Enterolactone modulates the ERK/NF-κB/Snail signaling pathway in triple-negative breast cancer cell line MDA-MB-231 to revert the TGF-β-induced epithelial–mesenchymal transition

Objective:Triple-negative breast cancer(TNBC)is highly metastatic,and there is an urgent unmet need to develop novel therapeutic strategies leading to the new drug discoveries against metastasis.The transforming growth factor-β(TGF-β)is known to promote the invasive and migratory potential of breast cancer cells through induction of epithelial–mesenchymal transition(EMT)via the ERK/NF-κB/Snail signaling pathway,leading to breast cancer metastasis.Targeting this pathway to revert the EMT would be an attractive,novel therapeutic strategy to halt breast cancer metastasis.Methods:Effects of enterolactone(EL)on the cell cycle and apoptosis were investigated using flow cytometry and a cleaved caspase-3 enzyme-linked immunosorbent assay(ELISA),respectively.Effects of TGF-βinduction and EL treatment on the functional malignancy of MDA-MB-231 breast cancer cells were investigated using migration and chemo-invasion assays.The effects of EL on EMT markers and the ERK/NF-κB/Snail signaling pathway after TGF-βinduction were studied using confocal microscopy,quantitative reverse transcription polymerase chain reaction(q RT-PCR),Western blot,and flow cytometry.Results:Herein,we report that EL exhibits a significant antimetastatic effect on MDA-MB-231 cells by almost reverting the TGF-β-induced EMT in vitro.EL downregulates the mesenchymal markers N-cadherin and vimentin,and upregulates the epithelial markers E-cadherin and occludin.It represses actin stress fiber formation via inhibition of mitogen-activated protein kinase p-38(MAPK-p38)and cluster of differentiation 44(CD44).EL also suppresses ERK-1/2,NF-κB,and Snail at the m RNA and protein levels.Conclusions:Briefly,EL was found to inhibit TGF-β-induced EMT by blocking the ERK/NF-κB/Snail signaling pathway,which is a promising target for breast cancer metastasis therapy.