Three-dimensional chromatin landscapes in somatotroph tumour.

BACKGROUND: The three-dimensional (3D) genome architecture plays a critical role inregulating gene expression. However, the specific alterations in thisarchitecture within somatotroph tumors and their implications for gene expression remain largely unexplored. METHODS: We employed Hi-C and RNA-seq analyses to compare the 3D genomic structures of somatotroph tumors with normal pituitary tissue. This comprehensive approachenabled the characterization of A/B compartments, topologically associateddomains (TADs), and chromatin loops, integrating these with gene expression patterns. RESULTS: We observed a decrease in both the frequency of chromosomal interactions andthe size of TADs in tumor tissue compared to normal tissue. Conversely, the number of TADs and chromatin loops was found to be increased in tumors. Integrated analysis of Hi-C and RNA-seq data demonstrated that changes inhigher-order chromat in structure were associated with alterations in gene expression. Specifically, genes in A compartments showed higher density and increased expression relative to those in B compartments. Moreover, the weakand enhanced insulation boundaries were identified, and the associated genes were enriched in the Wnt/ß-Catenin signaling pathway. We identified the gainedand lost loops in tumor and integrated these differences with transcriptional changes to examine the functional relevance of the identified loops. Notably, we observed an enhanced insulation boundary and a greater number of loops in the TCF7L2 gene region within tumors, which was accompanied by an upregulation of TCF7L2 expression. Subsequently, TCF7L2 expression was confirmed through qRT-PCR, and upregulated TCF7L2 prompted cell proliferation and growth hormone (GH) secretion in vitro. CONCLUSION: Our results provide comprehensive 3D chromatin architecture maps of somatotroph tumors and offer a valuable resource for furthering the understanding of the underlying biology and mechanisms of gene expression regulation.

Clinicopathological and Molecular Profile of Sellar Neurocytoma.

OBJECTIVE: To investigate the clinical features, imaging characteristics and molecular profile of Sellar neurocytoma (SN). METHODS: Clinical, imaging, and pathological features of eleven cases of sellar neurocytoma were retrospectively analyzed. Electron microscopy was performed in five cases. Molecular features were detected in tumor tissue by RNA sequencing, qPCR and IHC. RESULTS: The clinical features of SN patients showed high incidence of hyponatremia (73%,8/11) and the tumors tended to invaded lateral side of saddle area from preoperative imaging analysis. The tumors had positive NeuN, SYN, NF, SSTR2 immunohistochemistry staining. Tumor transcriptomic analysis suggested a new LMCD1-AS1:GRM7-AS1 fusion gene event and increased expression of 10 hypothalamus-secreted hormones in SN. 15 differentially expressed genes were verified for qPCR verification. SSTR2 has been verified by immunohistochemistry. CONCLUSIONS: Hyponatremia is the dominant clinical features of SN. Preoperative imaging suggests that growth toward the dorsal region is the imaging feature of SN. SSTR2 expression and LMCD1-AS1:GRM7-AS1 fusion gene event expected to become a new molecular marker for SN. Somatostatin receptor ligand therapy may be a potential therapy for SN.

HSPB1 promotes tumor invasion by inducing angiogenesis in PitNETs.

The clinical diagnosis and treatment of pituitary neuroendocrine tumors (PitNETs) that invade the cavernous sinus are fraught with difficulties and challenges. Exploring the biological characteristics involved in the occurrence and development of PitNETs that invade the cavernous sinus will help to elucidate the mechanism of cavernous sinus invasion. There are differences between intrasellar tumors (IST) and cavernous sinus-invasion tumors (CST) in ultramicrostructure, tumor microenvironment (TME), gene expression, and signaling pathways. The microvascular endothelial cell is increased in CST. The VEGFR signaling pathway, VEGF signaling pathway, and chemokine signaling pathway are activated in CST. HSPB1 is upregulated in CST and promotes cell proliferation, cell viability, and migration. HSPB1 promotes the release of VEGF from GT1-1 cells and activates the VEGF signaling pathway in bEnd.3 cells. HSPB1 promotes the migration of bEnd.3 cells to GT1-1 cells and promotes the formation of blood vessels of bEnd.3 cells. bEnd.3 cells can release CCL3 and CCL4 and promote the vitality, proliferation, and migration of GT1-1 cells. HSPB1 promotes the formation of blood vessels of bEnd.3 cells and ultimately leads to tumor growth in vivo. HSPB1 acts as a key gene for invasion of the cavernous sinus in PitNETs, remodeling TME by promoting the formation of blood vessels of brain microvascular endothelial cells. The synergistic effect of tumor cells and microvascular endothelial cells promotes tumor progression. The mechanism by which HSPB1 promotes tumor invasion by inducing angiogenesis in PitNETs may be a new target for the treatment of PitNETs invading the cavernous sinus.

