Pituitary tumour transforming gene (PTTG) expression correlates with the proliferative activity and recurrence status of pituitary adenomas: a clinical and immunohistochemical study

Update on Current Evidence for the Diagnosis and Management of Nonfunctioning Pituitary Neuroendocrine Tumors

Pituitary neuroendocrine tumors (PitNETs) are the third most frequently diagnosed intracranial tumors, with nonfunctioning PitNETs (nfPitNETs) accounting for 30% of all pituitary tumors and representing the most common type of macroPitNETs. NfPitNETs are usually benign tumors with no evidence of hormone oversecretion except for hyperprolactinemia secondary to pituitary stalk compression. Due to this, they do not typically present with clinical syndromes like acromegaly, Cushing's disease or hyperthyroidism and instead are identified incidentally on imaging or from symptoms of mass effects (headache, vision changes, apoplexy). With the lack of effective medical interventions, first-line treatment is transsphenoidal surgical resection, however, nfPitNETs often have supra- or parasellar extension, and total resection of the tumor is often not possible, resulting in residual tumor regrowth or reoccurrence. While functional PitNETs can be easily followed for recurrence using hormonal biomarkers, there is no similar parameter to predict recurrence in nfPitNETs, hence delaying early recognition and timely management. Therefore, there is a need to identify prognostic biomarkers that can be used for patient surveillance and as therapeutic targets. This review focuses on summarizing the current evidence on nfPitNETs, with a special focus on potential new biomarkers and therapeutics.

Multiomics Approach to Acromegaly: Unveiling Translational Insights for Precision Medicine

The clinical characteristics and prognoses of acromegaly vary among patients. Assessment of current and novel predictors can lead to multilevel categorization of patients, allowing integration into new clinical guidelines and a reduction in the increased morbidity and mortality associated with acromegaly. Despite advances in the diagnosis and treatment of acromegaly, its pathophysiology remains unclear. Recent advancements in multiomics technologies, including genomics, transcriptomics, proteomics, metabolomics, and radiomics, have offered new opportunities to unravel the complex pathophysiology of acromegaly. This review comprehensively explores the emerging role of multiomics approaches in elucidating the molecular landscape of acromegaly. We discuss the potential implications of multiomics data integration in the development of novel diagnostic tools, identification of therapeutic targets, and the prospects of precision medicine in acromegaly management. By integrating diverse omics datasets, these approaches can provide valuable insights into disease mechanisms, facilitate the identification of diagnostic biomarkers, and identify potential therapeutic targets for precision medicine in the management of acromegaly.

Phosphorylated PTTG1 switches its subcellular distribution and promotes β-catenin stabilization and subsequent transcription activity

The Wnt/β-catenin signaling is usually abnormally activated in hepatocellular carcinoma (HCC), and pituitary tumor-transforming gene 1 (PTTG1) has been found to be highly expressed in HCC. However, the specific mechanism of PTTG1 pathogenesis remains poorly understood. Here, we found that PTTG1 is a bona fide β-catenin binding protein. PTTG1 positively regulates Wnt/β-catenin signaling by inhibiting the destruction complex assembly, promoting β-catenin stabilization and subsequent nuclear localization. Moreover, the subcellular distribution of PTTG1 was regulated by its phosphorylation status. Among them, PP2A induced PTTG1 dephosphorylation at Ser165/171 residues and prevented PTTG1 translocation into the nucleus, but these effects were effectively reversed by PP2A inhibitor okadaic acid (OA). Interestingly, we found that PTTG1 decreased Ser9 phosphorylation-inactivation of GSK3β by competitively binding to PP2A with GSK3β, indirectly leading to cytoplasmic β-catenin stabilization. Finally, PTTG1 was highly expressed in HCC and associated with poor patient prognosis. PTTG1 could promote the proliferative and metastasis of HCC cells. Overall, our results indicated that PTTG1 plays a crucial role in stabilizing β-catenin and facilitating its nuclear accumulation, leading to aberrant activation of Wnt/β-catenin signaling and providing a feasible therapeutic target for human HCC.

Molecular targets in acromegaly

Molecular therapeutic targets in growth hormone (GH)-secreting adenomas range from well-characterized surface receptors that recognize approved drugs, to surface and intracellular markers that are potential candidates for new drug development. Currently available medical therapies for patients with acromegaly bind to somatostatin receptors, GH receptor, or dopamine receptors, and lead to attainment of disease control in most patients. The degree of control is variable: however, correlates with both disease aggressiveness and tumor factors that predict treatment response including somatostatin receptor subtype expression, granulation pattern, kinases and their receptors, and other markers of proliferation. A better understanding of the mechanisms underlying these molecular markers and their relationship to outcomes holds promise for expanding treatment options as well as a more personalized approach to treating patients with acromegaly.

A case of aggressive pituitary neuroendocrine tumour with extremely rapid progression: possible diagnostic value of TERT promoter methylation

Most pituitary adenoma/neuroendocrine tumours (PitNET) are histologically benign and grow slowly; however, a subset of these tumours exhibit a more aggressive clinical course characterized by local invasiveness and early recurrence. These high-risk PitNETs often require multiple surgeries and radiation over several years and may eventually acquire carcinomatous characteristics, such as metastasis in some cases. Herein, we report a rare case of PitNET causing oculomotor paresis with extremely rapid recurrence only 3 months after initial surgery, followed by lethal liver metastasis. Preoperative magnetic resonance imaging and intraoperative findings were consistent with typical PitNETs, other than moderate invasion of the cavernous sinus. Pathological examination of the specimen obtained from the initial transsphenoidal surgery revealed increased mitosis and elevated rates of cells positive for Ki-67 and p53. Based on the immunohistochemical assessment for transcription factors and pituitary hormones, the diagnosis was determined to be a silent sparsely granulated corticotroph PitNET with focal malignant transformation. Aggressive features represented by Ki-67 and p53 positivity were more robust in recurrent and metastatic specimens, but hormone immunostaining was decreased. Epigenetic analysis revealed methylation of the telomerase reverse transcriptase (TERT) promoter in the tumour, resulting in TERT upregulation. Despite extensive research, markers for distinguishing extremely aggressive PitNETs have not been determined. Although further analysis is needed, our case demonstrates the possible usefulness of assessing TERT promoter methylation status in the stratification of recurrence risk in extremely high-risk variants of PitNET.

PTTG1/ZEB1 Axis Regulates E-Cadherin Expression in Human Seminoma

Simple Summary

Seminoma represents one of the most common neoplasms in Caucasian males between 15 and 40 years old. The molecular pathways underlying its clinical behavior are far from being understood yet. We previously demonstrated that nuclear Pituitary-tumor transforming-gene 1 (PTTG1), overexpressed in several neoplasms, promotes invasiveness through its transcriptional target matrix-metalloproteinase-2 (MMP2). PTTG1 sustains the migratory and invasive properties of cancer cells through the induction of the epithelial-to-mesenchymal transition (EMT). E-Cadherin (E-CAD) repression is the first step of EMT. Therefore, we investigated the role of PTTG1 in EMT in human seminoma using an in vitro and in vivo model and through Atlas database interrogation. Our data showed a PTTG1-mediated E-CAD transcriptional repression through Zinc finger E-box binding homeobox 1 (ZEB1), a master regulator of the EMT process. Our data provide insights into the molecular characterization of seminoma, promoting PTTG1 as a prognostic marker useful in human seminoma clinical management.

