Targeting inflammatory cytokines using adenoviruses- gene delivery of biological therapies in ovarian cancer


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Michael Salako1, Hagen Kulbe1, Iain McNeish2, Frances Balkwill1

1Institute of Cancer and CR-UK Clinical Centre, Centre for Cancer and Inflammation, Barts and The London School of Medicine and Dentistry, London, UK, 2Institute of Cancer and CR-UK Clinical Centre, Centre for Molecular Oncology and Imaging, Barts and The London School of Medicine and Dentistry, London, UK

Abstract

Targeting inflammatory cytokines using adenoviruses- gene delivery of biological therapies in ovarian cancer

The cytokine TNF-α is central to initiating the inflammatory reactions of the innate immune system. Constitutive TNF-α expression is characteristic of malignant ovarian surface epithelium. We hypothesised that delivering TNF-α RNAi to ovarian cancer cells using an oncolytic adenovirus could reduce the inflammatory reaction that is generated by adenoviruses, and the tumour promoting action of TNF-.

shRNA was used to knock down TNF-α protein expression in IGROV1 ovarian cancer cells that constitutively express this cytokine. These cells were then infected with the tumour selective oncolytic virus dl922-947. We repeatedly found that dl922-947 had a log scale greater cytotoxic capacity in cells with reduced TNF-α expression compared to controls.

In mice bearing intraperitoneal IGROV1 xenografts stably knocked down for TNF-α and expressing luciferase, treatment with dl922-947 increased survival significantly compared to controls.

We next constructed a replicating adenovirus, dlCR2 shTNF-α, which is similar to dl922-947 but contains a TNF-α shRNA sequence. Antitumour potency of dlCR2 shTNF-α in IGROV1 cells was greater than control viruses and was comparable to that observed with dl922-947 infection of IGROV1 TNF-α knockdown cells. In addition, infection of the ovarian cancer cell line TOV-21G with dlCR2 shTNF-α produced similar results. Quantitative RT-PCR was performed on IGROV1 cells infected with dlCR2 shTNF-α. In addition to decreasing TNF-α gene expression levels, infection with dlCR2 shTNF-α also decreased levels of the inflammatory cytokine IL-6.

In conclusion, our data suggest that inhibition of TNF-α in ovarian cancer cells increases the anti-tumour capacity of replicating adenoviruses. Inhibition of TNF-α directly using an oncolytic gene therapy approach may be a beneficial therapeutic strategy.