IRF-1 EXPRESSION IN NORMAL HUMAN EPIDERMAL-KERATINOCYTES

Interferon gamma (IFN-gamma) is a potent inducer of cell growth arrest in human epidermal keratinocytes, Interferon regulatory factor-1 (IRF -1), an interferon-inducible gene, is a mediator of interferon action, It has also been suggested that IRF-1 may have a functional role as a tumor suppressor gene and may be associated with the antiproliferativ e effect of IFN-gamma, We examined the expression of IRF-1 mRNA in nor mal human epidermal keratinocytes (NHEK), Northern blot analysis demon strated an increased expression of IRF-1 mRNA by IFN-gamma in NHEKs, T his increased expression of IRF-1 mRNA by IFN-gamma was not blocked by treatment with cycloheximide, but was abolished by treatment with act inomycin D. In addition, neither pretreatment with TPA, a protein kina se: C (PKC) activator, nor treatment with H7, a PKC inhibitor, affecte d the induction of IRF-1 mRNA by IFN-gamma, These results indicate tha t IFN-gamma-induced IRF-1 mRNA in NHEKs is transcriptional and PKC-ind ependent.