Phosphorylation of PBK at Thr9 by CDK5 correlates with invasion of prolactinomas.

CONTEXT: Prolactinomas are the most prevalent functional pituitary neuroendocrine tumors (PitNETs), and they are invasive to surrounding anatomic structures. The detailed mechanisms of invasion are not yet clear. OBJECTIVE: We explored the role of PBK phosphorylation in the proliferation and invasion of prolactinomas and its possible mechanism. RESULTS: We report that PBK directly binds to and is phosphorylated at Thr9 by cyclin-dependent kinase 5 (CDK5), which promotes GH3 cell EMT progression and proliferation. Phosphorylation of PBK at Thr9 (pPBK-T9) by CDK5 enhances the stability of PBK. p38 is one of the downstream targets of PBK, and its phosphorylation is reduced as pPBK-T9 increases in vivo and in vitro. Furthermore, we found that pPBK-T9 is highly expressed in invasive PitNETs and was significantly correlated with invasion by univariate and multivariate analyses. CONCLUSIONS: Phosphorylation of PBK at Thr9 by CDK5 promotes cell proliferation and EMT progression in prolactinomas.

Single-cell transcriptomic analysis reveals tumor cell heterogeneity and immune microenvironment features of pituitary neuroendocrine tumors.

BACKGROUND: Pituitary neuroendocrine tumors (PitNETs) are one of the most common types of intracranial tumors. Currently, the cellular characteristics of normal pituitary and various other types of PitNETs are still not completely understood. METHODS: We performed single-cell RNA sequencing (scRNA-seq) on 4 normal samples and 24 PitNET samples for comprehensive bioinformatics analysis. Findings regarding the function of PBK in the aggressive tumor cells were validated by siRNA knockdown, overexpression, and transwell experiments. RESULTS: We first constructed a reference cell atlas of the human pituitary. Subsequent scRNA-seq analysis of PitNET samples, representing major tumor subtypes, shed light on the intrinsic cellular heterogeneities of the tumor cells and tumor microenvironment (TME). We found that the expression of hormone-encoding genes defined the major variations of the PIT1-lineage tumor cell transcriptomic heterogeneities. A sub-population of TPIT-lineage tumor cells highly expressing GZMK suggested a novel subtype of corticotroph tumors. In immune cells, we found two clusters of tumor-associated macrophages, which were both highly enriched in PitNETs but with distinct functional characteristics. In PitNETs, the stress response pathway was significantly activated in T cells. While a majority of these tumors are benign, our study unveils a common existence of aggressive tumor cells in the studied samples, which highly express a set of malignant signature genes. The following functional experiments confirmed the oncogenic role of selected up-regulated genes. The over-expression of PBK could promote both tumor cell proliferation and migration, and it was also significantly associated with poor prognosis in PitNET patients. CONCLUSIONS: Our data and analysis manifested the basic cell types in the normal pituitary and inherent heterogeneity of PitNETs, identified several features of the tumor immune microenvironments, and found a novel epithelial cell sub-population with aggressive signatures across all the studied cases.

Drug resistance mechanisms in dopamine agonist-resistant prolactin pituitary neuroendocrine tumors and exploration for new drugs.

