Isolation and partial characterization of human cell mutants differing in sensitivity to killing and mutation by methylnitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine.

摘要: Isogenic variants resistant to alkylating agents have been isolated from the human lymphoblast cell line TK6. The lines may be divided into four classes on basis of resistance N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). sensitive TK6 parental shows a 37% survival after 45-min exposure 0.04 microM MNNG; three more mutants show 2 (MF lines), 6 (MT and greater than or equal 10 (MX line) MNNG. A representative MF line, MF1, is both killing mutation by MNNG N-methyl-N-nitrosourea. An MT clone, MT1, highly but hypermutable MT1 like TK6, does not remove O6-methylguanine adducts DNA. Our data are consistent with hypothesis that possesses nonexcision pathway defense against agents. Rather preventing alkylation DNA removing alkylated adducts, cells appear tolerant removed