Responses of Fanconi anemia fibroblasts to adenine and purine analogues.

Fanconi anemia (FA) fibroblasts are known to be exceptionally sensitive to the cytotoxic action of mitomycin C (MMC). The survival of FA cells was enhanced significantly when 0.5 mM caffeine or 0.5 mM adenine was added for 72 h after the cells were exposed to MMC. In other experiments in which MMC was not used, FA fibroblasts were shown to be significantly more sensitive than control cells to 6-mercaptopurine (6-MP), 6-thioguanine (6-TG), and 6-azauridine (6-AU). These observations offer a new approach to defining the basic biochemical defect in FA.