BACKGROUND: The treatment of dopamine agonists (DA) resistant prolactinomas remains a formidable challenge, as the mechanism of resistance is still unclear, and there are currently no viable alternative drug therapies available. This study seeks to investigate the mechanism of DA resistance in prolactinomas and identify new potentially effective drugs. METHODS: To explore the mechanism of DA resistance in prolactinomas, this study conducted transcriptome sequencing analysis on 27 cases of DA-resistant prolactinomas and 10 cases of sensitive prolactinomas. In addition, single-cell sequencing analysis was performed on 3 cases of DA-resistant prolactinomas and 3 cases of sensitive prolactinomas. Furthermore, to screen for potential therapeutic drugs, the study successfully established an organoids model for DA-resistant prolactinomas and screened 180 small molecule compounds using 8 organoids. The efficacy of the identified drugs was verified through various assays, including CCK-8, colony formation, CTG, and flow cytometry, and their mechanisms of action were confirmed through WB and IHC. The effectiveness of the identified drugs was evaluated both in vitro and in vivo. RESULTS: The results of transcriptome sequencing and single-cell sequencing analyses showed that DA resistance in prolactinomas is associated with the upregulation of the Focal Adhesion (FA) signaling pathway. Additionally, immunohistochemical validation revealed that FAK and Paxillin were significantly upregulated in DA-resistant prolactinomas. Screening of 180 small molecule compounds using 8 organoids identified Genistein as a potentially effective drug for DA-resistant prolactinomas. Experimental validation demonstrated that Genistein inhibited the proliferation of pituitary tumor cell lines and organoids and promoted apoptosis in pituitary tumor cells. Moreover, both the cell sequencing results and WB validation results of the drug-treated cells indicated that Genistein exerts its anti-tumor effect by inhibiting the FA pathway. In vivo, experiments also showed that Genistein can inhibit subcutaneous tumor formation. CONCLUSION: DA resistance in prolactinomas is associated with upregulation of the Focal Adhesion (FA) signaling pathway, and Genistein can exert its anti-tumor effect by inhibiting the expression of the FA pathway.

Identification of biomarkers associated with the invasion of nonfunctional pituitary neuroendocrine tumors based on the immune microenvironment.

Introduction: The invasive behavior of nonfunctioning pituitary neuroendocrine tumors (NF-PitNEts) affects complete resection and indicates a poor prognosis. Cancer immunotherapy has been experimentally used for the treatment of many tumors, including pituitary tumors. The current study aimed to screen the key immune-related genes in NF-PitNEts with invasion. Methods: We used two cohorts to explore novel biomarkers in NF-PitNEts. The immune infiltration-associated differentially expressed genes (DEGs) were obtained based on high/low immune scores, which were calculated through the ESTIMATE algorithm. The abundance of immune cells was predicted using the ImmuCellAI database. WGCNA was used to construct a coexpression network of immune cell-related genes. Random forest analysis was used to select the candidate genes associated with invasion. The expression of key genes was verified in external validation set using quantitative real-time polymerase chain reaction (qRT‒PCR). Results: The immune and invasion related DEGs was obtained based on the first dataset of NF-PitNEts (n=112). The immune cell-associated modules in NF-PitNEts were calculate by WGCNA. Random forest analysis was performed on 81 common genes intersected by immune-related genes, invasion-related genes, and module genes. Then, 20 of these genes with the highest RF score were selected to construct the invasion and immune-associated classification model. We found that this model had high prediction accuracy for tumor invasion, which had the largest area under the receiver operating characteristic curve (AUC) value in the training dataset from the first dataset (n=78), the self-test dataset from the first dataset (n=34), and the independent test dataset (n=73) (AUC=0.732/0.653/0.619). Functional enrichment analysis revealed that 8 out of the 20 genes were enriched in multiple signaling pathways. Subsequently, the 8-gene (BMP6, CIB2, FABP5, HOMER2, MAML3, NIN, PRKG2 and SIDT2) classification model was constructed and showed good efficiency in the first dataset (AUC=0.671). In addition, the expression levels of these 8 genes were verified by qRT‒PCR. Conclusion: We identified eight key genes associated with invasion and immunity in NF-PitNEts that may play a fundamental role in invasive progression and may provide novel potential immunotherapy targets for NF-PitNEts.

