment of Cushing's disease. METHODS A systematic literature review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A PubMed search of select medical subject heading (MeSH) terms was performed to identify all studies that reported gene- and protein-expression findings in ACTH-PAs from January 1, 1990, to August 24, 2014, the day the search was performed. The inclusion criteria were studies on functional ACTH-PAs compared with normal pituitary glands, on human PA tissue only, with any method of analysis, and published in the English language. Studies using anything other than resected PA tissue, those that compared other adenoma types, those without baseline expression data, or those in which any pretreatment was delivered before analysis were excluded. RESULTS The primary search returned 1371 abstracts, of which 307 were found to be relevant. Of those, 178 were selected for secondary full-text analysis. Of these, 64 articles met the inclusion criteria and an additional 4 studies were identified from outside the search for a total of 68 included studies. Compared with the normal pituitary gland, significant gene overexpression in 43 genes and 22 proteins was reported, and gene underexpression in 58 genes and 15 proteins was reported. Immunohistochemistry was used in 39 of the studies, and reverse transcriptase polymerase chain reaction was used in 26 of the studies, primarily, and as validation for 4 others. Thirteen studies used both immunohistochemistry and reverse transcriptase polymerase chain reaction. Other methods used included microarray, in situ hybridization, Northern blot analysis, and Western blot analysis. Expression of prioritized genes emphasized in multiple studies were often validated on both the gene and protein levels. Genes/proteins found to be overexpressed in ACTH-PAs relative to the normal pituitary gland included hPTTG1/securin, NEUROD1/NeuroD1 (Beta2), HSD11B2/11β-hydroxysteroid dehydrogenase 2, AKT/Akt, protein kinase B, and CCND1/cyclin D1. Candidate genes/proteins found to be underexpressed in ACTH-PAs relative to the normal pituitary gland included CDKN1B/p27(Kip1), CDKN2A/p16, KISS1/kisspeptin, ACTHR/ACTH-R, and miR-493. CONCLUSIONS On the basis of the authors' systematic review, many significant gene and protein targets that may contribute to tumorigenesis, invasion, and hormone production/secretion of ACTH have been identified and validated in ACTH-PAs. Many of these potential targets have not been fully analyzed for their therapeutic and diagnostic potential but may represent candidate molecular targets for biomarker development and drug targeting. This review may help catalyze additional research efforts using modern profiling and sequencing techniques and alteration of gene expression.

Aggressive pituitary tumors

Pituitary adenomas are common intracranial tumors that are mainly considered as benign. Rarely, these tumors can exhibit an aggressive behavior, characterized by gross invasion of the surrounding tissues, resistance to conventional treatment leading to early and frequent recurrences. Even more rarely, pituitary tumors can give rise to cerebrospinal or systemic metastases qualifying as pituitary carcinomas according to the latest WHO definition. In the same classification, a subset of tumors with relatively distinct histopathological features was identified and defined as atypical adenomas designated to follow a more aggressive clinical course. This classification, although clinically useful, does not provide an accurate correlation between histopathological findings and the clinical behavior of these tumors, neither is it adequate to convey the precise features of 'aggressive' tumors. Thus, 'aggressive' pituitary adenomas need to be properly defined with clinical, radiological, histological and molecular markers in order to identify patients at increased risk of early recurrence or subsequent tumor progression. At present, no single marker or classification system of pituitary tumor aggressiveness exists, and clinically useful information in the literature is insufficient to guide diagnostic and therapeutic decisions. Treatment of patients with aggressive pituitary tumors is challenging since conventional treatments often fail, necessitating multiple surgical procedures with additional radiotherapy. Although traditional chemotherapy applied in other neuroendocrine tumors has not been shown to be efficacious, newer agents, particularly temozolomide, have shown promising results and are currently used despite the lack of data from a randomized prospective trial. Molecular targeted therapies such as mTOR and epidermal growth factor inhibitors have also been applied and might prove to be useful in the management of these patients. In the present review, we provide information regarding the epidemiology and clinical, histopathological and molecular features of aggressive pituitary tumors using recent employed definitions. In addition, we review currently employed therapeutic means providing a therapeutic algorithm and highlight the need to identify more specific disease-related and prognostic markers and the necessity for central registration of these tumors.

Growth patterns of pituitary adenomas and histopathological correlates

CONTEXT

The factors associated with pituitary adenoma (PA) growth rate remain unclear.

OBJECTIVE

The objective of the study was to establish whether the preoperative growth and extension pattern of PA can predict postoperative growth rate and recurrence in addition to whether the PA growth rate correlates with proliferation and growth factor expression.

PATIENTS

One hundred fifty-three consecutive patients who underwent surgery for pituitary adenoma from 1999 to 2011 at Toronto Western Hospital were identified.

MAIN OUTCOME MEASURES

The PA growth rate was measured both pre- and postoperatively, and its association with patient demographics, magnetic resonance imaging, and histolopathological parameters was determined.

RESULTS

The preoperative growth rate was associated with age (P = .0001), suprasellar growth (P = .003), the presence of a cyst/hemorrhage (P = .004), the mindbomb homolog-1 (P = .005), fibroblast growth factor receptor-4 positivity (P = .047), and p27 negativity (P = .007). After surgery, there were 34.6% residual volumes, which were associated with older age (P = .038) and also with growth patterns including anterior, posterior, suprasellar, and cavernous sinus extension (P = .001); 43.3% of these residuals grew and postoperative growth rate was calculated. Pre- and postoperative growth rates were correlated (r = 0.497, P = .026). Postoperative growth rate was associated with age (P = .015) and gender (P = .017).

