Lower PRDM2 expression is associated with dopamine-agonist resistance and tumor recurrence in prolactinomas

Genomics and tumor microenvironment of breast mucoepidermoid carcinoma based on whole-exome and RNA sequencing

Mammary mucoepidermoid carcinoma (MEC) is a rare entity. The molecular characteristics of breast MEC have not been fully investigated due to its rarity. We performed a retrospective study among 1000 patients with breast carcinomas and identified four cases of breast MEC. Clinical and demographic data were collected. Immunohistochemistry panels which were used to diagnose salivary gland MEC and breast carcinomas were also performed. MAML2 rearrangements were detected by FISH and fusion partners were identified by RNA sequencing. Whole-exome sequencing (WES) was used to reveal the genomes of these four breast MEC. Then, the biological functions and features of breast MEC were further compared with those of invasive breast carcinomas and salivary gland MEC.According to Ellis and Auclair's methods, these four breast MEC could be classified as low-grade breast MEC. All the patients were alive, and disease-free survival (PFS) ranged from 20 months to 67 months. Among these four breast MEC, two cases were triple-negative, and the other two cases were found to be ER positive, with one also showing HER2 equivocal by immunohistochemical staining, but no amplification in FISH. FISH analysis confirmed the presence of the MAML2 translocation in three of four tumors, and CRTC1-MAML2 fusion was confirmed in two of them by RNA-sequencing. The average coverage size of WES for the tumor mutation burden estimation was 32 Mb. MUC4, RP1L1 and QRICH2 mutations were identified in at least three tumors, and these mutation also existed in breast invasive carcinoma databases (TCGA, Cell 2015; TCGA, Nature 2012). The results showed that there were many genes in breast MEC overlapping with the breast invasive carcinoma databases mentioned above, range from 5 to 63 genes (median:21 genes). Next, we assessed immune cell infiltration levels in these tumors. In all these tumors, M2 macrophages and plasma cell were in the high infiltration group. Our breast MEC showed different results from the salivary gland MEC, whose plasma cells were in the low infiltration group. Overall, we first analyzed the genomics and tumor microenvironment of breast mucoepidermoid carcinoma and proposed our hypothesis that although MECs arising in the breast resemble their salivary gland counterparts phenotypically, our findings indicate that breast MECs probably resemble invasive breast carcinomas at the genetic level and immune cell infiltration levels. More cases and in deep research need to be done to further understand this rare carcinoma.

Prevalence and clinical correlations of SF3B1 variants in lactotroph tumours

OBJECTIVE

A somatic mutational hotspot in the SF3B1 gene was reported in lactotroph tumours. The aim of our study was to examine the prevalence of driver SF3B1 variants in a multicentre independent cohort of patients with lactotroph tumours and correlate with clinical data.

DESIGN AND METHODS

This was a retrospective, multicentre study involving 282 patients with lactotroph tumours (including 6 metastatic lactotroph tumours) from 8 European centres. We screened SF3B1 exon 14 hotspot for somatic variants using Sanger sequencing and correlated with clinicopathological data.

RESULTS

We detected SF3B1 variants in seven patients with lactotroph tumours: c.1874G > A (p.Arg625His) (n = 4, 3 of which metastatic) and a previously undescribed in pituitary tumours variant c.1873C > T (p.Arg625Cys) (n = 3 aggressive pituitary tumours). In two metastatic lactotroph tumours with tissue available, the variant was detected in both primary tumour and metastasis. The overall prevalence of likely pathogenic SF3B1 variants in lactotroph tumours was 2.5%, but when we considered only metastatic cases, it reached the 50%. SF3B1 variants correlated with significantly larger tumour size; higher Ki67 proliferation index; multiple treatments, including radiotherapy and chemotherapy; increased disease-specific death; and shorter postoperative survival.

CONCLUSIONS

SF3B1 variants are uncommon in lactotroph tumours but may be frequent in metastatic lactotroph tumours. When present, they associate with aggressive tumour behaviour and worse clinical outcome.

[Modern concepts of genetic and immunohistochemical features of prolactin-secreting pituitary adenomas]

Prolactinomas are the most common secreting adenomas of the pituitary. In 20% of cases resistance to dopamine-agonists treatment is observed. Medical therapy resistance causes progression of pathological symptoms of hyperprolactinemia and negative topographic and anatomical changes of prolactinoma. The causes of ineffectiveness of dopamine agonists therapy are not fully understood as well as approaches to managing patients require clarification. Current concepts of resistance are based on the data obtained as a result of surgery or after a period of long-term ineffective therapy. Thus, it is very important to find methods of assessing the sensitivity of prolactin-secreting adenomas to drug therapy before surgical treatment. Genetic and immunohistochemical studies find special place among these methods, making it possible to predict adenoma's response to drug therapy at early diagnostic stage. Obtained results will allow us to form personalized algorithm for managing patients.