The SF3B1R625H mutation promotes prolactinoma tumor progression through aberrant splicing of DLG1.

BACKGROUND: Recently, a hotspot mutation in prolactinoma was observed in splicing factor 3b subunit 1 (SF3B1R625H), but its functional effects and underlying molecular mechanisms remain largely unexplored. METHODS: Using the CRISPR/Cas9 genome editing system and rat pituitary GH3 cells, we generated heterozygous Sf3b1R625H mutant cells. Sanger and whole-genome sequencing were conducted to verify the introduction of this mutation. Transcriptome analysis was performed in SF3B1-wild-type versus mutant human prolactinoma samples and GH3 cells. RT-PCR and minigene reporter assays were conducted to verify aberrant splicing. The functional consequences of SF3B1R625H were evaluated in vitro and in vivo. Critical makers of epithelial-mesenchymal transition and key components were detected using western blot, immunohistochemistry, and immunofluorescence. Suppressing proteins was achieved using siRNA. RESULTS: Transcriptomic analysis of prolactinomas and heterozygous mutant cells revealed that the SF3B1R625H allele led to different alterations in splicing properties, affecting different genes in different species. SF3B1R625H promoted aberrant splicing and DLG1 suppression in both rat cells and human tumors. In addition, SF3B1R625H and knocking down DLG1 promoted cell migration, invasion, and epithelial-mesenchymal transition through PI3K/Akt pathway. CONCLUSIONS: Our findings elucidate a mechanism through which mutant SF3B1 promotes tumor progression and may provide a potent molecular therapeutic target for prolactinomas with the SF3B1R625H mutation.

A Novel Three-LncRNA Signature Predicting Tumor Recurrence in Nonfunctioning Pituitary Adenomas.

The nonfunctioning pituitary adenoma (NFPA) recurrence rate is relatively high after surgical resection. Here, we constructed effective long noncoding RNA (lncRNA) signatures to predict NFPA prognosis. LncRNAs expression microarray sequencing profiles were obtained from 66 NFPAs. Sixty-six patients were randomly separated into a training (n = 33) and test group (n = 33). Univariable Cox regression and a machine learning algorithm was used to filter lncRNAs. Time-dependent receiver operating characteristic (ROC) analysis was performed to improve the prediction signature. Three lncRNAs (LOC101927765, RP11-23N2.4 and RP4-533D7.4) were included in a prognostic signature with high prediction accuracy for tumor recurrence, which had the largest area under ROC curve (AUC) value in the training/test group (AUC = 0.87/0.73). The predictive ability of the signature was validated by Kaplan-Meier survival analysis. A signature-based risk score model divied patients into two risk group, and the recurrence-free survival rates of the groups were significantly different (log-rank p < 0.001). In addition, the ROC analysis showed that the lncRNA signature predictive ability was significantly better than that of age in the training/testing/entire group (AUC = 0.87/0.726/0.798 vs. AUC = 0.683/0.676/0.679). We constructed and verified a three-lncRNA signature predictive of recurrence, suggesting potential therapeutic targets for NFPA.

Screening and Identification of Key Microenvironment-Related Genes in Non-functioning Pituitary Adenoma.