CONCLUSIONS

Our data suggest that the growth rate of PAs are influenced by various patient- and tumor-specific characteristics including the age and sex of the patient, the specific subtype of PA, its hormonal activity, its immunohistochemical profile including the mindbomb homolog 1 labeling index status, and its preponderance for different growth directions relative to the pituitary fossa. Furthermore, the pre- and postoperative PA growth rates were correlated, suggesting that postoperative PA growth rates can be predicted, in part, by preoperative growth rates, thus better informing postoperative outcome.

FGFR4 polymorphic variants modulate phenotypic features of Cushing disease

Cushing disease is a potentially lethal condition resulting from hormone excess, usually due to a small pituitary tumor that fails to respond to negative feedback inhibition. A minority of patients develop larger, more aggressive tumors of the same lineage but with modest hormone excess. Here we show that a common polymorphism in the fibroblast growth factor receptor 4 (FGFR4) transmembrane domain yields receptor isoforms with distinct properties that mediate these biological differences. Forced expression of the major FGFR4-G388 variant allele supports pY-signal transducer and activator of transcription (STAT3) responses. In contrast, expression of the minor FGFR4-R388 allele enhances STAT3 serine phosphorylation, driving cellular growth. In addition, FGFR4-R388 enhances glucocorticoid receptor phosphorylation and nuclear translocation. Consistent with these findings, glucocorticoid administration resulted in enhanced hormone negative feedback in mice with knock-in of the FGFR4 variant allele. Moreover, clinical data from patients with pituitary tumors revealed that those homozygous for the R388 allele have a higher frequency of silent corticotroph macroadenomas than FGFR4-G388 carriers, who were more likely to have small but hormonally active microadenomas. These findings demonstrate that the FGFR4 transmembrane polymorphic variants can modulate cellular growth and sensitivity to glucocorticoid hormone negative feedback through distinct STAT3 modifications of relevance to the human forms of Cushing disease.

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.

Angiogenic markers: molecular targets for personalized medicine in pituitary adenoma

AIM

Pituitary adenomas are typically slow-growing and histologically benign tumors that can occasionally behave in a malignant-like manner, invading adjacent structures or recurring after treatment. Using protein analysis methods and multiplex xMAP assays, we aimed to find out if these particular types of tumors express angiogenic markers VEGF and basic FGF (bFGF), which are associated with tumor growth and invasiveness, and quantify them in order to establish their usefulness as biomarkers.

MATERIALS & METHODS

We have analysed the expression of angiogenic markers VEGF and bFGF in serum and tissue specimens from 66 pituitary adenomas (43 invasive and 23 noninvasive). For serum analysis, we used xMAP and ELISA, and for tissue analysis, we performed histopathology and immunohistochemistry.

RESULTS & CONCLUSION

We measured the serum angiogenic factors in pituitary adenomas. The quantification methods revealed significant differences between pituitary adenoma patients and controls, for both VEGF (212.4 vs 112.5 pg/ml in controls) and bFGF (mean value of 12.6 vs 10.8 pg/ml in controls), and also differentiated between invasive and noninvasive adenomas (p < 0.05). The tissue expression of VEGF and bFGF strongly correlated with their serum level increase. Our findings can be further developed into methods for selection of patients suitable for personalized, antiangiogenic therapy.

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.

The molecular pathogenesis of corticotroph tumours

BACKGROUND

The pathogenesis of tumour formation in the anterior pituitary including adrenocorticotropic hormone (ACTH)-secreting tumours has been intensively studied, but the causative mechanisms involved in pituitary cell transformation and tumourigenesis remain unclear.

MATERIALS AND METHODS

We searched PubMed on any paper related with molecular pathology of pituitary corticotroph adenomas and have included to this review all relevant references published up to June 2011.

RESULTS

Current studies increased our knowledge on the genetic basis of McCune-Albright syndrome (MAS), multiple endocrine neoplasia type 1 (MEN1), Carney complex (CNC), pituitary adenoma predisposition syndromes and tuberous sclerosis, but they have performed little to elucidate the causes of sporadic pituitary tumours including Cushing disease.

DISCUSSION

The aim of this review was to focus on the most recently published advances in the molecular pathology of corticotroph adenomas, which are presented in the context of changes seen in all types of pituitary adenomas, as well as in terms of corticotrophin-releasing hormone/ACTH/cortisol-specific pathways.

CONCLUSIONS

We would expect that over the next 5 years, more detailed analysis of inter-cellular communication pathways between pituitary cells, including the cadherins and integrins, and their interactions with other signalling pathways such as the β-catenin cascade will help elucidate what exactly goes awry in the formation of a benign corticotroph adenoma. This should in turn predict novel forms of pharmacological tumour control.

Fibroblast growth factor 19 expression correlates with tumor progression and poorer prognosis of hepatocellular carcinoma

Background

Although fibroblast growth factor 19 (FGF19) can promote liver carcinogenesis in mice, its involvement in human hepatocellular carcinoma (HCC) has not been well investigated. FGF19, a member of the FGF family, has unique specificity for its receptor FGFR4. This study aimed to clarify the involvement of FGF19 in the development of HCC.

