Mechanism of inhibition of ascites tumor growth in mice by curcumin is mediated by NF-kB and caspase activated DNase

One of the most clinically relevant biological activities of curcumin is its anti-cancer property, implicating multiple intracellular pathways in the process. In the present report, we investigated the effect of curcumin on the activation of apoptotic and anti-angiogenic pathways in Ehrlich Ascites Tumor (EAT) cells. Treatment with curcumin in vivo resulted in inhibition of proliferation of EAT cells and ascites formation. Further, we demonstrate that the induction of apoptosis in EAT cells showed nuclear condensation, DNA fragmentation and translocation of caspase-activated DNase (CAD) to nucleus upon curcumin treatment. Curcumin-induced apoptosis is mediated through activation of caspase-3, which is specifically inhibited by the caspase-3 inhibitor, Ac-DEVD-CHO. On the other hand, the decreased secretion of ascites by EAT cells is corroborated by reduction in VEGF secretion upon curcumin treatment. Further, CD31 immunohistological staining of peritoneum sections in curcumin-treated mice suggests its efficacy in acting as anti-angiogenic compound in EAT cells by inhibiting proliferation of endothelial cells in mouse peritoneum. However, immunoflurescence studies of NF-kB revealed that the inhibition of nuclear translocation of NF-kB p65, a transcription factor required for VEGF gene expression, in curcumin-treated EAT cells. These results suggest a further possible clinical application of this diet-derived compound curcumin, as both proapoptotic and anti-angiogenic compound in association with conventional chemotherapeutic agents.