Expression and Clinical Significance of MDM2 in Non-Functioning PitNETs

Background and Objective: Non-functioning pituitary neuroendocrine tumors (NF-PitNETs) represent a heterogeneous tumor type that lacks effective medical treatment. MDM2, the main negative regulator of p53, binds to and forms a stable complex with p53 to regulate its activity. In this study, we measured the expression levels and role of MDM2 in non-functioning PitNET patients' combined clinical features and investigated the effect of etoposide on the cell bioactivity of the GT1-1 cell line in vivo and in vitro. Methods: RT-PCR and immunochemistry measured the expression levels and role of MDM2 in 103 NF-PitNET patients' combined clinical features. Cell proliferation, migration, colony and apoptosis experiments measured the effect of etoposide on the GT1-1 cell line in vivo and in vitro. Results: There was more invasive behavior (p = 0.013) in patients with high MDM2, who were also younger (p = 0.007), were more frequently female (p = 0.049) and had larger tumor sizes (p = 0.018) compared with patients with low MDM2. Patients with high p53 were younger (p = 0.017) and had larger tumor sizes (p = 0.034) compared with patients with low p53. Univariate (p = 0.018) and multivariate (p = 0.023) Cox regression analysis showed that MDM2 was the independent factor for invasive behavior in NF-PitNET patients. Log-rank analysis showed that the average progression-free survival (PFS) time in the low MDM2 patients was longer than that in the high MDM2 patients (p = 0.044). Functional studies indicated that etoposide inhibited cell proliferation and cell migration and induced apoptosis in p53 independence in GT1-1 cells. Furthermore, etoposide significantly inhibited the growth of GT1-1-xenograft in BALB/c nude mice. The tumor growth inhibition rate of etoposide was 67.4 ± 4.6% after 14 d of treatment, which suggested the anti-tumor activity of etoposide. Conclusions: MDM2 played the role of tumorigenesis of NF-PitNET in a p53 independence manner, and an MDM2 inhibitor could be a potential choice for the treatment of NF-PitNET patients.

Analysis of Differentially Expressed Genes That Aggravate Metabolic Diseases in Depression

Depression is considered the second leading cause of the global health burden after cancer. It is recognized as the most common physiological disorder. It affects about 350 million people worldwide to a serious degree. The onset of depression, inadequate food intake, abnormal glycemic control and cognitive impairment have strong associations with various metabolic disorders which are mediated through alterations in diet and physical activities. The regulatory key factors among metabolic diseases and depression are poorly understood. To understand the molecular mechanisms of the dysregulation of genes affected in depressive disorder, we employed an analytical, quantitative framework for depression and related metabolic diseases. In this study, we examined datasets containing patients with depression, obesity, diabetes and NASH. After normalizing batch effects to minimize the heterogeneity of all the datasets, we found differentially expressed genes (DEGs) common to all the datasets. We identified significantly associated enrichment pathways, ontology pathways, protein–protein cluster networks and gene–disease associations among the co-expressed genes co-expressed in depression and the metabolic disorders. Our study suggested potentially active signaling pathways and co-expressed gene sets which may play key roles in crosstalk between metabolic diseases and depression.

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.

Molecular Pathways in Prolactinomas: Translational and Therapeutic Implications

Prolactinoma has the highest incidence rate among patients with functional pituitary tumours. Although mostly benign, there is a subgroup that can be aggressive. Some clinical, radiological and pathology features have been associated with a poor prognostic. Therefore, it can be considered as a group of heterogeneous tumours. The aim of this paper is to give an overview of the molecular pathways involved in the behaviour of prolactinoma in order to improve our approach and gain deeper insight into the better understanding of tumour development and its management. This is essential for identifying patients harbouring aggressive prolactinoma and to establish personalised therapeutics options.

Drug resistance in pituitary tumours: from cell membrane to intracellular signalling

The pharmacological treatment of pituitary tumours is based on the use of stable analogues of somatostatin and dopamine. The analogues bind to somatostatin receptor types 2 and 5 (SST2 and SST5) and dopamine receptor type 2 (DRD2), respectively, and generate signal transduction cascades in cancerous pituitary cells that culminate in the inhibition of hormone secretion, cell growth and invasion. Drug resistance occurs in a subset of patients and can involve different steps at different stages, such as following receptor activation by the agonist or during the final biological responses. Although the expression of somatostatin and dopamine receptors in cancer cells is a prerequisite for these drugs to reach a biological effect, their presence does not guarantee the success of the therapy. Successful therapy also requires the proper functioning of the machinery of signal transduction and the finely tuned regulation of receptor desensitization, internalization and intracellular trafficking. The present Review provides an updated overview of the molecular factors underlying the pharmacological resistance of pituitary tumours. The Review discusses the experimental evidence that supports a role for receptors and intracellular proteins in the function of SSTs and DRD2 and their clinical importance.

Treatment Strategies for Dopamine Agonist-Resistant and Aggressive Prolactinomas: A Comprehensive Analysis of the Literature

Despite most of the prolactinomas can be treated with endocrine therapy and/or surgery, a significant percentage of these tumors can be resistant to endocrine treatments and/or recur with prominent invasion into the surrounding anatomical structures. Hence, clinical, pathological, and molecular definitions of aggressive prolactinomas are important to guide for classical and novel treatment modalities. In this review, we aimed to define molecular endocrinological features of dopamine agonist-resistant and aggressive prolactinomas for designing future multimodality treatments. Besides surgery, temozolomide chemotherapy and radiotherapy, peptide receptor radionuclide therapy, estrogen pathway modulators, progesterone antagonists or agonists, mTOR/akt inhibitors, pasireotide, gefitinib/lapatinib, everolimus, and metformin are tested in preclinical models, anecdotal cases, and in small case series. Moreover, chorionic gonadotropin, gonadotropin releasing hormone, TGFβ and PRDM2 may seem like possible future targets for managing aggressive prolactinomas. Lastly, we discussed our management of a unique prolactinoma case by asking which tumors' proliferative index (Ki67) increased from 5-6% to 26% in two subsequent surgeries performed in a 2-year period, exerted massive invasive growth, and secreted huge levels of prolactin leading up to levels of 1 605 671 ng/dl in blood.

