Introduction & Objective: All-trans retinoic acid, a derivative of retinoids, is widely used to in-duce prolifferation, differentiation and apoptosis in normal, precancareous and cancerous cells. Cisplatin, an effective drug for cancer treatment, induces apoptosis via cross-linking to DNA. Previous studies on ovarian and melanoma cancer cells have showed synergistic ef-fects of cisplatin and retinoic acid. Our aim is to study such synergistic effect on gastric de-rived cell line, AGS.

Materials & Methods: In this experimental study gastric cancer cell line was cultured with dif-ferent concentration of retinoic acid and cisplatin and their combination. The cell death was evaluated with clonogenic assay and Acridine Orange/ Ethidium Bromide staining.

Results: The results showed that all-trans retinoic acid had not significant effect on cell death in gastric cancer. The results showed that high doses of retinoic acid and cisplatin can cause cell death via necrosis and early apoptosis, respectively. The plates were treated with the combination of 10 µM retinoic acid and 5, 10 µg cisplatin, and more cell death were ob-served (P<0.001). It seems that, suseptability of this cell line to retinoic acid is dose dependent.

Conclusion: In this study, we concluded that the combination of retinoic acid and cisplatin was more effective on cell death than cisplatin and retinoic acid alone.