PDF file - 395K, Figure S1. Selective apoptosis in DU145 cells induced by HVJ-E. Figure S2. The effect of poly (I:C) on cell survival. Figure S3. No significant changes in the expression of Bax, Puma, Bcl-xL or Bcl-2 were observed in cells treated with HVJ-E. Figure S4. Selective expression of the death receptors for TRAIL in PC3 cells and the decoy receptors for TRAIL in PNT2 cells. Figure S5. Suppression of HVJ-E-induced cell death by IRF7 siRNA in PC3 cells and by IRF3 siRNA in DU145 cells. Figure S6. Histological analysis and TUNEL staining of subcutaneous tumors injected with HVJ-E.
ARTICLE ABSTRACT
Purpose: The treatment of cancer with oncolytic viruses primarily depends on the selective viral replication in cancer cells. However, a replication-incompetent hemagglutinating virus of Japan (HVJ; Sendai virus) envelope (HVJ-E) suppresses the growth of human cancer cells as effectively as replication-competent live HVJ without producing toxic effects in nonmalignant cells. Here, we analyze the molecular mechanism of the oncolytic activity of HVJ-E.Experimental Design: The molecules responsible for HVJ-E–induced cancer cell death were elucidated in prostate cancer cell lines, and the effect of HVJ-E on orthotopic prostate cancers was evaluated in nonobese diabetic-severe combined immunodeficient (NOD-SCID) mice.Results: The liposome-mediated transfer of viral RNA genome fragments from HVJ-E suppressed the viability of prostate cancer cells but not the viability of the noncancerous prostate epithelium. Knockdown experiments using siRNAs showed that the cancer cell–selective killing induced by HVJ-E was mediated by retinoic acid–inducible gene I (RIG-I) and mitochondrial antiviral signaling protein (MAVS). Downstream of the RIG-I/MAVS pathway, both TNF-related apoptosis-inducing ligand (TRAIL) and Noxa were upregulated by HVJ-E in the castration-resistant prostate cancer cell line PC3 but not in the noncancerous prostate epithelial cell line PNT2. TRAIL siRNA but not Noxa siRNA significantly inhibited HVJ-E–induced cell death in PC3 cells. However, Noxa siRNA effectively suppressed HVJ-E–induced cell death in DU145 cells, another castration-resistant prostate cancer cell line, in which Noxa but not TRAIL was upregulated by HVJ-E. Furthermore, the orthotopic prostate cancers were dramatically eradicated in immunodeficient mice injected with HVJ-E.Conclusion: The RIG-I/MAVS signaling pathway represents an attractive target for cancer therapy. Clin Cancer Res; 18(22); 6271–83. ©2012 AACR.
