MiR-202 promotes endometriosis by regulating SOX6 expression.

Objectives: This study is to investigate the role and mechanism of microRNA-202 (miR-202) in endometriosis.
Methods: Forty-five cases of ectopic endometrial tissues, 25 cases of eutopic endometrial tissues and 26 cases of normal endometrial tissues were collected. MiR-202 expression was detected by quantitative RT-PCR. The protein expressions of SOX6 (sex determining region Y-box 6) and its downstream proteins (p21, cyclin D1 and pRb (retinoblastoma protein)) were detected by immunochemistry and western blot. MTT and transwell assays were used to examine cell proliferation and cell migration. The dual luciferase assay was applied to validate whether miR-202 can directly target SOX6 gene.
Results: MiR-202 was highly expressed in eutopic and ectopic endometrial tissues than normal endometrial tissues (P < 0.05), and the expression was higher in tissues with III/IV stages than I/II stages (P < 0.05). The expression of SOX6 protein was lower in ectopic endometrial tissues than in normal endometrial tissues. In ectopic endometrial tissues, the expression of p21 was decreased while cyclin D1 and pRb was up-regulated than in normal endometrial tissues (P < 0.05). In cultured endometrial cells, miR-202 down-regulation induced up-regulation of SOX6 and p21 whereas down-regulation of cyclin D1 and pRb. MiR-202 promoted the proliferation and metastasis of endometrial cells. And, miR-202 could complementary bind to SOX6 3'UTR to regulate the expression of SOX6.
Conclusion: MiR-202 was up-regulated in the endometriosis. Through targeting SOX6 and its downstream proteins (p21, cyclin D1 and pRb), miR-202 can promote the progression of endometriosis.