Sensitivity of cervical carcinoma cells to vesicular stomatitis virus-induced oncolysis: potential role of human papilloma virus infection Fabrice Le Boeuf 1,2 *, Nima Niknejad 1,2 *, Jiahu Wang 1,2 , Rebecca Auer 1,3 , Johanne I. Weberpals 1,3 , John C. Bell 1,2 and Jim Dimitroulakos 1,2 1 Centre for Cancer Therapeutics, Ottawa Hospital Research Institute, Ottawa, Canada 2 Department of Biochemistry, University of Ottawa, Ottawa, Canada 3 Faculty of Medicine, University of Ottawa, Ottawa, Canada High-risk carcinogenic subtypes of human papilloma virus (HPV) are associated with the development of squamous cell carcinomas of the cervix (CC) and a subset of head and neck (HNSCC). Recurrent metastatic diseases of these sites display a dismal prognosis. Therefore, there is an urgent need to uncover innovative therapeutic strategies in this clinical setting. Oncolytic viruses, including vesicular stomatitis virus (VSV), were identified due to their ability to specifically target tumor cells that generally display defects in interferon (IFN) signaling. HPV expressed proteins can inhibit IFN signaling; therefore, HPV-infected cells may be particularly sensitive to VSV oncolysis. In this study, we evaluated the sensitivity of four CC (HPV1) and four HNSCC (HPV2) derived cell lines to VSV oncolysis. Interestingly, the CC cell lines were consistently more sensitive to VSV cytotoxicity than the HNSCC cell lines tested. Exogenous IFN addition or infection with two attenuated VSV variants that are more susceptible to IFN inhibition failed to attenuate VSV oncolysis in hypersensitive CC cell lines. Furthermore, the expression of HPV-E6, that inhibits IFN receptor signaling, in the VSV-resistant HNSCC cell line SCC25 attenuated VSV-induced IFN response and significantly enhanced VSV cytotoxicity. Finally, differential VSV infection and replication was confirmed in xenograft murine tumor models and explant tumor tissues from two patients with CC. Taken together, these results demonstrate that HPV-infected cells are susceptible to oncolytic virus therapy and that this approach may represent a novel therapeutic approach in HPV positive CC and HNSCC patients. Human papilloma viruses (HPV) are small double-stranded DNA tumor viruses that replicate in differentiating keratino- cytes of the skin and anogenital tract. 1–3 Three oncogenes, E5, E6 and E7, modulate the transformation process, two reg- ulatory proteins, E1 and E2, modulate transcription and rep- lication and two structural proteins, L1 and L2, form the viral capsid. 4 E6 and E7 proteins delay keratinocyte differentiation, trigger host DNA synthesis and enhance cell cycle progres- sion, hijacking host DNA synthetic enzymes to replicate its genome. HPVs induce benign warts and papillomas; however, infection with high-risk types (HPV-16, 18, 31 and 45) is a major risk factor for the development of 100% of cervical carcinomas (CC), 50% of other anogenital carcinomas, 20% of head and neck squamous cell carcinomas (HNSCC) and may also play a role in oropharyngeal cancer. 5 The E6 and E7 genes are of particular importance as they are retained and expressed in most CC and their continued expression is required to maintain the malignant phenotype. 6 An important target for E6 is E6-associated protein, a pro- tein-ligase of the ubiquitin pathway that targets the tumor suppressor protein p53 for degradation. Loss of p53 leads to genetic instability and rapid malignant progression. 5,7 The E7 protein binds to the retinoblastoma protein and members of the retinoblastoma family enhancing cell cycle progression and DNA synthesis. 6 E6 and E7 exert overlapping effects on cell cycle control, and in combination, they efficiently immortalize human keratinocytes. 8 More recently, E6 has been shown to inhibit the cellular anti-viral interferon (IFN) response as its binding to Tyk2 inhibits its interaction with Key words: cervical cancer, human papilloma virus (HPV), vesicular stomatitis virus (VSV), interferon, oncolytics Abbreviations: CC: carcinomas of the cervix; HNSCC: squamous cell carcinomas of the head and neck; HPV: human papilloma virus; IFN: interferon; IRF: interferon regulatory factor; MOI: multiplicity of infection; VSV: vesicular stomatitis virus Additional Supporting Information may be found in the online version of this article. Grant sponsors: Canadian Institute of Health Research, Ontario Institute for Cancer Research, CIHR/SME Collaborative Research Program Fellowships *F.L.B. and N.N. contributed equally to this work. DOI: 10.1002/ijc.27404 History: Received 3 May 2011; Accepted 17 Nov 2011; Online 15 Dec 2011 Correspondence to: Jim Dimitroulakos, Centre for Cancer Therapeutics, Ottawa Hospital Research Institute, 501 Smyth Road, Box 926, Ottawa, Ontario, K1H 8L6, Canada, Tel: þ613-737-7700x70335, Fax: 613-247-3524, E-mail: jdimitroulakos@ohri.ca Cancer Cell Biology Int. J. Cancer: 131, E204–E215 (2012) V C 2011 UICC International Journal of Cancer IJC