MicroRNA involvement in a metastatic non-functioning pituitary carcinoma

Clinical features of pituitary carcinoma: analysis based on a case report and literature review

Introduction

Pituitary carcinoma (PC) is an extremely rare tumor of the adenohypophysis, which manifests as craniospinal dissemination and/or systemic metastasis. The diagnosis of PC is particularly difficult, as the clinical diagnosis only can be made after the metastasis is found. Owing to the complex diagnostic process and less effective treatments, the clinical prognosis of PC is usually very poor. Hence, it is of great significance to illustrate the diagnosis and treatment course of PC.

Methods

In this case report, we described a 48-year-old male patient who was diagnosed with pituitary adenoma (PA) initially and then was diagnosed with PC eventually after spinal cord metastasis was found, and we illustrated the treatment course as well. Furthermore, we summarized all the published case reports until now and provided a comprehensive review of the diagnosis, treatment, prediction, and clinical outcome of PC.

Results and Conclusions

We found that most PC patients had adrenocorticotropic hormone/prolactin (ACTH/PRL)-secreting tumors, Ki-67 ≥ 10%, and P53 positivity, which may have the potential to predict the transformation from PA to PC; surgery excision combined with temozolomide (TMZ) and radiotherapy is helpful to prolong the survival of PC patients.

MiRNA Signatures Related to Invasiveness and Recurrence in Patients With Non-Functioning Pituitary Neuroendocrine Tumors

PURPOSE

This preliminary study aimed to analyze and identify differentially expressed miRNAs in Bulgarian patients with non-functioning pituitary neuroendocrine tumors (NFPitNET). The relationship between deregulated miRNAs and tumor invasiveness, recurrence, and size was determined.

METHODS

Twenty patients with NFPitNET were selected and fresh pituitary tumor tissues were collected. RNA containing miRNAs were isolated using miRNAeasy mini kit and analyzed by quantitative real-time polymerase chain reaction (PCR) using LNA miRNA Cancer-Focus PCR Panel (Qiagen).

RESULTS

Three miRNAs (miR-210-3p, miR-149-3p, and miR-29b-3p) were deregulated in invasive compared to non-invasive NFPitNETs. Differential expression of four-miRNA signatures - miRNA-17, miR-19, miR-106a, and miR-20, correlated with patient recurrence.

CONCLUSION

This prospective pilot study selected a unique miRNA expression profile, that correlates with invasiveness and recurrence in non-functioning pituitary neuroendocrine tumors. Moreover, some of the selected miRNAs are reported for the first time in patients with this disease, shedding light on the molecular mechanisms involved in pituitary pathogenesis. The identified miRNAs demonstrate potential as biomarkers, deserving further investigation in a larger cohort to validate their clinical applicability.

Discerning the Prospects of miRNAs as a Multi-Target Therapeutic and Diagnostic for Alzheimer's Disease

Although over the last few decades, numerous attempts have been made to halt Alzheimer's disease (AD) progression and mitigate its symptoms, only a few have been proven beneficial. Most medications available, still only cater to the symptoms of the disease rather than fixing the cause at the root level. A novel approach involving the use of miRNAs, which work on the principle of gene silencing, is being explored by scientists. Naturally present miRNAs in the biological system help to regulate various genes than may be implicated in AD-like BACE-1 and APP. One miRNA thus, holds the power to keep a check on several genes, conferring it the ability to be used as a multi-target therapeutic. With aging and the onset of diseased pathology, dysregulation of these miRNAs is observed. This flawed miRNA expression is responsible for the unusual buildup of amyloid proteins, fibrillation of tau proteins in the brain, neuronal death and other hallmarks leading to AD. The use of miRNA mimics and miRNA inhibitors provides an attractive perspective for fixing the upregulation and downregulation of miRNAs that led to abnormal cellular activities. Furthermore, the detection of miRNAs in the CSF and serum of diseased patients might be considered an earlier biomarker for the disease. While most of the therapies designed around AD have not succeeded completely, the targeting of dysregulated miRNAs in AD patients might give a new direction to scholars to develop an effective treatment for Alzheimer's disease.

Non-coding RNAs and exosomal non-coding RNAs in pituitary adenoma

Pituitary adenoma (PA) is the third most common primary intracranial tumor in terms of overall disease incidence. Although they are benign tumors, they can have a variety of clinical symptoms, but are mostly asymptomatic, which often leads to diagnosis at an advanced stage when surgical intervention is ineffective. Earlier identification of PA could reduce morbidity and allow better clinical management of the affected patients. Non-coding RNAs (ncRNAs) do not generally code for proteins, but can modulate biological processes at the post-transcriptional level through a variety of molecular mechanisms. An increased number of ncRNA expression profiles have been found in PAs. Therefore, understanding the expression patterns of different ncRNAs could be a promising method for developing non-invasive biomarkers. This review summarizes the expression patterns of dysregulated ncRNAs (microRNAs, long non-coding RNAs, and circular RNAs) involved in PA, which could one day serve as innovative biomarkers or therapeutic targets for the treatment of this neoplasia. We also discuss the potential molecular pathways by which the dysregulated ncRNAs could cause PA and affect its progression.