PURPOSE: Non-functioning pituitary adenoma (NFPA) is a very common type of intracranial tumor, which can be locally invasive and can have a high recurrence rate. The tumor microenvironment (TME) shows a high correlation with tumor pathogenesis and prognosis. The current study aimed to identify microenvironment-related genes in NFPAs and assess their prognostic value. METHODS: 73 NFPA tumor samples were collected from Beijing Tiantan Hospital and transcriptional expression profiles were obtained through microarray analysis. The immune and stromal scores of each sample were calculated through the ESTIMATE algorithm, and the patients were divided into high and low immune/stromal score groups. Intersection differentially expressed genes (DEGs) were then obtained to construct a protein-protein interaction (PPI) network. Potential functions and pathways of intersection DEGs were then analyzed through Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes. The prognostic value of these genes was evaluated. The quantitative real-time polymerase chain reaction in another set of NFPA samples was used to confirm the credibility of the bioinformatics analysis. RESULTS: The immune/stromal scores were significantly correlated with cavernous sinus (CS) invasion. The Kaplan-Meier curve indicated that the high immune score group was significantly related to poor recurrence-free survival. We identified 497 intersection DEGs based on the high vs. low immune/stromal score groups. Function enrichment analyses of 497 DEGs and hub genes from the PPI network showed that these genes are mainly involved in the immune/inflammatory response, T cell activation, and the phosphatidylinositol 3 kinase-protein kinase B signaling pathway. Among the intersection DEGs, 88 genes were further verified as significantly expressed between the CS invasive group and the non-invasive group, and five genes were highly associated with NFPA prognosis. CONCLUSION: We screened out a series of critical genes associated with the TME in NFPAs. These genes may play a fundamental role in the development and prognosis of NFPA and may yield new therapeutic targets.

Identifying critical protein-coding genes and long non-coding RNAs in non-functioning pituitary adenoma recurrence.

Non-functioning pituitary adenoma (NFPA) is a very common type of intracranial tumor. Monitoring and predicting the postoperative recurrence of NFPAs is difficult, as these adenomas do not present with serum hormone hypersecretion. Long non-coding RNAs (lncRNAs) and protein-coding genes (PCGs) play critical roles in the development and progression of numerous tumors. However, the complex network of RNA interactions related to the mechanisms underlying the postoperative recurrence of NFPA is still unclear. In the present study, 73 patients with NFPA were investigated using high-throughput sequencing and follow-up investigations. In total, 6 of these patients with recurrence within 1 year after surgery were selected as the fast recurrence group, and 6 patients with recurrence 5 years after surgery were selected as the slow recurrence group. By performing differential expression analysis of the fast recurrence and slow recurrence groups, a set of differentially expressed PCGs and lncRNAs were obtained (t-test, P<0.05). Next, protein-protein interaction coregulatory networks and lncRNA-mRNA coexpression networks were identified. In addition, the hub lncRNA-mRNA modules related to NFPA recurrence were further screened and transcriptome expression markers for NFPA regression were identified (log-rank test, P<0.05). Finally, the ability of the hub and module genes to predict recurrence and progression-free survival in patients with NFPA was evaluated. To confirm the credibility of the bioinformatic analyses, nucleolar protein 6 and LL21NC02-21A1.1 were randomly selected from among the genes with prognostic significance for validation by reverse transcription-quantitative PCR in another set of NFPA samples (n=9). These results may be helpful for evaluating the slow and rapid recurrence of NFPA after surgery and exploring the mechanisms underlying NFPA recurrence. Future effective biomarkers and therapeutic targets may also be revealed.

Germline mutations in MEN1 are associated with the tumorigenesis of pituitary adenoma associated with meningioma.

Pituitary adenoma and meningioma are two of the most common benign tumors in the central nervous system. Pituitary adenoma associated with meningioma (PAM) is a rare disease, the tumorigenesis of which remains unclear. Therefore, the aim of the present study was to investigate the tumorigenesis of PAM. A total of 8,197 patients with pituitary adenoma were analyzed. Furthermore, the clinical data of 57 patients with PAM were compared with patients with multiple endocrine neoplasia 1 (MEN-1) syndrome. Whole exome sequencing (WES) was performed on 23 samples from patients with PAM and the germline mutation was verified by Sanger sequencing. The age of tumor penetrance (age of patients at diagnosis) for PAM was significantly higher than that for patients with MEN-1. Compared with MEN-1 patients, there was a significant association between PAM and female sex (P=0.004). Clonal analysis and phylogenetic tree construction suggested that the pituitary adenoma and meningioma in PAM don't originate from a common progenitor. WES revealed that 5/23 PAM samples had the recurrent germline mutation MEN1 c.1523G>A; p.G508D, which may be a genetic risk factor for PAM. Compared with patients with sporadic pituitary adenoma, the difference was statistically significant (P=0.0004). Compared with wild-type MEN1, there was a significant association between the MEN1 mutation and recurrence of pituitary adenoma, young age and larger diameter of the meningioma. The present study indicated that germline mutations in MEN1 may be associated with the tumorigenesis of PAM.

