MiR-202-5p/PTEN mediates doxorubicin-resistance of breast cancer cells via PI3K/Akt signaling pathway.

We intended to explore the effect of miR-202-5p and phosphatase and tensin homolog (PTEN) on doxorubicin (DOX) resistance of breast cancer cells. The result of quantitative reverse transcription-polymerase chain reaction (qRT-PCR) reveals that miR-202-5p was highly expressed in drug-resistant breast cancer tissues, while PTEN was expressed less. MiR-202-5p directly targeted PTEN. Further, it was found that the overexpression of miR-202-5p promoted the DOX resistance and proliferation as well as decreased apoptosis of MCF-7 cells. The lower expression of miR-202-5p inhibited DOX resistance and proliferation as well as increased the apoptosis of MCF-7/DOX cells. In vivo experiments showed that mice with downregulated miR-202-5p had smaller tumor volume and lower Ki67 level. The overexpression of PTEN declined the proliferation of MCF7 cells, while miR-202-5p's overexpression could offset the function of overexpression of PTEN. The knockdown of PTEN promoted MCF7/DOX cell proliferation that could be counteracted by miR-202-5p silence. Moreover, we also revealed that downregulated miR-202-5p expression inhibited PI3k/Akt signaling pathway-related protein by regulating expression of PTEN.