Methods

We investigated human FGF19 and FGFR4 expression in 40 hepatocellular carcinoma specimens using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) analysis and immunohistochemistry. Moreover, we examined the expression and the distribution of FGF19 and FGFR4 in 5 hepatocellular carcinoma cell lines (HepG2, HuH7, HLE, HLF, and JHH7) using RT-PCR and immunohistochemistry. To test the role of the FGF19/FGFR4 system in tumor progression, we used recombinant FGF19 protein and small interfering RNA (siRNA) of FGF19 and FGFR4 to regulate their concentrations.

Results

We found that FGF19 was significantly overexpressed in HCCs as compared with corresponding noncancerous liver tissue (P < 0.05). Univariate and multivariate analyses revealed that the tumor FGF19 mRNA expression was an independent prognostic factor for overall and disease-free survival. Moreover, we found that the FGF19 recombinant protein could increase the proliferation (P < 0.01, n = 12) and invasion (P < 0.01, n = 6) capabilities of human hepatocellular carcinoma cell lines and inhibited their apoptosis (P < 0.01, n = 12). Inversely, decreasing FGF19 and FGFR4 expression by siRNA significantly inhibited proliferation and increased apoptosis in JHH7 cells (P < 0.01, n = 12). The postoperative serum FGF19 levels in HCC patients was significantly lower than the preoperative levels (P < 0.01, n = 29).

Conclusions

FGF19 is critically involved in the development of HCCs. Targeting FGF19 inhibition is an attractive potential therapeutic strategy for HCC.

PAX3-FOXO1 and FGFR4 in alveolar rhabdomyosarcoma

We and others have identified FGFR4 as a direct transcriptional target of the alveolar rhabdomyosarcoma (ARMS) specific fusion protein, PAX3-FOXO1. We hypothesized fibroblast growth factor receptor 4 (FGFR4) may act as an effector of PAX3-FOXO1, contributing to PAX3-FOXO1 tumorigenic phenotypes. However, we demonstrate that enhanced expression of FGFR4 does not contribute to inhibited differentiation, enhanced proliferation, or transformation downstream of PAX3-FOXO1 in primary mouse myoblasts. Therefore we were unable to identify any contribution of up regulation of wild type FGFR4 to PAX3-FOXO1 driven tumorigenesis. Conversely, a constitutively active mutant of FGFR4 can enhance primary myoblast proliferation and transformation, indicating activating mutations of FGFR4 could contribute to the development and progression of ARMS. We sequenced the FGFR4 mRNA from five ARMS cell lines and identified no somatic mutations, nor any association with any human single nucleotide polymorphism within the FGFR4 coding region.

Clival invasion on multi-detector CT in 390 pituitary macroadenomas: correlation with sex, subtype and rates of operative complication and recurrence

BACKGROUND AND PURPOSE

Clival invasion, a rare but potentially significant complication of pituitary adenoma, is difficult to detect on MR imaging. Because CT is widely used in adjunct guidance of pituitary surgery and it has recently been suggested that preoperative CT may add useful diagnostic information in addition to pituitary MR imaging, we performed the first large cross-sectional imaging study to define the image attributes, clinical correlates, and prognostic implications of clival invasion on CT for pituitary adenoma surgical guidance.

MATERIALS AND METHODS

Preoperative CT images from 390 patients with histopathologically diagnosed pituitary macroadenoma were reviewed retrospectively and classified by the presence and degree of clival invasion. Tumor volume, tumor subtype, patient sex, operative complication, and recurrence rates were compared between groups.

RESULTS

After we corrected for multiple correlations, the most significant independent risk factor for clival invasion was female sex (OR=3.62, P=.014, multinomial logistic regression), followed by large tumor volume (OR=1.08, P<.001), and null-cell subtype (OR=5.47, P<.001). Larger tumor volume correlated with null-cell subtype (Mann-Whitney U test, P=.006), incidence of clival invasion (P<.001), and extent of clival invasion (P=.038). Clival invasion was associated with a significantly higher ratio of operative complications (15.63%, χ(2)=7.067, P=.008) and recurrence (57.14%, χ(2)=10.739, P=.001).

CONCLUSIONS

CT detection of clival invasion by pituitary macroadenoma is significantly more common in women, in patients with large tumors, and in patients with null-cell tumors, and it is associated with a higher rate of operative complications and recurrences. Attention to the presence of clival invasion on preoperative CT and prospective investigation of its prognostic significance are indicated. Attention to this finding on pituitary guidance CT is warranted.

Biomarkers of pituitary neoplasms: a review (Part II)

Several new markers have shown a capacity to predict the clinicopathological behavior of pituitary neoplasms; these markers have shown potential to correlate with tumor subtype and size and patient age and sex. These various markers are involved in a host of cellular functions, including cell-cycle progression, cell proliferation, apoptosis, cell adhesion, and tumor vascularity. In this companion article to our first review of Ki-67 as a marker of pituitary adenomas, we present and analyze the literature regarding matrix metalloproteinases and their inhibitors (tissue inhibitor metalloproteinases), vascular endothelial growth factor, fibroblast growth factor and its receptor, apoptotic markers and p53, as well as cyclooxygenase-2, galectin-3, and pituitary tumor transforming gene. Some of these markers, such as fibroblast growth factor and fibroblast growth factor receptor and matrix metalloproteinases, show particular promise in their ability to identify pituitary tumors that behave in an aggressive manner. We suggest the need for uniform design and application of methods and standardized criteria for the interpretation of results. A uniform approach will establish clinicopathological utility of emerging markers.

