Targeting Raf/MEK/ERK pathway in pituitary adenomas

Advances in the extracellular signal-regulated kinase signaling pathway in silkworms, Bombyx mori (Lepidoptera)

Signaling pathways regulate the transmission of signals during organism growth and development, promoting the smooth and accurate completion of numerous physiological and biochemical reactions. The extracellular signal-regulated kinase (ERK) signaling pathway is an essential pathway involved in regulating various physiological processes, such as cell proliferation, differentiation, adhesion, migration, and more. This pathway also contributes to several important physiological processes in silkworms, including protein synthesis, reproduction, and immune defense against pathogens. Organizing related studies on the ERK signaling pathway in silkworms can provide a better understanding of its mechanism in Lepidopterans and develop a theoretical foundation for improving cocoon production and new strategies for pest biological control.

INTERLEUKIN-6 AND NKG2D AS PROGNOSTIC FACTORS IN IRAQI FEMALES WITH PITUITARY GAND ADENOMA: A LONGITUDINAL STUDY

OBJECTIVE

The aim: To assess the role of circulating IL-6 & NKG2D in the prognosis of pituitary adenoma.

PATIENTS AND METHODS

Materials and methods: Thirty female with new diagnosis of prolactinoma (pituitary gland adenoma) were enrolled in the study. ELISA test was used to evaluate the level of IL6 and NKG2D. ELISA tests were conducted before the initiation of treatment and six months later.

RESULTS

Results: There are significant differences in mean levels of IL-6 and NKG2D, and the anatomical type (tumor size) (-418.7 & 418.9, p<0.001) of anatomical tumor (-373.72 & -373.920, p=0.001). There is a significant difference between the two immunological markers (IL-6 & NKG2D) (-0.305; p<0.001). The IL-6 markers significantly decreased in means on follow up (-197.8; p-value≤0.0001) while the reverse occur in NKG2D, which increased in levels post-treatment compared with baseline measurement. The high expression of IL-6 positively correlated with the risk of macroadenoma (>10 microns) and poor resonse to treatment and vice versa (p<0.024). High expression of NKG2D significantly (p<0.005) correlated with good prognosis and increased chance for tumor response to medicine and shrinkage in size compared with low concentration.

CONCLUSION

Conclusions: The higher the level of IL-6, the larger the size of adenoma (macroadenoma) and the poorer the response to treatment. The higher the level of NKG2D indidcate a better prognosis, therefore, IL-6 and NKG2D correlate negatively in prolactinoma patients.

PDCD10 promotes the aggressive behaviors of pituitary adenomas by up-regulating CXCR2 and activating downstream AKT/ERK signaling

As the second most common primary intracranial neoplasms, about 40% of pituitary adenomas (PAs) exhibit aggressive behaviors and resulting in poor patient prognosis. The molecular mechanisms underlying the aggressive behaviors of PAs are not yet fully understood. Biochemical studies have reported that programmed cell death 10 (PDCD10) is a component of the striatin-interacting phosphatase and kinase (STRIPAK) complex and plays a dual role in cancers in a tissue- or disease-specific manner. In the present study, we report for the first time that the role of PDCD10 in PAs. Cell proliferation, migration and invasion were either enhanced by overexpressing or inhibited by silencing PDCD10 in PA cells. Moreover, PDCD10 significantly promoted epithelial–mesenchymal transition (EMT) of pituitary adenoma cells. Mechanistically, we showed that the expression of CXCR2, together with phosphorylation levels of AKT and ERK1/2 were regulated by PDCD10. Activation of CXCR2 inversed inactivation of AKT/ERK signal pathways and the tumor-suppressive effects induced by PDCD10 silencing. Finally, the pro-oncogenic effect of PDCD10 was confirmed by in vivo tumor grafting. Taken together, we demonstrate for the first time that PDCD10 can induce aggressive behaviors of PAs by promoting cellular proliferation, migration, invasion and EMT through CXCR2-AKT/ERK signaling axis.

Hypogonadism in Male Patients with Pituitary Adenoma and Its Related Mechanism: A Review of Literature

Maintaining normal gonadal axis hormone levels is important for improving the condition of male patients with pituitary adenoma. The current literature is somewhat divided on the results of evaluations of gonadal axis function in male patients with pituitary adenoma before and after treatment, and the increasing demand for better quality of life has provided motivation for this research to continue. In this article, we summarize the feasibility of using testosterone as an indicator for assessing male function and discuss the changes reported in various studies for gonadal hormones before and after treatment in male patients with pituitary adenoma. It is important for clinicians to understand the advantages of each treatment option and the effectiveness of assessing gonadal function. The rationale behind the theory that pituitary adenomas affect gonadal function and the criteria for evaluating pituitary–gonadal axis hormones should be explored in more depth.

