title: Molecular determinants of susceptibility to oncolytic vesicular stomatitis virus in pancreatic adenocarcinoma.
abstract: BACKGROUND
  M protein mutant vesicular stomatitis virus (M51R-VSV) has oncolytic properties against many cancers. However, some cancer cells are resistant to M51R-VSV. Herein, we evaluate the molecular determinants of vesicular stomatitis virus (VSV) resistance in pancreatic adenocarcinoma cells.
  
  
  METHODS
  Cell viability and the effect of β-interferon (IFN) were analyzed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. Gene expression was evaluated via microarray analysis. Cell infectability was measured by flow cytometry. Xenografts were established in athymic nude mice and treated with intratumoral M51R-VSV.
  
  
  RESULTS
  Four of five pancreatic cancer cell lines were sensitive to M51R-VSV, whereas Panc 03.27 cells remained resistant (81 ± 3% viability 72 h after single-cycle infection). Comparing sensitive MiaPaCa2 cells with resistant Panc 03.27 cells, significant differences in gene expression were found relating to IFN signaling (P = 2 × 10(-5)), viral entry (P = 3 × 10(-4)), and endocytosis (P = 7 × 10(-4)). MiaPaCa2 cells permitted high levels of VSV infection, whereas Panc 03.27 cells were capable of resisting VSV cell entry even at high multiplicities of infection. Extrinsic β-IFN overcame apparent defects in IFN-mediated pathways in MiaPaCa2 cells conferring VSV resistance. In contrast, β-IFN decreased cell viability in Panc 3.27 cells, suggesting intact antiviral mechanisms. VSV-treated xenografts exhibited reduced tumor growth relative to controls in both MiaPaCa2 (1423 ± 345% versus 164 ± 136%; P < 0.001) and Panc 3.27 (979 ± 153% versus 50 ± 56%; P = 0.002) tumors. Significant lymphocytic infiltration was seen in M51R-VSV-treated Panc 03.27 xenografts.
  
  
  CONCLUSIONS
  Inhibition of VSV endocytosis and intact IFN-mediated defenses are responsible for M51R-VSV resistance in pancreatic adenocarcinoma cells. M51R-VSV treatment appears to induce antitumor cellular immunity in vivo, which may expand its clinical efficacy.
authors.affiliation: Division of Surgical Sciences, Department of General Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Aaron U
authors.initials: AU
authors.lastname: Blackham
authors.affiliation: Division of Surgical Sciences, Department of General Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Northrup
authors.affiliation: Department of Pathology, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Mark
authors.initials: M
authors.lastname: Willingham
authors.affiliation: Department of Pathology, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Joseph
authors.initials: J
authors.lastname: Sirintrapun
authors.affiliation: Division of Public Health Sciences, Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Greg B
authors.initials: GB
authors.lastname: Russell
authors.affiliation: Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Lyles
authors.affiliation: Division of Surgical Sciences, Department of General Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina. Electronic address: jhstewar@wfubmc.edu.
authors.forename: John H
authors.initials: JH
authors.lastname: Stewart
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D000818:Animals; D000970:Antineoplastic Agents / Q000276:immunology / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000276:immunology; D019008:Drug Resistance, Neoplasm; D004705:Endocytosis / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular / Q000276:immunology; D016899:Interferon-beta / Q000276:immunology / Q000494:pharmacology; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology; D051379:Mice; D008819:Mice, Nude; D050130:Oncolytic Virotherapy / Q000379:methods*; D010190:Pancreatic Neoplasms / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D014763:Viral Matrix Proteins / Q000276:immunology / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; C094460:M protein, Vesicular stomatitis virus; D014763:Viral Matrix Proteins; D016899:Interferon-beta
keywords: Interferon; Pancreatic adenocarcinoma; Vesicular stomatitis virus; Viral endocytosis; Xenograft