Non-functioning pituitary carcinoma: Case report and literature review

INTRODUCTION AND IMPORTANCE

Non-functional pituitary carcinoma is a rare neuroendocrine tumor. It is characterized by the presence of cerebrospinal or distant metastasis of an adenohypophysis tumor without any hypersecretion. Only a few cases of non-functional pituitary carcinomas have been reported in the literature.

CASE PRESENTATION

In this paper, we report the case of a 48-year-old female patient who presented with spinal pain and a mass facing the second thoracic vertebrae. Spinal magnetic resonance imaging (MRI) revealed the presence of pituitary and bilateral adrenal incidentalomas. The patient was operated and the histopathological examination of the specimen revealed a non-functional pituitary carcinoma variety "Null Cell".

DISCUSSION AND CONCLUSION

There are no clinical, biological, or radiological characteristics that reliably differentiate between non-functional pituitary adenoma and non-functional pituitary carcinoma. Management remains a challenge for clinicians and neurosurgeons. A combination of surgery, chemotherapy, and radiotherapy seems necessary to achieve tumor control.

The Involvement of miRNAs in Pituitary Adenomas Pathogenesis and the Clinical Implications

Pituitary adenomas (PAs) account for the top three primary intracranial tumors in terms of total incidence rate. PAs can cause severe endocrine disorders and even malignant features, such as invasion, metastasis, and recurrence. Therefore, the early diagnosis and accurate prognosis would be greatly beneficial for clinical treatment of PAs. MicroRNAs (miRNAs) are small, protein-noncoding RNAs that regulate gene expression posttranscriptionally. They regulate essential physiological processes, including proliferation, growth, and apoptosis, and also they involve in the invasion and metastasis of malignant tumors. At the tissue level, differential miRNA expression in endocrine malignancies including PAs has been reported. When miRNAs have been successfully detected in various biofluids and cell-free environments, their important roles as potential screening or prognostic biomarkers have been extensively investigated. The current work reviews recent studies on the emerging roles of miRNAs in PAs and the clinical significance.

The Role of MicroRNAs in Therapeutic Resistance of Malignant Primary Brain Tumors

Brain tumors in children and adults are challenging tumors to treat. Malignant primary brain tumors (MPBTs) such as glioblastoma have very poor outcomes, emphasizing the need to better understand their pathogenesis. Developing novel strategies to slow down or even stop the growth of brain tumors remains one of the major clinical challenges. Modern treatment strategies for MPBTs are based on open surgery, chemotherapy, and radiation therapy. However, none of these treatments, alone or in combination, are considered effective in controlling tumor progression. MicroRNAs (miRNAs) are 18-22 nucleotide long endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level by interacting with 3'-untranslated regions (3'-UTR) of mRNA-targets. It has been proven that miRNAs play a significant role in various biological processes, including the cell cycle, apoptosis, proliferation, differentiation, etc. Over the last decade, there has been an emergence of a large number of studies devoted to the role of miRNAs in the oncogenesis of brain tumors and the development of resistance to radio- and chemotherapy. Wherein, among the variety of molecules secreted by tumor cells into the external environment, extracellular vesicles (EVs) (exosomes and microvesicles) play a special role. Various elements were found in the EVs, including miRNAs, which can be transported as part of these EVs both between neighboring cells and between remotely located cells of different tissues using biological fluids. Some of these miRNAs in EVs can contribute to the development of resistance to radio- and chemotherapy in MPBTs, including multidrug resistance (MDR). This comprehensive review examines the role of miRNAs in the resistance of MPBTs (e.g., high-grade meningiomas, medulloblastoma (MB), pituitary adenomas (PAs) with aggressive behavior, and glioblastoma) to chemoradiotherapy and pharmacological treatment. It is believed that miRNAs are future therapeutic targets in MPBTs and such the role of miRNAs needs to be critically evaluated to focus on solving the problems of resistance to therapy this kind of human tumors.

Corticotroph Aggressive Pituitary Tumors and Carcinomas Frequently Harbor ATRX Mutations

CONTEXT

Aggressive pituitary tumors (APTs) are characterized by unusually rapid growth and lack of response to standard treatment. About 1% to 2% develop metastases being classified as pituitary carcinomas (PCs). For unknown reasons, the corticotroph tumors are overrepresented among APTs and PCs. Mutations in the alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene, regulating chromatin remodeling and telomere maintenance, have been implicated in the development of several cancer types, including neuroendocrine tumors.

OBJECTIVE

To study ATRX protein expression and mutational status of the ATRX gene in APTs and PCs.

DESIGN

We investigated ATRX protein expression by using immunohistochemistry in 30 APTs and 18 PCs, mostly of Pit-1 and T-Pit cell lineage. In tumors lacking ATRX immunolabeling, mutational status of the ATRX gene was explored.

RESULTS

Nine of the 48 tumors (19%) demonstrated lack of ATRX immunolabelling with a higher proportion in patients with PCs (5/18; 28%) than in those with APTs (4/30;13%). Lack of ATRX was most common in the corticotroph tumors, 7/22 (32%), versus tumors of the Pit-1 lineage, 2/24 (8%). Loss-of-function ATRX mutations were found in all 9 ATRX immunonegative cases: nonsense mutations (n = 4), frameshift deletions (n = 4), and large deletions affecting 22-28 of the 36 exons (n = 3). More than 1 ATRX gene defect was identified in 2 PCs.

