Autophagy of breast cancer cells induced by 5-aza-2'-deoxycytidine is associated with DNA damage / 肿瘤

ABSTRACT

Objective: To investigate the effect of 5-aza-2'-deoxycytidine on the autophagy of human breast cancer cells, and to explore the possible mechanism. Methods: Breast cancer cells were treated with etoposide, cisplatin and 5-aza-2'-deoxycytidine. DNA damage was detected by comet assay, and the expressions of p53 and p21 proteins were examined by Western blotting. The autophagy of breast cancer cells was monitored by three methods: (1) The expression of microtubule-associated protein 1 light chain 3-II (LC3-II) was detected by Western blotting; (2) The breast cancer cells presenting autophagosome vacuoles were counted under a fluorescence microscope after staining with monodansylcadaverine (MDC), and the percentage of cells presenting autophagosome vacuoles was calculated; (3) The green fluorescent protein (GFP)-positive breast cancer cells after transfection with pEGFP-LC3 were counted under a fluorescence microscope, and the percentage of GFP-positive breast cancer cells was calculated. Results: Etoposide and cisplatin induced the DNA damage and autophagy in breast cancer cells. Compared with the untreated breast cancer cells, the comet tail length was increased (P <0.01) and the expression levels of p53, p21 and LC3-II proteins were all up-regulated in the breast cancer cells treated with etoposide and cisplatin. The 5-aza-2'-deoxycytidine could also induce the DNA damage and autophagy in breast cancer cells, and the comet tail length was increased (P <0.01), the expression levels of p53, p21 and LC3-II proteins were up-regulated, as well as the percentages of MDC-positive breast cancer cells and GFP-positive breast cancer cells were both increased (P <0.05, P <0.01). Conclusion: 5-Aza-2'- deoxycytidine can induce the autophagy of breast cancer cells, and the mechanism may be associated with DNA damage. Copyright © 2012 by TUMOR.