Somatic SF3B1 hotspot mutation in prolactinomas.

The genetic basis and corresponding clinical relevance of prolactinomas remain poorly understood. Here, we perform whole genome sequencing (WGS) on 21 patients with prolactinomas to detect somatic mutations and then validate the mutations with digital polymerase chain reaction (PCR) analysis of tissue samples from 227 prolactinomas. We identify the same hotspot somatic mutation in splicing factor 3 subunit B1 (SF3B1R625H) in 19.8% of prolactinomas. These patients with mutant prolactinomas display higher prolactin (PRL) levels (p = 0.02) and shorter progression-free survival (PFS) (p = 0.02) compared to patients without the mutation. Moreover, we identify that the SF3B1R625H mutation causes aberrant splicing of estrogen related receptor gamma (ESRRG), which results in stronger binding of pituitary-specific positive transcription factor 1 (Pit-1), leading to excessive PRL secretion. Thus our study validates an important mutation and elucidates a potential mechanism underlying the pathogenesis of prolactinomas that may lead to the development of targeted therapeutics.

Integrated analysis of DNA methylation and mRNA expression profiles to identify key genes involved in the regrowth of clinically non-functioning pituitary adenoma.

Tumour regrowth is a key characteristic of clinically non-functioning pituitary adenoma (NFPA). No applicable prognosis evaluation method is available for post-operative patients. We aimed to identify DNA methylation biomarkers that can facilitate prognosis evaluation. Genome-wide DNA methylation and mRNA microarray analyses were performed for tumour samples from 71 NFPA patients. Differentially expressed genes and methylated genes were identified based on the regrowth vs non-regrowth grouping. There were 139 genes that showed alterations in methylation status and expression level, and only 13 genes showed a negative correlation. The progression-free analysis found that FAM90A1, ETS2, STAT6, MYT1L, ING2 and KCNK1 are related to tumour regrowth. A prognosis-prediction model was built based on all 13 genes from integrated analysis, and the 6-gene model achieved the best area under the receiver operating characteristic curves (AUC) of 0.820, compared with 0.785 and 0.568 for the 13-gene and 7-gene models, respectively. Our prognostic biomarkers were validated by pyrosequencing and RT-PCR. FAM90A1 and ING2 was found to be independent prognostic factors of tumour regrowth with univariate Cox regression. The DNA methylation and expression levels of FAM90A1 and ING2 are associated with tumour regrowth, and may serve as biomarkers for predicting the prognosis of patients with NFPA.

JAG1, Regulated by microRNA-424-3p, Involved in Tumorigenesis and Epithelial-Mesenchymal Transition of High Proliferative Potential-Pituitary Adenomas.

Pituitary adenomas (PAs) are a neoplastic proliferation of anterior pituitary. Signature of Notch pathway relies upon the histopathological type of PAs. The details of Notch pathway that are involved in the migration and invasion of Pas are still unclear. This paper filters and testifies the relation between Notch signaling pathway and the migration/invasion in subtypes of PAs. The diversity of genes and pathways is investigated based on transcriptome data of 60 patients by KEGG pathway analysis and GSEA. A series of functional experiments demonstrate the role of candidate genes by overexpression and antibody blocking in GH3 cell line. Volcano map and GSEA results exhibit the differential and the priority of Jagged1 canonical Notch Ligand (JAG1) in the Notch pathway combined with clinical features. JAG1 is involved in epithelial-mesenchymal transition (EMT) in PAs by correlation analysis of RNA-seq data. Progression-free survival (PFS) of patients with high JAG1 was shorter than patients with low JAG1 according to follow-up data (P = 0.006). Furthermore, overexpression and antibody blocking experiments in GH3 cell line indicate that JAG1 could promote cell proliferation, migration, and G1/S transition. Double luciferase reporter assay gives manifests that JAG1 is the target gene of miR-424-3p, and mimics or inhibitor of miR-424-3p can regulate the level of JAG1 which, in turn, affects cell proliferation and the levels of MMP2 and VIM in GH3 cell line, respectively. Our study delves into the relation between the Notch signaling pathway and cell proliferation and EMT in PAs, providing a potential treatment through targeting JAG1.

