[Research on the correlation between DNA recombinational mutation and cancer malignancy in human colon cancers]

The mutagenicity of quercetin, a flavonoid, was examined by means of DNA fingerprint analysis using the Pc-1 and Pc-2 minisatellite probes that efficiently detect mutations due to recombination. Treatment of FM3A and BMT-11 tumor cells with 55 microM quercetin resulted in gain and loss of bands in the fingerprints in both cell lines. The frequencies of the clones having undergone mutation were 9/26 and 2/11, using Pc-1 probe, respectively, in the two lines. These results seem to provide a molecular basis for the phenotypic variations of BMT-11 tumor cells induced by quercetin, giving direct evidence of genetic instability of the tumor cells. Moreover, we examined for a possible correlation between frequencies of DNA recombinational mutations and cancer malignancy in human colon cancers. DNA of four human colon cancer tissues and corresponding peripheral blood cells were prepared, respectively, and examined by DNA fingerprint analysis using hPc-1 polymorphic minisatellite probe. These four specimens exhibited no extra-bands resulting from recombination and/or DNA slippage at present. We would explain how the prognosis of cancer patients is related to frequencies of DNA recombinational mutation.