Induction of Immune-Stimulating Factors and Oncolysis Upon p14 ARF Gene Transfer in Melanoma Cell Lines.

Together with an anti-tumor immune response, oncolysis using a recombinant viral vector promises to eliminate cancer cells by both gene transfer and host-mediated functions. In this study we explore oncolysis induced by nonreplicating adenoviral vectors used for p14 ARF and interferon-β (hIFNβ) gene transfer in human melanoma cell lines, revealing an unexpected role for p14 ARF in promoting cellular responses predictive of immune stimulation. Oncolysis was confirmed when UACC-62 (p53 wild-type) cells succumbed upon p14 ARF gene transfer in vitro , whereas SK-Mel-29 (p53-mutant) benefitted from its combination with hIFNβ. In the case of UACC-62, in situ gene therapy in nude mice yielded reduced tumor progression in response to the p14 ARF and hIFNβ combination. Potential for immune stimulation was revealed where p14 ARF gene transfer in vitro was sufficient to induce emission of immunogenic cell death factors in UACC-62 and upregulate pro-immune genes, including IRF1, IRF7, IRF9, ISG15, TAP-1, and B2M. In SK-Mel-29, p14 ARF gene transfer induced a subset of these factors. hIFNβ was, as expected, sufficient to induce these immune-stimulating genes in both cell lines. This work is a significant advancement for our melanoma gene therapy strategy because we revealed not only the induction of oncolysis, but also the potential contribution of p14 ARF to immune stimulation.