Curcumin induces caspase and calpain-dependent apoptosis in HT29 human colon cancer cells

This study aimed to elucidate the mode of action of curcumin (CCM) as an anticancer agent, and to investigate its effects on the proliferation and induction of apoptosis in HT29 human colon cancer cells. We examined the effect of CCM on two cysteine protease families, namely caspases and calpains, which are known to induce apoptosis in a number of cancer cells. We demonstrated that CCM reduces cell proliferation in HT29 cells with an IC50 value of 50±0.015 µM. Western blot analysis indicated that CCM induced apoptosis in HT29 cells by activating the expression of caspases-3 and -12, but not caspase-9. CCM also induced apoptosis in these cells through the involvement of calpain. These findings indicate that CCM-induced apoptosis in HT29 cells follows the caspase-12 apoptotic pathway, and also involves calpain.