CONCLUSION

ATRX mutations occur in a subset of APTs and are more common in corticotroph tumors. The findings provide a rationale for performing ATRX immunohistochemistry to identify patients at risk of developing aggressive and potentially metastatic pituitary tumors.

Non-functional recurrent pituitary adenoma with intracranial metastasis-Pituitary carcinoma: A case report and review of the literature

INTRODUCTION

Pituitary carcinomas are rare, with only a few case reports to date. We present a null cell type non-functioning pituitary carcinoma (NFPC) with intracranial metastases and a review of the literature.

CASE REPORT

A 56-year-old male with a history of an aggressive pituitary adenoma was admitted. Initial MRI highlighted a large intracranial mass with leptomeningeal involvement, simulating meningioma. Based on his previous pathology report of the sellar mass, a diagnosis of null cell type non-functioning pituitary carcinoma has been made.

CONCLUSIONS

An aggressive recurrent pituitary tumor with suprasellar and/or cavernous sinus invasion is the main characteristics of the NFPC. Single or multiple enhancing dural-based mass(es) mimicking meningioma is the most common MRI finding. The proof of malignancy is the same histopathological features of the recurrent aggressive pituitary tumor in the metastases. The histology alone is not distinctive in terms of malignancy. Most patients require a combined surgery, radiotherapy and chemotherapy.

Novel Insights into Pituitary Tumorigenesis: Genetic and Epigenetic Mechanisms

Substantial advances have been made recently in the pathobiology of pituitary tumors. Similar to many other endocrine tumors, over the last few years we have recognized the role of germline and somatic mutations in a number of syndromic or nonsyndromic conditions with pituitary tumor predisposition. These include the identification of novel germline variants in patients with familial or simplex pituitary tumors and establishment of novel somatic variants identified through next generation sequencing. Advanced techniques have allowed the exploration of epigenetic mechanisms mediated through DNA methylation, histone modifications and noncoding RNAs, such as microRNA, long noncoding RNAs and circular RNAs. These mechanisms can influence tumor formation, growth, and invasion. While genetic and epigenetic mechanisms often disrupt similar pathways, such as cell cycle regulation, in pituitary tumors there is little overlap between genes altered by germline, somatic, and epigenetic mechanisms. The interplay between these complex mechanisms driving tumorigenesis are best studied in the emerging multiomics studies. Here, we summarize insights from the recent developments in the regulation of pituitary tumorigenesis.

MiRNAs as Noninvasive Biomarkers and Therapeutic Agents of Pituitary Adenomas

Pituitary adenoma (PA) accounts for 10-15% of all intracranial neoplasms. Even though most pituitary adenomas are benign, it is known that almost 35% of them exhibit an aggressive clinical course, including rapid proliferative activity and invasion of neighboring tissues. MicroRNAs (miRNAs) are short single-stranded RNA molecules that can influence post-transcriptional regulation by controlling target genes. Based on research data on miRNAs over the past 20 years, more than 60% of genes encoding human proteins are regulated by miRNAs, which ultimately control basic cellular mechanisms, including cell proliferation, differentiation, and apoptosis. Dysregulation of miRNAs has been observed in a number of diseases, especially tumors like PA. A majority of miRNAs are expressed within the cells themselves. However, the circulating miRNAs can be detected in several biological fluids of the human body. The identification of circulating miRNAs as new molecular markers may increase the ability to detect a tumor, predict the course of a disease, plan to choose suitable treatment, and diagnose at the earliest signs of impending neoplastic transformation. Therapy of PAs with aggressive behavior is a complex task. When surgery and chemotherapy fail, radiotherapy becomes the treatment of choice against PAs. Therefore, the possibility of implementing circulating miRNAs as innovative diagnostic and therapeutic agents for PA is one of the main exciting ideas.

L-type amino acid transporter 1, LAT1, in growth hormone-producing pituitary tumor cells

Pituitary tumors (PTs) can cause significant mortality and morbidity due to limited therapeutic options. L-type amino acid transporters (LATs), in particular, the LAT1 isoform, is expressed in a variety of tumor cells. Pharmacological inhibition or genetic ablation of LAT1 can suppress leucine transport into cancer cells, resulting in suppression of cancer cell growth. However, roles of LAT1 in PTs have not been elucidated. Therefore, we assessed LAT1 expression in PTs and evaluated a LAT1-specific inhibitor, JPH203, on rat somatomammotroph tumor cells, GH4 cells. GH4 cells dominantly express LAT1 mRNA rather than other LAT isoforms, whereas LAT2 transcripts were most abundant in normal rat pituitary tissues. JPH203 inhibited leucine uptake and cell growth in GH4 cells in a concentration-dependent manner, and appeared to be independent of the mechanistic target, the rapamycin pathway. Although JPH203 did not induce apoptosis, it suppressed growth hormone production in GH4 cells. Also, genetic downregulation of LAT1 showed similar effects on cell growth and hormone production. These results indicated that restriction of LAT1 substrates by JPH203 modulated both cell growth and hormone production. In conclusion, LAT1 may be a new therapeutic target for PTs because its inhibition leads to suppression of cell growth as well as hormone production. JPH203 may represent a promising drug for clinical use in patients with PTs, with the potential of hormonal control and tumor suppression.