Characterization of Dopamine Receptor Associated Drugs on the Proliferation and Apoptosis of Prostate Cancer Cell Lines

BACKGROUND

Dopamine Receptor (DR) gene family play an essential role in the regulation of Interleukin- 6 (IL-6) production. Our prior analysis of human prostate biopsy samples demonstrated the increased expression of IL-6 and a downregulating trend for dopamine receptor gene family.

OBJECTIVE

The objective was to investigate the expression of dopamine receptors, their catabolizing enzyme and IL-6 in prostate cancer cell lines and assess pharmacological effect of dopamine receptor modulators as a novel class of drugs repurposed for the treatment of prostate cancer.

METHODS

The therapeutic effect of dopamine, DR agonists, and DR antagonist were examined using LNCaP and PC3 cell lines. Cell viability and proliferation were assessed by MTT assay and proliferating cell nuclear antigen expression analysis, respectively. Furthermore, bax/bcl2 ratio, immunofluorescence assay and flow cytometric assay were performed for apoptosis analysis. RT- qPCR analysis was used to characterize the relative expression of dopamine-related genes, catabolic enzyme Catechol-o-Methyl-Transferase (COMT) and IL-6 before and after treatment to assess the therapeutic effects of drugs.

RESULTS

LNCaP cells express DRD1, DRD2, DRD5 and COMT genes and PC3 cells only express IL-6 gene. In-vitro, dopamine receptor agonists reduced cell viability of LNCaP and PC3 cells. In contrast, dopamine and dopamine receptor antagonist significantly increased tumor growth in PC3 cells.

CONCLUSION

Our results offer novel suggestion for a pathogenic role of dopamine receptor signaling in prostate cancer adenocarcinoma and indicates that modulators of DR- IL-6 pathway, including FDA-approved drug bromocriptine, might be utilized as novel drug repurposing strategy.

Dysregulated miR-137 and its target EGFR contribute to the progression of pituitary adenomas

Pituitary adenomas (PAs) hypersecrete hormones or cause mass effect symptoms, with 10%-35% patients showing resistance to standard therapies. Targeting epidermal growth factor receptor (EGFR) has significantly improved the clinical outcome in many cancers. In this study, immunochemistry results showed that EGFR associated H-scores in 116 PA samples were higher than those in pituitary glands, and that p21, p27-and Wif-1 associated H-scores were lower (P < 0.05 for all). Patients with high levels of EGFR had increased PA invasion, lower total resection, and lower p21 and p27 expression than those with low levels of EGFR expression. Dual-luciferase reporter gene assays showed that EGFR was the target gene of miR-137, and miR-137 mimic could inhibit the cell proliferation of GH3 cells and induce apoptosis and G1-phase arrest of GH3 cells. A combination of miR-137 mimic and AZD9291 had stronger inhibition on GH3 cells compared with miR-137 mimic or AZD9291 alone; furthermore, miR-137 inhibitor partially reversed the inhibition of AZD9291. p21 and p27 were shown to be involved in the miR-137- and AZD9291-mediated effects on GH3 cells. In all, activation of EGFR in PAs was related to tumor invasive behavior, which reduced the total resection of PAs in patients. A combination of miR-137 and AZD9291 provided a potential treatment for PAs, especially for patients who show resistance to standard treatment.

Sex-Specific Genetic Associations for Barrett's Esophagus and Esophageal Adenocarcinoma

BACKGROUND & AIMS

Esophageal adenocarcinoma (EA) and its premalignant lesion, Barrett's esophagus (BE), are characterized by a strong and yet unexplained male predominance (with a male-to-female ratio in EA incidence of up to 6:1). Genome-wide association studies (GWAS) have identified more than 20 susceptibility loci for these conditions. However, potential sex differences in genetic associations with BE/EA remain largely unexplored.

METHODS

Given strong genetic overlap, BE and EA cases were combined into a single case group for analysis. These were compared with population-based controls. We performed sex-specific GWAS of BE/EA in 3 separate studies and then used fixed-effects meta-analysis to provide summary estimates for >9 million variants for male and female individuals. A series of downstream analyses were conducted separately in male and female individuals to identify genes associated with BE/EA and the genetic correlations between BE/EA and other traits.

RESULTS

We included 6758 male BE/EA cases, 7489 male controls, 1670 female BE/EA cases, and 6174 female controls. After Bonferroni correction, our meta-analysis of sex-specific GWAS identified 1 variant at chromosome 6q11.1 (rs112894788, KHDRBS2-MTRNR2L9, PBONF = .039) that was statistically significantly associated with BE/EA risk in male individuals only, and 1 variant at chromosome 8p23.1 (rs13259457, PRSS55-RP1L1, PBONF = 0.057) associated, at borderline significance, with BE/EA risk in female individuals only. We also observed strong genetic correlations of BE/EA with gastroesophageal reflux disease in male individuals and obesity in female individuals.

CONCLUSIONS

The identified novel sex-specific variants associated with BE/EA could improve the understanding of the genetic architecture of the disease and the reasons for the male predominance.

