| BACKGROUNDS AND AIMS: Gastric cancer is one of the most common cancerworldwide. In our country, the motality of gastric cancer occupies the top site in themalignant tumor. In recent years, despite the great progress in the treatment of gastriccancer, the survival rate and prognosis of patients with gastric cancer is still notsatisfactory. Clinic datas suggest that ω-3Polyunsaturated fatty acids（PUFAs） canimprove the cachexia and the life quality of patients with cancer. The experimentaldatas from animal models and cell lines demonstrate that ω-3PUFAs can inhibittumour growth in a variety of cancer models, and there is the synergistic anticancereffect of combination ω-3PUFAs with the chemotherapeutic drugs. However, thesemechanisms are not clear, the report in gastric cancer is particularly rare. Theevidence of ω-3PUFAs applied in clinic is still insufficient. Therefore, the purpose ofour study is to determine the mechanisms of the effect on the treatment with ω-3PUFAs in gastric cancer, and to provide a theoretical basis for clinical appliction.Methods: The effect of DHA and EPA inhibited-proliferation on gastric cancer cellswas detected by CCK-8at24h,48h,72h after the treatment with differentconcentrations of DHA, EPA and ethanol as control. The effect of DHA and EPA onapoptosis and cellular cycle was analysised by flow cytometry. The role of DHA, EPAon apoptosis related proteins was analysised by Western-Blot.The effect on proliferation of gastric caner cells treated with different concentrationsof cisplatin alone or combined with DHA, EPA was detected by CCK-8, and thecisplatin-induced cell growth inhibition was measured by the inhibitory rate andIC50(50%inhibitory concentrations). We used the combination index (CI) method ofChou–Talalay to determine the effects of cisplatin plus DHA or cisplatin plus EPA combination. According to the previous results that DHA and EPA inhibited theproliferation of gastric cancer cells, we selected the appropriate concentrations, andmeasured the inhibitory rate when the cells were exposed to cisplatin alone,cisplatinplus DHA or plus EPA, respectively. The effect on apoptosis and cell cycle of gastriccancer cells treated with theses drugs was assessed by flow cytometry.In order to further determine the mechanism of effect on the gastric cancer cellstreated by ω-3PUFAs, cDNA microarray was used to detect and sceen the expressionof genes associated with apoptosis in MKN45cells treated with DHA and EPA.Meanwhile, we selected one gene to analysis his function after supplement with DHA,EPA in gastric cancer.Results: DHA, EPA inhibited the prolifertion of gastric cancer cells in aconcentration-dependent manner, no in time-dependent manner. DHA, EPA couldinduce the apoptosis of gastric cancer cells, and arrest cell in G0/G1phase. DHA, EPAactivited Caspase-3, Caspase-8, Bax, Bid and inhibited anti-apoptic prtein Bcl-2evaluated by Western-Blot.We found that DHA, EPA enhanced in a dose-dependent manner the cell growthinhibitory activity of cisplatin in MKN45and MKN28cells. Possible cisplatin-DHAor cispaltin-EPA interactions at the cellular level were assessed employing thecombination index (CI) method of Chou-Talalay. Both methods showed an overallsynergism between DHA or EPA and cisplatin in MKN45and MKN28cells. Wefound the early phase of apoptosis was increased in the combination-treatment cells,which arrested in G0/G1phase and S phase.cDNA microarray assay screened54genes associated with apoptosis of gastric cancercell. Among them,29genes were up-regulated,25genes were down-regulated inMKN45cells after treatment with DHA and EPA. We selected a up-regulated gene,ADORA1to analysis the function of ADORA1under the effect of DHA, EPA.Wefound that the expression of ADORA1mRNA was detected in different gastric cancercell lines. DHA and EPA could up-regulate the expression of ADORA1in MKN45cells. The combination treatment with DHA or EPA and cisplatin could up-regulatethe expression of ADORA1.After treated by DPCPX, an antagonist of ADORA1, the decrease of apoptosis induced by ω-3PUFAs or by the combination with ω-3PUFAsand cisplatin in gastric cancer cells were detected.Conclusion: ω-3PUFAs can inhibite the proliferation and induce the apoptosis ofgastric cancer cells. The combination between ω-3PUFAs and cisplatin offers asynergistic effect for inhibiting the growth of gastric cancer cell lines. ADORA1receptor mediates the apoptosis of gastric cancer cells induced by ω-3PUFAs, and thesynergistic interaction between ω-3PUFAs and cisplatin in gastric cancer cells. |
