Curcumin suppresses 4-hydroxytamoxifen resistance in breast cancer cells by targeting SLUG/Hexokinase 2 pathway.

Triple negative breast cancer (TNBC) is the hardest breast cancer subtype to treat due to lacking therapeutic target and treatment options. In this study, we found that SLUG expression was much higher in TNBC MDA-MB-231 cells than estrogen receptor alpha (ERα) positive breast cancer MCF7 cells. 4-hydroxytamoxifen (4-OHT) promoted SLUG expression, which was blocked by curcumin. Further investigation showed that SLUG activated the transcription of hexokinase-2 (HK2) by binding to HK2 promoter. SLUG knockdown inhibited HK2 expression and weakened 4-OHT resistance of MDA-MB-231 cells. Conversely, SLUG overexpression elevated HK2 level and increased 4-OHT resistance of MCF7 cells. Combination of curcumin and 4-OHT suppressed SLUG and HK2 expression, leading to mitochondrion-mediated apoptosis. These results suggested SLUG as a potential target and curcumin as a promising natural agent for overcoming 4-OHT resistance of TNBC.