The absence of PRDM2 involved the tumorigenesis of somatotroph adenomas through regulating c-Myc

Somatotroph adenoma is the main cause of acromegaly which have peripheral signs with growth of soft tissues and multiple comorbidities. Surgery and adjuvant therapy with somatostatin analogs (SSA) fail in more than 25% of patients. PRDM2, a tumor suppressor, plays an important role in cancer and obesity, including pituitary adenomas. In this study, we analyze the correlation of PRDM2 and oncogene c-Myc in 70 somatotroph adenomas according immunohistochemical staining, furthermore, we probed that whether PRDM2 participates in c-Myc signaling pathway in vitro experiment. 70 somatotroph adenomas patients were divided into low patients and high patients according to median of H-score of PRDM2 or c-Myc. Low PRDM2 patients had higher risk of invasive behavior, larger tumor volume and recurrence chance than high PRDM2 group (P = 0.015, P = 0.031, P = 0.017). High c-Myc patients had higher risk of invasive behavior, larger tumor volume and recurrence chance than low c-Myc group (P = 0.012, P = 0.002, P = 0.015). It was a negative correlation between H-score of PRDM2 and c-Myc (PRDM2 = -0.163 × c-Myc + 67.11, r = -0.407). The ability of cell proliferation was declined in a time dependent manner after overexpression of PRDM2 (PRDM2 group) compared to that in control GH3 cells (P < 0.05). Through flow cytometry assay, PRDM2 could induce the apoptosis and G2/M arrest in GH3 cell (both p < 0.05). Transwell experiment proved less trans-membrane cells in PRDM2 group than those in control group (415 ± 76 vs 145 ± 37, P < 0.01). RT-PCR and western blot both proved PRDM2 could inhibit the level c-Myc and elevate the levels of CDKN1A and CDKN1B. Combined with c-Myc inhibitor 10058-F4, PRDM2 further inhibited cell proliferation and induced more apoptosis in GH3 cell. Taken together, we found that PRDM2 negatively regulated the expression of c-Myc in somatotroph adenomas, and testified the synergism between PRDM2 gene therapy and c-Myc inhibitor in vitro experiment.

The Genomic Landscape of Sporadic Prolactinomas

Somatic GNAS and USP8 mutations have been implicated in sporadic somatotrophinomas and corticotrophinomas, respectively. However, no genes are known to be recurrently mutated in sporadic prolactinomas. The prevalence of copy number variants (CNV), which is emerging as a mechanism of tumorigenesis in sporadic pituitary adenomas in general, is also unclear in prolactinomas. To characterize the genetic events underpinning sporadic prolactinomas, we performed whole exome sequencing of paired tumor and germline DNA from 12 prolactinoma patients. We observed recurrent large-scale CNV, most commonly in the form of copy number gains. We also identified sequence variants of interest in 15 genes. This included the DRD2, PRL, TMEM67, and MLH3 genes with plausible links to prolactinoma formation. Of the 15 genes of interest, CNV was seen at the gene locus in the corresponding tumor in 10 cases, and pituitary expression of eight genes was in the top 10% of tissues. However, none of our shortlisted somatic variants appeared to be classical driver mutations as no variant was found in more than one tumor. Future directions of research include mechanistic studies to investigate how CNV may contribute to prolactinoma formation, larger studies of relevant prolactinoma subsets according to clinical characteristics, and additional genetic investigations for aberrations not captured by whole exome sequencing.

Unusual Course of an Aggressive Pituitary Prolactinoma: Case Report and Review of the Literature

Pituitary carcinomas are rare tumors with heterogeneous behaviors. Their carcinogenesis is still unknown. Consequently, treatment is multimodal and not standardized. Dopamine (DA) agonists are used as first-line treatments, while radiotherapy and surgery may be used for local control of invasive tumors. We describe the case of a 35-year-old male who presented with an invasive prolactinoma, managed initially with a transsphenoidal resection, postsurgical radiotherapy and DA agonists. The patient posteriorly presented a sole metastatic lesion to the lumbar spine that was later managed with local radiotherapy. Due to pituitary recurrence of the lesion, multiple surgical resections were needed until further treatment was declined. The clinical course in this patient was unusual. He lived for 13 years after initial diagnosis, with a very invasive tumor without systemic chemotherapy. Radiotherapy is used in pituitary tumors in which surgery fails; we hypothesize that it contributed to the malignant transformation and the late resistance to DA agonists in our patient. Several biomarkers in tumoral tissue have been evaluated regarding their association with malignancy and aggressive behaviors, although more studies are still needed. Therapeutic strategies are limited, without evidence on the impact on overall survival and prognosis. Risk factors associated with early malignancy in pituitary prolactinomas include recurrent behavior, increase in prolactin levels with a stable sellar mass, and secondary development of DA agonist resistance. However, there are still no conclusive answers as to whether physicians should rigorously follow up these patients or provide direct therapy with aggressive approaches.

miRNA-199a-5p functions as a tumor suppressor in prolactinomas

Prolactinomas are the most frequently observed pituitary adenomas (PAs), and 5%–18% tumors were resistant to the dopamine agonists (DAs). MicroRNAs (miRNAs) dysfunction play a key role in tumorigenesis. Agilent miRNA and an expression chip were used for six prolactinomas and three normal pituitary specimens. Differentially expressed genes were confirmed by RT-qPCR. The level of DDR1 and SAT1 was determined with tissue micro-array (TMA) and western blot. A MMQ cell line was used for functional experiments. We have identified 5-miRNA and 12 target gene signatures of prolactinomas through gene ontology analysis. miRNA-199a-5p was selected for experiments that integrated the results from prolactinomas specimens and a rat prolactinoma model induced by 17-b-estradiol. Tumors with low miRNA-199a-5p had a significantly invasive behavior and a higher tumor volume (p<0.05). DDR1 and SAT1, target genes of miRNA-199a-5p, had higher H-scores in the invasive group than those of the non-invasive group through TMA. An overexpression of miRNA-119a-5p suppressed the PRL secretion and the cell viability through upregulated the apoptosis level in MMQ cells (p<0.01). Furthermore, we found the target genes expression of DDR1 and SAT1 were affected by miRNA-199a-5p regardless of mRNA levels or protein levels. This study provided evidence that downregulation of miRNA-199a-5p may contribute to prolactinoma tumorigenesis.

