Induction and regulation of mRNA encoding 26-kDa protein in human cell lines treated with recombinant human tumor necrosis factor.

A 26-kDa protein, originally described in human fibroblasts superinduced for interferon beta (IFN-beta) production, and termed IFN-beta 2 by other investigators, is induced by cycloheximide and by a 22-kDa, interleukin 1 (IL-1)-related factor. Although the structure and sequence of the corresponding gene show nonhomology with the IFN-beta gene, the gene is identical to that of B-cell stimulatory factor 2, a human interleukin, and displays a very potent growth and differentiation factor activity for B lymphocytes. In this work we show that IL-1 beta and tumor necrosis factor (TNF) strongly induce the 26-kDa protein in FS-4 fibroblasts and in some transformed cell lines. Addition of cycloheximide to recombinant (r)IL-1 beta and rTNF further enhances the level of 26-kDa-protein mRNA. We determined the kinetics of induction and the amounts of rTNF and rIL-1 beta required for optimal induction of this mRNA in FS-4 cells and in HeLa H21 cells and found that rIL-1 beta is a more efficient inducer of 26-kDa protein mRNA than is TNF. By analyzing the inducibility of the 26-kDa protein gene by rTNF and rIL-1 beta in a series of transformed cell lines that differ in their sensitivity to the cytotoxic action of TNF, we report a direct correlation between the 26-kDa protein mRNA expression and the resistance of these cells to the cytotoxic effect of TNF.