Abstract B31: Establishment of a 5-fluorouracil-resistant esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase gene amplification

Abstract

Abstract 5-Fluorouracil (5-FU) is the key drug for the treatment of esophageal squamous cell carcinoma (ESCC), however, resistance to 5-FU remains a critical limitation to the clinical use. To clarify the mechanisms of 5-FU resistance in ESCC, we have established a 5-FU-resistant ESCC cell line TE-5R from parental TE-5 cells, by treatment with the step-wise continuous increasing concentrations of 5-FU. The half maximal inhibitory concentration of 5-FU showed that TE-5R cells were 15.6-fold resistant to 5-FU in comparison with TE-5 cells. Intracellular 5-FU concentration was significantly lower in TE-5R cells than in TE-5 cells. TE-5R cells showed regional copy number amplification of chromosome 1p including the DPYD gene, as well as high mRNA and protein expressions of dihydropyrimidine dehydrogenase (DPD), an enzyme involved in 5-FU degradation, whereas copy number of the other 5-FU metabolism-related genes in TE-5R cells did not changed from TE-5 cells. Gimeracil, a DPD inhibitor, sharply restored 5-FU resistance and increased intracellular 5-FU concentration in TE-5R cells. Next, to investigate whether other 5-FU metabolism-related genes contributed to 5-FU resistance in TE-5R cells, we added microarray gene expression assay and no significant differences in the expression of 5-FU metabolism-related genes were detected. These results indicate that 5-FU resistance in TE-5R cells is based on a DPD-dependent rapid degradation of 5-FU. Taken together, we established novel 5-FU-resistant TE-5R cells, which may have obtained 5-FU resistance with DPD copy number amplification and consequent overexpression, providing a critical insight to explore a new strategy against 5-FU-resistant ESCC using DPD inhibitor. Citation Format: Osamu Kikuchi, Kiichiro Baba, Shinya Ohashi, Manabu Muto. Establishment of a 5-fluorouracil-resistant esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase gene amplification. [abstract]. In: Proceedings of the Fourth AACR International Conference on Frontiers in Basic Cancer Research; 2015 Oct 23-26; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2016;76(3 Suppl):Abstract nr B31.