Clinical management of difficult to treat macroprolactinomas

INTRODUCTION

Prolactinomas represent the most common pituitary adenomas encountered in the clinic. While a majority of these tumors will be successfully treated by dopamine agonist (DA) such as cabergoline, their management becomes problematic since a resistance to DA can occur and/or if the tumor displays features of aggressiveness, two conditions that are closely related.

AREAS COVERED

Epidemiology and medical treatment of prolactinomas; resistance to DA and molecular basis of DA-resistance; therapeutical alternatives in case of DA-resistant Prolactinomas and therapies in development; summarizing conclusions.

EXPERT OPINION

The management of DA-resistant prolactinomas requires a multidisciplinary approach by an expert team. Along with discussions about surgery with or without gamma knife radiosurgery, genetic screening for multiple endocrine neoplasia type 1 (MEN1) syndrome is actively discussed in a case-by-case approach. In case of surgery, a careful analysis of the tumor sample can provide information about its aggressivity potential according to recent criteria. Ultimately, temozolomide can be indicated if the tumor is rapidly growing and/or threatening for the patient.

The Prospective Value of Dopamine Receptors on Bio-Behavior of Tumor

Dopamine receptors are belong to the family of G protein-coupled receptor. There are five types of dopamine receptor (DR), including DRD1, DRD2, DRD3, DRD4, and DRD5, which are divided into two major groups: the D1-like receptors (DRD1 and DRD5), and the D2-like receptors (DRD2, DRD3, and DRD4). Dopamine receptors are involved in all of the physiological functions of dopamine, including the autonomic movement, emotion, hormonal regulation, dopamine-induced immune effects, and tumor behavior, and so on. Increasing evidence shows that dopamine receptors are associated with the regulation of tumor behavior, such as tumor cell death, proliferation, invasion, and migration. Recently, some studies showed that dopamine receptors could regulate several ways of death of the tumor cell, including apoptosis, autophagy-induced death, and ferroptosis, which cannot only directly affect tumor behavior, but also limit tumor progress via activating tumor immunity. In this review, we focus mainly on the function of the dopamine receptor on Bio-behavior of tumor as a potential therapeutic target.

Aggressive and Malignant Prolactinomas

Prolactin-secreting tumors (prolactinomas) represent the most common pituitary tumor type, accounting for 47-66% of functional pituitary tumors. Prolactinomas are usually benign and controllable tumors as they express abundant levels of dopamine type 2 receptor (D2), and can be treated with dopaminergic drugs, effectively reducing prolactin levels and tumor volume. However, a proportion of prolactinomas exhibit aggressive features (including invasiveness, relevant growth despite adequate dopamine agonist treatment, and recurrence potential) and few may exhibit metastasizing potential (carcinomas). In this context, the clinical, pathological, and molecular definitions of malignant and aggressive prolactinomas remain to be clearly defined, as primary prolactin-secreting carcinomas are similar to aggressive adenomas until the presence of metastases is detected. Indeed, standard molecular and histological analyses do not reflect differences between carcinomas and adenomas at a first glance and have limitations in prediction of the aggressive progression of prolactinomas, wherein the causes underlying the aggressive behavior remain unknown. Herein we present a comprehensive, multidisciplinary review of the most relevant epidemiological, clinical, pathological, genetic, biochemical, and molecular aspects of aggressive and malignant prolactinomas.

Dopamine Agonists: From the 1970s to Today

The discovery of dopamine inhibitory effects on prolactin secretion has led to an era of successful dopaminergic therapy for prolactinomas. Herein we provide an overview of the evolution of dopamine agonists and their use in patients with PRL-secreting pituitary tumors, starting from the 1970s up to today, highlighting that normalization of PRL levels, restoration of eugonadism, and reduction of tumor mass can be achieved in the majority of patients by treatment with dopamine agonists.

The Treatment of Refractory Pituitary Adenomas

Refractory pituitary adenomas (PAs) are defined as aggressive-invasive PAs characterized by a high Ki-67 index, rapid growth, frequent recurrence, and resistance to conventional treatments. It is notoriously difficult to manage refractory PAs because the efficacy of current therapeutic options is limited. The purpose of this review is to address currently employed and promising therapeutic strategies for the treatment of refractory PAs. Except for prolactinomas, neurosurgery is the first-line option, but most refractory PAs often recur or re-grow after initial surgery and require further treatments. Medical therapy, radiotherapy and re-operation are explored when surgery has failed to completely resect tumors; however, refractory PAs are usually resistant to these treatments. As a salvage treatment, temozolomide (TMZ) has shown promising results and is currently used for all types of refractory PAs. However, not all refractory PAs are responsive to TMZ treatment, and some of these PAs are resistant to TMZ. Although targeted therapies such as vascular endothelial growth factor, epidermal growth factor and mTOR inhibitors have also been used to treat refractory PAs, the effectiveness of these targeted therapies is still not known due to a lack of data from randomized prospective trials. As a novel therapeutic method, cancer immunotherapy is a promising strategy for the treatment of refractory PAs, but further preclinical research and clinical trials are needed to assess the efficacy of this new approach. In summary, early identification and a multidisciplinary approach are required to treat refractory PAs.

