| Research Abstract |
We investigated the correlation between gene expression profiles and anticancer drug sensitivity using six human colorectal cancer cell lines, C1, H630, H508, H716, C2A, and C4. Anticancer drug sensitivity was determined by MTT assay after 96 hours drug exposure to respective cancer cell lines. The drugs used were 5-fluorouracil(5-FU) and raltitrexed (RTX) which were typically categorized as thymidylate synthase(TS) inhibitor and were one of the most active drugs against gastrointestinal cancers. IC50's of each drug were as follows(5-FU:μM, RTX:nM) ; C1(0.18、-)H630 (39.0、9.3) H508 (0.06、-) H716 (813、65.0) C2A (11.0, 6.6) C4 (0.62、0.82).Various gene expression profiles in six cell lines were evaluated using DNA microarray assay enabling us to explore many genes of interest. which were TS, DPD, NADPH, cytochromeP450, glutathione, GST, GSTπ, cMOAT, MDR1, MRP, α tubulin, β tubulin, orotate phosphoribosyltransferase (OPRT), proliferating cyclic nuclear antigen(PCNA) and so forth. Significant close correlation between 5-FU sensitivity and gene expression level of OPRT and PCNA were revealed after multivariate statistical analysis (p<0.05). Since increased level,of OPRT gene expression can be related to increased level of 5-fluorouridinemonophosphate generation, it appeared to be quite reasonable for. 5-FU sensitivity. Gene expression level of thymidine phosphorylase (TP) and DPD were not correlated with 5-FU sensitivity. RTX sensitivity was close correlated with 5-FU sensitivity and TS binding capacity, indicating that both 5-FU and RTX shared the same target of TS..
While TS, DPD and TP have been considered to be pivotal factors regarding 5-FU sensitivity in view of biochemical or gene expression profile aspects, the level of OPRT gene expression can be also important in 5-FU sensitivity.
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