Drug Design, Development and Therapy (Oct 2016)
Ursolic acid sensitizes cisplatin-resistant HepG2/DDP cells to cisplatin via inhibiting Nrf2/ARE pathway
Abstract
Shouhai Wu,1,2 Tianpeng Zhang,1 Jingsheng Du3 1School of Life Sciences, Sun Yat-sen University, 2Center for Regenerative and Translational Medicine, 3Department of Pharmacy, The Second Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, People’s Republic of China Background: Combinations of adjuvant sensitizers with anticancer drugs is a promising new strategy to reverse chemoresistance. Ursolic acid (UA) is one of the natural pentacyclic triterpene compounds known to have many pharmacological characteristics such as anti-inflammatory and anticancer properties. This study investigates whether UA can sensitize hepatocellular carcinoma cells to cisplatin.Materials and methods: Cells were transfected with nuclear factor erythroid-2-related factor 2 (Nrf2) small interfering RNA and Nrf2 complementary DNA by using Lipofectin 2000. The cytotoxicity of cells was investigated by Cell Counting Kit 8 assay. Cell apoptosis, cell cycle, reactive oxygen species, and mitochondrial membrane potential were detected by flow cytometry fluorescence-activated cell sorting. The protein level of Nrf2, NAD(P)H quinone oxidoreductase 1 (NQO1), glutathione S-transferase (GST), and heme oxygenase-1 (HO-1) was detected by Western blot analysis.Results: The results showed that the reverse index was 2.9- and 9.69-fold by UA of 1.125 µg/mL and 2.25 µg/mL, respectively, for cisplatin to HepG2/DDP cells. UA–cisplatin combination induced cell apoptosis and reactive oxygen species, blocked the cell cycle in G0/G1 phase, and reduced the mitochondrial membrane potential. Mechanistically, UA–cisplatin dramatically decreased the expression of Nrf2 and its downstream genes. The sensibilization of UA–cisplatin combination was diminished in Nrf2 small interfering RNA-transfected HepG2/DDP cells, as well as in Nrf2 complementary DNA-transfected HepG2/DDP cells.Conclusion: The results confirmed the sensibilization of UA on HepG2/DDP cells to cisplatin, which was possibly mediated via the Nrf2/antioxidant response element pathway. Keywords: ursolic acid, chemoresistance, cisplatin, liver cancer, Nrf2/ARE
