Ultraviolet light induction of skin carcinoma in the mouse; influence of cAMP modifying agents

A short review of pathogenic factors in U.V. light skin carcinogenesis in the mouse is presented. Caffeine and theophylline applied locally during U.V. irradiation caused a 50 percent reduction of skin tumour induction in Swiss mice. These two chemicals are inhibitors of DNA postreplication repair, but they also raise the intracellular level of cyclic AMP by inhibiting cAMP phosphodiesterase with, as a consequence, a possible slowing down of cellular growth. Control experiments using three different chemicals capable of raising the cAMP level in epidermal cells gave negative results. These experimental data are compatible with our original hypothesis according to which production of skin cancers by U.V. radiation is in same way related to DNA repair which helps the cell to survive but allows or favours the occurrence of errors in cellular DNA.