| Background：Epithelial ovarian cancer (EOC) is characterized by multifocal intraperitonealdissemination and the formation of large volumes of ascitic fluid accompanied by intenseneovascularization. As with most other solid tumors, angiogenesis is regulated at an earlyevent in EOC progression and may precede neoplastic transformation. Moreover, surgicalstress could enhance ovarian cancer angiogenesis. Therefore, antiangiogenic therapy is oneof the more promising modalities for EOC treatment. Bevacizumab, a monoclonal antibodydirected against vascular endothelial growth factor A (VEGF-A), has been approved forinitial treatment of ovarian cancer. However, the clinical benefits are limited and recurrentovarian cancer has been observed in patients. The hypoxic stress produced by initialsuccessful therapy may lead to upregulation of alternative proangiogenic factors.Overcoming this evasive resistance further supports the need for a novel therapeutic in thisarea. In recent years, GPCRs have been linked to the initiation and progression of multiplecancers. thus, regulators of GPCR signaling are also likely to be important to thepathophysiology of cancer. Regulator of G-protein signaling-5(RGS5) is a member of theRGS family that is a diverse group of multifunctional proteins that regulate cellularsignaling events downstream of G-protein coupled receptors (GPCRs). RGS5has beenrecently identified as a master upregulated gene in pericytes and is responsible for suchmorphologic changes in tumor vessels. Thus, targeting RGS5may affect both tumor cellsand tumor vessels.Objective:Endothelial cells in malignant tumors are genetically unstable and are different fromnormal vessel endothelial cells at the molecular and functional level. To eventually utilizeODMECs for drug screening, it is critical to further study the exact role of RGS5in EOCtumor development in these cells. RGS5play important roles in the development of vasculature. Recently, we have found that RGS5was abundantly expressed in EOCcompared with normal ovarian. However, the distribution of RGS5in EOC and itssignificance need further study. We therefore investigated the expression of RGS5in EOC,as well as its relationship with clinicopathologic parameters. We also measured the status ofRGS5on primary endothelial cells derived from human epithelial ovarian cancer.Methods:1. Tumor tissues from87EOC patients were analyzed and expression of RGS5andEndoglin in tumor tissues was examined by immunohistochemistry. Chi-square test (orFisher’s exact test), Breslow test and multivariate Cox regression model were performed forstatistical analysis.2. We developed a reliable and reproducible method for isolating, passaging, andcharacterizing the phenotypic and functional properties of endothelial cells derived fromhuman epithelial ovarian tumors. We tested Endoglin and RGS5expression characteristicsin ODMECs. We specially analyzed the ability of ODMECs form capillary networks byusing a fibrin gel-based in vitro and detected endoglin expression at different stages of thecapillary structures formation.3. To gain new insights into the role of the RGS5protein in angiogenesis in ODMECs,RGS5gene expression was specifically inhibited using an RNAi approach. TheEndoglin-siRNA sequences were inserted into a linerized pGV118-GFP Lentiviral vectors(LV) and named LV-siRGS5.Results and Conclusion:1. most of the blood vessels expressed CD31, whereas microvascular ECs are endoglinpositive. Importantly, compared with CD31, endoglin staining was associated moredistinctively with vessels at the tumor periphery or close to the tumor capsule andsignificantly reduced or even absent in the central part of the tumor.2. This study first expounds the RGS5protein expression in ovarian cancer cells andthe expression of RGS5was significantly associated with peritoneal metastasis in patientswith ovarian cancer. High express RGS5incidence of peritoneal metastasis in patients withsignificantly lower than the lower expression RGS5patients. Moreover RGS5expressionwas negatively correlated with the average MVD. The RGS5expression in ECO was notrelated with age, tumor size, clinical stage and differentiation of the tumor. 3. ODMECs can be isolated from EOC tissue with their the original endothelialcharacteristics retained and revealed overexpression of growth factor receptors endoglinand VEGFR-2, displayed abnormal characteristics in terms of angiogenic properties. RGS5was lower expression at tubular structure forming stage.4. The overexpression of RGS5both in QDMECs and HASMC were not detected.Speculated that may due to leave tumor microenvironment. VEGF and PDGF-BB did notstimulate the expression of RGS5in vitro, indicating expression of RGS5in tumor tissuemay not rely on the VEGFR and PDGF-β signaling pathway.5. Hypoxia increases RGS5expression in ODMECs. The capacity of ODMECs toproliferate exhibit a significant inhibition in response to selectively reducing RGS5expression using RNAi. RGS5reduced CDC25A expression through decreasedPhosphorylation of MAPK/ERK, making cell cycle arrest in G1phase and proliferationability Attenuated. |
