Synergistic antitumor effect of Andrographolide and cisplatin through ROS-mediated ER stress and STAT3 inhibition in colon cancer

Colon cancer is one of the most leading death-causing cancers in the world. Cisplatin has been widely used as the first-line treatment of cancer. However, its clinical application is limited by the side effects or acquired drug resistance. Hence, it is of vital clinical significance to develop novel agents that synergize with cisplatin and decrease its side effects. The aim of this study was to investigate whether Andrographolide (AP) synergistically potentiates the anti-tumor effect of cisplatin on colon cancer cells. Here, we found that AP synergizes with cisplatin in exerting anticancer activity in colon cancer cells. Further studies showed that AP potentiates cisplatin-induced endoplasmic reticulum stress and STAT3 inhibition through increasing intracellular ROS. Notably, pre-treatment of NAC, a ROS scavenger, reversed apoptosis induced by combined treatment of AP and cisplatin, while relieving the activation of endoplasmic reticulum stress as well as STAT3 inhibition. These findings indicated that ROS plays a pivotal role in mediating synergistic anticancer effects of AP and cisplatin on colon cancer cells. Overall, this study presents a potential new therapeutic strategy for the treatment of colon cancer.