Danthron suppresses autophagy and sensitizes pancreatic cancer cells to doxorubicin

In contrast to the steady increase in survival observed for most cancer types, advances have been slow for pancreatic cancers. Current chemotherapy has limited benefits for patients with pancreatic cancer. Therefore, there is an urgent need for effective pancreatic cancer treatment strategies. At present, targeting the autophagic pathway is regarded as a promising new strategy for cancer treatment. Danthron (1,8-dihydroxyanthrquinone), a component from Rheum palmatum L. (polygonaceae), has several biological activities. However, the inhibition of autophagy by danthron has never been recognized, previously. Here we find that danthron may prevent autophagy, inhibit proliferation and induce apoptosis in pancreatic cancer cells in vitro. Autophagy induced by doxorubicin plays a protective role in pancreatic cancer cells and inhibition of autophagy by chloroquine or silencing autophagy protein 5 (Atg5) may chemosensitize pancreatic cancer cell lines to doxorubicin. Similarly, inhibition of autophagy by danthron also enhances toxicity of doxorubicin to pancreatic cancer cells. These results indicate that danthron has an anticancer effect and can sensitize the chemotherapeutic effect of doxorubicin on pancreatic cancer cells. These findings also suggest that inhibition of autophagy may be an effective way to promote the chemotherapy of pancreatic cancer.