Abstract

(1) Background: PTTG1 sustains the EMT process and the invasiveness of several neoplasms. We previously showed the role of nuclear PTTG1 in promoting invasiveness, through its transcriptional target MMP2, in seminoma in vitro models. Here, we investigated the key players involved in PTTG1-mediated EMT in human seminoma. (2) Methods: Two seminoma cell lines and four human seminoma tumor specimens were used. E-Cadherin gene regulation was investigated using Western blot, real-time PCR, and luciferase assay. Immunoprecipitation, ChIP, RE-ChIP, and confocal microscopy analysis were performed to evaluate the interplay between PTTG1 and ZEB1. Matrigel invasion and spheroid formation assays were applied to functionally investigate PTTG1 involvement in the EMT of seminoma cell lines. RNA depletion and overexpression experiments were performed to verify the role of PTTG1/ZEB1 in E-Cadherin repression and seminoma invasiveness. E-Cadherin and ZEB1 levels were analyzed in human testicular tumors from the Atlas database. (3) Results: PTTG1 transcriptionally represses E-Cadherin in seminoma cell lines through ZEB1. The cooperation of PTTG1 with ZEB1 has a significant impact on cell growth/invasion properties involving the EMT process. Analysis of the Atlas database of testicular tumors showed significantly lower E-Cadherin levels in seminoma, where PTTG1 showed nuclear staining. Finally, PTTG1 and ZEB1 strongly localize together in the periphery of the tumors. (4) Conclusions: These results strengthen the evidence for a role of PTTG1 in the EMT process in human seminomas through its cooperation with the transcriptional repressor ZEB1 on the E-Cadherin gene. Our data enrich the molecular characterization of seminoma, suggesting that PTTG1 is a prognostic factor in seminoma clinical management.

Pituitary adenomas evade apoptosis via noxa deregulation in Cushing's disease

Sporadic pituitary adenomas occur in over 10% of the population. Hormone-secreting adenomas, including those causing Cushing’s disease (CD), cause severe morbidity and early mortality. Mechanistic studies of CD are hindered by a lack of in vitro models and control normal human pituitary glands. Here, we surgically annotate adenomas and adjacent normal glands in 25 of 34 patients. Using single-cell RNA sequencing (RNA-seq) analysis of 27594 cells, we identify CD adenoma transcriptomic signatures compared with adjacent normal cells, with validation by bulk RNA-seq, DNA methylation, qRT-PCR, and immunohistochemistry. CD adenoma cells include a subpopulation of proliferating, terminally differentiated corticotrophs. In CD adenomas, we find recurrent promoter hypomethylation and transcriptional upregulation of PMAIP1 (encoding pro-apoptotic BH3-only bcl-2 protein noxa) but paradoxical noxa downregulation. Using primary CD adenoma cell cultures and a corticotroph-enriched mouse cell line, we find that selective proteasomal inhibition with bortezomib stabilizes noxa and induces apoptosis, indicating its utility as an anti-tumor agent.

Asuzu et al. perform single-cell transcriptomic profiling in Cushing’s disease (CD) adenomas and find overexpression and DNA hypomethylation of PMAIP1, which encodes the pro-apoptotic protein noxa. Noxa is degraded by the proteasome. Proteasomal inhibition rescues noxa and induces apoptosis in CD.

Prognostic Factors for Recurrence in Pituitary Adenomas: Recent Progress and Future Directions

Pituitary adenomas (PAs) are benign lesions; nonetheless, some PAs exhibit aggressive behaviors, which lead to recurrence. The impact of pituitary dysfunction, invasion-related risks, and other complications considerably affect the quality of life of patients with recurrent PAs. Reliable prognostic factors are needed for recurrent PAs but require confirmation. This review summarizes research progress on two aspects—namely, the clinical and biological factors (biomarkers) for recurrent PAs. Postoperative residue, age, immunohistological subtypes, invasion, tumor size, hormone levels, and postoperative radiotherapy can predict the risk of recurrence in patients with PAs. Additionally, biomarkers such as Ki-67, p53, cadherin, pituitary tumor transforming gene, matrix metalloproteinase-9, epidermal growth factor receptor, fascin actin-bundling protein 1, cyclooxygenase-2, and some miRNAs and lncRNAs may be utilized as valuable tools for predicting PA recurrence. As no single marker can independently predict PA recurrence, we introduce an array of comprehensive models and grading methods, including multiple prognostic factors, to predict the prognosis of PAs, which have shown good effectiveness and would be beneficial for predicting PA recurrence.

Architects of Pituitary Tumour Growth

The pituitary is a master gland responsible for the modulation of critical endocrine functions. Pituitary neuroendocrine tumours (PitNETs) display a considerable prevalence of 1/1106, frequently observed as benign solid tumours. PitNETs still represent a cause of important morbidity, due to hormonal systemic deregulation, with surgical, radiological or chronic treatment required for illness management. The apparent scarceness, uncommon behaviour and molecular features of PitNETs have resulted in a relatively slow progress in depicting their pathogenesis. An appropriate interpretation of different phenotypes or cellular outcomes during tumour growth is desirable, since histopathological characterization still remains the main option for prognosis elucidation. Improved knowledge obtained in recent decades about pituitary tumorigenesis has revealed that this process involves several cellular routes in addition to proliferation and death, with its modulation depending on many signalling pathways rather than being the result of abnormalities of a unique proliferation pathway, as sometimes presented. PitNETs can display intrinsic heterogeneity and cell subpopulations with diverse biological, genetic and epigenetic particularities, including tumorigenic potential. Hence, to obtain a better understanding of PitNET growth new approaches are required and the systematization of the available data, with the role of cell death programs, autophagy, stem cells, cellular senescence, mitochondrial function, metabolic reprogramming still being emerging fields in pituitary research. We envisage that through the combination of molecular, genetic and epigenetic data, together with the improved morphological, biochemical, physiological and metabolically knowledge on pituitary neoplastic potential accumulated in recent decades, tumour classification schemes will become more accurate regarding tumour origin, behaviour and plausible clinical results.

The Roles of the Colon Cancer Associated Transcript 2 (CCAT2) Long Non-Coding RNA in Cancer: A Comprehensive Characterization of the Tumorigenic and Molecular Functions

Colon cancer-associated transcript 2 (CCAT2) is an intensively studied lncRNA with important regulatory roles in cancer. As such, cumulative studies indicate that CCAT2 displays a high functional versatility due to its direct interaction with multiple RNA binding proteins, transcription factors, and other species of non-coding RNA, especially microRNA. The definitory mechanisms of CCAT2 are its role as a regulator of the TCF7L2 transcription factor, enhancer of MYC expression, and activator of the WNT/β-catenin pathway, as well as a role in promoting and maintaining chromosome instability through the BOP1–AURKB pathway. Additionally, we highlight how the encompassing rs6983267 SNP has been shown to confer CCAT2 with allele-specific functional and structural particularities, such as the allelic-specific reprogramming of glutamine metabolism. Additionally, we emphasize CCAT2’s role as a competitive endogenous RNA (ceRNA) for multiple tumor suppressor miRNAs, such as miR-4496, miR-493, miR-424, miR-216b, miR-23b, miR-34a, miR-145, miR-200b, and miR-143 and the pro-tumorigenic role of the altered regulatory axis. Additionally, due to its upregulation in tumor tissues, wide distribution across cancer types, and presence in serum samples, we outline CCAT2’s potential as a biomarker and disease indicator and its implications for the development of resistance against current cancer therapy regiments and metastasis.

