Effects Of Docosahexaenoic Acid On Chemosensitivity Of Human Breast Cancer Cells

Objective: This study aims to investigate the effects of docosahexaenoic acid(DHA)plus5-fluorouracil(5-FU) on proliferation and apoptosis of human breast cancerMDA-MB-231cells, study the role of Wnt/β-catenin signaling transduction pathway,to explore its possible molecular mechanism of DHA on breast cancer, This studycould provide a new way of breast cancer therapy.Methods: The human breast cancer cell line MDA-MB-231was used in vitro.MTT assay was used to examine the different concentrations (10,20,30,40,50μg/ml)of DHA and DHA(20,40μg/ml) combine5-FU (50μg/ml) on proliferation ofMDA-MB-231cells. The cell cycle arrest and apoptosis of MDA-MB-231cells weretested by PI staining flow cytometry. The mRNA expression of β-catenin and GSK-3βin MDA-MB-231cells were investigated by Reverse transcription polymerase chainreaction (RT-PCR). The expression and their activity change of β-catenin, GSK-3β andphospho-GSK-3β (Ser9) protein in MDA-MB-231cells were investigated by Westernblot. Immunocytochemistry test was used to investigate the subcellular location ofβ-catenin protein after DHAand the GSK-3β inhibitor (LiCl,20mmol/l) combined withDHA treated cells.Results: DHA (10,20,30,40,50μg/ml) could inhibit the proliferation ofMDA-MB-231cells in a concentration–dependent manner, the inhibitary rateincreased with the prolonged time (p<0.05).20μg/ml,40μg/ml concentrations ofDHA combined with5-fluorouracil significantly increased the cytotoxicity of5-fluorouracil on MDA-MB-231cells (p<0.05), and induced a time-dependentreduction of cell viability (p<0.05). DHA (20μg/ml) combined with5-fluorouracilpromoted MDA-MB-231cells effect of G0/G1phase arrest(77.08±0.71%) andapoptosis(8.22±0.15%), When treatd with DHA(20μg/ml) and5-fluorouracil onMDA-MB-231cells respectively after48h, the cell cycle was arrest in G0/G1phase (63.71±0.82%,73.36±0.71%), induced apoptosis (4.66±0.44%,6.99±0.10%). Treatedwith DHA on MDA-MB-231cells for48h, the expression levels of mRNAβ-catenin,β-catenin and phospho-GSK-3β (Ser9) protein were decreased(p<0.05), mRNAGSK-3β and GSK-3β protein were not significantly changed(p>0.05). After theGSK-3β inhibitor LiCl combined with DHA treated cells, the level of β-catenin proteinwas higher than DHA treated.Conclusions:1. DHA enhances the effect of growth inhibition and apoptosis induction of5-fluorouracil on MDA-MB-231cells.2. The effect of DHA inhibit the proliferation of MDA-MB-231cells may be throughinducing GSK-3β dephosphorylation inhibition of Wnt/β-catenin signaling pathway.