Effects of IFN-beta on growth of human prostatic JCA-1 cells.

Addition of IFN-beta resulted in a dose-dependent reduction of growth, a drop in [3H]thymidine incorporation into DNA, and a concurrent 69% and 15% increase in the S and G2/M phases, of the human prostatic JCA-1 cells. No correlation existed between the antimitogenicity of IFN and increases in the double-stranded RNA-dependent protein kinase activity. Although IFN elicited a large increase in 2-5A synthetase activity, activation of the 2-5A-dependent RNase L could not be demonstrated in JCA-1 cells rendered permeable to 2-5A, implying that the 2-5A pathway is not involved in the anti-proliferative effects of IFN. Analysis of endogenous proteins phosphorylated in vitro show that some IFN-inducible phosphoproteins were dependent upon the presence of double-stranded DNA.