Aggressive pituitary tumours and pituitary carcinomas

Although usually benign, anterior pituitary tumours occasionally exhibit aggressive behaviour, with invasion of surrounding tissues, rapid growth, resistance to conventional treatments and multiple recurrences. In very rare cases, they metastasize and are termed pituitary carcinomas. The time between a 'classical' pituitary tumour and a pituitary carcinoma can be years, which means that monitoring should be performed regularly in patients with clinical (invasion and/or tumour growth) or pathological (Ki67 index, mitotic count and/or p53 detection) markers suggesting aggressiveness. However, although both invasion and proliferation have prognostic value, such parameters cannot predict outcome or malignancy without metastasis. Future research should focus on the biology of both tumour cells and their microenvironment, hopefully with improved therapeutic outcomes. Currently, the initial therapeutic approach for aggressive pituitary tumours is generally to repeat surgery or radiotherapy in expert centres. Standard medical treatments usually have no effect on tumour progression but they can be maintained on a long-term basis to, at least partly, control hypersecretion. In cases where standard treatments prove ineffective, temozolomide, the sole formally recommended treatment, is effective in only one-third of patients. Personalized use of emerging therapies, including peptide receptor radionuclide therapy, angiogenesis-targeted therapy and immunotherapy, will hopefully improve the outcomes of patients with this severe condition.

Association of PTTG1 expression with invasiveness of non-functioning pituitary adenomas

Background

Pituitary tumor transforming gene 1 (PTTG1), paired-like homeodomain 2 (PITX2), and galectin-3 have been widely studied as predictive biomarkers for various tumors and are involved in tumorigenesis and tumor progression. We evaluated the usefulness of PTTG1, PITX2, and galectin-3 as predictive biomarkers for invasive non-functioning pituitary adenomas (NFPAs) by determining the relationship between the expressions of these three proteins and the invasiveness of the NFPAs. We also investigated whether PTTG1, E-cadherin, and Ki-67, which are known to be related to each other, show a correlation with NFPA features.

Methods

A retrospective study was conducted on 87 patients with NPFAs who underwent surgical removal. The NFPAs were classified into three groups based on magnetic resonance imaging findings of suprasellar extension and cavernous sinus invasion. Immunohistochemical staining for PTTG1, PITX2, galectin-3, E-cadherin, and Ki-67 was performed on tissue microarrays.

Results

PTTG1 expression showed a statistically significant correlation with the invasiveness of NFPAs, whereas PITX2 and galectin-3 did not have a relationship with the invasiveness of NFPAs. Moreover, there was no association among PTTG1, E-cadherin, and Ki-67 expression.

Conclusion

PTTG1 has the potential to serve as a predictive biomarker for invasive NFPA. Furthermore, this study may serve as a reference for the development of PTTG1-targeted therapeutic agents.

Ki-67/MIB-1 and Recurrence in Pituitary Adenoma

Objectives Ki-67/MIB-1 is a marker of cellular proliferation used as a pathological parameter in the clinical assessment of pituitary adenomas, where its expression has shown utility in predicting the invasiveness of these tumors. However, studies have shown variable results when using Ki-67/MIB-1 association with recurrence. The purpose of this study is to determine if a high Ki-67/MIB-1 labeling index (LI) is predictive of recurrence in pituitary adenomas.

Methods A retrospective chart review was performed for patients undergoing pituitary adenoma resection with at least 1 year of follow-up. Additionally, systematic data searches were performed and included studies that correlated recurrence rate to Ki-67/MIB-1 LI. Our institutional data were included in a synthesis with previously published data.

Results Our institutional review included 79 patients with a recurrence rate of 26.6%. We found that 8.8% of our patients had a high Ki-67/MIB-1 LI (>3%); however, high Ki-67/MIB-1 was not associated with recurrence. The systematic review identified 244 articles and 49 full-text articles that were assessed for eligibility. Quantitative analysis was performed on 30 articles including our institutional data and 18 studies reported recurrence by level of Ki-67/MIB-1 LI. Among studies that compared Ki-67/MIB-1 ≥3 vs. <3%, 10 studies reported odds ratios (OR) greater than 1 of which 6 were statistically significant. A high Ki-67/MIB-1 had higher odds of recurrence via the pooled odds ratio (OR = 4.15, 95% confidence interval [CI]: 2.31–7.42).

Conclusion This systematic review suggests that a high Ki-67/MIB-1 should prompt an increased duration of follow-up due to the higher odds of recurrence of pituitary adenoma.

Towards precision medicine for clinically non-functioning pituitary tumours

OBJECTIVE

Clinically non-functioning pituitary tumours (NFPT) are a heterogenous group of neoplasms with diverse outcomes. The purpose of this narrative review was to summarize available data on predictive factors, both in routine practice and research settings.

DESIGN

A literature review was conducted for papers published in peer-reviewed journals, investigating clinical, radiological, pathological and genetic predictive factors in NFPT.

RESULTS

Several clinical and radiological factors have been associated with NFPT recurrence and/or aggressiveness, including larger size and pre-/post-operative growth rates. Application of transcription factor immunohistochemistry has given rise to improved subtype identification, including 'higher-risk' subtypes, in routine clinical practice. Numerous other pathological and genetic biomarkers have demonstrated promise for prognostication in the research setting.

CONCLUSION

NFPT are a heterogenous group of tumours, characterized by diverse presentation, pathogenesis and outcomes. Ongoing refinements in understanding of tumour biology are likely to pave the way to improved integrative prognostication and precision medicine for NFPT.

Nuclear Localization of PTTG1 Promotes Migration and Invasion of Seminoma Tumor through Activation of MMP-2

Simple Summary

Seminoma is the most common subtype of testicular germ cell tumors (TGCTs) and its molecular patterns have not been clarified. The pituitary tumor-transforming gene 1 (PTTG1) is a securin and its overexpression is reported in many cancers. We previously demonstrated that PTTG1 is mainly localized at the neoplasm periphery and infiltration area of seminoma. Therefore, we aim to investigate in vitro the role of PTTG1 on the invasive properties of seminoma. Our results elucidate the role of nuclear PTTG1 in promoting invasiveness and the metastatic process of these cells through its transcriptional target matrix-metalloproteinase-2 (MMP-2). Analysis of human testicular tumors from the Atlas database revealed an exclusive PTTG1 nuclear localization and a concomitant increase of MMP-2 levels in seminoma compared to non-seminoma tumors. Our data provide insights into the molecular characterization of seminoma, promoting PTTG1 as a prognostic marker useful in human seminoma clinical management.

Abstract

(1) Background: PTTG1 sustains the invasiveness of several cancer types. We previously reported that in seminomas, PTTG1 was detected in the peripheral area of the tumor and in the leading infiltrative edge. Here, we investigate the PTTG1 role on the invasive properties of seminoma. (2) Methods: three seminoma cell lines were used as in vitro model. PTTG1 levels and localization were investigated by biochemical and immunofluorescence analyses. Wound-healing, Matrigel invasion assays, and zymography were applied to study migratory and invasive capability of the cell lines. RNA interference and overexpression experiments were performed to address the PTTG1 role in seminoma invasiveness. PTTG1 and its target MMP-2 were analyzed in human testicular tumors using the Atlas database. (3) Results: PTTG1 was highly and differentially expressed in the seminoma cell lines. Nuclear PTTG1 was positively correlated to the aggressive phenotype. Its modulation confirms these results. Atlas database analysis revealed that PTTG1 was localized in the nucleus in seminoma compared with non-seminoma tumors, and that MMP-2 levels were significantly higher in seminomas. (4) Conclusions: nuclear PTTG1 promotes invasiveness of seminoma cell lines. Atlas database supported these results. These data lead to the hypothesis that nuclear PTTG1 is an eligible prognostic factor in seminomas.

