miR-142 Suppresses Endometrial Cancer Proliferation In Vitro and In Vivo by Targeting Cyclin D1.

Endometrial cancer (EC), a prevalent gynecologic tumor, is a great threat to women. We aimed to explore miR-142's effects on EC and the relevant mechanisms. Cell proliferation was evaluated with MTT, cell counting, and colony formation assay. MRNA abundances of miR-142 and cyclin D1 (CCND1) were examined with quantitative real-time PCR. CCND1 protein level in cells was analyzed with Western blot. miR-142's downstream target was identified with targetscan and luciferase reporter assay. Nude mice were injected subcutaneously with Ishikawa (ISK) cells transfected with or without miR-142 mimics. Ki-67 and CCND1 expressions in tumors of xenograft mice were analyzed with immunohistochemical assay. miR-142 was expressed at a lower level in human EC tumor samples than matched normal tissues, and its mRNA level in EC patients without metastasis was higher than that in patients with metastatic EC. Additionally, low-level miR-142 was closely linked with the poor prognosis of EC patients. miR-142 restricted ISK and HEC-1A cell proliferation. Targetscan and luciferase reporter assay proved the target relationship between miR-142 and CCND1. Moreover, high-level CCND1 was positively correlated with the poor prognosis of EC patients. Besides, miR-142 mimics restricted tumor growth in ISK xenografted mice, as well as inhibited the expression of Ki67 and CCND1 in excised tumors. miR-142 restricted EC proliferation by targeting CCND1.