Functional characterization of DLK1/MEG3 locus on chromosome 14q32.2 reveals the differentiation of pituitary neuroendocrine tumors.

Pituitary neuroendocrine tumors (PitNETs) represent the neoplastic proliferation of the anterior pituitary gland. Transcription factors play a key role in the differentiation of PitNETs. However, for a substantial proportion of PitNETs, the etiology is poorly understood. According to the transcription data of 172 patients, we found the imprinting disorders of the 14q32.2 region and DLK1/MEG3 locus associated with the differentiation of PitNETs. DLK1/MEG3 locus promoted somatotroph differentiation and inhibited tumor proliferation in PIT1(+) patients, furthermore, the level of DLK1 played a critical role in the trend of somatotroph or lactotroph differentiation. Anti-DLK1 monoclonal antibody blockade or siMEG3 both indicated that the DLK1/MEG3 significantly promoted the synthesis and secretion of GH/IGF-1 and inhibited cell proliferation. In addition, loss of DLK1 activated the mTOR signaling pathway in high DLK1-expressing and PIT1(+) GH3 cell lines, a mild effect in the low DLK1-expressing and PIT1(+) MMQ cell lines and no effect in the PIT1(-) ATT20 cell line. These findings emphasize that expression at the DLK1/MEG3 locus plays a key role in the differentiation of PitNETs, especially somatotroph adenomas, and provide potential molecular target data for patient stratification and treatment in the future.

Genomic and transcriptomic analysis of pituitary adenomas reveals the impacts of copy number variations on gene expression and clinical prognosis among prolactin-secreting subtype.

Pituitary adenomas (PAs) are slow growing and benign primary intracranial tumors that often cause occupying effects or endocrine symptoms. PAs can be classified into various subtypes according to hormone secretion. Although widespread transcriptional alterations that cause aberrant hormone secretion have been characterized, the impact of genomic variations on transcriptional alterations is unclear due to the rare occurrence of single-nucleotide variations in PA. In this study, we performed whole-genome sequencing (WGS) on 76 PA samples across three clinical subtypes (PRL-PAs; GH-PAs, and NFPAs); transcriptome sequencing (RNA-seq) of 54 samples across these subtypes was also conducted. Nine normal pituitary tissues were used as controls. Common and subtype-specific transcriptional alterations in PAs were identified. Strikingly, widespread genomic copy number amplifications were discovered for PRL-PAs, which are causally involved in transcriptomic changes in this subtype. Moreover, we found that the high copy number variations (CNVs) in PRL-PA cause increased prolactin production, drug resistance and proliferative capacity, potentially through key genes with copy number amplification and transcriptional activation, such as BCAT1. This study provides insight into how genomic CNVs affect the transcriptome and clinical outcomes of PRL-PA and sheds light on the development of potential therapeutics for aberrantly activated targets.

Identification of key genes in invasive clinically non-functioning pituitary adenoma by integrating analysis of DNA methylation and mRNA expression profiles.