Ki67 in endocrine neoplasms: to count or not to count, this is the question! A systematic review from the English language literature

BACKGROUND

Endocrine neoplasms are generally slow-growing tumors that can show hormonal activity and give metastases. In most cases they are benign and clearly malignant forms are easy to diagnose. However, borderline forms may occur and be, for the pathologists, very difficult to classify. In these cases, there is a strong need to identify factors that may aid. Official classification systems for endocrine neoplasms are based on the evaluation of proliferation and, in most cases, they rely on mitotic count. In support, the study of Ki67 is carried out which, however, has not yet been included in any official classification system, except for neuroendocrine neoplasms of the gastro-entero-pancreatic tract.

PURPOSE

The aim of the present study was to investigate the proven or unproven role of Ki67 in endocrine neoplasms, in different districts, in order to bring to light the substantial differences, in terms of proliferation, existing between neoplasms so similar, but at the same time, so different.

METHODS

A thorough search of English language literature was performed, looking for articles concerning Ki67 in five endocrine neoplasms (pituitary adenomas, thyroid neoplasms, adrenocortical neoplasms, pheochromocytomas and paragangliomas).

RESULTS

From 2170, 236 articles were selected and it was seen that the endocrine neoplasm in which Ki67 was most studied was the pituitary, where it still shows a controversial role. In other neoplasms different roles were identified.

CONCLUSION

The pathologist should be aware of the contribution that this proliferative marker can give to the diagnosis and, sometimes, to the therapy selection, for the clinician.

Pituitary Hyperplasia, Hormonal Changes and Prolactinoma Development in Males Exposed to Estrogens-An Insight From Translational Studies

Estrogen signaling plays an important role in pituitary development and function. In sensitive rat or mice strains of both sexes, estrogen treatments promote lactotropic cell proliferation and induce the formation of pituitary adenomas (dominantly prolactin or growth-hormone-secreting ones). In male patients receiving estrogen, treatment does not necessarily result in pituitary hyperplasia, hyperprolactinemia or adenoma development. In this review, we comprehensively analyze the mechanisms of estrogen action upon their application in male animal models comparing it with available data in human subjects. Sex-specific molecular targets of estrogen action in lactotropic (PRL) cells are highlighted in the context of their proliferative and secretory activity. In addition, putative effects of estradiol on the cellular/tumor microenvironment and the contribution of postnatal pituitary progenitor/stem cells and transdifferentiation processes to prolactinoma development have been analyzed. Finally, estrogen-induced morphological and hormone-secreting changes in pituitary thyrotropic (TSH) and adrenocorticotropic (ACTH) cells are discussed, as well as the putative role of the thyroid and/or glucocorticoid hormones in prolactinoma development, based on the current scarce literature.

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.

Multimodal therapy in aggressive pituitary tumors

The concept of aggressive pituitary tumor (APT) has been precisely defined in recent years. These tumors are characterized by morphological (radiological or histopathological) data of invasion, proliferative activity superior to that of typical adenomas and a clinical behavior characterized by resistance to standard therapies and frequent recurrences. The absence of cerebrospinal or distant metastases differentiates them from the pituitary carcinoma. APTs account for about 10% of all pituitary neoplasm. Proper diagnostic implies participation not only of radiological and hormonal investigation but also a thorough pathological assessment including proliferation markers and immunohistochemistry for hormones and transcription factors. Surgical resection, aiming gross total resection or tumor debulking, is the mainstay initial therapy in most patients. Most patients with APTs need more than one surgical intervention, pituitary radiation, sometimes on more than one occasion, and multiple sequential or combined medical treatments, to finally be doomed to unusual treatments, such as alkylating agents (temozolomide alone or in combination), molecular targeted therapies, or peptide receptor radionuclide therapy. Multimodal therapy, implemented by experts, preferably in specialized centers with high volume caseload, is the only way to improve the prognosis of patients with these uncommon tumors. The research needs in this area are multiple and include a greater knowledge of the molecular biology of these tumors, establishment of protocols for monitoring and sequencing of treatments, development of multicenter studies and international registries.

Genetic and Epigenetic Characterization of Growth Hormone-Secreting Pituitary Tumors

Somatic driver mechanisms of pituitary adenoma pathogenesis have remained incompletely characterized; apart from mutations in the stimulatory Gα protein (Gα_s encoded by GNAS) causing activated cAMP synthesis, pathogenic variants are rarely found in growth hormone-secreting pituitary tumors (somatotropinomas). The purpose of the current work was to clarify how genetic and epigenetic alterations contribute to the development of somatotropinomas by conducting an integrated copy number alteration, whole-genome and bisulfite sequencing, and transcriptome analysis of 21 tumors. Somatic mutation burden was low, but somatotropinomas formed two subtypes associated with distinct aneuploidy rates and unique transcription profiles. Tumors with recurrent chromosome aneuploidy (CA) were GNAS mutation negative (Gsp^- ). The chromosome stable (CS) -group contained Gsp⁺ somatotropinomas and two totally aneuploidy-free Gsp^- tumors. Genes related to the mitotic G₁-S-checkpoint transition were differentially expressed in CA- and CS-tumors, indicating difference in mitotic progression. Also, pituitary tumor transforming gene 1 (PTTG1), a regulator of sister chromatid segregation, showed abundant expression in CA-tumors. Moreover, somatotropinomas displayed distinct Gsp genotype-specific methylation profiles and expression quantitative methylation (eQTM) analysis revealed that inhibitory Gα (Gα_i) signaling is activated in Gsp⁺ tumors. These findings suggest that aneuploidy through modulated driver pathways may be a causative mechanism for tumorigenesis in Gsp^- somatotropinomas, whereas Gsp⁺ tumors with constitutively activated cAMP synthesis seem to be characterized by DNA methylation activated Gα_i signaling. IMPLICATIONS: These findings provide valuable new information about subtype-specific pituitary tumorigenesis and may help to elucidate the mechanisms of aneuploidy also in other tumor types.

Predictive modeling for pituitary adenomas: single center experience in 501 consecutive patients

BACKGROUND

Personalized postoperative management of patients with pituitary adenomas requires an early risk stratification system.

METHODS

We reviewed 501 cases operated between 10/27/2011 and 5/5/2016 by a single neurosurgeon. We determined biochemical remission and tumor resection at 3 months, and biochemical recurrence, tumor recurrence, radiation and reoperation during follow-up. We considered age, gender, tumor diameter, cavernous sinus invasion (CSI) by MRI, diagnostic category (clinical, biochemical and immunohistochemical), and proliferation markers in a Cox proportional hazards model. We built predictive models with the significant parameters and used Kaplan-Meier survival curves for time-dependent analyses.

RESULTS

The 501 cases comprised 141 functional and 360 nonfunctional adenomas. Tumor diameter, CSI, and ki-67 index predicted long-term events. Model 1 (CSI, diameter ≥ 2.9 cm and ki-67 > 3%) identified 18 (3.6%) adenomas and predicted persistent hypersecretory syndrome and residual tumor with 98.7% specificity (OR 8.6; CI 3.0-24.7). Model 2 (ki-67 > 3% and CSI) identified 48 (9.6%) adenomas and had 93.1% specificity (OR 3.3; CI 1.8-6.0). Model 3 (ki-67 > 3%, mitoses and p53, former "atypical" adenoma) identified 26 (5.2%) adenomas and had 96.0% specificity (OR 2.3; CI 1.0-5.0). Model 1 best predicted the long-term event-free survival and was strengthened when Knosp 3-4 CSI grades were used. Model 2 better identified the smaller adenomas at risk. Among the WHO 2017 special PA subtypes, patients with silent corticotroph adenoma had a lower event-free survival than ACTH-negative nonfunctional adenomas.

