| Abstract |
The aim of this study was to correlate O6-methylguanine-DNA methyltransferase (MGMT) and mismatch repair gene (hMLH1) expression in gallbladder carcinoma cells with drug sensitivity to the bifunctional alkylating agent 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU). Using 5 gallbladder carcinoma cell lines and 1 colon carcinoma cell line (SW48), the MGMT and hMLH1 status was assessed both by RT-PCR and Western blot analyses. Sensitivity to ACNU was estimated by the MTT assay. MGMT+/hMLH1+ status was revealed in 2 gallbladder carcinoma cells, MGMT-/hMLH1+ in another 3 gallbladder carcinomas and MGMT-/hMLH1- in SW48. MGMT-/hMLH1+ and MGMT-/hMLH1- cells were more sensitive to ACNU compared with MGMT+/hMLH1+ cells. These results indicate that MGMT, but not hMLH1, expression is an important determinant for drug sensitivity to ACNU in gallbladder carcinoma cells. The drug effect of ACNU, which depends on the MGMT status, was verified using xenograft tumors grown in nude mice. Furthermore, the apoptotic index of MGMT- GB-dl xenografts was significantly increased by ACNU treatment, compared with that of MGMT+ KMG-C. In conclusion, the sensitivity to ACNU was not associated with hMLH1 status, but was found to depend only on the MGMT status. ACNU might be a useful chemotherapeutic agent for MGMT- gallbladder carcinoma, which is associated with poor patient outcome.
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