Pannexin-1 promotes the invasion of pituitary adenoma by modulating ATP release

Background Pannexin-1 (Panx1) channel participates in the development of many tumor subtypes, however, its role of Panx1 in pituitary adenoma (PA) remains largely unknown. The current study was designed to investigate the role of Panx1 in PA, especially in the invasion of PA. Methods We examined the expression of Panx1 in 56 surgical PA samples, which were divided into invasive and noninvasive groups. We also established Panx1-overexpressing (Panx1-OE) PA cells using the GH3 and MMQ cell lines in vitro. Results We found that the expression of Panx1 in invasive PA was significantly upregulated compared with noninvasive PA and pituitary gland and that Panx1-OE could promote the invasion of these cell lines but had no effect on their proliferation. Further metabolomics experiments confirmed that Panx1-OE could trigger changes in several metabolic pathways of GH3 cells. Among the dysregulated cellular metabolites, we found that adenosine triphosphate (ATP) could be released to the extracellular matrix through the Panx1 channel and thereby enhance the invasion of GH3 cells. Mechanistically, ATP promoted extracellular Ca2+ influx and upregulated the expression of secretagogin and MMP-2/9 by activating the P2X7 receptor (P2X7R). We also found that the Panx1-ATP-P2X7R signaling pathway may promote GH3 cell invasion by remodeling the actin cytoskeleton. Conclusion Taken together, our findings point to a pivotal role of Panx1 in promoting PA invasion, indicating its use as a potential therapeutic target for invasive PA.

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.

GPR101 drives growth hormone hypersecretion and gigantism in mice via constitutive activation of Gs and Gq/11

Growth hormone (GH) is a key modulator of growth and GH over-secretion can lead to gigantism. One form is X-linked acrogigantism (X-LAG), in which infants develop GH-secreting pituitary tumors over-expressing the orphan G-protein coupled receptor, GPR101. The role of GPR101 in GH secretion remains obscure. We studied GPR101 signaling pathways and their effects in HEK293 and rat pituitary GH3 cell lines, human tumors and in transgenic mice with elevated somatotrope Gpr101 expression driven by the rat Ghrhr promoter (GhrhrGpr101). Here, we report that Gpr101 causes elevated GH/prolactin secretion in transgenic GhrhrGpr101 mice but without hyperplasia/tumorigenesis. We show that GPR101 constitutively activates not only Gs, but also Gq/11 and G12/13, which leads to GH secretion but not proliferation. These signatures of GPR101 signaling, notably PKC activation, are also present in human pituitary tumors with high GPR101 expression. These results underline a role for GPR101 in the regulation of somatotrope axis function.

Histone Citrullination Represses MicroRNA Expression, Resulting in Increased Oncogene mRNAs in Somatolactotrope Cells

ABSTRACT Peptidylarginine deiminase (PAD) enzymes convert histone arginine residues into citrulline to modulate chromatin organization and gene expression. Although PADs are expressed in anterior pituitary gland cells, their functional role and expression in pituitary adenomas are unknown. To begin to address these issues, we first examined normal human pituitaries and pituitary adenomas and found that PAD2, PAD4, and citrullinated histones are highest in prolactinomas and somatoprolactinomas. In the somatoprolactinoma-derived GH3 cell line, PADs citrullinate histone H3, which is attenuated by a pan-PAD inhibitor. RNA sequencing and chromatin immunoprecipitation (ChIP) studies show that the expression of microRNAs (miRNAs) let-7c-2, 23b, and 29c is suppressed by histone citrullination. Our studies demonstrate that these miRNAs directly target the mRNA of the oncogenes encoding HMGA, insulin-like growth factor 1 (IGF-1), and N-MYC, which are highly implicated in human prolactinoma/somatoprolactinoma pathogenesis. Our results are the first to define a direct role for PAD-catalyzed histone citrullination in miRNA expression, which may underlie the etiology of prolactinoma and somatoprolactinoma tumors through regulation of oncogene expression.

Influence of ghrelin on rat pituitary GH3 cell line proliferation

Introduction. Human ghrelin is the endogenous ligand of the growth hormone secretagogue receptor type 1a (GHSR1a). It is suggested that ghrelin is involved in pituitary adenomas pathogenesis. There are inconsistent data regarding the effect of ghrelin on cell proliferation. In this study the outcome of ghrelin in the rat pituitary adenoma GH3 cell line on morphology and proliferation ratio was evaluated. The ghrelin receptor (Ghsr) mRNA expression in GH3 cell line was established as well, because it was found that heterogeneous expression pattern characterized physiological and pathological conditions of tissues of different origin.Material and Methods. Suitable experimental model pituitary tumor (rat GH3 cell line) was stimulated with ghrelin in the final concentrations 10–12 M, 10–9 M and 10–6 M. Reverse transcription followed by real time polymerase chain reaction was used for ghrelin receptor gene transcript detection. The morphology as well as cell cycle of those cells were analyzed using Axio Vert.A1 Microscope (Zeiss) and BD FACSCalibur™ flow cytometer (Beckton Dickinson), respectively. The percentages of cells in the G0/G1, S, G2/M cycle phases were evaluated using the ModFit™ software (Verity Software, Inc., USA). Results. Ghsr mRNA presence was confirmed in GH3 cells. Ghrelin did not affect conspicuously GH3 cells morphology, however the ghrelin-induced proliferation index increase was caused by both decline of G0/G1 phases cells count and increase those being in S+G2/M (p < 0.05). Conclusions. In conclusion, this study indicates that ghrelin stimulates GH3 cells proliferation and may play role in pituitary tumorigenesis via an autocrine/paracrine pathway.

Influence of ghrelin on rat pituitary GH3 cell line proliferation

Introduction. Human ghrelin is the endogenous ligand of the growth hormone secretagogue receptor type 1a (GHSR1a). It is suggested that ghrelin is involved in pituitary adenomas pathogenesis. There are inconsistent data regarding the effect of ghrelin on cell proliferation. In this study the outcome of ghrelin in the rat pituitary adenoma GH3 cell line on morphology and proliferation ratio was evaluated. The ghrelin receptor (Ghsr) mRNA expression in GH3 cell line was established as well, because it was found that heterogeneous expression pattern characterized physiological and pathological conditions of tissues of different origin.Material and Methods. Suitable experimental model pituitary tumor (rat GH3 cell line) was stimulated with ghrelin in the final concentrations 10–12 M, 10–9 M and 10–6 M. Reverse transcription followed by real time polymerase chain reaction was used for ghrelin receptor gene transcript detection. The morphology as well as cell cycle of those cells were analyzed using Axio Vert.A1 Microscope (Zeiss) and BD FACSCalibur™ flow cytometer (Beckton Dickinson), respectively. The percentages of cells in the G0/G1, S, G2/M cycle phases were evaluated using the ModFit™ software (Verity Software, Inc., USA). Results. Ghsr mRNA presence was confirmed in GH3 cells. Ghrelin did not affect conspicuously GH3 cells morphology, however the ghrelin‑induced proliferation index increase was caused by both decline of G0/G1 phases cells count and increase those being in S+G2/M (p < 0.05). Conclusions. In conclusion, this study indicates that ghrelin stimulates GH3 cells proliferation and may play role in pituitary tumorigenesis via an autocrine/paracrine pathway.