The in vitro data show that polyphenol QU increases the sensitivity of SKOV-3/CDDP cisplatin-resistant human ovarian adenocarcinoma subline cells to cisplatin due to their biological effects, including alteration of the cell cycle, classical pro-oxidation, upregulation of ROS and downregulation of the thioredoxin antioxidant system (Trx/TrxR), and cell signaling (mTOR/STAT3) suppression, which collectively lead to the enhancement of the mitochondrial apoptotic pathway (Cas9, 7, and 3 and PARP). The gene discussed is STAT3; the disease is ovarian adenocarcinoma.