RESUMEN
Glioblastoma multiform (GBM) is a highly aggressive primary brain tumor. Exosomes derived from glioma cells under a hypoxic microenvironment play an important role in tumor biology including metastasis, angiogenesis and chemoresistance. However, the underlying mechanisms remain to be elucidated. In this study, we aimed to explore the role of connexin 43 on exosomal uptake and angiogenesis in glioma under hypoxia. U251 cells were exposed to 3% oxygen to achieve hypoxia, and the expression levels of HIF-1α and Cx43, involved in the colony formation and proliferation of cells were assessed. Exosomes were isolated by differential velocity centrifugation from U251 cells under normoxia and hypoxia (Nor-Exos and Hypo-Exos), respectively. Immunofluorescence staining, along with assays for CCK-8, tube formation and wound healing along with a transwell assay were conducted to profile exosomal uptake, proliferation, tube formation, migration and invasion of HUVECs, respectively. Our results revealed that Hypoxia significantly up-regulated the expression of HIF-1α in U251 cells as well as promoting proliferation and colony number. Hypoxia also increased the level of Cx43 in U251 cells and in the exosomes secreted. The uptake of Dio-stained Hypo-Exos by HUVECs was greater than that of Nor-Exos, and inhibition of Cx43 by 37,43gap27 or lenti-Cx43-shRNA efficiently prevented the uptake of Hypo-Exos by recipient endothelial cells. In addition, the proliferation and total loops of HUVECs were remarkably increased at 24 h, 48 h, and 10 h after Hypo-Exos, respectively. Notably, 37,43gap27, a specific Cx-mimetic peptide blocker of Cx37 and Cx43, efficiently alleviated Hypo-Exos-induced proliferation and tube formation by HUVECs. Finally, 37,43gap27 also significantly attenuated Hypo-Exos-induced migration and invasion of HUVECs. These findings demonstrate that exosomal Cx43 contributes to glioma angiogenesis mediated by Hypo-Exos, and suggests that exosomal Cx43 might serve as a potential therapeutic target for glioblastoma.
Asunto(s)
Exosomas , Glioblastoma , MicroARNs , Neovascularización Patológica , Hipoxia de la Célula , Línea Celular Tumoral , Conexina 43/genética , Conexina 43/metabolismo , Células Endoteliales/metabolismo , Exosomas/metabolismo , Glioblastoma/genética , Humanos , MicroARNs/metabolismo , Neovascularización Patológica/genética , Neovascularización Patológica/metabolismo , Microambiente TumoralRESUMEN
Long noncoding RNAs (lncRNAs) are related to the development of atherosclerosis (AS). However, the role of lncRNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) in tumor necrosis factorα (TNFα)induced rat aortic endothelial cell (RAOEC) pyroptosis, as well as the underlying mechanisms, remain unclear. RAOEC morphology was assessed using an inverted microscope. The mRNA and/or protein expression levels of MALAT1, microRNA(miR)30c5p and connexin 43 (Cx43) were assessed using reverse transcriptionquantitative PCR (RTqPCR) and/or western blotting, respectively. The relationships among these molecules were validated by dualluciferase reporter assays. Biological functions, such as LDH release, pyroptosisassociated protein levels and the proportion of PIpositive cells, were evaluated using a LDH assay kit, western blotting and Hoechst 33342/PI staining, respectively. The present study demonstrated that compared with the control group, the mRNA expression levels of MALAT1 and protein expression levels of Cx43 were significantly upregulated, whereas miR30c5p mRNA expressions levels were significantly decreased in TNFαtreated RAOEC pyroptosis. Knockdown of MALAT1 or Cx43 significantly attenuated the increase in LDH release, pyroptosisassociated protein expression and PIpositive cell numbers among RAOEC treated using TNFα, whereas an miR30c5p mimic exerted the opposite effect. Furthermore, miR30c5p was demonstrated to be a negative regulator of MALAT1 and could also target Cx43. Finally, cotransfection with siMALAT1 and miR30c5p inhibitor could attenuate the protective effect of MALAT1 knockdown against TNFαmediated RAOEC pyroptosis by upregulation of Cx43 expression. In conclusion, MALAT1 might serve an important role in TNFαmediated RAOEC pyroptosis by regulating the miR30c5p/Cx43 axis, which would provide a potential novel diagnostic and therapeutic target for AS.