Abstract 2544: Analysis of the mechanism for acquiring resistance to 5-FU in gastric cancer cell lines

Abstract

Abstract Background 5-Fluorouracil (5-FU) still remains the key drug for the treatment of gastric cancer. Thus, analysis of the mechanism for acquiring resistance of gastric cancer cells to 5-FU and the development of effective chemotherapy for 5-FU-resistant gastric cancer are important. Methods From the parent human gastric cancer cell lines (MKN45, MKN74, KATOIII and NCI-N87), we established several 5-FU-resistant cell lines (MKN45/5FU, MKN74/5FU, KATOIII/5FU and NCI-N87/5FU) by continuous exposure of the cells to progressively increasing concentrations of 5-FU over a year. We then compared the sensitivity of the parent cell lines to 5-FU-resistant cell lines by MTT assay. We also quantitatively evaluated the mRNA expression levels of four genes known to be associated with 5-FU metabolism, namely, thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), and orotate phosphoribosyltransferase (OPRT), by real-time RT-PCR assay. Results The IC50 ratio of each 5-FU resistant cell line to its parent cell line was as follows; MKN45/5FU: 10.0; MKN74/5FU: 5.5; KATOIII/5FU: 2.2; NCI-N87/5FU: 4.8. Comparing with the corresponding parent cell lines, the 5-FU resistant cell lines, MKN45/5FU, MKN74/5FU, KATOIII/5FU and NCI-N87/5FU, showed a 0.62, 0.40, 0.37 and 0.56-fold decrease in TS gene expression, respectively. In addition, three of the four resistant cell lines showed a tendency towards increase in the gene expression level of DPD and decrease in that of TP. No significant changes in the expression level of the gene encoding OPRT was noted in any of the 5-FU-resistant cell lines. Conclusion We established four 5-FU-resistant lines from the corresponding parent gastric cancer cell lines and demonstrated the various changes in the expression profiles of the genes known to be associated with 5-FU metabolism. These results suggest that the mechanism of acquiring resistance to 5-FU may vary among gastric tumors. To identify the genetic characteristics of these resistant cell lines, we propose to analyze the gene expression profiles at several time-points from the beginning of establishment of 5-FU-resistance, using microarray-based technology. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2544.