CONCLUSION

Use of CSI, ki-67 and tumor diameter in prediction models facilitates tailored surveillance and management of patients with pituitary adenomas.

Hormonal aggressiveness according to the expression of cellular markers in corticotroph adenomas

PURPOSE

The molecular mechanisms underlying tumor growth in Cushing's disease (CD) still remain a challenge. Moreover, clinical manifestations of CD may vary depending on hormonal activity; however, factors involved in the hormonal aggressiveness of adrenocorticotropic hormone (ACTH)-secreting pituitary tumors have not been fully clarified. We investigated the association between the expression of cellular markers regarding pituitary tumor progression and initial or postoperative hormone levels in patients with CD.

METHODS

Tumor tissues from 28 corticotroph adenomas (female 26, male 2, mean age 39.21 ± 10.39 years) were subject to immunohistochemical study using the following antibodies: pituitary tumor-transforming gene 1 (PTTG1), cyclin D1, p16, p27, brahma related-gene 1 (Brg1), and Ki-67. We then analyzed the relationship between each cellular marker expression and hormone levels, including 24 h urinary free cortisol (UFC), plasma ACTH, and serum cortisol.

RESULTS

PTTG1 and Ki-67 were expressed in 100% and 50% of patients, respectively. However, the levels did not reflect initial hormonal activity. The cyclin D1-negative group showed higher serum cortisol levels compared to the cyclin D1-positive group (p = 0.01). The 24 h UFC levels were significantly higher in the p27-negative group than in the p27-positive group (p = 0.04), whereas the Brg1-positive group revealed higher serum cortisol levels than in the Brg1-negative group (p = 0.02).

CONCLUSIONS

Although PTTG1 and Ki-67 play an essential role in developing ACTH-secreting tumors, cyclin D1, p27, and Brg1 may be better biomarkers to determine hormonal aggressiveness of the tumor. Further research is needed to understand the influence of cellular markers on hormonal activity in CD.

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.

Recurrences of Pituitary Adenomas or Second De Novo Tumors: Comparisons with First Tumors

BACKGROUND

Recurrences of pituitary adenomas are not so rare.

METHODS

In the German Registry of Pituitary Tumors, more than 12,000 surgical specimens were collected between 1967 and 2012, of which 312 patients with altogether 334 recurrences (n = 646 specimens) were included in our study.

RESULTS

The histopathology of 162 recurrent adenomas could be compared with the original tumor and 37 second recurrences could be compared with the first recurrence. Comparing the proliferation index (Ki-67) of the original and the first recurrent tumor (n = 162), we found an unchanged index in 43 cases (26%), whereas in 69 cases (43%) the index increased and in 50 cases (31%) it decreased. Comparing the first with the second recurrence (n = 37), we found an unchanged index in 8 cases (22%), an increased index in 15 cases (40%), and a decreased index in 14 cases (38%). The third recurrence showed an unchanged index in 1 case (20%), an increased index in 2 cases (40%), and a decreased index in 2 cases (40%). p53 was unchanged in recurrences in 44% of cases, increased in 33%, and decreased in 22%. In 4 cases, adenomas developed into adenomas with strongly increased proliferation (formerly atypical adenomas, now aggressive adenomas) for the first recurrence, and 9 recurrences became aggressive adenomas. A change of tumor type without change of the common transcription factor occurred in 82 cases.

CONCLUSIONS

A second independent de novo adenoma was present in 10 cases, probably due to changes of transcription factors.

PTTG-1 (Securin) immunoexpression in meningiomas correlates with tumor grade and proliferation rate: potential use as a diagnostic marker of malignancy

This study essentially aims to contribute to the immunohistochemical investigation of the use of pituitary tumor transforming gene (PTTG) as a marker of cell proliferation or advanced tumor grade in meningiomas of various WHO grades. In all, 51 cases were recovered in total, 21 Grade-I, 23 Grade-II and 7 Grade-III meningiomas. Mitotic index (MI), Ki-67/MiB-1 positivity percentage and PTTG expression were analyzed in correlation to each other as well as to the tumor WHO grades. All three biomarkers showed a high diagnostic significance and a strong association with WHO grades. In comparison, PTTG expression was on a par with the other two indices, and performed very well regarding identification of advanced grade tumors. PTTG may be considered an important diagnostic tool and serve in the future as a novel prognosticator of the biological behavior of all grade meningiomas as well as a useful high-risk patient selection tool.

Expression of Matrix Metalloproteinase-9, Pituitary Tumor Transforming Gene, High Mobility Group A 2, and Ki-67 in Adrenocorticotropic Hormone-Secreting Pituitary Tumors and Their Association with Tumor Recurrence

OBJECTIVE

Matrix metalloproteinase-9 (MMP-9), pituitary tumor transforming gene (PTTG), and high mobility group A 2 (HMGA2) play important roles in the tumorigenesis of adrenocorticotrophic hormone (ACTH)-secreting pituitary tumors, but their associations with tumor recurrence after transsphenoidal adenomectomy remain unclear. The aim of the study was to investigate the immunohistochemical expression profiles of MMP-9, PTTG, HMGA2, and Ki-67 in recurrent and nonrecurrent ACTH-secreting pituitary tumors and to identify their associations with tumor behavior and recurrence status.

METHODS

A retrospective study was performed including 55 patients with sporadic Cushing's disease with long-term remission after transsphenoidal adenomectomy. Fifty-five ACTH-secreting pituitary tumor specimens and 2 normal pituitary glands were collected. After an intensive follow-up (33-59 months, mean 41.8 months), patients were divided into 2 groups based on their recurrence status: the nonrecurrent group (n = 28) and the recurrent group (n = 27). The expression of MMP-9, PTTG, HMGA2, and Ki-67 in each sample was examined and quantified by immunohistochemistry. The association between MMP-9, PTTG, HMGA2, and Ki-67 expression and clinicopathologic characteristics and tumor recurrence were evaluated.

RESULTS

There was a significantly increased expression of MMP-9 in the recurrent group compared with the nonrecurrent group (P = 0.022), and this was strongly associated with the recurrence-free interval (P = 0.007, correlation coefficient. = -0.354). PTTG, HMGA2, and Ki-67 expression were not significantly different between the recurrent group and the nonrecurrent group. No expression of MMP-9, PTTG, HMGA2, or Ki-67 was detected in the 2normal pituitary glands.

CONCLUSIONS

ACTH-secreting pituitary tumors with greater levels of MMP-9 were associated with a greater recurrence rate and a shorter recurrence-free interval. MMP-9 could be a valuable tool for predicting recurrence of ACTH-secreting pituitary tumors.

Variability and Lack of Prognostic Value Associated With Atypical Pituitary Adenoma Diagnosis: A Systematic Review and Critical Assessment of the Diagnostic Criteria

BACKGROUND

Atypical pituitary adenomas (APAs) are a subset of pituitary adenomas (PAs) characterized by the 2004 World Health Organization (WHO) guidelines to have higher risk histopathological features than typical PAs. In July 2017, the WHO published an update to their classification of pituitary tumors and abandoned the APA terminology.

OBJECTIVE

To assess the prevalence and outcomes of patients diagnosed with APA through a literature review. Focus was placed on variation in the application of the previous WHO criteria and on rates of recurrence.

METHODS

A systematic review of PubMed (2004-July 2017) was performed to identify studies reporting prevalence and clinical characteristics/outcomes of APA. Eight studies were analyzed for prevalence. Six studies reporting histopathological details were analyzed in depth.