Increased expression of HMGA1 correlates with tumour invasiveness and proliferation in human pituitary adenomas

AIMS

High-mobility group A1 (HMGA1) is highly expressed in various benign and malignant tumours. The development of pituitary adenoma in Hmga1 transgenic mice has been reported. However, no studies have investigated HMGA1 expression and its clinical significance in human pituitary adenomas.

METHODS AND RESULTS

Immunohistochemical expression of HMGA1 was analysed with respect to various clinicopathological factors in 95 pituitary adenomas. Nuclear expression of HMGA1 was observed in 62% of pituitary adenomas, whereas normal adenohypophysial tissues were negative. Although HMGA1 expression was frequently detected in clinically non-functioning adenomas - 90% of silent adrenocorticotropic hormone (ACTH), 76.2% of follicle-stimulating hormone/luteinizing hormone and 100% of null cell adenomas - it was also detected in 48.1% of growth hormone (GH), 60% of mixed GH/prolactin (PRL), 62.5% of PRL, 66.6% of thyroid-stimulating hormone and 37.5% of ACTH adenomas. HMGA1 expression was significantly higher in invasive adenomas or macroadenomas than in non-invasive adenomas or microadenomas (invasive versus non-invasive, P < 0.05; macroadenoma versus microadenoma, P < 0.05). In addition, HMGA1 showed the highest level in grade IV, more aggressive pituitary adenomas, than in grades I, II and III (IV versus I, P = 0.01; IV versus II, P = 0.01; IV versus III, P = 0.07). Furthermore, a significant correlation between HMGA1 expression and MIB-1 labelling index was observed (R = 0.368, P < 0.0002).

CONCLUSIONS

These findings suggest that HMGA1 up-regulation has an important oncogenic role in pituitary tumorigenesis, as well as being a novel molecular marker of tumour proliferation and invasiveness.

The pathophysiology of pituitary adenomas

The pathogenesis of tumour formation in the anterior pituitary has been intensively studied, but the causative mechanisms involved in pituitary cell transformation and tumourigenesis remain elusive. Most pituitary tumours are sporadic, but some arise as a component of genetic syndromes such as the McCune-Albright syndrome, multiple endocrine neoplasia type 1, Carney complex and, the most recently described, a MEN1-like phenotype (MEN4) and pituitary adenoma predisposition syndromes. Some specific genes have been identified that predispose to pituitary neoplasia (GNAS, MEN1, PRKAR1A, CDKN1B and AIP), but these are rarely involved in the pathogenesis of sporadic tumours. Mutations of tumour suppressor genes or oncogenes, as seen in more common cancers, do not seem to play an important role in the great majority of pituitary adenomas. The pituitary tumour transforming gene (PTTG; securin) was the first transforming gene found to be highly expressed in pituitary tumour cells, and seems to play an important role in the process of oncogenesis. Many tumour suppressor genes, especially those involved in the regulation of the cell cycle, are under-expressed, most often by epigenetic modulation - usually promoter hypermethylation - but the regulator of these co-ordinated series of methylations is also unclear. Cell signalling abnormalities have been identified in pituitary tumours, but their genetic basis is unknown. Both Raf/MEK/ERK and PI3K/Akt/mTOR pathways are over-expressed and/or over-activated in pituitary tumours: these pathways share a common root, including initial activation related to the tyrosine kinase receptor, and we speculate that a change to these receptors or their relationship to membrane matrix-related proteins may be an early event in pituitary tumourigenesis.

Overexpression of HMGA2 relates to reduction of the let-7 and its relationship to clinicopathological features in pituitary adenomas

High-mobility group A2 is highly expressed during embryogenesis and in various benign and malignant tumors. Recent studies report that high-mobility group A2 is negatively regulated by the let-7 microRNAs (miRNAs) family in vitro. The development of pituitary adenomas in high-mobility group A2 transgenic mice showed that high-mobility group A2 may be involved in pituitary tumorigenesis. However, no studies have investigated the clinical significance of high-mobility group A2 and its relationship to the let-7 miRNA family in human pituitary adenomas. Using immunohistochemistry, we analyzed high-mobility group A2 expression with respect to various clinicopathologic factors in 98 pituitary adenomas. Overexpression of high-mobility group A2 was observed in 39% (38/98) of pituitary adenomas compared with normal adenohypophysial tissue and was frequently found in adenomas including prolactin (PRL), adrenocorticotrophic hormone, or follicle-stimulating hormone/luteinizing hormone and in null cell adenomas, but relatively rare in growth hormone (GH) and mixed GH/PRL adenomas. High-mobility group A2 expression was significantly associated with tumor invasion (P<0.05) and was significantly higher in grade IV than in grades I, II, and III adenomas (P<0.05). High levels of high-mobility group A2 expression were more frequently observed in macroadenomas than in microadenomas (P<0.05). High levels of high-mobility group A2 expression also significantly correlated with the proliferation marker Ki-67 (P<0.0001). Real-time quantitative RT-PCR analysis was carried out to evaluate the expression of let-7 in 55 pituitary adenomas. Subsequently, decreased expression of let-7 was confirmed in 23 of 55 (42%) adenomas and was correlated with high-grade tumors (P<0.05). An inverse correlation between let-7 and high-mobility group A2 expression was evident (R=-0.33, P<0.05). These findings support a causal link between let-7 and high-mobility group A2 whereby loss of let-7 expression induces high-mobility group A2 upregulation that represents an important mechanism in pituitary tumorigenesis and progression.

