In the present study, we treatment PCOS ovarian granulosa cells with difference concentration of sRAGE, and examined the expression of VEGF and EGF-like growth factors AREG, BTC and EREG. Our results show that sRAGE decrease the production of VEGF and EGF-like growth factors AREG, BTC and EREG, and the effects were dependent on the concentrations of sRAGE. It demonstrated that sRAGE may downregulate VEGF expression via EGF-like growth factor pathway in PCOS ovarian granulosa cells and sRAGE may play a potential protective role in polycystic ovary syndrome.
AGE-RAGE axis can activate p21 RAS, MAPK (p38), PI3K, NF-kB and other cell signaling molecules, contribute to angiogenesis, apoptosis and inflammatory response processes. In PCOS ovaries, AGEs and RAGE were stronger displayed in the granulosa cell layer compared to healthy ovaries. To date, emerging evidences have supported that PCOS was related to hyperandrogenism, insulin resistance and chronic inflammation. Our previous study shown that sRAGE concentrations were decreased in the follicular fluid of PCOS patients, and these sRAGE were inversely associated with VEGF, TNF-α, IL-6, and CRP protein levels. According to Boulanger, the activation of AGEs-RAGE axis in human peritoneal mesothelial cells can induce the release of VEGF and subsequently the formation of capillary tubes, while anti-receptor for AGEs (RAGE) antibody reduced capillary tube formation. As a decoy receptor for AGEs, sRAGE can block multiple cell signaling pathways induced by AGE-RAGE aixs. Psoriasin (S100A7) increases the expression of VEGF through the RAGE pathway and promote endothelial cell proliferation, however treatment with sRAGE inhibited endothelial cell proliferation and tube formation enhanced by recombinant psoriasin. In the present study, we demonstrated that sRAGE reduced the expression of VEGF mRNA and protein in a dose-dependent manner in PCOS granulosa cells. Culturing human esophageal cancer cells with the administration of 0.2 ug/ml sRAGE for 24 h, sRAGE significantly inhibit the proliferation of esophageal cancer cells and VEGF-C expression. Moreover, Emman found that treatmeng human umbilical vein Vascular endothelial cells (HUVECs) with 50 ng/ml sRAGE for 30 minutes, the amount of VEGF mRNA was significantly reduced.
EGF-like growth factor AREG, BTC and EREG is the upstream regulators of VEGF, regulate the production of VEGF. Recombinant human AREG has been shown stimulated FLS to proliferate and produce VEGF in a dose-dependent manner in patients with rheumatoid arthritis . In addition, BTC upregulate VEGF expression by activation of EGFR in HNSCCs, it also demonstrated that EGFR and c-erbB-2 signaling pathway(s) plays a role in VEGF regulation in HNSCCs. In the female reproductive system, EGF-like growth factor and its receptor EGFR is widely expressed in ovarian tissue, and involved in female reproductive function. In the menstrual cycle, LH peak induce EGF-like growth factor AREG, BTC and EREG transient increase, and these three factors have LH-like effect, inhibite AREG, BTC and EREG pathway can block LH signaling pathway. As we all know, LH peak can promote the expression of VEGF in theca cells and luteinized granulosa cells . AREG significantly increase VEGF production in the human granulosa cell line, KGN .
In the present study, we found that sRAGE reduced the expression of AREG, BTC and EREG in a dose-dependent manner in PCOS ovarian granulosa cells. Many studies have shown that sRAGE inhibits inflammatory responses and oxidative stress. Moreover, overexpression of soluble RAGE in mesenchymal stem cells enhances their immunoregulatory potential for cellular therapy in autoimmune arthritis, indicating that sRAGE has no toxicity to cells. Taken together, sRAGE reduced EGF-like growth factors AREG, BTC and EREG expression while simultaneously reducing VEGF production in PCOS ovarian granulosa cells, as AREG, BTC and EREG are upstream regulators of VEGF, so these results demonstrated that sRAGE downregulates VEGF expression via EGF-like growth factor pathway in PCOS ovarian granulosa cells. The mechanisms underlying the effects of sRAGE on EGF-like growth factor and VEGF expression involve specific factor-mediated signaling pathways. In immortalized human granulosa cells, SVOG, treatment with AREG, BTC, or EREG upregulated COX-2 expression, the AREG-, BTC-, and EREG-induced COX-2 expression in turn contributed to PGE2 production. The expression PGE2 and VEGF are closely related, both of which are important factors for regulating angiogenesis and vascular permeability. In human granulosa cells PGE2 can promote the expression of VEGF, involved in the regulation of angiogenesis of the pathological ovary. AGE-bovine serum albumin increased production of COX-2 and PGE2, while sRAGE reduced AGE-stimulated COX-2 and PGE2. Taken together, these evidences implicating the involvement of PGE2 in the regulation of VEGF expression mediated by sRAGE. So far did not see the reports that whether sRAGE could reduce influence PGE2 synthesis through AREG, BTC and EREG, subsequently inhibiting the production of VEGF in PCOS granulosa cells, it is necessary to further study.
In conclusion, sRAGE may downregulate VEGF expression in PCOS ovarian granulosa cells,and EGF-like growth factor pathway may be involved in this process.
From the new perspective of sRAGE, we want to provide further new ideas for the
prevention and treatment of PCOS.