Dual Role of Autophagy in Colon Cancer Cell Survival

Excerpt

We read with interest the article by Li et al. that describes the association of autophagy with the 5-fluorouracil (5-FU)-induced apoptosis in colon cancer cells.1 In the paper the authors found that the inhibition of autophagy enhances 5-FU-induced colon cancer cell apoptosis and improves the chemotherapeutic effect of 5-FU. Autophagy is a cellular process of autodigestion involving excess proteins and old organelles being recycled and is termed type II programmed cell death to distinguish it from apoptosis. Autophagy and apoptosis display large differences in cellular morphology and the molecular pathways that govern them. The relationship between them has not been well elicited. Although Li et al. showed that autophagy might play a role of self-defense in 5-FU-treated colon cancer cells, a recent study demonstrated that autophagic cell death might also be induced as an alternative cell death pathway in apoptosis-defective colon cancer cells.1 ^, 2 These data suggest a paradoxical role of autophagy as a target for adjuvant therapy. On the one hand, it allows for cell survival against cytotoxicity of anticancer agents in apoptosis-competent cancer. On the other, it acts as a backup cell death mechanism in apoptosis-defective cancer. …