title: The effect of o6-methylguanine-DNA methyltransferase (MGMT) and mismatch repair gene (hMLH1) status on the sensitivity to alkylating agent 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea(ACNU) in gallbladder carcinoma cells.
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.
authors.affiliation: Department of Surgery, Saga University Faculty of Medicine, Saga, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Sato
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Kitajima
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Koga
authors.forename: Kohji
authors.initials: K
authors.lastname: Miyazaki
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D020137:Base Pair Mismatch; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D045744:Cell Line, Tumor; D004260:DNA Repair; D004354:Drug Screening Assays, Antitumor; D005260:Female; D005706:Gallbladder Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D000070957:MutL Protein Homolog 1; D015376:Nimustine / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018906:Antineoplastic Agents, Alkylating; D002352:Carrier Proteins; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D012333:RNA, Messenger; D015376:Nimustine; D019853:O(6)-Methylguanine-DNA Methyltransferase; D000070957:MutL Protein Homolog 1