CircVPS13C promotes pituitary adenoma growth by decreasing the stability of IFITM1 mRNA via interacting with RRBP1

CircRNAs play important roles in a variety of biological processes by acting as microRNA sponges and protein scaffolds or by encoding functional proteins. However, their functions and underlying mechanisms remain largely unknown. Distinctive circRNA patterns were explored by comparing nonfunctioning pituitary adenomas (NFPAs) and normal pituitary tissues with a circRNA array. The biological functions of selected circRNAs were determined in vitro and in vivo. RNA-seq and circRNA pulldown assays were applied to investigate the underlying mechanisms. The circRNA profile of NFPAs is tremendously different from that of normal pituitary tissues. CircVPS13C is significantly upregulated in NFPA samples and cell lines. Gain- and loss-of-function experiments demonstrate that silencing circVPS13C inhibits the proliferation of pituitary tumor cells in vitro and in vivo. Mechanistically, circVPS13C silencing increases the expression of IFITM1 and subsequently activates its downstream genes involved in MAPK- and apoptosis-associated signaling pathways. Rescue experiments show that IFITM1 overexpression partly reverses the biological effects of circVPS13C. Further studies reveal that circVPS13C inhibits IFITM1 expression through a novel mechanism mainly by competitively interacting with RRBP1, a ribosome-binding protein of the endoplasmic reticulum membrane, and thereby alleviating the stability of IFITM1 mRNA. Clinically, circVPS13C expression is markedly higher in high-risk NFPA samples and is downregulated in patient serum 7 days post-transsphenoidal adenoma resection. Our findings suggest that circVPS13C is a critical regulator in the proliferation and development of NFPAs through a novel mechanism, whereby regulating mRNA stability via interacting with ribosome-binding proteins on the endoplasmic reticulum membrane.

Research advances on the immune research and prospect of immunotherapy in pituitary adenomas

Background

Pituitary adenomas are one type of intracranial tumor, which can be divided into microadenoma (≤ 1 cm), macroadenoma (> 1 cm), and giant adenoma (≥ 4 cm) according to their diametral sizes. They are benign, typically slow-progressing, whereas the biological behavior of some of them is invasive, which presents a major clinical challenge. Treatment of some pituitary adenomas is still difficult due to drug resistance or multiple relapses, usually after surgery, medication, and radiation. At present, no clear prediction and treatment biomarkers have been found in pituitary adenomas and some of them do not cause clinical symptoms, so patients are often found to be ill through physical examination, and some are even found through autopsy. With the development of research on pituitary adenomas, the immune response has become a hot spot and may serve as a novel disease marker and therapeutic target.

The distribution and function of immune cells and their secreted molecules in pituitary adenomas are extremely complex. Researchers found that infiltration of immune cells may have a positive effect on the treatment and prognosis of pituitary adenomas. In this review, we summarized the advance of tumor immunity in pituitary adenomas, revealing the immunity molecules as potential biomarkers as well as therapeutic agents for pituitary adenomas.

Conclusion

The immune studies related to pituitary adenomas may help us find relevant immune markers. At the same time, the exploration of immunotherapy also provides new options for the treatment of pituitary adenomas.

Neurofibromatosis Type 1 with Concurrent Multiple Endocrine Disorders: Adenomatous Goiter, Primary Hyperparathyroidism, and Acromegaly

We encountered a 70-year-old Japanese woman with neurofibromatosis type 1 (NF1) who had a history of pheochromocytoma and concurrently developed adenomatous goiter, primary hyperparathyroidism, and acromegaly. The patient had a somatotroph adenoma of the adenohypophysis that predisposed her to multinodular goiter. Three parathyroid tumors were detected by cervical ultrasonography and cervicothoracic computed tomography. Genetic analyses did not reveal genetic alterations (e.g. loss-of-function mutation) in the causative genes of endocrine tumors, including MEN1, RET, VHL, CDKN1B, and CDKN2C. The NF1 gene could not be analyzed genetically due to the patient's refusal. The pathophysiologic mechanisms of endocrinopathy concurrence in NF1 remain to be elucidated.

