Cytotoxic effect of a combination of bluetongue virus and radiation on prostate cancer

Abstract

This study aimed to investigate the lethal effect of the combination of bluetongue virus (BTV) and radiation on RM-1 murine prostate cancer cells in vitro and in vivo. Various cell lines were infected with BTV and the cytotoxicity was tested by a lactate dehydrogenase (LDH) release bioassay. Additionally, the RM-1 cells were treated with radiation and/or BTV to assess cell viability using the Cell Counting Kit-8 method. The levels of apoptosis of the RM-1 cells were detected by fluorescence-activated cell sorting (FACS). To identify a possible mechanism for the radiation-induced change in the oncolytic activity of BTV, cell cycle analyses were performed. The effects of different schedules of BTV and radiotherapy on cytotoxicity were assessed in vitro and the combined effect was also assessed in tumor models in vivo. The results demonstrated that BTV had a selective cytotoxic effect on RM-1 and PC-3 cancer cells, but did not affect normal cells, specifically, human umbilical vein endothelial cells and smooth muscle cells. The combination of BTV and radiation enhanced the cytotoxicity compared with that of each agent alone and had a synergistic effect in vitro and in vivo. The results of the FACS confirmed that radiotherapy induced apoptosis, as did BTV alone, and the combination treatment generated the most prominent levels of apoptosis, which were the highest in the early stage. The analysis of the cell cycle indicated that the G2-M phase levels increased after irradiation followed by infection with BTV. In conclusion, the combination of BTV and radiotherapy had an enhanced cytotoxic effect on RM-1 cells in vitro and in vivo compared with that of either treatment alone, and demonstrated a synergistic efficacy, in addition to a marked apoptosis-inducing effect. These results support the future investigation of BTV for potential clinical use in patients with prostate cancer.

Bluetongue Viruses Act as Novel Oncolytic Viruses to Effectively Inhibit Human Renal Cancer Cell Growth In Vitro and In Vivo

“…The HPTEC cells were subcultured in Renal Epithelial Cell Growth Medium (PromoCell). Bluetongue virus serotype 10 (BTV-10) was used throughout this study as described previously [ 14 ]. The origin, passage, and propagation of the virus was determined as described previously.…”

“…In brief, the renal cancer cell lines and HPTEC cells were plated at the density of 10 000 cells/well in 96-well flat-bottom plates with 150 μL of media. After the cells adhered to the surface, they were infected with BTVs at MOI of 0.001, 0.01, 0.1, 1, or 10 in triplicate for 24, 48, or 72 h. After treatment, the percentage survival for each group was determined as described previously [ 14 ]. The experiments were performed in triplicate.…”

“…It has been reported to primarily affect sheep and cattle but not humans [ 12 ]. Recent studies indicated that BTVs are capable of infecting and selectively lysing human hepatic carcinoma cells (Hep-3B) and prostate carcinoma cells (pc-3) [ 13 , 14 ]. Given this background, we evaluated BTVs as a novel oncolytic agent against human RCC in vitro and in vivo .…”

Trial Watch: Immunotherapy plus radiation therapy for oncological indications

“…28,64,66,67 Classically, radiation therapy has been employed in the context of combinatorial treatment regimens (involving surgery and chemotherapy), either with a curative objective (i.e., with the aim to eradicate primary neoplasms or prevent recurrence) or with a palliative intent (i.e., to limit the pain/discomfort caused by malignancies at specific anatomical locations). 5,6 Along with the recognition that radiation therapy can mediate potent immunostimulatory effects, considerable interest has been attracted by combinatorial regimens involving EBRT plus one (or more) immunotherapeutic agent(s), [68][69][70][71] including checkpoint blockers, [72][73][74][75] immunostimulatory antibodies, 72,76 recombinant cytokines, [77][78][79] anticancer vaccines, 80-84 indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors, 85,86 adoptively transferred cells, [87][88][89] oncolytic viruses, [90][91][92][93] Toll-like receptor (TLR) agonists, 94,95 and various small molecules that operate on the immunological tumor microenvironment. In this Trial Watch, we summarize recent preclinical and clinical advances in the development of combinatorial anticancer regimens based on EBRT plus immunotherapy.…”