Deoxybouvardin Glucoside Induces Apoptosis in Oxaliplatin-Sensitive and -Resistant Colorectal Cancer Cells via Reactive Oxygen Species-Mediated Activation of JNK and p38 MAPK

Abstract

The roots of Rubia spp. (Rubiaceae) have been employed to treat hematemesis, inflammatory disease, and tumor. Cyclohexapeptides derived from Rubia spp. have been reported to have antitumor potential; however, the mechanism of action for their antitumor activity remains unclear. We aimed to examine the antitumor effect of deoxybouvardin glucoside (DBG), a cyclohexapeptide from Rubia spp. on oxaliplatin (Ox)-resistant human HCT116 colorectal cancer (CRC) cells. Cell viability in the presence of DBG was monitored using an MTT viability assay, and flow cytometry was used to analyze changes in apoptosis, cell cycle, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) activity. The antiproliferative activity involved apoptosis and phosphorylation of JNK and p38 MAPK. Inhibition of JNK and p38 MAPK by specific inhibitors prevented DBG-induced apoptosis, underscoring the close involvement of these kinases. Further, DBG induced cell cycle arrest in CRC cells at the G2/M phase by regulating the p21, p27, cyclin B1, and cdc2 proteins. DBG-induced apoptosis was accompanied mitochondrial membrane depolarization, resulting in cytochrome c release into the cytoplasm and caspase activation. Remarkably, DBG induced apoptosis by generating high ROS levels. The mediation of apoptosis by increased ROS generation was confirmed by pretreatment with the ROS scavenger N-acetyl cysteine (NAC). Collectively, DBG exhibited anticancer activity against both Oxsensitive and Ox-resistant CRC cells by targeting JNK and p38 MAPK, inducing cell cycle arrest, elevating cellular ROS levels, and disrupting MMP. This study suggests that DBG has the potential to be utilized as a therapeutic agent for treating Ox-resistant CRC.