B7-H6 Promotes Cell Proliferation, Migration and Invasion of Non-Hodgkin Lymphoma via Ras/MEK/ERK Pathway Based on Quantitative Phosphoproteomics Data

Purpose

B7 homologue 6 (B7-H6) has been found at an up-regulated level in multiple cancer cells and identified to be positively correlated with inferior clinical features. In non-Hodgkin lymphoma (NHL), however, the roles of B7-H6 and the underlying mechanism of action remain unclear. Through in vivo and in vitro experiments, the aim of this study was to explore the regulatory mechanism of B7-H6 in NHL in order to provide new therapeutic strategies that can potentially be applied in clinical practice.

Methods

The expression of B7-H6 in T-lymphoblastic lymphoma (TLBL), diffuse large B cell lymphoma (DLBCL) and lymph node reactive hyperplasia (LRH) tissues were compared by immunohistochemistry. A total of 10 NHL cell lines were screened by Western blot to evaluate the expression of B7-H6. The effects of B7-H6 knockdown on cell proliferation, migration and invasion of NHL cells were studied in vivo using a transplanted tumor mice model, and in vitro by Cell Counting Kit-8 (CCK-8) and Transwell assays. Quantitative phosphoproteomics was performed to identify the changes of protein phosphorylation and related pathways affected by B7-H6. The effects of B7-H6 on NHL were validated via B7-H6 overexpression and pathway inhibitor assays.

Results

The expression levels of B7-H6 in NHL cell lines, and TLBL and DLBCL tissues were significantly increased compared with those in the control groups. Inhibition of cell proliferation, migration and invasion was observed in Jurkat and Raji cells with B7-H6 knockdown. The ability of B7-H6 in promoting tumorigenesis was further validated by in vivo experiments. In addition, Ras and HIF-1 signaling pathways were shown to be significantly affected by B7-H6 through quantitative phosphorylation proteomics analysis. Ras/MEK/ERK pathway was verified to be significantly inhibited after B7-H6 knockdown by Western blot analysis. Strikingly, MEK inhibitor AZD8330 was found to have the ability to sufficiently inhibit Ras/MEK/ERK pathway, partially reverse cell proliferation and completely reverse cell migration and invasion induced by B7-H6.

Conclusion

B7-H6 promotes cell proliferation, migration and invasion in NHL via Ras/MEK/ERK pathway. Hence, B7-H6 or Ras/MEK/ERK pathway targeting may be used as potential therapeutics for treating NHL.

Targeting Opsin4/Melanopsin with a Novel Small Molecule Suppresses PKC/RAF/MEK/ERK Signaling and Inhibits Lung Adenocarcinoma Progression

The identification of oncogenic biomolecules as drug targets is an unmet need for the development of clinically effective novel anticancer therapies. In this study, we report for the first time that opsin 4/melanopsin (OPN4) plays a critical role in the pathogenesis of non-small cell lung cancer (NSCLC) and is a potential drug target. Our study has revealed that OPN4 is overexpressed in human lung cancer tissues and cells, and is inversely correlated with patient survival probability. Knocking down expression of OPN4 suppressed cells growth and induced apoptosis in lung cancer cells. We have also found that OPN4, a G protein-coupled receptor, interacted with Gα11 and triggered the PKC/BRAF/MEK/ERKs signaling pathway in lung adenocarcinoma cells. Genetic ablation of OPN4 attenuated the multiplicity and the volume of urethane-induced lung tumors in mice. Importantly, our study provides the first report of AE 51310 (1-[(2,5-dichloro-4-methoxyphenyl)sulfonyl]-3-methylpiperidine) as a small-molecule inhibitor of OPN4, suppressed the anchorage-independent growth of lung cancer cells and the growth of patient-derived xenograft tumors in mice. IMPLICATIONS: Overall, this study unveils the role of OPN4 in NSCLC and suggests that targeting OPN4 with small molecules, such as AE 51310 would be interesting to develop novel anticancer therapies for lung adenocarcinoma.

Lineage-dependent role of miR-410-3p as oncomiR in gonadotroph and corticotroph pituitary adenomas or tumor suppressor miR in somatotroph adenomas via MAPK, PTEN/AKT, and STAT3 signaling pathways

PURPOSE

miR-410-3p plays opposite roles in different cancers and may act as an oncomiR or tumor suppressor miR. The purpose of this study was to assess the role of miR-410-3p in somatotroph, gonadotroph, and corticotroph pituitary adenomas.

