[Knockdown of TRAIL-DR5 gene inhibits autophagy of ER-positive MCF-7 breast cancer cells induced by SAHA].

Objective To clarify the regulation role of tumor necrosis factor-related apoptosis inducing ligand-death receptor 5 (TRAIL-DR5) in cell autophagy induced by suberoylanilidehydroxamic acid (SAHA) in ER-positive breast cancer cell MCF-7. Methods The logarithmic growth phase of MCF-7 cells were divided into control group, SAHA treatment group, TRAIL-DR5 siRNA group and SAHA combined with TRAIL-DR5 siRNA treatment group. Western blotting was used to verify the results of TRAIL-DR5 gene silencing. Real-time quantitative PCR was performed to detect the mRNA levels of autophagy-related gene 9B (ATG9B), microtubule-associated protein 1 light chain 3A (LC3A) and LC3B in the different groups. The expressions of beclin-1, ATG3, ATG5, ATG7, ATG12, ATG16, ATG4A, ATG4B, ATG9B, LC3II, cathepsin B (CTSB) in the breast cancer cells were detected by Western blotting. The level of CTSB in the breast cancer cell culture supernatant was analyzed by ELISA. Immunofluorescence cytochemical staining was used to determine the expression and distribution of LC3II in the breast cancer cells. Results TRAIL-DR5 siRNA transfection significantly decreased the levels of TRAIL-DR5 in MCF-7 cells. After the knock-down of TRAIL-DR5 gene in MCF-7, the mRNA and protein levels of the autophagy-related factors in breast cancer cells markedly decreased, and the protein level of CTSB also decreased. After SAHA treatment of MCF-7 cells, the level of LC3II increased; when knockdown of TRAIL-DR5 receptor, LC3II level was significantly lower than that in the SAHA-alone-treated cells. Conclusion Down-regulating the TRAIL-DR5 gene can inhibit cell autophagy induced by SAHA in ER-positive MCF-7 breast cancer cells.