Expression of p18(INK4C) is down-regulated in human pituitary adenomas

Cyclin-dependent kinase inhibitors represented by the INK4 family comprising p16(INK4A), p15(INK4B), p18(INK4C), and p19(INK4D) are regulators of the cell cycle shown to be aberrant in many types of cancer. Mice lacking p18(Ink4c) exhibit a series of phenotypes including the development of widespread organomegaly and pituitary adenomas. The objective of our study is to examine the role of p18(INK4C) in the pathogenesis of human pituitary tumors. The protein and mRNA levels of p18(INK4C) were examined by immunohistochemistry and real-time reverse transcription-polymerase chain reaction, respectively. The methylation status of the p18(INK4C) gene promoter and somatic mutations of the p18(INK4C) gene were also investigated. p18(INK4C) protein expression was lost or significantly reduced in 64% of pituitary adenomas compared with levels in normal pituitary glands. p18(INK4C) mRNA levels were low in all ACTH adenomas and non-functioning (NF)-FSH and in 42%, 70% and 66% of GH, PRL, and subtype 3 adenomas, respectively. p18(INK4C) mRNA levels were significantly associated with p18(INK4C) protein levels. Neither methylated promoters in pituitary adenomas, except in one NF-FSH adenoma, nor somatic mutations of the p18(INK4C) gene in any pituitary adenomas were detected. The down-regulation of p18(INK4C) expression may contribute to the tumorigenesis of pituitary adenomas.

Discovery of dominant and dormant genes from expression data using a novel generalization of SNR for multi-class problems

Background

The Signal-to-Noise-Ratio (SNR) is often used for identification of biomarkers for two-class problems and no formal and useful generalization of SNR is available for multiclass problems. We propose innovative generalizations of SNR for multiclass cancer discrimination through introduction of two indices, Gene Dominant Index and Gene Dormant Index (GDIs). These two indices lead to the concepts of dominant and dormant genes with biological significance. We use these indices to develop methodologies for discovery of dominant and dormant biomarkers with interesting biological significance. The dominancy and dormancy of the identified biomarkers and their excellent discriminating power are also demonstrated pictorially using the scatterplot of individual gene and 2-D Sammon's projection of the selected set of genes. Using information from the literature we have shown that the GDI based method can identify dominant and dormant genes that play significant roles in cancer biology. These biomarkers are also used to design diagnostic prediction systems.

Results and discussion

To evaluate the effectiveness of the GDIs, we have used four multiclass cancer data sets (Small Round Blue Cell Tumors, Leukemia, Central Nervous System Tumors, and Lung Cancer). For each data set we demonstrate that the new indices can find biologically meaningful genes that can act as biomarkers. We then use six machine learning tools, Nearest Neighbor Classifier (NNC), Nearest Mean Classifier (NMC), Support Vector Machine (SVM) classifier with linear kernel, and SVM classifier with Gaussian kernel, where both SVMs are used in conjunction with one-vs-all (OVA) and one-vs-one (OVO) strategies. We found GDIs to be very effective in identifying biomarkers with strong class specific signatures. With all six tools and for all data sets we could achieve better or comparable prediction accuracies usually with fewer marker genes than results reported in the literature using the same computational protocols. The dominant genes are usually easy to find while good dormant genes may not always be available as dormant genes require stronger constraints to be satisfied; but when they are available, they can be used for authentication of diagnosis.

Conclusion

Since GDI based schemes can find a small set of dominant/dormant biomarkers that is adequate to design diagnostic prediction systems, it opens up the possibility of using real-time qPCR assays or antibody based methods such as ELISA for an easy and low cost diagnosis of diseases. The dominant and dormant genes found by GDIs can be used in different ways to design more reliable diagnostic prediction systems.

Expression of pituitary tumour-derived, N-terminally truncated isoform of fibroblast growth factor receptor 4 (ptd-FGFR4) correlates with tumour invasiveness but not with G-protein alpha subunit (gsp) mutation in human GH-secreting pituitary adenomas

OBJECTIVE

Apart from the constitutively activating mutation of the G-protein alpha subunit (Gsalpha) (gsp mutation), factors involved in tumorigenesis or those in tumour behaviour remain elusive in sporadic GH-secreting pituitary adenomas. Recently, the N-terminally truncated form of fibroblast growth factor receptor-4 (ptd-FGFR4) was identified in pituitary adenomas. This aberrant receptor has transforming activity, and causes pituitary adenomas in transgenic mice. The clinical relevance of this receptor warrants investigation. Our objective was twofold: first, to examine how the expression of ptd-FGFR4 relates to gsp mutations; and second, to see whether patients with this receptor have unique clinical characteristics.