Aberrant expression of the sFRP and WIF1 genes in invasive non-functioning pituitary adenomas

Non-functioning pituitary adenomas (NFPAs) are the most common pituitary tumors and mainly invade the sphenoid, cavernous sinus or dura mate. Aberrant regulation of the Wnt signaling pathway plays an important role in tumorigenesis. This study was designed to investigate the relationships between secreted frizzled-related proteins (sFRPs), WIF1 genes and the invasion of NFPAs by tissue microassays (TMAs) of samples from 163 patients. Significantly weaker staining of WIF1 and sFRP4 were detected in the invasive group compared with the non-invasive group by TMAs (p = 0.002, p < 0.001). Univariate analysis showed a significant correlation between tumor invasion and low expression of WIF1 and sFRP4 (p = 0.002, p < 0.001). A similar trend was observed when analyzing the mRNA and protein levels through RT-PCR and western blot experiments. Methylation of the WIF1 promoter was significantly increased in invasive NFPAs compared with the noninvasive group (p = 0.004). The average progression free survival time in the high WIF1 group was longer than that in the low WIF1 group (p = 0.025). Furthermore, RT-PCR measured the levels of 11 miRNAs targeting WIF1 according to the Targetscan database and PubMed. The levels of miRNA-137, miRNA-374a-5p and miRNA-374b-5p in the invasive group were 0.037-fold, 0.577-fold and 0.44-fold that of the noninvasive group (p = 0.003, p = 0.049 and p = 0.047). Overexpression of miRNA-137 could inhibit the proliferation and invasion of GH3 cells through cell viability and Transwell experiments (p < 0.05). Furthermore, the WIF1 level was upregulated after overexpression of miRNA-137 compared with miRNA-137-NC (control miRNA) in GH3 cells. Our data suggest that WIF1 may be potential biomarker for the aggressiveness of NFPAs. miRNA-137 plays an important role in the Wnt signaling pathway by affecting promoter methylation of WIF1.

The role of NR2C2 in the prolactinomas

Prolactinomas are the most frequently observed pituitary adenomas. Prolactinomas invasion is a key risk factor associated with operation results, and it is highly correlated with clinical prognosis. Nuclear receptor subfamily 2 group C member 2 (NR2C2) first cloned from testis is involved in the invasion and metastasis of several human tumors. In 46 patients with prolactinamas, the expression levels of CCNB1, Notch2, and NR2C2 was determined with tissue micro-array (TMA). The association between NR2C2 levels and clinical parameters was established with univariate analysis. The levels of Notch2 and CCNB1 were analyzed by RT-PCR and western blot techniques.The average methylation levels of the NR2C2 promoter were 0.505 and 0.825 in invasive prolactinomas (IPA) and non-IPA groups, respectively (p = 0.013). Univariate analysis also showed that there is a significant relationship between high NR2C2 expression and invasion (x2 = 7.043, p = 0.008), prolactin granules (x2 = 8.712, p = 0.003), and tumor size (x2 = 4.261, p = 0.039.) With the knockdown of NR2C2, cell proliferation was inhibited. Genes related to epithelial-mesenchymal transition (EMT) induced the apoptosis in MMQ cells. In addition, the level of Notch2 and CCNB1 were down-regulated with the knockdown of NR2C2. Moreover, miR-129-5p reduced mRNA levels of NR2C2, and they inhibited cell proliferation by inducing apoptosis levels of MMQ cells. Our findings proved NR2C2 played the important role in tumorigenesis tumor invasion of prolactinomas; moreover, NR2C2 is identified as a potential target.

Alterations of DNA methylation in parathyroid tumors

Parathyroid tumors are common endocrine neoplasias associated with primary hyperparathyroidism, a metabolic disorder characterized by parathormone hypersecretion. Parathyroid neoplasia are frequently benign adenomas or multiple glands hyperplasia, while malignancies are rare. The epigenetic scenario in parathyroid tumors has just begun to be decoded: DNA methylation, histones and chromatin modifiers expression have been investigated so far. The main findings suggest that DNA methylation and chromatin remodeling are active and deregulated in parathyroid tumors, cooperating with genetic alterations to drive the tumor phenotype: the tumor suppressors menin and parafibromin, involved in parathyroid tumorigenesis, interact with chromatin modifiers, defining distinct epigenetic derangements. Many epigenetic alterations identified in parathyroid tumors are common to those in human cancers; moreover, some aspects of the epigenetic profile resemble epigenetic features of embryonic stem cells. Epigenetic profile may contribute to define the heterogeneity of parathyroid tumors and to provide targets for new therapeutic approaches.

P21Waf1/Cip1 and p27Kip1 are correlated with the development and invasion of prolactinoma

Cell cycle control can prevent excessive proliferative response in the pituitary homeostasis. Cyclin dependent kinases (Cdks) are modulated by cyclins or Cdk inhibitors, such as p21 and p27, which can regulate cell cycle progression from the G1 to S phases. This study was conducted to evaluate the levels and the promoter region methylation status of p21 and p27 in prolactinomas (PRL) and analyze their association with clinicopathologic features. We found high-p21 level cases were featured by 5/23 and H-scores 142.3 ± 23.7 in invasive-PRL specimens, and 19/25 and 221.3 ± 45.4 in non-invasive specimens (x² = 14.11, p = 0.000), while high-p27 level cases were featured by 6/23 and H-scores 129.8 ± 31.1 in invasive-PRL specimens, and 18/25 and 197.1 ± 46.6 in non-invasive specimens (x² = 10.11, p = 0.001). A similar trend was also observed for p21 and p27 protein levels in PRL specimens through western-blot (P < 0.01, respectively). The Ki-67 index was much higher in invasive specimens than in non-invasive specimens (x² = 10.10, p = 0.001). Average 33 CpG sites per sample were analyzed by using MALDI-TOF Mass array, and 7/33 CpG sites methylation levels of p27 were higher than 50%. There existed significant differences in 4 CpG sites between invasive specimens and non-invasive specimens (p < 0.01). We found that D2 receptor was closely correlated with p21 levels (P < 0.05, r = 0.567) and p27 levels (P < 0.05, r = 0.591). In PRL, the deficiency in p21 and p27 contributed to the tumor proliferation and migration and Cdk inhibitors may be used as a new therapeutic approach.

