Epigenetic modifiers enhance vesicular Stomatitis virus-mediated oncolysis in the refractory PC3 cell line

Abstract

Introduction: Vesicular stomatitis Virus (VsV) is an oncolytic virus that preferentially replicates in and kills cancerous cells. however, many cancer cell lines are resistant to VsV treatment alone. previous work has shown that treating cancerous cells with histone deacetylase inhibitors makes them more susceptible to VsV infection and oncolysis. We hypothesize that treatment with a histone deacetylase inhibitor, suberoylanilide hydroxamic acid (saha or Voronistat), and a methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-aza or Decitabine), will result in an increase in VsV replication and virus-induced oncolysis in vitro. Methods: pC3 prostate cancer cells were treated with 1 μm saha, 1 μm 5-aza or both. of these samples, half were infected with oncolytic Vesicular stomatitis Virus expressing green fluorescent protein VsV aV1 – gFp at a multiplicity of infection of 1 × 10-2, 24 hours after treatment. Cells were then collected and subjected to either FaCs analysis or protein extraction at 12, 24, 48 and 72 hours post-infection. We confirmed increases in cell death by western blotting for cleavage of poly a Riboprotein, an important downstream effector of the Caspase pathway, as well as Caspases 8 and 9, hallmarks for the extrinsic and intrinsic apoptotic pathways respectively. results: Treatment with saha, 5-aza or a combination of both resulted in increases in VsV replication and cell death. These observations were consistent over four time points spanning 72 hours. discussion: Treatment with histone deacetylase inhibitor/methyltransferase inhibitor combination increases VsV replication and cell death in tumour cell lines resistant to VsV infection. In combination with previous work, this data suggests that modulation of the antiviral response and apoptotic pathways increases susceptibility to VsV.