The key findings of this study include: i) SIN treatment may reduce cell viability and prominently increase tumor cell apoptosis; ii) addition of SIN may reduce the effective dose of 5-FU for gastric cancer treatment; iii) the inhibitory effect of 5-FU was notably elevated when combined with SIN, as evidenced by the detection of cell proliferation (tumor growth), apoptosis-related protein and the 5-FU-associated gene TS; and iv) the data obtained in vivo indicate that SIN has potential as a novel agent that sensitizes gastric cancer cells to 5-FU. This evidence concerns the gene TYMS and neoplasm.