OBJECTIVETo evaluate the effect of the combination of docosahexaenoic acid (DHA) and fluorouracil (FU) on human gastric carcinoma cell strain MGC803 in vitro.

METHODSThe influences of DHA and FU alone or in combination on cell proliferation was detected using MTT assay. Dose of median (Dm) of drugs (alone or in combination) and the combination index (CI) were calculated using the combination index equation of Chou-Talalay. Cell cycle were examined using flow cytometry. Cell apoptosis was determined by Annexin V-FITC/PI double staining method. The expression of apoptosis-related protein was detected using Western blot.

RESULTSDHA significantly inhibited the growth of MGC803, and low-dose DHA induced the proliferation of human embryonic lung fibroblast (P < 0.05). DHA remarkably strengthened the inhibitive effect of FU on the growth of MGC803, and decreased the Dm of FU by 3.6-2.5 folds (P < 0.05). When the inhibitory ratio reached 30%, the combination of DHA and FU showed synergism (CI < 1) and significant G(0)/G(1) arrest (vs FU, P < 0.05). DHA increased the apoptosis-inducing effect of FU and upregulated the cleaved-caspase-3 expression.

CONCLUSIONSDHA can inhibit the growth of MGC803. When combined with FU, DHA has synergetic effect in inhibiting the proliferation of gastric cancer cells and meanwhile decrease the dose of FU.