Reversal Effect Of Docosahexaenoic Acid On Taxol Resistance In Human Ovarian Carcinoma A2780/T Cells

Objective: To assess the effect of DHA on reversing drug resistance and explore the possible mechanisms in ovarian cancer cells A2780/T.Methods: 1. To determine the optimal dose of DHA on A2780, CCK-8 was used to assay the cytotoxicity of DHA(0-512μmol/L)on the ovarian cancer cell line A2780. 2. To determine the optimal dose of DHA on A2780/T, CCK-8 was used to assay the cytotoxicity of DHA(0-1000μmol/L)on the ovarian cancer cell line A2780/T. 3.Pretreated with DHA for 48 h, the IC50 values of A2780 and A2780/T cells to expose Taxol alone or in combination with DHA were analyzed by CCK-8. 4. Drug efflux treated with DHA(0μmol/L, 11μmol/L, 33μmol/L, 100μmol/L, 296μmol/L) or in combination with DHA was examined by flow cytometry using Rhodamine123 intracellular accumulation assay. 5. Cell cycle treated with DHA(0μmol/L,11μmol/L,33μmol/L,100μmol/L, 296μmol/L) was analyzed by flow cytometry. 6.Expression of MDR1 m RNA treated with DHA was detected by Real-time quantitative PCR. 7.Expression of drug resistance-related protein(P-gp,MDR1, MRP, BCRP and LRP) and signal associated proteins(p38MAPK、NF-κB) treated with DHA was detected by western blot assay.Results: 1. CCK-8 showed that at the concentration of 64 u M/L, DHA had no effect on the proliferation of A2780 cells. 2. CCK-8 showed that at the concentration of 296μmol/L, DHA had no effect on the proliferation of A2780 cells. Treatment of DHA at 64μmol/L and 296μmol/L was selected in subsequent experiments. 3. DHA significantly enhanced the cancer cells sensitivity to Taxol in A2780/T cell line p<0.05, while it had almost no effects on the Taxol toxicity of A2780. 4. The higher dosage of DHA pretreated, the more Rhodamine 123 accumulated in A2780/T cells(P<0.05). 5. With increasing concentration of DHA, the proportion of A2780/T cells in G0/G1 was increased. 6. Real-time quantitative PCR analysis indicated that the expression of MDR1 m RNA obviously decreased in the group of DHA. 7. Western blot analysis indicated that pretreated with DHA, the expression of drug resistance-related protein(P-gp,MDR1, MRP, BCRP and LRP) were decreased in the A2780/T cells. Furthermore, The results showed pp38 MAPK and NF-κB were conformed suppressed in A2780/T pretreated with DHA and Taxol, whereas no significant changes in total p38 MAPK expression were noted in the experiments.Conclusion: DHA reversed Taxol resistance by inhibiting expression and function of P-gp and MDR related proteins, as well as blocking NF-KB and p38 MAPK pathways.