Supplementary Figure S4. The cells were exposed to 5 µM DPP-23 for 72 h after 48-h scr siRNA and p53 and Nrf2 siRNA transfection. The apoptotic cell fractions were measured and the error bars represent the standard error of three replicates. * and **P < 0.01 relative to control and scr siRNA, respectively.
Funding
NEF
Ministry of Science, ICT and Future Planning
KHIDI
Ministry of Health and Welfare
Republic of Korea
ARTICLE ABSTRACT
Many cancer cells show acquired resistance to chemotherapeutic agents, such as cisplatin. This is a major cause of cancer treatment failure, and novel agents to overcome resistance are thus urgently required. A novel synthetic polyphenol conjugate, (E)-3-(3,5-dimethoxyphenyl)-1-(2-methoxyphenyl)prop-2-en-1-one (DPP-23), selectively kills tumor cells via the reactive oxygen species (ROS)–mediated unfolded protein response. We investigated the ability of DPP-23 to overcome cisplatin resistance in head and neck cancer (HNC) cells and further clarified its molecular mechanisms of action. Cisplatin-resistant HNC cell lines and their parental and other HNC cell lines were used. The effects of cisplatin and DPP-23 were assessed alone and in combination in HNC and normal cells using cell viability, cell cycle, and cell death assays, by measuring glutathione (GSH), ROS, and protein levels, and via preclinical mouse studies. DPP-23 induced selective cell death in HNC cells, including cisplatin-resistant HNC cells, but spared normal cells, via cellular GSH depletion and ROS accumulation. The effect was blocked by the antioxidant N-acetyl-L-cysteine. DPP-23 activated p53 and its related cell death pathways via a robust accumulation of cellular ROS that involved inhibition of nuclear factor erythroid 2–related factor 2 antioxidant defense mechanisms. Thus, DPP-23 significantly overcame cisplatin resistance in HNC cells in vitro and in vivo. As a promising anticancer strategy, ROS generation and subsequent selective cancer cell killing by DPP-23 might help to overcome cisplatin resistance in HNC. Mol Cancer Ther; 15(11); 2620–9. ©2016 AACR.
