Abstract
Cisplatin/cisplatin-based combination chemotherapy is the main therapy strategy against hepatocellular carcinoma. However, the cisplatin efficiency is dimmed by the development of drug resistance. Numerous clinical trials are now revealing the promising role of chloroquine, an autophagy inhibitor, as a novel antitumor drug. In the present study, we investigated the regulation by chloroquine on the autophagy and on the sensitivity of hepatocellular carcinoma cells in vitro. Reverse transcription quantitative-polymerase chain reaction (RT-qPCR), western blotting assay, confocal microscopy and flow cytometry (FCM) were used to analyze the autophagy induction by cisplatin in hepatocellular carcinoma HepG2 cells, to examine the chloroquine-mediated autophagy inhibition on the cisplatin-induced apoptosis in HepG2 cells, and to explore the possible involvement of mitochondrial dysfunction in such process. Our results found the autophagy induction by cisplatin in HepG2 cells, basing on such results as increased induction of autophagic vesicles and upregulated conversion of A subunit (LC3-A) to B (LC3-B) subunit of microtubule-associated protein 1 light chain 3. Flow cytometry analysis results demonstrated that the cisplatin-induced apoptosis was aggravated by chloroquine. In addition, the mitochondrial function was downregulated by cisplatin and was deteriorated by chloroquine in HepG2 cells; the mitochondrial membrane potential (MMP) downregulation, the accumulation of reactive oxygen species (ROS) and the mitochondrial superoxide were markedly higher in the chloroquine/cisplatin-treated HepG2 cells than in the cisplatin-treated cells. In conclusion, we concluded that chloroquine sensitized the chemotherapy efficiency of cisplatin against hepatocellular carcinoma HepG2 cells, probably via blocking autophagy and via deteriorating the mitochondrial dysfunction. Chloroquine might be a potential adjuvant agent for overcoming chemotherapy resistance in hepatocellular carcinoma.