In conclusion, our study demonstrated that 1) miR-497 was downregulated in cisplatin-resistant ovarian cancer cell lines and tumors; 2) DNA hypermethylation contribute to downregulation of miR-497; 3) mTOR and p70S6K1 are two direct targets of miR-497 with biological function that are associated with development of cisplatin-resistance phonotype; and 4) overexpression of miR-497 decreases cisplatin resistance of ovarian cancer cells in vitro and in vivo. This evidence concerns the gene MTOR and ovarian cancer.