Contemporary Management of Clinically Non-functioning Pituitary Adenomas: A Clinical Review

Non-functioning pituitary adenomas (NFPAs) are benign pituitary tumours that constitute about one-third of all pituitary adenomas. They typically present with symptoms of mass effects resulting in hypopituitarism, visual symptoms, or headache. Most NFPAs are macroadenomas (>1 cm in diameter) at diagnosis that can occasionally grow quite large and invade the cavernous sinus causing acute nerve compression and some patients may develop acute haemorrhage due to pituitary apoplexy. The progression from benign to malignant pituitary tumours is not fully understood; however, genetic and epigenetic abnormalities may be involved. Non-functioning pituitary carcinoma is extremely rare accounting for only 0.1% to 0.5 % of all pituitary tumours and presents with cerebrospinal, meningeal, or distant metastasis along with the absence of features of hormonal hypersecretion. Pituitary surgery through trans-sphenoidal approach has been the treatment of choice for symptomatic NFPAs; however, total resection of large macroadenomas is not always possible. Recurrence of tumours is frequent and occurs in 51.5% during 10 years of follow-up and negatively affects the overall prognosis. Adjuvant radiotherapy can decrease and prevent tumour growth but at the cost of significant side effects. The presence of somatostatin receptor types 2 and 3 (SSTR3 and SSTR2) and D2-specific dopaminergic receptors (D2R) within NFPAs has opened a new perspective of medical treatment for such tumours. The effect of dopamine agonist from pooled results on patients with NFPAs has emerged as a very promising treatment modality as it has resulted in reduction of tumour size in 30% of patients and stabilization of the disease in about 58%. Despite the lack of long-term studies on the mortality, the available limited evidence indicates that patients with NFPA have higher standardized mortality ratios (SMR) than the general population, with women particularly having higher SMR than men. Older age at diagnosis and higher doses of glucocorticoid replacement therapy are the only known predictors for increased mortality.

Increased E2F1 mRNA and miR-17-5p Expression Is Correlated to Invasiveness and Proliferation of Pituitary Neuroendocrine Tumours

miR-17-5p and E2F1 have been described as deregulated in cancer, but they have scarcely been studied in pituitary neuroendocrine tumours (PitNETs). This study evaluates the relationship of E2F1 and miR-17-5p with the invasiveness and proliferation of PitNETs. In this cross-sectional descriptive study, we evaluated the expression of E2F1, MYC, and miR-17-5p by quantitative real time PCR analysis in 60 PitNETs: 29 gonadotroph (GT), 15 functioning somatotroph (ST), and 16 corticotroph (CT) tumours, of which 8 were silent (sCT). The clinical data were collected from the Spanish Molecular Register of Pituitary Adenomas (REMAH) database. We defined invasiveness according to the Knosp classification and proliferation according to a molecular expression of Ki-67 ≥ 2.59. E2F1 was more expressed in invasive than in non-invasive tumours in the whole series (p = 0.004) and in STs (p = 0.01). In addition, it was overexpressed in the silent subtypes (GTs and sCTs; all macroadenomas) and normoexpressed in the functioning ones (fCTs and STs; some microadenomas). miR-17-5p was more expressed in proliferative than in non-proliferative tumours (p = 0.041) in the whole series but not by subtypes. Conclusions: Our study suggests that in PitNETs, E2F1 could be a good biomarker of invasiveness, and miR-17-5p of proliferation, helping the clinical management of these tumours.

MiR-219a-2-3p suppresses cell proliferation and promotes apoptosis by targeting MDM2/p53 in pituitary adenomas cells

Pituitary adenomas constitute one of the most common intracranial tumors. MicroRNAs play an important role in development and progression of pituitary adenomas. In this study, we showed that miR-219a-2-3p was significantly down-regulated in pituitary adenomas cells. Overexpression of miR-219a-2-3p suppressed the proliferation and promoted apoptosis of pituitary adenomas cells. After bioinformatics analysis, we found that MDM2 was one of the downstream targets of miR-219a-2-3p. Further researches showed that miR-219a-2-3p could reduce the protein level of MDM2 by binding to the 3'-UTR of MDM2 and promoted p53 expression. Then, we overexpressed both miR-219a-2-3p and MDM2 in the same group and found that it could counteract the effect of overexpressing miR-219a-2-3p alone on proliferation and apoptosis of pituitary adenoma cells. Taken together, these results suggested that miR-219a-2-3p regulated the proliferation and apoptosis by targeting MDM2/p53 in pituitary adenomas. Therefore, miR-219a-2-3p may serve as a novel marker and therapeutic target for pituitary adenomas.

Epigenetic dysregulation in pituitary tumors

Pituitary tumors are common intracranial neoplasms associated with significant morbidity due to hormonal dysregulation and neurologic symptoms. Somatic mutations are uncommon in sporadic pituitary adenomas, and only few monogenic conditions are associated with pituitary tumors. However, increasing evidence suggests that aberrant epigenetic modifications are found in pituitary tumors. In this review, we describe these mechanisms, including DNA methylation, histone modification and microRNA expression, and the evidence supporting their dysregulation in pituitary tumors, as well as their regulation of pro-tumorigenic genes. In addition, we provide an overview of findings from preclinical studies investigating the use of histone deacetylase inhibitors to treat pituitary adenomas and the need for further studies involving epigenetic drugs and functional characterization of epigenetic dysregulation.