METHODS

Tissue samples were obtained from 75 patients with pituitary adenoma. miR-410-3p expression was assessed using qRT-PCR performed on RNA isolated from fresh frozen samples. In vitro experiments were performed on cell lines derived from somatotroph (GH3), gonadotroph (RC-4B/C), and corticotroph (AtT-20) pituitary tumors. Cells were transfected with synthetic mimic of miR-410-3p or non-targeting scrambled-miR control. Subsequently, proliferation assays and transwell invasion assays were performed. The expression of cyclin D1, E1, and B1 in cells after transfection was determined using qRT-PCR. The activation of MAPK, PTEN/AKT and STAT3 signaling pathways were assessed using western blot.

RESULTS

We have found that the level of expression of miR-410-3p differs in particular types of pituitary adenomas. miR-410-3p significantly upregulates proliferation and invasiveness of RC-4B/C and AtT-20 cells, while inhibiting GH3 cells. We observed that the levels of cyclin B1 upon transfection with miR-410-3p mimic were increased in RC-4B/C and AtT-20, yet decreased in GH3 cells. We have shown that miR-410-3p promoted the activation of MAPK, PTEN/AKT, and STAT3 signaling pathways in RC-4B/C and AtT-20 cells, but suppressed their activity in GH3 cells.

CONCLUSIONS

miR-410-3p acts as an oncomiR in gonadotroph and corticotroph adenoma cells, while as a tumor suppressor miR in somatotroph adenoma cells.

Co-expression Network Analysis Elucidated a Core Module in Association With Prognosis of Non-functioning Non-invasive Human Pituitary Adenoma

Non-functioning pituitary adenomas (NFPAs) are tumors with clinically challenging features since they have insidious progression. A complex network of gene interactions is thought to have roles in tumor formation and progression. Therefore, revealing the genetic network behind NFPA tumorigenesis is not only essential to attain further knowledge of tumor biology, but also plays a fundamental role in the development of efficacious treatment strategies. Differential co-expression network analysis is an outstanding approach for elucidation of groups of genes which show distinct co-expression patterns among phenotypes. In this study, we carried out a differential co-expression network analysis of NFPA-associated transcriptome dataset (n = 40) considering invasive (n = 22) and non-invasive (n = 18) phenotypes. Furthermore, we identified differentially co-expressed and co-regulated mRNA modules, which might be considered as potential systems biomarkers for NFPA prognosis and invasiveness. As a result, we have identified a novel 13-gene module, including CEACAM6, CYP4B1, EIF2S2, HID1, IFFO1, MYO18A, PDCD2, SGIP1, SWSAP1, and four unknown genes (A_24_P127621, A_24_P255786, A_24_P683553, and A_24_P916979), which was able to categorize the patients into two groups as invasive and non-invasive NFPA with distinct prognosis. The prognostic core module genes were associated with progression and prognosis of brain and glandular based cancers as well. Furthermore, these module genes were also expressed in blood, salivary gland, and spinal cord tissues. These results may provide the evidence on featured gene module which might play a prominent role in NFPA prognosis and sub-typing as effective biomarkers and therapeutic targets in the future.

Correlation Between Raf/MEK/ERK Signaling Pathway and Clinicopathological Features and Prognosis for Patients With Breast Cancer Having Axillary Lymph Node Metastasis

Objective:

This study aims to investigate the correlations between rapidly accelerated fibrosarcoma/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase signaling pathway and clinicopathological features and prognosis for patients with breast cancer having axillary lymph node metastasis.

Methods:

A total of 118 breast cancer tissues with axillary lymph node metastasis (axillary lymph node metastasis group), 150 breast cancer tissues with non-axillary lymph node metastasis (non-axillary lymph node metastasis group), and 216 normal breast tissues (normal group) were enrolled in this study. The messenger RNA and protein expressions of rapidly accelerated fibrosarcoma, MEK, extracellular signal-regulated kinase, and their phosphorylated (p-) proteins were examined by reverse transcriptase quantitative polymerase chain reaction and immunohistochemistry, respectively. All patients received a 1-year follow-up, and the clinical follow-up data were collected. The multiple factors on the prognosis of patients with breast cancer having axillary lymph node metastasis were tested by Cox regression analysis.