High expression of diffuse panbronchiolitis critical region 1 gene promotes cell proliferation, migration and invasion in pancreatic ductal adenocarcinoma

Diffuse panbronchiolitis critical region 1 (DPCR1) is located in the major histocompatibility complex (MHC) class I. It was reported to be downregulated in invasive pituitary adenoma compared with that in non-invasive tumors, but upregulated in the precursor of gastric carcinogenesis. However, the direct effect of DPCR1 on cancer cells has rarely been reported, and the role DPCR1 in pancreatic ductal adenocarcinoma (PDAC) remains unclear. The clinical sample validation and public data analysis of the present study demonstrated that DPCR1 was upregulated markedly in PDAC and this high expression was negatively correlated with the patient prognosis. Functionally, knocking down DPCR1 in PDAC cell lines inhibited cell proliferation, migration and invasion in vitro. Tumor xenograft experiments further showed that suppression of DPCR1 inhibited tumor growth in vivo. In addition, the results of RNA deep sequencing and qRT-PCR assay showed that DPCR1 participated in PADC progression by regulating nuclear factor-kappa B signaling pathway, suggesting that it might be a novel oncogene in tumor progression and a potential therapeutic target in PDAC as well.

RIZ1 and histone methylation status in pituitary adenomas

RIZ1 displays strong tumor-suppressive activities, which has a potential histone methyltransferase activity. The objective of the study was to evaluate the level and the methylation status of RIZ1 and analyze its association with clinicopathological features and the histone in the pituitary adenomas. We found that RIZ1-positive cases were 11/50 and H-Scores 22.75 ± 11.83 in invasive pituitary adenomas and 26/53 and 66.3 ± 21.7 in non-invasive pituitary adenomas (χ² = 8.182, p = 0.004). RIZ1 and C-myc showed the opposite trend in these cases. The methylation levels of RIZ1 were more than 50% in 30.4% (7/23) CpG sites through MALDI-TOF Mass array. There was significant difference (p < 0.01) in 4 CpG sites between invasive pituitary adenoma group and non-invasive pituitary adenoma group; furthermore, the relieved methylation levels of H3K4/H3K9 and enhanced methylation levels of H3K27 in the patients' serum were found. Furthermore, there was statistic difference of H3K4 and H3K27 methylation between invasive pituitary adenoma and non-invasive pituitary adenoma group (p < 0.01). The average progression-free survival in high RIZ1 group was 52.63 ± 7.62 months and 26.06 ± 4.23 months in low RIZ1 group (p < 0.05). Promoter region methylation of RIZ1 may play an important role in the epigenetic silencing of RIZ1 expression in pituitary adenomas, which may translate into important diagnostic and therapeutic applications.

ESR1 and its antagonist fulvestrant in pituitary adenomas

Estrogen has a key role in the pathogenesis of pituitary adenomas (PAs). The study was to evaluate the estrogen receptor alpha (ESR1) level in 289 PAs cases, its association with clinicopathologic features and serving as a target of cancer treatment. In this study, the ESR1 level was evaluated by tissue microarray (TMA). The effect of fulvestrant was determined by an animal model of prolactinoma established by subcutaneous injection of 17β-estradiol in F344 rats. The volume and weight of the pituitary were assessed in the different groups. The effects of fulvestrant on cell proliferation and cell invasion were explored in the pituitary adenoma cell lines GH3 and JT1-1. The ESR1-positive cells rates of 191/289 cases were more than 50%. And ESR1 high level cases (age≥50) were 103/133, and 88/156 in cases (age<50) (X² = 14.17, p = 0.0001). The average weight of the pituitary gland in F344 rat tumor model induced by 17-β-estradiol was 38.6 ± 11.2 mg, almost 6 times higher than control group (6.2 ± 1.7 mg). Fulvestrant significantly reduced the weight of the pituitary and its inhibition rate was 68.4 ± 8.3%. TUNEL assay and Western blotting showed that fulvestrant induced apoptotic cell death in vivo and in vitro. PTEN/MAPK signaling pathways were activated in response to fulvestrant treatment in GH3 cells. U0126 partly rescued cell viability of GH3 cells after fulvestrant exposure. ESR1 can be a potential target for PAs, especially for elder GHomas and NFPAs. Fulvestrant may be a new choice for the treatment of PAs.

Inhibition of SKP2 Sensitizes Bromocriptine-Induced Apoptosis in Human Prolactinoma Cells

PURPOSE

Prolactinoma (prolactin-secreting pituitary adenoma) is one of the most common estrogen-related functional pituitary tumors. As an agonist of the dopamine D2 receptor, bromocriptine is used widely to inhibit prolactinoma progression. On the other hand, it is not always effective in clinical application. Although a dopamine D2 receptor deficiency contributes to the impaired efficiency of bromocriptine therapy to some extent, it is unknown whether there some other underlying mechanisms leading to bromocriptine resistance in prolactinoma treatment. That is the main point addressed in this project.

