Expression of $O^6$-methylguanine-DNA methyltransferase and Sensitivity to Anticancer Alkylating Agents in Human Cancer Cells

사람 암세포에서의 $O^6$-methylguanine-DNA methyltransferase의 발현과 알킬화 항암제에 대한 감수성

  • 오혜영 (국립보건안전연구원 독성부 유전독성과) ;
  • 정해관 (국립보건안전연구원 독성부 유전독성과) ;
  • 한의식 (국립보건안전연구원 독성부 유전독성과) ;
  • 정성철 (국립보건안전연구원 독성부 유전독성과) ;
  • 허옥순 (국립보건안전연구원 독성부 유전독성과) ;
  • 손수정 (국립보건안전연구원 독성부 유전독성과) ;
  • 김영미 (국립보건안전연구원 독성부 유전독성과) ;
  • 홍성렬 (국립보건안전연구원 독성부 유전독성과) ;
  • 이향우 (성균관대학교)
  • Published : 1995.06.01

Abstract

Five human cancer cell lines (HeLa S3, Hep 3B, KATO III, Hs 683, HeLa MR) and one human normal cell line (WI-38) were examined cell viability, northern blot analysis, western blot analysis, and in situ hybridization for the expression $O_{6}$ -methylguanine-DNAmethyltransferase (MGMT), which can repair $O_{6}$ -methylguanine produced in DNA by alkylating agents. In cell viability test, the lethal sensitivities of each strain against anti-tumor drug N,N-bis(2-chloroethyl)- N-nitrosourea (BCNU) were counted, and both BCNU treated and untreated cell extracts were examined for their MGMT inducibility by RNA dot blot analysis. Cell lines did not show MGMT induction by BCNU pretreatment. Tlle MGMT activity was assayed by measuring the $^3$H radioactivity transferred from the substrate DNA containing [methyl-$^3$H)-O$_{6}$ -methylguanine to acceptor molecules in the cell extracts. Extracts from the majority of tumor strains and normal cells contained substantial MGMT activity of varying degree, while the known Mer$^{[-10]}$ cell (lacked or severely depleted in MGMT activity) Hela MR, and Hs 683 (proved to be Mer$^{[-10]}$ ) were much more sensitive to BCNU than the rest of tumor strains, as measured by cell viability test. Overall results above, KATO III showed the highest expression level of MGMT among the strains examined. Furthermore, with all the tumor and normal strains tested, a good correlation was observed between MGMT expression and cellular resistance to BCNU. The varying levels of expression of MGMT in human cancer cells found in this study should provide a molecular basis for MGMT expression among tumor strains from different tissue origin, the information of antitumor agents selection for chemotherapy of cancers.

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