Results:

The messenger RNA expressions of rapidly accelerated fibrosarcoma, MEK, and extracellular signal-regulated kinase and positive rates of rapidly accelerated fibrosarcoma, MEK, phosphorylated MEK, extracellular signal-regulated kinase, and p-extracellular signal-regulated kinase in the axillary lymph node metastasis group were higher than in the non-axillary lymph node metastasis and normal groups (all P < .05). The protein expressions of rapidly accelerated fibrosarcoma, MEK, phosphorylated MEK, extracellular signal-regulated kinase, and p-extracellular signal-regulated kinase were associated with tumor size, clinical stage, and axillary lymph node metastasis number (all P < .05). Rapidly accelerated fibrosarcoma, MEK, and extracellular signal-regulated kinase expressions were significantly correlated with the prognosis of patients with breast cancer (all P < .05). Patients with BC having positive rapidly accelerated fibrosarcoma, MEK, phosphorylated MEK, extracellular signal-regulated kinase, and phosphorylated ERK expressions had a higher survival rate than patients with BC having the negative ones (all P < .05). Rapidly accelerated fibrosarcoma and extracellular signal-regulated kinase protein expressions, clinical stage, pathological grade, and axillary lymph node metastasis number were independent prognostic factors in patients with breast cancer having axillary lymph node metastasis (all P < .05).

Conclusion:

Our study proved that rapidly accelerated fibrosarcoma/MEK/extracellular signal-regulated kinase signaling pathway is significantly correlated with the clinicopathological features and prognosis for patients with BC having axillary lymph node metastasis. Rapidly accelerated fibrosarcoma and extracellular signal-regulated kinase protein expressions are independent prognostic factors for patients with breast cancer having axillary lymph node metastasis.

Triptolide suppresses growth and hormone secretion in murine pituitary corticotroph tumor cells via NF-kappaB signaling pathway

Triptolide is a principal diterpene triepoxide from the Chinese medical plant Tripterygium wilfordii Hook. f., whose extracts have been utilized in dealing with diverse diseases in traditional Chinese medicine for centuries. Recently, the antitumor effect of triptolide has been found in several pre-clinical neoplasm models, but its effect on pituitary corticotroph adenomas has not been investigated so far. In this study, we are aiming to figure out the antitumor effect of triptolide and address the underlying molecular mechanism in AtT20 murine corticotroph cell line. Our results demonstrated that triptolide inhibited cell viability and colony number of AtT20 cells in a dose- and time-dependent pattern. Triptolide also suppressed proopiomelanocortin (Pomc) mRNA expression and extracellular adrenocorticotropic hormone (ACTH) secretion in AtT20 cells. Flow cytometry prompted that triptolide leaded to G2/M phase arrest, apoptosis program and mitochondrial membrane depolarization in AtT20 cells. Moreover, dose-dependent activation of caspase-3 and decreased Bcl2/Bax proportion were observed after triptolide treatment. By western blot analysis we found that triptolide impeded phosphorylation of NF-κB p65 subunit and extracellular signal-regulated kinase (ERK), along with reduction of cyclin D1, without any impact on other NF-κB related protein expression like total p65, p50, IκB-α, p-IκB-α. Furthermore, the mouse xenograft model revealed the inhibition of tumor growth and hormone secretion after triptolide administration. Altogether this compound might be a potential pharmaceutical choice in managing Cushing's disease.

PI3K/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways inhibitors as anticancer agents: Structural and pharmacological perspectives

The protein kinases regulate cellular functions such as transcription, translation, proliferation, growth and survival by the process of phosphorylation. Over activation of signaling pathways play a major role in oncogenesis. The PI3K signaling pathway is dysregulated almost in all cancers due to the amplification, genetic mutation of PI3K gene and the components of the PI3K pathway themselves. Stimulation of the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK pathways enhances growth, survival, and metabolism of cancer cells. Recently, the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways have been identified as promising therapeutic targets for cancer therapy. The kinase inhibitors with enhanced specificity and improved pharmacokinetics have been considered for design and development of anticancer agents. This review focuses primarily on the Ras/Raf/MEK/ERK and PI3K/Akt/mTOR signaling pathways as therapeutic targets of anticancer drugs, their specific and dual inhibitors, structure activity relationships (SARs) and inhibitors under clinical trials.

