Synergistic Suppression of Melanoma Growth by a Combination of Natural dsRNA and Panaxadiolsaponins.

Melanoma is one of the most lethal skin malignancies in the world. Interferons (IFNs) have been also demonstrated in response to tumor cell and IFNs such as IFN-α have been used for melanoma treatment. The long chain double-stranded RNA (dsRNA) (from a variety of nonviral sources) is a potent activator of the IFN system and an inducer of cell apoptosis. Panaxadiolsaponins (PDS) is a major Panax ginseng-derived active component with known antitumor activity and immune modulation. Here, we investigated a hypothesis that the combination of PDS and total natural dsRNA (as opposed to the synthetic dsRNA) will suppress tumor growth better than the individual agents. We have evaluated the antitumor and immunostimulatory effects of the combination of natural long chain dsRNA (derived from yeast) and PDS on melanoma cell line B16 and mice xenograft model. The underlying mechanisms of growth suppression were investigated by analyzing dsRNA-activated pathways, apoptosis, and cell cycle. Natural dsRNA and PDS exert superior anticancer effects than either agent alone. Natural dsRNA and PDS combination might be a promising strategy for treating malignancies, including melanoma.