miR-133a enhances the sensitivity of Hep-2 cells and vincristine-resistant Hep-2v cells to cisplatin by downregulating ATP7B expression

摘要

The expression levels of the copper transporter P-type adenosine triphosphatase?(ATP7B) are known correlate with tumor cell sensitivity to cisplatin. However, the mechanisms underlying cisplatin resistance remained poorly understood. Therefore, in the present study, we treated Hep-2?cells and in-house-developed vincristine-resistant Hep-2v?cells with 50, 100, or 200?μM cisplatin and assessed cell viability after 24 or 48?h. Hep-2v cells were shown to be resistant to 50-200?μM cisplatin. Furthermore, using immunofluorescence staining and western blot analysis, we noted that ATP7B, but not copper-transporting ATPase?1?(ATP7A), expression was significantly increased in Hep-2v cells, and this increase was maintained at a higher level compared with Hep-2?cells. As ATP7B is a target of microRNA 133a?(miR?133a), the ability of miR?133a to influence cisplatin sensitivity in Hep-2v cells was then assessed by CCK-8 assay. We noted that miR?133a expression was lower in both Hep-2 and Hep-2v?cells compared with epithelial NP69 cells. Following treatment with 50?μM cisplatin, in Hep-2v cells expressing exogenous miR?133a we noted reduced ATP7B expression, and these cells had a significantly lower survival rate compared with the control. The present study demonstrates that miR?133a enhances the sensitivity of multidrug-resistant Hep-2v cells to cisplatin by downregulating ATP7B expression.