MATERIALS AND METHODS

mRNA was extracted from excised adenomas of 45 Japanese acromegalic patients. ptd-FGFR4 expression and gsp mutations were determined by reverse transcription polymerase chain reaction (RT-PCR) and direct sequencing. Preoperative clinical data were collected by reviewing medical charts and pituitary magnetic resonance imaging (MRI) scans.

RESULTS

ptd-FGFR4 mRNA expression was detected in 19 out of 45 tumours (42.2%) while gsp mutations were detected in 25 out of 45 tumours (55.6%). The prevalence of ptd-FGFR4 expression did not differ between gsp-positive (44.0%) and gsp-negative (40.0%) tumours (P = 1.00). ptd-FGFR4-positive tumours invaded the cavernous sinus more frequently (P = 0.0098) than did the ptd-FGFR4-negative tumours. Tumour size was not statistically different between ptd-FGFR4-positive and -negative tumours (P = 0.198). The presence of ptd-FGFR4 did not correlate with age at operation, sex, preoperative serum GH or IGF-1 levels.

CONCLUSIONS

We found that ptd-FGFR4 expression and gsp mutations occur independently of each other, and that ptd-FGFR4 expression is associated with more invasive tumours in patients with GH-secreting pituitary adenomas.

Tumor-specific downregulation and methylation of the CDH13 (H-cadherin) and CDH1 (E-cadherin) genes correlate with aggressiveness of human pituitary adenomas

The gene products of CDH13 and CDH1, H-cadherin and E-cadherin, respectively, play a key role in cell-cell adhesion. Inactivation of the cadherin-mediated cell adhesion system caused by aberrant methylation is a common finding in human cancers, indicating that the CDH13 and CDH1 function as tumor suppressor and invasion suppressor genes. In this study, we analyzed the expression of H-cadherin mRNA and E-cadherin protein in 5 normal pituitary tissues and 69 primary pituitary adenomas including all major types by quantitative real-time RT-PCR (qRT-PCR) and immunohistochemistry, respectively. Reduced expression of H-cadherin was detected in 54% (28/52) of pituitary tumors and was significantly associated with tumor aggressiveness (P<0.05). E-cadherin expression was lost in 30% (21 of 69) and significantly reduced in 32% (22 of 69) of tumors. E-cadherin expression was significantly lower in grade II, III, and IV than in grade I adenomas (P=0.015, P=0.029, and P=0.01, respectively). Using methylation-specific PCR (MSP), promoter hypermethylation of CDH13 and CDH1 was detected in 30 and 36% of 69 adenomas, respectively, but not in 5 normal pituitary tissues. Methylation of CDH13 was observed more frequently in invasive adenomas (42%) than in non-invasive adenomas (19%) (P<0.05) and methylation of CDH1 was more frequent in grade IV adenomas compared with grade I adenomas (P<0.05). Methylation of either CDH13 or CDH1 was identified in 35 cases (51%) and was more frequent in grade IV invasive adenomas than in grade I non-invasive adenomas (P<0.05 and P<0.05, respectively). Downregulation of expression was correlated with promoter hypermethylation in CDH13 and CDH1. In conclusion, the tumor-specific downregulation of expression and methylation of CDH13 and CDH1, alone or in combination, may be involved in the development and invasive growth of pituitary adenomas.

A study of the correlation between morphological findings and biological activities in clinically nonfunctioning pituitary adenomas

OBJECTIVE

The aims of this study are to review the histology of the clinically nonfunctioning pituitary adenomas (CNFPAs) we have observed and to determine whether or not the frequency of cavernous sinus invasion is different among each type of morphology.

METHODS

In addition, several proliferative markers, including Ki67, p53, E-cadherin, matrix metallo-proteinase 9 and pituitary tumor derived fibroblast growth factor receptor 4 (ptd-FGFR4), were also investigated in invasive and non-invasive tumors.

RESULTS

Our consequent 213 CNFPAs were diagnosed as follows: 64% were silent gonadotroph adenomas, 18% were null cell adenomas, 12% were silent corticotroph adenomas, 4% were silent Subtype 3 adenomas, and 1% were other types of adenomas. Female patients or younger patients showed a significant preponderance in silent corticotroph adenomas and in silent Subtype 3 adenomas, respectively. Cavernous sinus invasion occurs most frequently in silent corticotroph adenomas (85%) followed by Subtype 3 adenomas (67%), null cell adenomas (38%), and silent gonadotroph adenomas (11%). There were no significant differences in the Ki67, p53, E-cadherin, matrix metallo-proteinase 9, and ptd-FGFR4 expression between tumors with and without cavernous sinus invasion.

CONCLUSION

From a clinical standpoint, it is quite important to differentiate morphological type in CNFPAs to aid the clinician in assessing the clinical behavior and prognosis of the tumor. Therefore, we suggest that all CNFPAs be examined not only by conventional light microscopy but also by immunohistochemistry, preferably by electron microscopy, to achieve a correct morphological diagnosis.