RESULTS

Of the 7105 included patients, 373 (5.2%) met criteria for APA (prevalence range: 3%-15%). Only 2 of 8 studies utilized identical grading criteria, demonstrating a lack of standardized application. Most APAs (84%) were macroadenomas, with 52% invasive on magnetic resonance imaging. Nonfunctional PAs were most common (37%), followed by prolactinomas (23%) and Growth Hormone adenomas (21%). Recurrence/progression occurred in 21% of APA patients (follow-up range 37-75 mo). Only 2 of 8 studies reported an association between APA diagnosis and recurrence/progression.

CONCLUSION

Based on diagnostic variability and lack of association with clinical outcomes, refinement of criteria for APA was necessary. The WHO update eliminates the ambiguity in APA diagnosis in favor of criteria that emphasize clinical behavior (invasion, recurrence, and resistance to treatment) and molecular markers. Our review supports abandonment of the previous APA designation due to limited prognostic utility.

Ki67 Labeling Correlated With Invasion But Not With Recurrence

Pituitary adenomas account for 10% to 15% of intracranial neoplasms. Multiple factors had been introduced for tumor recurrence. MIB-1 monoclonal antibody, a marker of the proliferative index, has been introduced in various tumors, but unfortunately, the usefulness of MIB-1 in predicting the behavior of pituitary adenoma has been debated recently. Hence, the aim of this study was to evaluate its role in the recurrence and the invasiveness of pituitary adenomas. In a cross-sectional study conducted between 2005 and 2010, patients with a diagnosis of pituitary adenoma, referred to 2 medical centers (Arad and Iran Mehr hospital) in Tehran, were enrolled. Clinical and laboratory data were gathered. Immunostaining for MIB-1 monoclonal antibody was performed for each slide and scored blindly by 2 pathologists. A total of 176 surgically treated patients met the inclusion criteria. Thirty-six of 176 cases had recurrent episodes. Eleven of 176 patients had invasive tumors. The mean Ki67 index was 2.7%±3.96% in recurrent cases and 2.24%±2.35% in nonrecurring cases, with no statistically significant difference between them (P>0.05). Ten of 11 invasive pituitary tumors had a Ki67>3%, and a statistically significant difference was observed between invasive and noninvasive tumors (P<0.05). Hence, the Ki67 index seems to be suitable for predicting invasion, but it failed to show any correlation between Ki67 and tumor recurrence.

Clinically non-functioning pituitary adenomas: Pathogenic, diagnostic and therapeutic aspects

Clinically non-functioning pituitary adenomas (NFPAs) are among the most common tumors in the sellar region. These lesions do not cause a hormonal hypersecretion syndrome, and are therefore found incidentally (particularly microadenomas) or diagnosed based on compressive symptoms such as headache and visual field defects, as well as clinical signs of pituitary hormone deficiencies. Immunohistochemically, more than 45% of these adenomas stain for gonadotropins or their subunits and are therefore called gonadotropinomas, while 30% of them show no immunostaining for any hormone and are known as null cell adenomas. The diagnostic approach to NFPAs should include visual field examination, an assessment of the integrity of all anterior pituitary hormone systems, and magnetic resonance imaging of the sellar region to define tumor size and extension. The treatment of choice is transsphenoidal resection of the adenoma, which in many instances cannot be completely accomplished. The recurrence rate after surgery may be up to 30%. Persistent or recurrent adenomas are usually treated with radiation therapy. In a small proportion of these cases, drug treatment with dopamine agonists and, to a lesser extent, somatostatin analogs may achieve reduction or at least stabilization of the tumor.

Expression of cell cycle regulators and biomarkers of proliferation and regrowth in human pituitary adenomas

PURPOSE

The pathogenesis of pituitary adenomas (PA) is complex. Ki-67, pituitary tumour transforming gene (PTTG), vascular endothelial growth factor (VEGF), cyclin D1, c-MYC and pituitary adenylate cyclase-activating peptide (PACAP) protein expression were analysed and correlated with tumour and patient characteristics.

METHODS

74 pituitary tumour samples (48 non-functional PA, 26 functional PAs); Immunohistochemical analysis of protein expression, retrospective analysis of MR images and in vitro analysis of octreotide treatment was carried out on GH3 cells.

RESULTS

PTTG expression was negatively associated with age and positively with PA size, regrowth and Ki-67 index. Cyclin D1 correlated with Ki-67 and tumour size. c-MYC negatively correlated with size of tumour and age; and correlated with PTTG expression. Somatostatin analogue treatment was associated with lower Ki-67, PTTG and Cyclin D1 expression while T2 hypointense PAs were associated with lower PTTG, cyclin D1, c-MYC and Ki-67. In vitro analyses confirmed the effect of somatostatin analogue treatment on Pttg and Cyclin D1 expression.

CONCLUSIONS

Interesting and novel observations on the differences in expression of tumour markers studied are reported. Correlation between Ki-67 expression, PTTG nuclear expression and recurrence/regrowth of PAs, emphasizes the role that Ki-67 and PTTG expression have as markers of increased proliferation. c-MYC and PTTG nuclear expression levels were correlated providing evidence that PTTG induces c-MYC expression in PAs and we propose that c-MYC might principally have a role in early pituitary tumorigenesis. Evidence is shown that the anti-proliferative effect of somatostatin analogue treatment in vivo occurs through regulation of the cell cycle.

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.

Predictors of aggressive clinical phenotype among immunohistochemically confirmed atypical adenomas

Despite formal pathological criteria, not all atypical pituitary adenomas display clinically aggressive behavior. We set out to determine which factors predict a clinically aggressive phenotype among a cohort of atypical pituitary adenomas. Medical records were retrospectively reviewed from April 2008 to July 2015. Of 569 pituitary adenomas, 47 (8.3%) patients were surgically treated for atypical adenomas as defined by the WHO criteria. Clinically aggressive adenomas were defined as occurring in those patients who necessitated additional therapeutic intervention after the index (first) surgery, including additional surgery, medical therapy, or radiosurgery. Forty-seven patients with histopathological and immunohistochemical confirmation of atypical adenomas were identified and of these, 23 were noted to have a clinically aggressive course. Among the remaining 24 patients, the disease remained quiescent after the index surgery. On univariate analysis, clinically aggressive lesions were more likely to have a larger axial diameter on MRI (2.9±1.9cm vs. 1.9±0.7cm, p=0.02), greater incidence of cavernous sinus invasion (65.2% vs. 20.8%, p<0.01), and greater incidence of clival extension (60.9% vs. 0, p<0.01) on preoperative imaging. The two groups were equivalent with regard to immunohistochemical staining for ACTH, HGH, LH, FSH, PRL, and TSH. Clinically aggressive lesions, however, trended towards a greater average MIB-1 proliferative index (7.5%±4.9 vs. 6.0%±3.6, p=0.03). On multivariate analysis, the MIB-1 proliferative index trended towards statistical significance (p=0.06) as an independent predictor of clinical aggressiveness. Atypical pituitary adenomas are defined by a rigid set of immunohistochemical markers, but not all necessarily demonstrate an aggressive clinical phenotype.

