BACKGROUND: The outcome of triple negative breast cancer is still poor and requires improvement with better therapy options. Autophagy has recently been shown to play a role in anticancer drug resistance. Therefore, we investigated if the effectiveness of doxorubicin was augmented by the inhibition of autophagy. METHODS: MDA-MB-231 was used as a model cell line for triple negative breast cancer and 3-methyladenine was used as an inhibitor of autophagy. Cells were treated with 0.46-1.84μM doxorubicin and 2.5-10μM 3-methyladenine for 48h. Cell death mode was examined with M30 and M65 ELISA assays. ROS level and LDH activity was examined and the cellular acidic compartment of cells was monitored by acridine orange staining. The expression of various autophagy and apoptosis related proteins/genes were evaluated with Western blotting and RT-qPCR respectively. RESULTS: Synergism was observed between the compounds (CI value<1.0). RT-qPCR analysis revealed that the combination resulted in a down-regulation of autophagy-related genes. Moreover, the combination resulted in a different cell death modality, upregulating necroptosis-related genes. This suggests that the mode of cell death may switch from apoptosis to necroptosis, which is a more severe form of cell death, when autophagy is inhibited. These results were further confirmed at protein level by Western blotting. CONCLUSION: Inhibition of autophagy seems to sensitize triple negative breast cancer cells to doxorubicin, warranting further in vivo studies for the proof of this concept. GENERAL SIGNIFICANCE: Autophagy has a key role in drug resistance in MDA-MB-231 cells. Therefore combinatorial approaches may effectively overcome resistance.
BACKGROUND: The outcome of triple negative breast cancer is still poor and requires improvement with better therapy options. Autophagy has recently been shown to play a role in anticancer drug resistance. Therefore, we investigated if the effectiveness of doxorubicin was augmented by the inhibition of autophagy. METHODS: MDA-MB-231 was used as a model cell line for triple negative breast cancer and 3-methyladenine was used as an inhibitor of autophagy. Cells were treated with 0.46-1.84μM doxorubicin and 2.5-10μM 3-methyladenine for 48h. Cell death mode was examined with M30 and M65 ELISA assays. ROS level and LDH activity was examined and the cellular acidic compartment of cells was monitored by acridine orange staining. The expression of various autophagy and apoptosis related proteins/genes were evaluated with Western blotting and RT-qPCR respectively. RESULTS: Synergism was observed between the compounds (CI value<1.0). RT-qPCR analysis revealed that the combination resulted in a down-regulation of autophagy-related genes. Moreover, the combination resulted in a different cell death modality, upregulating necroptosis-related genes. This suggests that the mode of cell death may switch from apoptosis to necroptosis, which is a more severe form of cell death, when autophagy is inhibited. These results were further confirmed at protein level by Western blotting. CONCLUSION: Inhibition of autophagy seems to sensitize triple negative breast cancer cells to doxorubicin, warranting further in vivo studies for the proof of this concept. GENERAL SIGNIFICANCE: Autophagy has a key role in drug resistance in MDA-MB-231 cells. Therefore combinatorial approaches may effectively overcome resistance.
Authors: Xinyu Deng; Sophia Apple; Hong Zhao; Jeongyoon Song; Minna Lee; William Luo; Xiancheng Wu; Debra Chung; Richard J Pietras; Helena R Chang Journal: Oncotarget Date: 2017-06-13
Authors: Min Liu; Ruizhe Li; Yang Tang; Jiwu Chang; Rong Han; Shumin Zhang; Ning Jiang; Fuling Ma Journal: Oncol Lett Date: 2017-02-13 Impact factor: 2.967
Authors: Lianna Y D'Brant; Habben Desta; Ting Chean Khoo; Anna V Sharikova; Supriya D Mahajan; Alexander Khmaladze Journal: J Biomed Opt Date: 2019-04 Impact factor: 3.170