Abstract 4359: TRAIL and Noxa are selectively up-regulated in prostate cancer cells downstream of the RIG-I/MAVS signaling pathway by non-replicating Sendai virus particles.
Authors: Hatano Koji , Nakai Yasutomo , Matsushima-Miyagi Taeko , Nomura Motonari , Nakata Wataru , Yoshida Takahiro , Sato Mototaka , Kawashima Atsunari , Nagahara Akira , Fujita Kazutoshi , Uemura Motohide , Takayama Hitoshi , Kaneda Yasufumi , Nonomura Norio 
Published: August 2014

PURPOSE: The treatment of cancer with oncolytic viruses primarily depends on the selective viral replication in cancer cells. However, we previously reported that a replication-incompetent hemagglutinating virus of Japan (HVJ; Sendai virus) envelope (HVJ-E) suppressed the growth of human cancer cells, including prostate 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 and also analyze the treatment efficacy of HVJ-E using an orthotopic prostate cancer model.

EXPERIMENTAL DESIGN: The molecules responsible for HVJ-E-induced cancer cell death were elucidated in human prostate cancer cell lines, PC3, DU145 and LNCap. The cell viability was examined using MTS assay after HVJ-E treatment or the transfer of viral RNA genome fragments from HVJ-E. The viral RNA genome fragments and siRNAs were transferred to cells using liposome transfection. The expression of TNF-related apoptosis-inducing ligand (TRAIL) and Noxa were examined using Western blot analysis. The orthotopic prostate cancers were established by the inoculation of PC3 cells into the prostate of nonobese diabetic-severe combined immunodeficient (NOD-SCID) mice. After the tumors increased and microscopically visualized, HVJ-E was injected into the prostate of NOD-SCID mice. Tumor sections were prepared, and then, histological analysis and TUNEL assay were performed.

RESULTS: The liposome-mediated transfer of viral RNA genome fragments from HVJ-E suppressed the viability of prostate cancer cells, PC3 and LNCaP, but not the viability of the noncancerous prostate epithelium, PNT2. 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 TRAIL and Noxa were up-regulated by either HVJ-E treatment or transfer of viral RNA genome fragments in PC3 cells but not in PNT2 cells. TRAIL siRNA and/or Noxa siRNA significantly inhibited HVJ-E-induced cell death in prostate cancer cells. Furthermore, the orthotopic prostate cancers were dramatically eradicated in NOD-SCID mice injected with HVJ-E. Although tubuloalveolar glands were histologically maintained in the prostate injected with HVJ-E, dramatic increase of TUNEL-positive apoptotic cells were detected exclusively in the tumors treated with HVJ-E.

CONCLUSION: The oncolytic activity of HVJ-E was mediated by TRAIL and Noxa, downstream of the RIG-I/MAVS signaling pathway, selectively up-regulated in prostate cancer cells by HVJ-E treatment. The RIG-I/MAVS signaling pathway represents an attractive target for cancer therapy.

Citation Format: Koji Hatano, Yasutomo Nakai, Taeko Matsushima-Miyagi, Motonari Nomura, Wataru Nakata, Takahiro Yoshida, Mototaka Sato, Atsunari Kawashima, Akira Nagahara, Kazutoshi Fujita, Motohide Uemura, Hitoshi Takayama, Yasufumi Kaneda, Norio Nonomura. TRAIL and Noxa are selectively up-regulated in prostate cancer cells downstream of the RIG-I/MAVS signaling pathway by non-replicating Sendai virus particles. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4359. doi:10.1158/1538-7445.AM2013-4359