The PTTG1-targeting miRNAs miR-329, miR-300, miR-381, and miR-655 inhibit pituitary tumor cell tumorigenesis and are involved in a p53/PTTG1 regulation feedback loop

Deregulation of the pituitary tumor transforming gene (PTTG1), a newly discovered oncogene, is a hallmark of various malignancies, including pituitary tumors. However, the mechanisms regulating PTTG1 expression are still needed to be explored. MicroRNAs (miRNAs) are a novel class of small RNA molecules that act as posttranscriptional regulators of gene expression and can play a significant role in tumor development. Here, we identified a series of miRNAs, namely, miR-329, miR-300, miR-381 and miR-655, which could target PTTG1 messenger RNA and inhibit its expression. Interestingly, all four miRNAs significantly that are downregulated in pituitary tumors were mapped to the 14q32.31 locus, which acts as a tumor suppressor in several cancers. Functional studies show that the PTTG1-targeting miRNAs inhibit proliferation, migration and invasion but induce apoptosis in GH3 and MMQ cells. Furthermore, overexpression of a PTTG1 expression vector lacking the 3′UTR partially reverses the tumor suppressive effects of these miRNAs. Next, we identified the promoter region of PTTG1-targeting miRNAs with binding sites for p53. In our hands, p53 transcriptionally activated the expression of these miRNAs in pituitary tumor cells. Finally, we found that PTTG1 could inhibit p53 transcriptional activity to the four miRNAs. These data indicate the existence of a feedback loop between PTTG1 targeting miRNAs, PTTG1 and p53 that promotes pituitary tumorigenesis. Together, these findings suggest that these PTTG1-targeting miRNAs are important players in the regulation of pituitary tumorigenesis and that these miRNAs may serve as valuable therapeutic targets for cancer treatment.

Epidemiological variations of aggressive growth hormone-secreting adenomas

Acromegaly is a chronic disorder characterized by increased morbidity and mortality in uncontrolled patients. Growth hormone-secreting pituitary adenoma is the hallmark in the majority of cases, generally considered as benign due to lack of distant metastases. However, clinical behavior in a certain proportion of these adenomas could be quite aggressive, causing difficulties in their management. Aggressive pituitary adenomas have some clinical, radiological, ultrastructural and molecular features in common and they are usually resistant to the standard treatment. In the recent years, efforts have been made to define the most appropriate markers of such adenomas that would allow an early detection and efficient individualized therapeutic strategy. The aim of this review is to give an update on epidemiology and certain markers predicting aggressive behavior of somatotropinomas.

Locally produced estrogen through aromatization might enhance tissue expression of pituitary tumor transforming gene and fibroblast growth factor 2 in growth hormone-secreting adenomas

Aromatase, a key enzyme in local estrogen synthesis, is expressed in different pituitary tumors including growth hormone (GH)-secreting adenomas. We aimed to evaluate aromatase, estrogen receptor α (ERα), estrogen receptor β (ERβ), pituitary tumor transforming gene (PTTG), and fibroblast growth factor 2 (FGF2) expressions in GH-secreting adenomas, and investigate their correlation with clinical, pathologic, and radiologic parameters. This cross-sectional study was conducted in a tertiary center in Turkey. Protein expressions were determined via immunohistochemical staining in ex vivo tumor samples of 62 patients with acromegaly and ten normal pituitary tissues. Concordantly increased aromatase, PTTG, and FGF2 expressions were detected in the tumor samples as compared with controls (p < 0.001 for all). None of the tumors expressed ERα while ERβ was detected only in mixed somatotroph adenomas. Aromatase, ERβ, PTTG expressions were not significantly different between patients with and without remission (p > 0.05 for all). FGF2 expression was significantly higher in patients without postoperative and late remission (p = 0.002 and p = 0.012, respectively), with sphenoid bone invasion, optic chiasm compression, and somatostatin analog resistance (p = 0.005, p = 0.033, and p = 0.013, respectively). Aromatase, PTTG and FGF2 expressions were positively correlated with each other (r = 0,311, p = 0.008 for aromatase, FGF2; r = 0.380, p = 0.001 for aromatase, PTTG; r = 0.400, p = 0.001 for FGF2, PTTG). PTTG-mediated FGF2 upregulation is associated with more aggressive tumor features in patients with acromegaly. Also, locally produced estrogen through aromatization might have a role in this phenomenon.

Atypical pituitary adenomas: clinical characteristics and role of ki-67 and p53 in prognostic and therapeutic evaluation. A series of 50 patients

The aim of the study was to assess incidence rate, hormonal activity, and local invasiveness and evaluate outcomes of so-diagnosed atypical pituitary adenomas that underwent endoscopic endonasal surgery at the Division of Neurosurgery of Università degli Studi di Napoli Federico II. According to the 2004 WHO classification, atypical pituitary adenomas are defined by an invasive growth, Ki-67/MIB-1 proliferative index greater than 3 %, high p53 immunoreactivity, and increased mitotic activity. A retrospective analysis of a series of 434 pituitary adenomas that underwent endoscopic endonasal surgery at our department between March 2007 and February 2013 was performed. Fifty adenomas (11.5 %) met the criteria of diagnosis of atypical lesions; 10 (21.6 %) of the 50 patients were recurrent tumors with a previous transsphenoidal surgery. Forty-one (82 %) were macroadenomas, and 21/50 (42 %) showed a clear invasion of the cavernous sinus. Histotype of atypical adenomas figured out to be nonfunctioning in 23 cases (46 %), PRL secreting in 10 cases (20 %), ACTH secreting and GH secreting each apart in 8 patients (16 %), and in a single case a GH/PRL secreting adenoma (2 %). The Ki-67 labeling index ranged from 3.5 to 22.5 % (mean 5.6 %). Tumor recurrence was observed in six cases (12 %) after a mean time of 18 months (range 9-24 months). Mean follow-up was 36.5 months (range 2-80 months). Atypical pituitary adenomas account for ca. 10 % of all pituitary adenomas; these lesions have peculiar features. It should be considered that a strong immunopositivity of p53 and higher Ki-67 LI could predict an increased risk of tumor recurrence, but more studies and larger series are expected to confirm and enlarge the diagnostic and therapeutic management process of these lesions.

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.

[Evaluation of the biological behavior of ACTH-secreting pituitary tumors using various methods]

This literature review is aimed at studying markers obtained by various research methods to assess the biological behavior of ACTH-secreting pituitary tumors. This paper presents the clinical, laboratory, instrumental. histological, and immunohistochemical aspects of ACTH-secreting pituitary tumors. Histological method allows assessing the structures of a tumor and differential diagnosis of other pathological process in the sella turcica. Immunohistochemical method enables determining the expression of multiple markers (fibroblast growth factors, matrix metalloproteinases, apoptotic factors, pituitary tumor transforming gene, and vascular markers), which reflect various processes of oncogenesis of studied tumors, and according to the authors, are promising with regard to predicting biological behavior using corticotropin. Epigenetic investigations including the study of micro-RNA expression, proteomics, and transcriptomics are the new methods in this area, which are expected to provide additional details regarding the prediction using corticotropin. Thus, the cumulative assessment using laboratory and instrumental methods, the study of immunoexpression of malignant potential markers in the tissue using corticotropin and micro-RNA allow predicting the future biological behavior of ACTH-secreting pituitary tumors.

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.

Pituitary Apoplexy

Pituitary apoplexy, a rare clinical syndrome secondary to abrupt hemorrhage or infarction, complicates 2%-12% of pituitary adenomas, especially nonfunctioning tumors. Headache of sudden and severe onset is the main symptom, sometimes associated with visual disturbances or ocular palsy. Signs of meningeal irritation or altered consciousness may complicate the diagnosis. Precipitating factors (increase in intracranial pressure, arterial hypertension, major surgery, anticoagulant therapy or dynamic testing, etc) may be identified. Corticotropic deficiency with adrenal insufficiency may be life threatening if left untreated. Computed tomography or magnetic resonance imaging confirms the diagnosis by revealing a pituitary tumor with hemorrhagic and/or necrotic components. Formerly considered a neurosurgical emergency, pituitary apoplexy always used to be treated surgically. Nowadays, conservative management is increasingly used in selected patients (those without important visual acuity or field defects and with normal consciousness), because successive publications give converging evidence that a wait-and-see approach may also provide excellent outcomes in terms of oculomotor palsy, pituitary function and subsequent tumor growth. However, it must be kept in mind that studies comparing surgical approach and conservative management were retrospective and not controlled.