Emerging Targets in Pituitary Adenomas: Role of the CXCL12/CXCR4-R7 System

Chemokines are chemotactic regulators of immune surveillance in physiological and pathological conditions such as inflammation, infection, and cancer. Several chemokines and cognate receptors are constitutively expressed in the central nervous system, not only in glial and endothelial cells but also in neurons, controlling neurogenesis, neurite outgrowth, and axonal guidance during development. In particular, the chemokine CXCL12 and its receptors, CXCR4 and CXCR7, form a functional network that controls plasticity in different brain areas, influencing neurotransmission, neuromodulation, and cell migration, and the dysregulation of this chemokinergic axis is involved in several neurodegenerative, neuroinflammatory, and malignant diseases. CXCR4 primarily mediates the transduction of proliferative signals, while CXCR7 seems to be mainly responsible for scavenging CXCL12. Importantly, the multiple intracellular signalling generated by CXCL12 interaction with its receptors influences hypothalamic modulation of neuroendocrine functions, although a direct modulation of pituitary functioning via autocrine/paracrine mechanisms was also reported. Both CXCL12 and CXCR4 are constitutively overexpressed in pituitary adenomas and their signalling induces cell survival and proliferation, as well as hormonal hypersecretion. In this review we focus on the physiological and pathological functions of immune-related cyto- and chemokines, mainly focusing on the CXCL12/CXCR4-7 axis, and their role in pituitary tumorigenesis. Accordingly, we discuss the potential targeting of CXCR4 as novel pharmacological approach for pituitary adenomas.

Emerging drugs for acromegaly

INTRODUCTION

Acromegaly is a rare disease that severely impacts patients' health all the while, being a slowly progressing illness. In the past decades, advancements in treatment modalities, especially development of new drugs, as well as focused guidelines has improved management of acromegaly. Still, many patients are considered not sufficiently treated and there remains an ongoing need for further development.

AREAS COVERED

This article reviews new medical treatments currently under clinical investigation (such as pasireotide, oral octreotide and somatoprim) and under experimental development (such as octreotide implants, CAM2029 and ATL-1103).

EXPERT OPINION

As it seems unlikely that one single agent may achieve cure in 100% of cases, there is an urgent need for new agents that help patients where current medication fails. Imperatively, this means we have to improve our understanding of the underlying pathogenetic and molecular mechanisms.

Genome-wide kinase-chromatin interactions reveal the regulatory network of ERK signaling in human embryonic stem cells

The extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase signal-transduction cascade is one of the key pathways regulating proliferation and differentiation in development and disease. ERK signaling is required for human embryonic stem cells' (hESCs') self-renewing property. Here, we studied the convergence of the ERK signaling cascade at the DNA by mapping genome-wide kinase-chromatin interactions for ERK2 in hESCs. We observed that ERK2 binding occurs near noncoding genes and histone, cell-cycle, metabolism, and pluripotency-associated genes. We find that the transcription factor ELK1 is essential in hESCs and that ERK2 co-occupies promoters bound by ELK1. Strikingly, promoters bound by ELK1 without ERK2 are occupied by Polycomb group proteins that repress genes involved in lineage commitment. In summary, we propose a model wherein extracellular-signaling-stimulated proliferation and intrinsic repression of differentiation are integrated to maintain the identity of hESCs.

Pituitary adenoma pathogenesis: an update

PURPOSE OF REVIEW

To describe the recent efforts to understand the molecular and genetic mechanisms involved in the tumorigenesis of pituitary adenomas.

RECENT FINDINGS

There is rapidly accumulating evidence for the roles of molecular abnormalities in pituitary adenoma tumorigenesis, including dysregulation of the cell cycle, signal transduction pathways, oncogenes and tumor suppressor genes. MicroRNAs have been identified as important participants in gene regulation and may have a role in therapy. Stem cells have also provided novel concepts for tumorigenesis and potentially treatment.

SUMMARY

Pituitary adenomas are relatively common neoplasms, whose pathogenesis is still poorly understood. Although considered by many as benign monoclonal proliferations, their clinical spectrum is diverse including hormone hypersecretion, and various degrees of invasiveness, suggesting multiple steps and mechanisms. This review summarizes recent development in the molecular tumorigenesis of pituitary adenomas emphasizing the dysregulation of the cell cycle components, tumor suppressor genes, oncogenes, stem cells and microRNAs.