Targeting FGF19 inhibits tumor growth in colon cancer xenograft and FGF19 transgenic hepatocellular carcinoma models

Although fibroblast growth factor 19 (FGF19) can promote liver carcinogenesis in mice its involvement in human cancer is not well characterized. Here we report that FGF19 and its cognate receptor FGF receptor 4 (FGFR4) are coexpressed in primary human liver, lung and colon tumors and in a subset of human colon cancer cell lines. To test the importance of FGF19 for tumor growth, we developed an anti-FGF19 monoclonal antibody that selectively blocks the interaction of FGF19 with FGFR4. This antibody abolished FGF19-mediated activity in vitro and inhibited growth of colon tumor xenografts in vivo and effectively prevented hepatocellular carcinomas in FGF19 transgenic mice. The efficacy of the antibody in these models was linked to inhibition of FGF19-dependent activation of FGFR4, FRS2, ERK and beta-catenin. These findings suggest that the inactivation of FGF19 could be beneficial for the treatment of colon cancer, liver cancer and other malignancies involving interaction of FGF19 and FGFR4.

Aryl hydrocarbon receptor-interacting protein gene mutations in familial isolated pituitary adenomas: analysis in 73 families

CONTEXT

An association between germline aryl hydrocarbon receptor-interacting protein (AIP) gene mutations and pituitary adenomas was recently shown.

OBJECTIVE

The objective of the study was to assess the frequency of AIP gene mutations in a large cohort of patients with familial isolated pituitary adenoma (FIPA).

DESIGN

This was a multicenter, international, collaborative study.

SETTING

The study was conducted in 34 university endocrinology and genetics departments in nine countries.

PATIENTS

Affected members from each FIPA family were studied. Relatives of patients with AIP mutations underwent AIP sequence analysis.

MAIN OUTCOME MEASURES

Presence/absence and description of AIP gene mutations were the main outcome measures.

INTERVENTION

There was no intervention.

RESULTS

Seventy-three FIPA families were identified, with 156 patients with pituitary adenomas; the FIPA cohort was evenly divided between families with homogeneous and heterogeneous tumor expression. Eleven FIPA families had 10 germline AIP mutations. Nine mutations, R16H, G47_R54del, Q142X, E174frameshift, Q217X, Q239X, K241E, R271W, and Q285frameshift, have not been described previously. Tumors were significantly larger (P = 0.0005) and diagnosed at a younger age (P = 0.0006) in AIP mutation-positive vs. mutation-negative subjects. Somatotropinomas predominated among FIPA families with AIP mutations, but mixed GH/prolactin-secreting tumors, prolactinomas, and nonsecreting adenomas were also noted. Approximately 85% of the FIPA cohort and 50% of those with familial somatotropinomas were negative for AIP mutations.

CONCLUSIONS

AIP mutations, of which nine new mutations have been described here, occur in approximately 15% of FIPA families. Although pituitary tumors occurring in association with AIP mutations are predominantly somatotropinomas, other tumor types are also seen. Further study of the impact of AIP mutations on protein expression and activity is necessary to elucidate their role in pituitary tumorigenesis in FIPA.

Discovering biomarkers from gene expression data for predicting cancer subgroups using neural networks and relational fuzzy clustering

Background

The four heterogeneous childhood cancers, neuroblastoma, non-Hodgkin lymphoma, rhabdomyosarcoma, and Ewing sarcoma present a similar histology of small round blue cell tumor (SRBCT) and thus often leads to misdiagnosis. Identification of biomarkers for distinguishing these cancers is a well studied problem. Existing methods typically evaluate each gene separately and do not take into account the nonlinear interaction between genes and the tools that are used to design the diagnostic prediction system. Consequently, more genes are usually identified as necessary for prediction. We propose a general scheme for finding a small set of biomarkers to design a diagnostic system for accurate classification of the cancer subgroups. We use multilayer networks with online gene selection ability and relational fuzzy clustering to identify a small set of biomarkers for accurate classification of the training and blind test cases of a well studied data set.

Results

Our method discerned just seven biomarkers that precisely categorized the four subgroups of cancer both in training and blind samples. For the same problem, others suggested 19–94 genes. These seven biomarkers include three novel genes (NAB2, LSP1 and EHD1 – not identified by others) with distinct class-specific signatures and important role in cancer biology, including cellular proliferation, transendothelial migration and trafficking of MHC class antigens. Interestingly, NAB2 is downregulated in other tumors including Non-Hodgkin lymphoma and Neuroblastoma but we observed moderate to high upregulation in a few cases of Ewing sarcoma and Rabhdomyosarcoma, suggesting that NAB2 might be mutated in these tumors. These genes can discover the subgroups correctly with unsupervised learning, can differentiate non-SRBCT samples and they perform equally well with other machine learning tools including support vector machines. These biomarkers lead to four simple human interpretable rules for the diagnostic task.

Conclusion

Although the proposed method is tested on a SRBCT data set, it is quite general and can be applied to other cancer data sets. Our scheme takes into account the interaction between genes as well as that between genes and the tool and thus is able find a very small set and can discover novel genes. Our findings suggest the possibility of developing specialized microarray chips or use of real-time qPCR assays or antibody based methods such as ELISA and western blot analysis for an easy and low cost diagnosis of the subgroups.

The 2004 World Health Organization classification of pituitary tumors: what is new?

The classification of pituitary tumors is a dynamic area that changes with advances in cell biology that provide a deeper insight and clearer understanding of cell lineages and pathogenetic mechanisms. The 2004 edition of the World Heath Organization (WHO) text "Histological typing of endocrine tumors" reflects the progress that has been achieved since the previous edition of 2000. Here we review the new information and identify areas of concern for the next effort at classification of pituitary tumors.

