Retinoic acid-inducible gene-I is induced by interferon-gamma and regulates the expression of interferon-gamma stimulated gene 15 in MCF-7 cells.

Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH box family proteins, which have diverse roles in regulation of gene expression and cellular functions. We found RIG-I mRNA and protein were expressed in MCF-7 human breast cancer cells stimulated with interferon-gamma (IFN-gamma). This effect of IFN-gamma was observed in concentration- and time-dependent manners, and IFN-gamma also induced promoter activity of RIG-I. Transfection of GFP-RIG-I cDNA into MCF-7 cells resulted in the expression of RIG-I protein in cytoplasm. Overexpression of RIG-I induced the upregulation of IFN-gamma stimulated gene 15, which has the potential to amplify the immunomodulatory effects. We conclude that IFN-gamma induces the expression of RIG-I, which may play a role in the immunological effects of IFN-gamma.