Genomic instability in multistage carcinogenesis

For a normal cell to accumulate multiple genetic changes during multistage carcinogenesis, the induction of genomic instability is considered advantageous. Since most human cancers are associated with exposure to environmental carcinogens, it is likely that environmental carcinogens interact with genomic instability. Our results indeed suggest that carcinogens contribute to the induction of microsatellite instability and induce more mutations in those cells which show microsatellite instability. We have recently developed a sensitive method to clearly detect changes in simple repeats of coding sequences of cancer genes and the results suggest that such sequences of different genes are mutated in different tumors.