ABSTRACT
Objective To investigate the inhibitory effects of docosahexaenoic acid (DHA)and 5-fluorouracil (5-FU)in combination on human gastric cancer cell line AGS in vitro .Methods Human gastric cancer line AGS was treated with different concentrations of DHA and 5-FU alone or in combination.The inhibition of cell proliferation was evaluated by MTT assay.Dose of median (IC50 )of drugs (alone or in combination)and the combination index (CI)were calculated using the median-effect equation and the combination index equation of Chou-Talalay.Flow cytometry was used to detect the cell cycle distribution.The expression of mitochondrial respiratory membrane protein complex in AGS cells was analyzed with Western blot.Results DHA and 5-FU alone or in combination could markedly suppress the proliferation of AGS in significantly time-dependent and dose-dependent manners (P <0.05).IC50 values with DHA or 5-FU administered for 24 h and 48 h were 5 1.60 μg/mL (DHA:24 h),34.82 μg/mL (DHA:48 h),45.90 μg/mL (5-FU:24 h),and 1 6.86 μg/mL (5-FU:48 h), respectively.DHA remarkably strengthened the inhibitory effect of 5-FU and decreased IC50 of 5-FU by 3.56 -2.1 5 folds.The combination of DHA and 5-FU showed synergism.Flow cytometry showed that AGS cells treated with DHA and 5-FU were arrested in G0/G1 phase and the proportion of AGS cells in G0/G1 phase increased compared with that in the control group,DHA group and 5-FU group,while the proportion of the cells in S phase decreased significantly (P < 0.05 ).Western blot showed after treatment with DHA and 5-FU for 48 h,the expression of mitochondrial respiratory membrane protein complex was significantly decreased compared with control group,DHA group and 5-FU group (P <0.05).Conclusion DHA could act synergistically with 5-FU in inhibiting the growth of gastric carcinoma cells,and meanwhile decrease the dose of 5-FU.The mechanism may be associated with cell cycle arrest in G0/G1 phase and interference in the energy metabolism of AGS cells due to inhibition of the expression of mitochondrial oxidative respiratory chain complexes by the two compounds.