Upregulated exosomal miR-221/222 promotes cervical cancer via repressing methyl-CpG-binding domain protein 2.

Abstract

Methyl-CpG-binding domain protein 2, a target gene of miR-221and miR-222, plays a crucial role in a large body of human cancers. In this study, we aim to explore the mechanism by which miR-221/222 promotes cervical cancer. We have analyzed mRNA expression of MeCP2 and MBD2 in cervical cancer tissues by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) and examined the expression of miR-221/222 in C33A, HeLa, and CaSki cells by Western blot. We found that the expression levels of MBD2 and MeCP2 were significantly reduced in cervical cancer samples as detected by the analysis of MeCP2 in matched tumor-normal samples of patients with cervical cancer, indicating a reduction in a significant percentage of patients. At the same time, we found that miR-221 and miR-222, which targeted MBD2, were upregulated in cervical cancer samples. To further elucidate the relation between miR-221/222 and MBD2, we used a lot of cell lines such as C33A, HeLa, and CaSki. Surprisingly, we found that the expression levels of MBD2 and MeCP2 were significantly lower in HeLa and CaSki than in C33A, as detected by qRT-PCR. Western blot analysis of MeCP2 of HeLa and CaSki was significantly lower than in C33A. MiR-221/222 was significantly higher in HeLa and CaSki than in C33A by qRT-PCR. The knockdown of miR-221/222 in HeLa and CaSki resulted in the downregulation of miR-221/222 levels, which rescued the expression levels of MBD2 and MeCP2 in HeLa and CaSki. However, transfection of miR-221/222 on C33A could upregulate the expression levels of miR-221/222 and decrease the expression levels of MBD2 and MeCP2. Our results demonstrate that the upregulated miR-221/222 promotes cervical cancer by repressing MBD2 and MeCP2.