Experimental Evidence On Di-Rigion Mechanism Of Carcinogensis With Ultraviolet Radiation

It is well known that ultraviolet radiation induces derma cancer especially in white European and American with epidemic investigation reports. And, ultraviolet radiation can induce cross-linking between DNA and Protein. In Di-region theory, a reasonable explanation of the mechanism of chemical carcinogenesis, professor Di assumes that it is critical in the chemical carcinogenesis procedure that the metabolized carcinogen induces the cross-linking between DNA complementary pair bases, and predicts that ultraviolet and ionization radiation initiates cancer by the cross-linking DNA inter-strand. This thesis primarily concerns whether ultraviolet radiation can induce the cross-linking DNA inter-strands and whether by hydroxyl free radical, HO.In this series of experiments, I discover the relation between the ultraviolet dose and the DNA cross-linking degree through DNA filter elution method. And we can see that DNA cross-linking ratio increase with ultraviolet dose increasing from 20 minutes' to 100 minutes' in 365 nm. Furthermore, the ferrous ion increased the cross-linking ratios as its concentration increased and the vitamin C makes the DNA cross-linking ratios decrease as its concentration increased.The mechanism lies in that the oxygenase produced and activated by ultraviolet induces the cross-linking both in DNA inter-strand and in DNA-protein with dosage correlation. The ferrous ion increased the cross-linking ratios through Fenton reaction and the vitamin C inhibited the cross-linking ratios by destroying the hydroxyl free radical. Above all, it is plausible that all of the cross-linkages are just induced by hydroxyl free radical, HO. This series experiments expand the field in which Di-region theory can be applied.