Human T-cell leukemia virus type 1 Tax protein stimulates the interferon-responsive enhancer element via NF-kappaB activity.

Gene expression in Rat-1 fibroblast cells transformed by Tax from human T-cell leukemia virus type 1 was studied using the reverse transcriptase polymerase chain reaction differential display technique. The analysis revealed eight genes that were upregulated and one gene that was suppressed in Tax-transformed cells. Interestingly, at least four of the upregulated genes were interferon-stimulated genes. Promoter analysis of the 2',5'-oligoadenylate synthetase gene, which was activated in both Tax-transformed Rat-1 cells and primary adult T-cell leukemia cells, demonstrated that Tax indirectly activates its interferon-responsive enhancer element in a nuclear factor-kappaB pathway-dependent manner, indicating a close association of interferon signaling with the transformation by Tax.