Melanoma differentiation associated gene-7 (mda-7) selectively promotes these effects in cancer cells. mda-7 was identified more than two decades ago by subtraction hybridization showing elevated expression during induction of terminal differentiation of metastatic melanoma cells following treatment with recombinant fibroblast interferon and mezerein (a PKC activating agent).
RA, co-administered with the dsRNA mimicker polyinosinic-polycytidylic acid (poly(I:C)), synergizes to mount a specific response program able to sense dsRNA through the concurrent upregulation of TLR3, the dsRNA helicases melanoma differentiation-associated antigen-5 (MDA-5) and RA-inducible gene-1 (RIG-1), and the dsRNA-activated protein kinase (PKR) expression, leading breast cancer cells to specifically express downstream transcriptional targets of dsRNA sensors, such as interferon-β (IFNβ), interleukin-8 (IL-8), chemokine (C-C motif) ligand 5 (CCL5), and C-X-C motif Chemokine 10 (CXCL10).