and Are Novel Mediators of Resistance to Oncolytic Vesicular Stomatitis Virus in Prostate Cancer Cells.

A key principle of oncolytic viral therapy is that many cancers develop defects in their antiviral responses, making them more susceptible to virus infection. However, some cancers display resistance to viral infection. Many of these resistant cancers constitutively express interferon-stimulated genes (ISGs). The goal of these experiments was to determine the role of two tumor suppressor genes, and , in viral resistance and ISG expression in PC3 prostate cancer cells resistant to oncolytic vesicular stomatitis virus (VSV). and are often co-deleted in aggressive prostate cancers. Silencing expression of and in PC3 cells increased susceptibility to the matrix (M) gene mutant M51R-VSV, as shown by increased expression of viral genes, increased yield of progeny virus, and reduction of tumor growth in nude mice. Silencing alone had a greater effect on virus susceptibility than did silencing . Silencing and decreased constitutive expression of ISG mRNAs and proteins, whereas silencing alone decreased expression of ISG proteins, but actually increased expression of ISG mRNAs. These results suggest a role for the protein product of , transforming growth factor β-activated kinase 1 (TAK1), in regulating translation of ISG mRNAs and a role of CHD1 in maintaining the transcription of ISGs.