Insights into pituitary tumorigenesis: from Sanger sequencing to next-generation sequencing and beyond

Introduction: This review explores insights provided by next-generation sequencing (NGS) of pituitary tumors and the clinical implications.Areas covered: Although syndromic forms account for just 5% of pituitary tumours, past Sanger sequencing studies pragmatically focused on them. These studies identified mutations in MEN1, CDKN1B, PRKAR1A, GNAS and SDHx causing Multiple Endocrine Neoplasia-1 (MEN1), MEN4, Carney Complex-1, McCune Albright Syndrome and 3P association syndromes, respectively. Furthermore, linkage analysis of single-nucleotide polymorphisms identified AIP mutations in 20% with familial isolated pituitary adenomas (FIPA). NGS has enabled further investigation of sporadic tumours. Thus, mutations of USP8 and CABLES1 were identified in corticotrophinomas, BRAF in papillary craniopharyngiomas and CTNNB1 in adamantinomatous craniopharyngiomas. NGS also revealed that pituitary tumours occur in the DICER1 syndrome, due to DICER1 mutations, and CDH23 mutations occur in FIPA. These discoveries revealed novel therapeutic targets and studies are underway of BRAF inhibitors for papillary craniopharyngiomas, and EGFR and USP8 inhibitors for corticotrophinomas.Expert opinion: It has become apparent that single-nucleotide variants and small insertion/deletion DNA mutations cannot explain all pituitary tumorigenesis. Integrated and improved analyses including whole-genome sequencing, copy number, and structural variation analyses, RNA sequencing and epigenomic analyses, with improved genomic technologies, are likely to further define the genomic landscape.

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.

Identification of microRNAs associated with the aggressiveness of prolactin pituitary tumors using bioinformatic analysis

Aggressive prolactin pituitary tumors, which exhibit aggressive behaviors and resistance to conventional treatments, are a huge challenge for neurosurgeons. Many studies have investigated the roles of microRNAs (miRNAs) in pituitary tumorigenesis, invasion and metastasis, but few have explored aggressiveness‑associated miRNAs in aggressive pituitary tumors. Differentially expressed miRNAs (DEMs) between aggressive and nonaggressive prolactin pituitary tumors were screened using the GSE46294 miRNA expression profile downloaded from the GEO database. The potential target genes of the top three most highly upregulated and downregulated DEMs were predicted by miRTarBase, and potential functional annotation and pathway enrichment analysis were performed using the DAVID database. Protein‑protein interaction (PPI) and miRNA‑hub gene interaction networks were constructed by Cytoscape software. A total of 43 DEMs were identified, including 19 upregulated and 24 downregulated miRNAs, between aggressive and nonaggressive prolactin pituitary tumors. One hundred and seventy and 680 target genes were predicted for the top three most highly upregulated and downregulated miRNAs, respectively, and these genes were involved in functional enrichment pathways, such as regulation of transcription from RNA polymerase II promoter, DNA‑templated transcription, Wnt signaling pathway, protein binding, and transcription factor activity (sequence‑specific DNA binding). In the PPI network, the top 10 genes with the highest degree of connectivity of the upregulated and downregulated DEMs were selected as hub genes. By constructing an miRNA‑hub gene network, it was found that most hub genes were potentially modulated by hsa‑miR‑489 and hsa‑miR‑520b. Targeting hsa‑miR‑489 and hsa‑miR‑520b may provide new clues for the diagnosis and treatment of aggressive prolactin pituitary tumors.

Pituitary carcinomas: review of the current literature and report of atypical case

Introduction: Pituitary carcinomas are poorly understood, rare entities. They are distinguished from adenomas not by histopathological features but rather by the presence of metastases.Objective: We discuss the diagnosis, mechanism of dissemination and pathogenesis based on a review of the literature and illustrated by a singular case.Case Report: A 59-year-old male presented with a dural-based posterior fossa lesion. He had been diagnosed with a pituitary chromophobe adenoma 43 years earlier that was treated at the time with surgery and radiation therapy. A presumptive diagnosis of a radiation-induced meningioma was made and surgery was recommended. At surgery the tumour resembled a pituitary adenoma. Histopathology, laboratory findings, and the patient's medical history confirmed the final diagnosis of a prolactin-secreting pituitary carcinoma. To our knowledge, this is the longest reported interval between the pituitary adenoma and metastatic lesion diagnosis (43 years).Conclusion: Management should be tailored to individual patient and may include a combination of treatments (surgery, radiation therapy, chemotherapy, and hormone-targeted therapy). Functionally active tumours may be monitored with hormone levels as tumour markers.

LINC01939 inhibits the metastasis of gastric cancer by acting as a molecular sponge of miR-17-5p to regulate EGR2 expression

Accumulating evidence have suggested that long noncoding RNAs (lncRNAs) are known to regulate diverse tumorigenic processes. Recently, a novel lncRNA LINC01939 was underexpressed and emerged as a tumor suppressive lncRNA in gastric cancer (GC). In this study, we aimed to investigate the biological function and molecular mechanism of LINC01939 in GC. We found that LINC01939 expression was significantly downregulated in GC tissues and cell lines. Low expression of LINC01939 was correlated with tumor metastasis and shorter survival in GC patients. Functionally, LINC01939 overexpression remarkably inhibited the invasion and migration of GC cells in vitro and in vivo. Mechanistically, LINC01939 regulated the expression of early growth response 2 (EGR2) protein by competitively binding to miR-17-5p. Upregulation of miR-17-5p reversed GC metastasis and EMT process caused by LINC01939 by rescue analysis. Taken together, these results suggested that LINC01939 repressed GC invasion and migration by functioning as a ceRNA for miR-17-5p to regulate EGR2 expression. Our findings provided a novel prognostic marker and therapeutic target for GC patients.

