Synergistic Effect of L-cycloserine and Capecitabine on Human Colon Cancer Cell Line

Introduction: Colon cancer comes in second place in the list of cancers in developed countries. Drug resistance is one of the causes of colorectal cancer therapeutic failure that usually occurs in most patients in advanced stage of colon cancer. This study investigates the effect of adding L-cycloserine to capecitabine in the HCT-116 colon cancer cell line. Materials and methods: We compared the combined L-cycloserine-capecitabine effect with each of the two drugs alone on the HCT-116 colon cancer cell line as a positive control group. The growth rate inhibition was examined by crystal violet assay. Results: The growth inhibition effect of L-cycloserine-capecitabine, L-cycloserine and capecitabine on HCT-116 cells was assessed with crystal violet assay, different concentrations including 3.12, 6.25, 12.5, 25, 50, and 100 μg/mL were used for L-cycloserine-capecitabine combination, and for both L-cycloserine and capecitabine. After incubation for 24 hours, results appeared that the combination of L-cycloserine and capecitabine increased the effect of both drugs alone as seen by a significant increase (p <0.05) of the growth inhibition percentages in the L-cycloserine-capecitabine combination as compared with the positive control groups. Conclusion: From the result, we can conclude that the L-cycloserine combination with capecitabine has a synergistic effect for colon cancer treatment that could be a more effective regimen.