BACKGROUND: Tumor surrounding the internal carotid artery or invading to the cavernous sinus is an important characteristic of invasive pituitary adenoma, and a pivotal factor of tumor residue and regrowth. Without specific changes in serum hormone related to the adenohypophyseal cell of origin, clinically non-functioning pituitary adenoma is more likely to be diagnosed at invasive stages compared with functioning pituitary adenoma. The underlying mechanism of tumor invasion remains unknown. In this study, we aimed to identify key genes in tumor invasion by integrating analyses of DNA methylation and gene expression profiles. METHOD: Genome-wide DNA methylation and mRNA microarray analysis were performed for tumor samples from 68 patients at the Beijing Tiantan Hospital. Differentially expressed genes and methylated probes were identified based on an invasive vs non-invasive grouping. Differentially methylated probes in the promoter region of targeted genes were assessed. Pearson correlation analysis was used to identify genes with a strong association between DNA methylation status and expression levels. Pyrosequencing and RT-PCR were used to validate the methylation status and expression levels of candidate genes, respectively. RESULTS: A total of 8842 differentially methylated probes, located on 4582 genes, and 661 differentially expressed genes were identified. Both promoter methylation and expression alterations were observed for 115 genes with 58 genes showing a negative correlation between DNA methylation status and expression level. Nineteen genes that exhibited notably negative correlations between DNA methylation and gene expression levels, are involved in various gene ontologies and pathways, or played an important role in different diseases, were regarded as candidate genes. We found an increased methylation with a decreased expression of PHYHD1, LTBR, C22orf42, PRR5, ANKDD1A, RAB13, CAMKV, KIFC3, WNT4 and STAT6, and a decreased methylation with an increased expression of MYBPHL. The methylation status and expression levels of these genes were validated by pyrosequencing and RT-PCR. CONCLUSIONS: The DNA methylation and expression levels of PHYHD1, LTBR, MYBPHL, C22orf42, PRR5, ANKDD1A, RAB13, CAMKV, KIFC3, WNT4 and STAT6 are associated with tumor invasion, and these genes may become the potential genes for targeted therapy.

Identification of a novel somatic mutation of POU6F2 by whole-genome sequencing in prolactinoma.

BACKGROUND: Pituitary adenomas (PAs) are one of the most common intracranial tumors; approximately half of PAs are prolactin (PRL)-secreting PAs (prolactinomas). The genetic alterations prevalent in prolactinomas are unknown. METHODS: Here, we present a patient with an extremely aggressive and giant prolactinoma accompanied by serious destruction of the surrounding bone mass. This patient exhibited resistance to dopaminergic drugs. Through whole-genome sequencing, we identified two novel somatic mutations in the POU6F2 gene (NM_001166018.2: c. 839 C>T; NM_001166018.2: c. 875A>G). RESULTS: This report is the first to identify these somatic mutations in the POU6F2 gene in a prolactinoma. We found that these two mutations obviously decreased the expression level of POU6F2. Inhibition of POU6F2 activity increased the cell proliferation and PRL secretion in rat pituitary cells, but proliferation and PRL secretion were decreased in cells with POU6F2 overexpression. CONCLUSIONS: POU6F2 might play a crucial role in the development of prolactinomas and may be a promising target for developing new therapies against prolactinomas.

The clinical characteristics and molecular mechanism of pituitary adenoma associated with meningioma.

BACKGROUND: Pituitary adenoma and meningioma are the most common benign tumors in the central nervous system. Pituitary adenoma associated with meningioma (PAM) is a rare disease and the clinical features and mechanisms of PAM are unclear. METHODS: We summarized the clinical data of 57 PAM patients and compared with sporadic pituitary adenoma (SPA) and sporadic meningioma (SM). 5 pituitary adenomas of PAM and 5 SPAs were performed ceRNA microarray. qRT-PCR, Western Blot, siMEN1 and rapamycin inhibition experiment were validated for ceRNA microarray. RESULTS: Clinical variable analyses revealed that significant correlations between PAM and female sex as well as older age when compared with SPA and significant correlations between PAM and transitional meningioma as well as older age when compared with SM. Additionally, the characteristics of PAM were significantly different for MEN1 patients. Functional experiments showed lower expression of MEN1 can upregulate mTOR signaling, in accordance with the result of ceRNA microarray. Rapamycin treatment promotes apoptosis in primary pituitary adenoma and meningioma cells of PAM. CONCLUSIONS: MEN1 plays an important role in PAM by upregulating mTOR signaling pathway. Rapamycin represents a potential therapeutic strategy for PAM in the future.