Effects of human interferon on cellular response to UV in UV-sensitive human cell strains

Cells of a human RSa cell line, with high sensitivity to UV killing and low capacity for DNA repair, when pretreated with 1-100 units/ml of human interferon (HuIFN) preparations for more than 12 h before irradiation, acquired an enhancement of UV-induced DNA-repair replication synthesis in association with recovery from inhibition of total cellular DNA synthesis and UV survival. Prompt and transient induction of plasminogen activator activities was also found within 5 min after UV irradiation in the cells pretreated with HuIFN but not in the cells non-pretreated with HuIFN. The enhancement and induction effects of HuIFN were observed, irrespective of the kind of HuIFN preparation used (alpha, beta or gamma, and natural or recombinant) and in other UV-sensitive fibroblast cells which were derived from Cockayne syndrome and xeroderma pigmentosum fibroblasts (XP1KY). However, all of the enhancement of DNA-repair synthesis and the induction of plasminogen activator activities by HuIFN was suppressed by treatment with cycloheximide immediately after UV irradiation.