Identification of Novel Genes Involved in the Pathogenesis of an ACTH-Secreting Pituitary Carcinoma: A Case Report and Literature Review

Pituitary carcinomas (PCs) is considerable uncommon entities with a poor prognosis that represents only 0. 1–0.2% of all pituitary tumors. There are fewer than 150 reported cases up to now. In addition, the molecular pathogenesis leading to malignant pituitary transformation remain unclear due to the rarity of PCs. Here we present an uncommon case of ACTH-secreting PCs and explore the gene mutation following pituitary adenoma transformation. Our detailed clinical, histopathological and molecular detection data suggest that novel genes of ATRX and PTEN were implicated in the pathogenesis of PCs by searching Pubmed and the Web of Science databases as well as Cosmic databank. To the best of our knowledge, this is the first documented rare PCs patient with novel gene mutations that included ATRX and PTEN in addition to TP53. Present finding may therefore provide significant information for targeted therapy of PCs.

Malignant transformation in non-functioning pituitary adenomas (pituitary carcinoma)

Non-functioning pituitary carcinomas (NFPC) are defined as tumours of adenophyseal origin with craniospinal or systemic dissemination, with the absence of a hormonal hypersecretion syndrome. These are a histologically heterogenous group of tumours, comprising gonadotroph, null cell, "silent" tumours of corticotroph, somatotroph or lactotroph cell lineages as well as plurihormonal Pit-1 tumours. NFPC are exceedingly rare, and hence few cases have been described. This review has identified 38 patients with NFPC reported in the literature. Recurrent invasive non-functioning pituitary adenomas (NFPA) were observed in a majority of patients. Various factors have been identified as markers of the potential for aggressive behaviour, including rapid tumour growth, growth after radiotherapy, gain or shift of hormone secretion and raised proliferative markers. Typically, there is a latency of several years from the original presentation with an NFPA to identification of metastases and only 5 cases reported with rapidly progressive malignant disease within 1 month of presentation. Therapeutic options include debulking surgery, radiation therapy and chemotherapy with temozolomide recommended as first line systemic treatment. Although long-term survivors are described, prognosis remains generally very poor (median survival 8 months). Improvements in molecular tumour profiling may assist in predicting tumour behaviour, guide therapeutic choices and identify novel therapies.

Roles of differential expression of microRNA-21-3p and microRNA-433 in FSH regulation in rat anterior pituitary cells

Follicle-stimulating hormone (FSH) secreted by adenohypophyseal cells plays an important role in the regulation of reproduction, but whether microRNAs (miRNAs) regulate the secretion of FSH remains unclear. In the present study, we predicted and screened miRNAs that might act on the follicle-stimulating hormone beta-subunit (FSHb) gene of rats using the TargetScan program and luciferase reporter assays, and the results identified two miRNAs, miR-21-3p and miR-433. We then transfected these miRNAs into rat anterior adenohypophyseal cells and assessed the FSHb expression levels in and FSH secretion by the transfected cells through quantitative PCR and ELISA. The results showed that both miR-21-3p and miR-433 down-regulated the expression levels of FSHb and resulted in the decrease of the secretion of FSH compared with the control group, and treatment with miR-21-3p and miR-433 inhibitors up-regulated the expression levels of FSHb and resulted in the increase of the secretion of FSH. Taken together, our results indicate that miR-21-3p and miR-433 can down-regulate the expression of FSHb by directly targeting the FSHb 3′UTR in rat primary pituitary cells. Our findings provide evidence that miRNAs can regulate FSHb expression and further affect the secretion of FSH and might contribute to the use of miRNAs for the regulation of animal reproduction.

MicroRNAs in pituitary tumors

Since the presence of microRNAs was first observed in normal pituitary, the majority of scientific publications addressing their role and the function of microRNAs in the pituitary have been based on pituitary tumor studies. In this review, we briefly describe the involvement of microRNAs in the synthesis of pituitary hormones and we present a comprehensive inventory of microRNA suppressors and inducers of pituitary tumors. Finally, we summarize the functional role of microRNAs in tumorigenesis, progression and aggressiveness of pituitary tumors, mechanisms contributing to the regulation (transcription factors, genomic modifications or epigenetic) or modulation (pharmacological treatment) of microRNAs in these tumors, and the interest of thoroughly studying the expression of miRNAs in body fluids.

Increased expression of the microRNA 106b~25 cluster and its host gene MCM7 in corticotroph pituitary adenomas is associated with tumor invasion and Crooke's cell morphology

PURPOSE

MCM7 (minichromosome maintenance complex component 7), a DNA replication licensing factor, is a host gene for the oncogenic miR-106b~25 cluster. It has been recently revealed as a relevant prognostic biomarker in a variety of cancers, including pituitary adenomas. The purpose of this study was to assess whether miR-106b~25 and MCM7 levels correlate with tumor invasiveness in a cohort of ACTH-immunopositive adenomas.

