Synergistic Cytotoxic Effects of Tamoxifen and 5-Fluorouracil in Gastric Cancer MKN-45 Cells

Gastric cancer is a major global health concern, and identifsying agents that inhibit cancer cell growth can improve treatment outcomes. Tamoxifen and 5-Fluorouracil (5-FU) have demonstrated antitumor effects, and their combination may enhance therapeutic efficacy. In this study, the MKN-45 gastric cancer cell line was cultured in DMEM/F12 medium with 10% FBS and antibiotics. Cytotoxicity of Tamoxifen, 5-FU, and their combination was assessed using the MTT assay, and synergism was analyzed with Compusyn software (P ≤ 0.05). Tamoxifen and 5-FU reduced cell viability in a dose-dependent manner, with IC₅₀ values of 7 µg/ml and 0.9 µg/ml, respectively. Their combination further decreased the IC₅₀ to 0.7 µg/ml. Combination index (CI) analysis showed synergism, with CI values <0.7 at Fa = 0.25 and ≈0.7 at Fa = 0.5 and 0.75. Dose-reduction index (DRI) values for both drugs were >1, indicating reduced doses required in combination. These results suggest that combining 5-FU with Tamoxifen may be a promising strategy to enhance gastric cancer treatment.