PTTG1 expression is associated with hyperproliferative disease and poor prognosis in multiple myeloma

Background

Multiple myeloma (MM) is an incurable haematological malignancy characterised by the clonal proliferation of malignant plasma cells within the bone marrow. We have previously identified pituitary tumour transforming gene 1 (Pttg1) as a gene that is significantly upregulated in the haematopoietic compartment of the myeloma-susceptible C57BL/KaLwRij mouse strain, when compared with the myeloma-resistant C57BL/6 mouse. Over-expression of PTTG1 has previously been associated with malignant progression and an enhanced proliferative capacity in solid tumours.

Methods

In this study, we investigated PTTG1 gene and protein expression in MM plasma cells from newly diagnosed MM patients. Gene expression profiling was used to identify gene signatures associated with high PTTG1 expression in MM patients. Additionally, we investigated the effect of short hairpin ribonucleic acid (shRNA)-mediated PTTG1 knockdown on the proliferation of the murine myeloma plasma cell line 5TGM1 in vitro and in vivo.

Results

PTTG1 was found to be over-expressed in 36–70 % of MM patients, relative to normal controls, with high PTTG1 expression being associated with poor patient outcomes (hazard ratio 2.49; 95 % CI 1.28 to 4.86; p = 0.0075; log-rank test). In addition, patients with high PTTG1 expression exhibited increased expression of cell proliferation-associated genes including CCNB1, CCNB2, CDK1, AURKA, BIRC5 and DEPDC1. Knockdown of Pttg1 in 5TGM1 cells decreased cellular proliferation, without affecting cell cycle distribution or viability, and decreased expression of Ccnb1, Birc5 and Depdc1 in vitro. Notably, Pttg1 knockdown significantly reduced MM tumour development in vivo, with an 83.2 % reduction in tumour burden at 4 weeks (p < 0.0001, two-way ANOVA).

Conclusions

This study supports a role for increased PTTG1 expression in augmenting tumour development in a subset of MM patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-015-0209-2) contains supplementary material, which is available to authorized users.

The New Molecular Landscape of Cushing's Disease

Cushing's disease (CD) is caused by corticotropin-secreting pituitary adenomas and results in substantial morbidity and mortality. Its molecular basis has remained poorly understood until the past few years, when several proteins and genes [such as testicular orphan nuclear receptor 4 (TR4) and heat shock protein 90 (HSP90)] were found to play key roles in the disease. Most recently, mutations in the gene of ubiquitin-specific peptidase 8 (USP8) increasing its deubiquination activity were discovered in a high percentage of corticotroph adenomas. Here, we will discuss emerging insights in the molecular alterations that finally result in CD. The therapeutic potential of these findings needs to be carefully evaluated in the near future, hopefully resulting in new treatment options for this devastating disorder.

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.

Update on prognostic factors in acromegaly: Is a risk score possible?

Certain clinical conditions and markers have recently been demonstrated to modify the natural history of acromegaly in affected patients. Thus, some clinical, histological, radiological and molecular factors are associated with more aggressive pituitary tumors that have higher biochemical activity, higher tumor volumes and decreased tumoral and biochemical responses to current therapies. However, these factors do not seem to have an equal influence on the prognosis of patients with acromegaly. We present a review of the factors that influence the clinical course of patients with acromegaly and propose a risk value for each factor that will allow prognostic scoring for affected patients by considering a combination of these factors.

The impact of immunohistochemical markers of Ki-67 and p53 on the long-term outcome of growth hormone-secreting pituitary adenomas: A cohort study

BACKGROUND AND OBJECTIVES

The tumoral biomarkers have a rather well known effect upon the tumor control period of several types of malignant lesions. The aim of this study was to evaluate the impact of immunohistochemical (IHC) markers of Ki-67 and p53 on the long-term outcome of growth hormone (GH)-secreting pituitary adenomas treated surgically.

MATERIALS AND METHODS

We conducted and followed a cohort of 47 consecutive patients with GH-secreting pituitary adenomas referred to our department during a 4 year period for trans-sphenoidal microsurgical adenomectomy. The expression levels of Ki-67 and p53 were determined by IHC study of the tissue samples. Periodical pituitary magnetic resonance imaging (MRI), visual field studies and hormonal evaluations (GH and insulin-like growth factor-1 [IGF-1]) performed during the follow-up period were the outcome measures.

RESULTS

The level of Ki-67 expression was higher among patients with postoperative residual tumor (3.5 vs. 1.7%) and those with a hormonal recurrence (4.3 vs. 1.6%). The p53 expression level was remarkably higher in patients with radiological recurrence (18 vs. 6.3%). Patients with invasive features (i.e. cavernous sinus and suprasellar invasion) had significantly higher p53 and Ki-67 values and higher IGF-1 levels during the follow-up period. The patients younger than 30 years of age and those with mixed GH-prolactin secreting adenomas had significantly higher hormonal remission and lower radiological recurrence rates.

CONCLUSION

Each of the biomarkers, Ki-67 and p53, along with patient's age and mixed GH-prolactin secretion showed a kind of correlation with each of aspects of the clinical, hormonal and radiologic outcome of GH-secreting pituitary adenomas in this series.

Typical and atypical pituitary adenomas: a single-center analysis of outcome and prognosis

BACKGROUND AND OBJECTIVE

In 2004, the World Health Organization defined atypical pituitary adenomas as those with a Ki-67 expression > 3%, an excessive p53 expression and increased mitotic activity. As the usefulness of this classification is controversial, we reviewed typical and atypical pituitary adenomas to compare the clinical and prognostic features.

PATIENTS AND METHODS

We retrospectively reviewed 343 consecutive pituitary adenomas. Atypical pituitary adenomas represented 18.7% of cases. All patients were operated on at the Department of Neurosurgery of our institution and were followed up at the Hypothalamic-Pituitary Disease Unit of the same institution. The median follow-up time was 75 months (range 7-345).

RESULTS

Younger age at diagnosis as well as immunohistochemical positivity for adrenocorticotropic hormone and prolactin correlated with a higher risk of atypical pituitary adenomas, whereas typical and atypical pituitary adenomas did not differ with regard to gender, tumor size, recurrence risk and disease-free survival time (DFST). Among the 219 patients who underwent radical surgery, a Ki-67 expression ≥ 1.5% was associated with a higher risk of recurrence and a worse DFST, even after correction for age at diagnosis, gender, immunohistochemical classification, tumor size, invasiveness and Knosp classification [p = 0.01; hazard ratio (HR) 2.572; 95% confidence interval (CI) 1.251-5.285). Pituitary adenomas with a Ki-67 expression ≥ 1.5% showed a worse DFST as compared to pituitary adenomas with a Ki-67 expression < 1.5% (HR 2.166; 95% CI 1.154-4.064).

CONCLUSION

In this series, atypical and typical pituitary adenomas did not differ with regard to recurrence and DFST. Pituitary adenomas with a Ki-67 expression ≥ 1.5% showed a higher recurrence risk and a worse DFST as compared to those with a Ki-67 expression < 1.5%. We suggest that a Ki-67 expression ≥ 1.5% may be useful as a prognostic marker, though this will need to be confirmed by prospective, multicenter data.

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.