METHODS

Tissue samples were obtained intraoperatively from 25 patients with pituitary adenoma. Tumor invasiveness was assessed according to the Knosp grading scale. MCM7, Ki-67 and TP53 levels were assessed by immunohistochemical staining, while the expression of miR-106b-5p, miR-93-5p, miR-93-3p and miR-25-3p were measured using quantitative real-time PCR performed on RNA isolated from FFPE tissues.

RESULTS

We have found a significant increase in MCM7 and Ki-67 labeling indices in invasive ACTHomas. Moreover, MCM7 was ubiquitously overexpressed in Crooke's cell adenomas. The expression of miR-93-5p was significantly elevated in invasive compared to noninvasive tumors. In addition, all four microRNAs from the miR-106b~25 cluster displayed marked upregulation in Crooke's cell adenomas. Remarkably, MCM7 and miR-106b-5p both strongly correlated with Knosp grade. A combination of MCM7 LI and miR-106b~25 cluster expression was able to accurately differentiate invasive from noninvasive tumors and had a significant discriminatory ability to predict postoperative tumor recurrence/progression.

CONCLUSIONS

miR-106b~25 and its host gene MCM7 are potential novel biomarkers for invasive ACTH-immunopositive pituitary adenomas. Additionally, they are both significantly upregulated in rare Crooke's cell adenomas and might therefore contribute to their aggressive phenotype.

Case report: ACTH-secreting pituitary carcinoma metastatic to the liver in a patient with a history of atypical pituitary adenoma and Cushing's disease

Background

Pituitary carcinoma is a rare entity requiring the presence of metastasis to confirm its malignant potential. We report a case of pituitary carcinoma and discuss the diagnosis and management of this lesion in relation to the existing literature.

Case presentation

The patient is a 51-year-old woman with Cushing’s disease and intact adrenal glands who was diagnosed with metastatic pituitary carcinoma to the liver, 29 months after initial resection of an ACTH-secreting primary atypical pituitary adenoma (APA). Prior to detection of this metastasis the patient underwent repeat resection and radiotherapy for residual cavernous sinus disease. The metastatic lesion was detected by interval surveillance of serum ACTH and 24-hour urine cortisol, which despite stable pituitary MRI, were significantly elevated. These abnormalities prompted a PET scan that demonstrated hypermetabolic liver parenchyma, which was suspicious for metastasis on abdominal MRI. An ultrasound-guided liver biopsy demonstrated nests of moderately-differentiated cells with intermediate-sized, monotonous nuclei, distinct nucleoli, and abundant basophilic cytoplasm, confirmed by immunohistochemistry to represent metastatic pituitary carcinoma. The liver lesion was subsequently successfully removed by wedge resection. One year later, the patient’s residual cavernous sinus disease grew markedly, and she was placed on dual-agent chemotherapy consisting of oral temozolomide and capecitabine, with stabilization of her intracranial disease to present, although liver metastases recurred.

Conclusions

Pituitary carcinoma is a rare entity impossible to recognize as a primary tumor because its diagnosis by definition requires the presence of metastasis. Maintaining awareness of the entity and its precursor lesion APA is essential for its accurate pathologic diagnosis and appropriate management.

Effect of miR-106b on Invasiveness of Pituitary Adenoma via PTEN-PI3K/AKT

Background

Pituitary adenomas are mostly benign tumors, although certain cases have invasiveness, which might be related with high expression of miR-106b. The PTEN-PI3K/AKT signal pathway is known to be related with cell migration and invasion. Among these, PTEN is the target gene for miR-106b. Whether miR-106b affects invasiveness of pituitary adenoma via PTEN-PI3K/AKT is unclear.

Material/Methods

Both invasive and non-invasive pituitary adenoma tissue samples were collected from our Neurosurgery Department, in parallel with brain tissues after head contusion surgery. Pituitary adenoma cell line HP75 was cultured in vitro and divided into NC and miR-106b inhibitor groups for measuring cell cycle/proliferation. Malignant growth of cells was measured by agarose gel clonal assay, while cell migration and invasion were reflected by starch assay and Transwell assay, respectively. The expression of PTEN, PI3K/AKT, and MMP-9 was measured.

Results

MiR-106b was significantly up-regulated in pituitary adenoma but PTEN was down-regulated, especially in invasive tumors. The inhibition of miR-106b remarkably suppressed proliferation and anchorage-independent growth of HP75 cells, with major arrest of cell cycles. The inhibition of miR-106b significantly depressed starch healing and invasive potency of cells. A negative targeted regulation existed between miR-106b and PTEN, as the inhibition of miR-106b significantly enhanced PTEN expression, affecting the activity of downstream PI3K/AKT signaling pathway, thus affecting migration and invasion of pituitary adenoma.

Conclusions

MiR-106b can affect migration and invasion of pituitary adenoma cells via regulating PTEN and further activity of the PI3K/AKT signaling pathway and MMP-9 expression.

