대한대장항문학회

PURPOSE: Thymidylate synthase (TS) is an important target for chemotherapeutic drugs such as 5-fluorouracil (5-FU). Overexpression of TS has been linked to chemotherapy resistance, but their relationship was not completely understood. We compared the<br>expression level of TS with resistance of colon and gastric cancer cell lines to 5-FU. METHODS: Expression of TS mRNA was determined by RT-PCR assay in 9 colon and 10 gastric cancer cell lines. Cytotoxicity of 5-FU was determined by MTT assay. Apoptosis<br>was determined using propidium iodide staining by flow cytometry. RESULTS: All cancer cell lines tested showed differential levels of TS mRNA expression. Colon cancer cell Colo320 (the highest expression of TS) was more resistant to 5-FU than SNU-C1<br>(the lowest expression of TS) was. Flow cytometry also showed that 5-FU induced apoptosis less in Colo320 than SNU-C1. But in gastric cancer cells SNU-1 (the highest expression of TS) was not resistant to 5-FU than SNU-16 (the lowest expression of TS)<br>was. CONCLUSIONS: The high level of expression of TS was correlated with resistance of colon cancer cells to 5-FU, but not in gastric cancer cells. Thus, TS may be differently involved in the resistance of gastric and colon cancer cells to 5-FU, which<br>may depend on the origin of cancer cells and status of apoptosis related genes.<br>