ASSESSMENT OF MITOMYCIN-C SENSITIVITY IN FANCONI-ANEMIA COMPLEMENTATION GROUP-C GENE (FAC) KNOCK-OUT MOUSE CELLS

Fanconi anemia (FA) is a genetic disorder defined by cellular hypersen sitivity to DNA cross-linking agents, such as mitomycin C (MMC). MMC c auses increased FA cell death, chromosome breakage, and accumulation i n the G2 phase of the cell cycle. Recently, Fanconi anemia complementa tion group C (fac) gene knock-out mice have been developed, and SV40-t ransformed fibroblasts were established from fac homozygous knock-out (-/-), heterozygous (+/-), and wild-type mice (+/+). MMC sensitivity o f these cell lines was assessed by three methods: colony-formation ass ay in the presence of MMC, chromosome breakage, and cell cycle analysi s to detect G2 phase arrest. The fac knock-out fibroblasts (-/-) showe d a significantly higher sensitivity to MMC than did fibroblasts from wild-type (+/+) or heterozygous (+/-)mice (three experiments). In addi tion, we analyzed hematopoietic progenitor colony assays of bone marro w cells from fac knock-out (-/-) and heterozygous (+/-) mice. CFU-E, B FU-E, and CFU-GM colony formation from fac nullizygous mouse progenito rs was markedly diminished by MMC when compared to growth of progenito rs from heterozygous mice. These results show that fac knock-out mouse cells mimic the behavior of human FA-C patient cells in terms of MMC hypersensitivity. The fac knock-out mouse may be used to model some as pects of human FA and should be useful for understanding the function of the FAC protein. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.