Genetic aspects of pituitary carcinoma: A systematic review

BACKGROUND

Pituitary carcinoma (PC) is a rare type of malignant intracranial neoplasm defined as distant metastasis of pituitary adenoma (PA). Although PC incidence is low because only 0.1% to 0.2% of PAs ultimately develop into PCs, the prognosis is poor and 66% of patients die within the first year. Existing therapeutic measures, including surgical removal, chemotherapy, and radiotherapy, have limited effectiveness. The lack of efficacy of current treatments is largely caused by the limited understanding of the molecular pathogenesis of PA and the malignant transformation to PC. Therefore, the aim of this systematic review was to summarize published research regarding gene and protein expression in PC to clarify the molecular mechanisms underlying PC genesis and development and identify new candidate diagnostic biomarkers and therapeutic targets for potential use in personalized treatment of PC.

METHODS

We followed the PRISMA guidelines to plan and conduct this systematic review. PubMed, Embase, and Web of Science databases were searched for relevant studies conducted before December 16, 2015 describing the association of PC with gene expression at the mRNA and protein levels. MeSH terms combined with free terms were used to retrieve the references.

RESULTS

In total, 207 records were obtained by primary search, and 32 were included in the systematic review. Compared with normal pituitary gland and/or PA, 30 and 18 genes were found to have higher or lower expression, respectively, in PCs using different analytical methods. Among them, we selected 9 upregulated and 7 downregulated genes for further analysis based on their identification as candidate treatment targets in other cancers, potential clinical application, or further research value.

CONCLUSION

Previous studies demonstrated that many genes promote PC malignant transformation, angiogenesis, invasion, metastasis, and recurrence. Although most of these genes and proteins have not been fully analyzed with regard to their downstream mechanisms or potential diagnostic and therapeutic application, they have the potential to become candidate PC biomarkers and/or molecular targets for guiding personalized treatment. Modern advanced technologies should be utilized in future research to identify more candidate genes for PC pathogenesis, as precisely targeted gene therapies against PC are urgently required.

Strategies to use microRNAs as therapeutic targets

MicroRNAs (miRNAs) are non-coding RNAs generated from endogenous hairpin-shaped transcripts that powerfully regulate gene expression at post-transcriptional level. Each miRNA is capable to regulate the expression levels of hundreds of transcripts and each mRNA may have more than one miRNA recognition sequence. There is emerging evidence that deregulation of miRNA expression leads to the alteration of pivotal physiological functions contributing to the development of diseases and neoplasms, including pituitary adenoma. This review is aimed at providing the up-to-date knowledge concerning deregulated miRNAs of pituitary tumors and their functions. In order to take stock, pituitary tumors have been sub-divided in different classes on the basis of tumor features (histotype, dimension, aggressiveness). The overview takes full consideration of the recent advances in miRNAs role as potential therapeutics and biomarkers.

MicroRNA-106b promotes pituitary tumor cell proliferation and invasion through PI3K/AKT signaling pathway by targeting PTEN

The purpose of this study was to investigate the expression of microRNA-106b (miR-106b) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in pituitary tumor and to confirm whether miR-106b promotes proliferation and invasion of pituitary tumor cells through the PI3K/AKT signaling pathway by targeted regulation of PTEN expression, and thereby to find new targets for the treatment of pituitary tumor. Fifty-five cases of pituitary tumor tissue samples were collected, including 29 cases of invasive pituitary tumor, non-invasive 26 cases, and 8 normal pituitaries. The expression level of miR-106b in pituitary tumor tissue was detected by quantitative real-time PCR, and the expression of PTEN protein was detected by immunohistochemistry. PTEN 3'-untranslated region (UTR) luciferase vector was constructed, and dual-luciferase reporter gene assay was employed to examine the effect of miR-106b on PTEN 3'-UTR luciferase activity. AtT-20 cells were transfected with miR-106b mimics, miR-106b inhibitor, PTEN expression plasmid, and miR-106b mimics + PTEN expression plasmid respectively, and the changes in cellular proliferation and invasion were observed via MTT method and transwell assay respectively. PTEN messenger RNA (mRNA) expression was determined by quantitative real-time PCR, and western blotting was performed to detect the expression of PTEN, PI3K, AKT, and pAKT. miR-106b showed up-regulation in invasive pituitary tumor tissue: the expression level was significantly up-regulated compared with normal tissues and the non-invasive pituitary tumor tissue (P < 0.05). The positive rate of PTEN protein expression in invasive pituitary tumor tissues was significantly lower than in normal and non-invasive tissues (P < 0.01). Dual-luciferase reporter gene assay showed that miR-106b could bind to the 3'-UTR of PTEN specifically and significantly inhibited the luciferase activity, cutting the 46 % (P < 0.01). Down-regulation of miR-106b or up-regulation of PTEN could suppress cell proliferation and invasion of AtT-20 cells, and PTEN expression plasmid could partially simulate the function of miR-106b. Expression of PTEN mRNA and protein decreased significantly in AtT-20 cells overexpressing miR-106b. The expression levels of PI3K and p-AKT were significantly inhibited by miR-106b inhibitor and increased by miR-106b mimics. The expression of miR-106b showed up-regulation in pituitary tumor tissues, while the protein expression of PTEN presented opposite results. The findings of this study further demonstrated that miR-106b as an oncogene regulated the pituitary tumor cell proliferation and invasion in vitro by directly targeting PTEN through the PI3K/AKT signaling pathway. Our study suggests that miR-106b and PTEN are likely to serve as potential diagnostic biomarkers or therapeutic targets for pituitary tumor treatment in the future.

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.