Ursolic acid potentiated oxaliplatin to induce apoptosis in colorectal cancer RKO cells.

Ursolic acid (UA) is found in multiple anticancer herbs and has shown anticancer effects in colorectal cancer (CRC) cells. The present study aimed to observe the effects of a combination of UA and oxaliplatin (Oxa), a frequently used chemotherapeutic drug in CRC, on human CRC RKO cells. The results showed that UA and Oxa synergistically inhibited the proliferation of RKO cells. A combination of UA and Oxa induced apoptosis in RKO cells and increased the activities of caspase-3, caspase-8, and caspase-9. Z-VAD-FMK, a caspase inhibitor, significantly antagonized UA- and Oxa-activated caspase-3, caspase-8, and caspase-9 and induced apoptosis. In addition, UA and Oxa downregulated the expression of X-linked inhibitor of apoptosis (XIAP) and Survivin in RKO cells. These observations suggested that a combination of UA and Oxa elicited synergistically anticancer effects in RKO cells and provided new evidence for potential application of UA and Oxa for CRC treatment.