Gene Expression Profiling of Human Sarcomas: Insights into Sarcoma Biology

Sarcomas are a biologically complex group of tumors of mesenchymal origin. By using gene expression microarray analysis, we aimed to find clues into the cellular differentiation and oncogenic pathways active in these tumors as well as potential biomarkers and therapeutic targets. We examined 181 tumors representing 16 classes of human bone and soft tissue sarcomas on a 12,601-feature cDNA microarray. Remarkably, 2,766 probes differentially expressed across this sample set clearly delineated the various tumor classes. Several genes of potential biological and therapeutic interest were associated with each sarcoma type, including specific tyrosine kinases, transcription factors, and homeobox genes. We also identified subgroups of tumors within the liposarcomas, leiomyosarcomas, and malignant fibrous histiocytomas. We found significant gene ontology correlates for each tumor group and identified similarity to normal tissues by Gene Set Enrichment Analysis. Mutation analysis done on 275 tumor samples revealed that the high expression of epidermal growth factor receptor (EGFR) in certain tumors was not associated with gene mutations. Finally, to further the investigation of human sarcoma biology, we have created an online, publicly available, searchable database housing the data from the gene expression profiles of these tumors (http://watson.nhgri.nih.gov/sarcoma), allowing the user to interactively explore this data set in depth.

Genetics and proteomics of pituitary tumors

Genetics and proteomics determine structure and function of normal tissues, and the molecular alterations that underlie tumorigenesis result in changes in these aspects of tissue biology in neoplasms. We review the known genetic alterations in pituitary tumors. These include the oncogenic Gsalpha protein (GSP)-activating mutations, and pituitary tumor-derived fibroblast growth factor receptor-4 (ptd-FGFR4), as well as tumor suppressor gene mutations associated with multiple endocrine neoplasia type 1 (MEN1). Other candidates identified from expression profiling include pituitary tumor-transforming gene (PTTG), GADD45, and bone morphogenic protein (BMP)4. Proteomic changes in pituitary tumors include classical alterations identified by immunohistochemistry as well as epigenetic reductions in p27. The underlying mechanisms for dysregulated cell adhesive molecules including cadherins and FGFRs are reviewed. The combined use of genetic and proteomic approaches will enhance novel drug therapeutic development.

Predictors and rates of treatment-resistant tumor growth in acromegaly

BACKGROUND

Multimodal therapy for acromegaly affords adequate disease control for many patients; however, there remains a subset of individuals that exhibit treatment-resistant disease. The issue of treatment-resistant pituitary tumor growth remains relatively under-explored.

METHODS

We assessed the literature for relevant data regarding the surgical, medical and radiotherapeutic treatment of acromegaly in order to identify the factors that were predictive of aggressive or treatment-resistant pituitary tumor behavior in acromegaly and undertook an assessment of the rates of failure to control tumor progression with available treatment modalities.

RESULTS

Young age at diagnosis, large tumor size, high growth hormone secretion and certain histological markers are predictors of future aggressive tumor behavior in acromegaly. Significant tumor regrowth occurs in less than 10% of cases thought to be cured surgically, whereas failure to control tumor growth is seen in less than 1% of patients receiving radiotherapy. Somatostatin analogs induce a variable degree of tumor shrinkage in acromegaly but up to 2.2% of somatostatin analog-treated tumors continue to grow. Relative to other therapies, limited data are available for pegvisomant, but these indicate that persistent tumor growth occurs in 1.6-2.9% of cases followed up regularly with serial magnetic resonance imaging scans.

CONCLUSIONS

Treatment-resistant tumor progression occurs in a small minority of patients with acromegaly, regardless of treatment modality. Young patients with large tumors or those with high pre-treatment levels of growth hormone particularly warrant close monitoring for continued tumor progression during treatment for acromegaly.

miR-15a and miR-16-1 down-regulation in pituitary adenomas

Micro RNAs (miRs) are small noncoding RNAs, functioning as antisense regulators of other RNAs. miR-15a and miR-16-1 genes are located at chromosome 13q14, a region which is frequently deleted in pituitary tumors. An inverse correlation has been shown in B cell chronic lymphocytic leukemia (B-CLL) between miR-15a and miR-16-1 expression and the expression levels of arginyl-tRNA synthetase (RARS), an enzyme which associates with the cofactor p43 in the aminoacyl-tRNA synthetase complex. When secreted, p43 regulates local inflammatory response and macrophage chemotaxis, and seems to have anti-neoplastic properties in mice. We explored miR-15a and miR-16-1 expression in 10 GH-secreting and in 10 PRL-secreting pituitary macroadenomas by Northern blot, and investigated the possible correlation with in vivo and in vitro characteristics. We found that miR-15a and miR-16-1 are expressed at lower levels in pituitary adenomas as compared to normal pituitary tissue. Moreover, their expression inversely correlates with tumor diameter and with RARS expression (P < 0.05), but directly correlates with p43 secretion (P < 0.02). Therefore, miR15 and miR16 down-regulation in pituitary adenomas correlates with a greater tumor diameter and a lower p43 secretion, suggesting that these genes may, at least in part, influence tumor growth.