MATERIALS AND METHODS

Human prolactinoma samples were used to analyze the S-phase kinase associated protein 2 (SKP2) expression level. Nutlin-3/adriamycin/cisplatin-treated GH3 and MMQ cells were used to analyze apoptosis in SKP2 overexpression or knockdown cells. SKP2 expression and the interaction partners of SKP2 were also detected after a bromocriptine treatment in 293T. Apoptosis was analyzed in C25 and bromocriptine-treated GH3 cells.

RESULTS

Compared to normal pituitary samples, most prolactinoma samples exhibit higher levels of SKP2 expression, which could inhibit apoptosis in a p53-dependent manner. In addition, the bromocriptine treatment prolonged the half-life of SKP2 and resulted in SKP2 overexpression to a greater extent, which in turn compromised its pro-apoptotic effect. As a result, the bromocriptine treatment combined with C25 (a SKP2 inhibitor) led to the maximal apoptosis of human prolactinoma cells.

CONCLUSION

These findings indicated that SKP2 inhibition sensitized the prolactinoma cells to bromocriptine and helped promote apoptosis. Moreover, a combined treatment of bromocriptine and C25 may contribute to the maximal apoptosis of human prolactinoma cells.

Whole-exome identifies RXRG and TH germline variants in familial isolated prolactinoma

Familial isolated pituitary adenoma (FIPA) is a rare genetic disorder. In a subset of FIPA families AIP germline mutations have been reported, but in most FIPA cases the exact genetic defect remains unknown. The present study aimed to determine the genetic basis of FIPA in a Brazilian family. Three siblings presented with isolated prolactin genes. Further mutation screening was performed using whole-exome sequencing and all likely causative mutations were validated by Sanger sequencing. In silico analysis and secreting pituitary adenoma diagnosed through clinical, biochemical and imaging testing. Sanger sequencing was used to genotype candidate prolactinoma-mutated additional predictive algorithms were applied to prioritize likely pathogenic variants. No mutations in the coding and flanking intronic regions in the MEN1, AIP and PRLR genes were detected. Whole-exome sequencing of three affected siblings revealed novel, predicted damaging, heterozygous variants in three different genes: RXRG, REXO4 and TH. In conclusion, the RXRG and TH possibly pathogenic variants may be associated with isolated prolactinoma in the studied family. The possible contribution of these genes to additional FIPA families should be explored.

Combining Cadherin Expression with Molecular Markers Discriminates Invasiveness in Growth Hormone and Prolactin Pituitary Adenomas

Although growth hormone (GH)- and prolactin (PRL)-secreting pituitary adenomas are considered benign, in many patients, tumour growth and/or invasion constitute a particular challenge. In other tumours, progression relies in part on dysfunction of intercellular adhesion mediated by the large family of cadherins. In the present study, we have explored the contribution of cadherins in GH and PRL adenoma pathogenesis, and evaluated whether this class of adherence molecules was related to tumour invasiveness. We have first established, by quantitative polymerase chain reaction and immunohistochemistry, the expression profile of classical cadherins in the normal human pituitary gland. We show that the cadherin repertoire is restricted and cell-type specific. Somatotrophs and lactotrophs express mainly E-cadherin and cadherin 18, whereas N-cadherin is present in the other endocrine cell types. This repertoire undergoes major differential modification in GH and PRL tumours: E-cadherin is significantly reduced in invasive GH adenomas, and this loss is associated with a cytoplasmic relocalisation of cadherin 18 and catenins. In invasive prolactinomas, E-cadherin distribution is altered and is accompanied by a mislocalisation of cadherin 18, β-catenin and p120 catenin. Strikingly, de novo expression of N-cadherin is present in a subset of adenomas and cells exhibit a mesenchymal phenotype exclusively in invasive tumours. Binary tree analysis, performed by combining the cadherin repertoire with the expression of a subset of known molecular markers, shows that cadherin/catenin complexes play a significant role in discrimination of tumour invasion.

Dopamine and Somatostatin Analogues Resistance of Pituitary Tumors: Focus on Cytoskeleton Involvement

Pituitary tumors, that origin from excessive proliferation of a specific subtype of pituitary cell, are mostly benign tumors, but may cause significant morbidity in affected patients, including visual and neurologic manifestations from mass-effect, or endocrine syndromes caused by hormone hypersecretion. Dopamine (DA) receptor DRD2 and somatostatin (SS) receptors (SSTRs) represent the main targets of pharmacological treatment of pituitary tumors since they mediate inhibitory effects on both hormone secretion and cell proliferation, and their expression is retained by most of these tumors. Although long-acting DA and SS analogs are currently used in the treatment of prolactin (PRL)- and growth hormone (GH)-secreting pituitary tumors, respectively, clinical practice indicates a great variability in the frequency and entity of favorable responses. The molecular basis of the pharmacological resistance are still poorly understood, and several potential molecular mechanisms have been proposed, including defective expression or genetic alterations of DRD2 and SSTRs, or an impaired signal transduction. Recently, a role for cytoskeleton protein filamin A (FLNA) in DRD2 and SSTRs receptors expression and signaling in PRL- and GH-secreting tumors, respectively, has been demonstrated, first revealing a link between FLNA expression and responsiveness of pituitary tumors to pharmacological therapy. This review provides an overview of the known molecular events involved in SS and DA resistance, focusing on the role played by FLNA.