Tumour-targeted delivery of TRAIL using Salmonella typhimurium enhances breast cancer survival in mice |
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Authors: | S Ganai R B Arenas N S Forbes |
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Affiliation: | 1Program in Molecular and Cellular Biology, University of Massachusetts Amherst, Amherst, MA 01003, USA;2Department of Surgery, Baystate Medical Center/Tufts University School of Medicine, Springfield, MA 01199, USA;3Pioneer Valley Life Sciences Institute, Springfield, MA 01107, USA;4Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, MA 01003, USA |
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Abstract: | Background: An effective cancer therapeutic must selectively target tumours with minimal systemic toxicity. Expression of a cytotoxic protein using Salmonella typhimurium would enable spatial and temporal control of delivery because these bacteria preferentially target tumours over normal tissue.Methods: We engineered non-pathogenic S. typhimurium to secrete murine TNF-related apoptosis-inducing ligand (TRAIL) under the control of the prokaryotic radiation-inducible RecA promoter. The response of the RecA promoter to radiation was measured using fluorometry and immunoblotting. TRAIL toxicity was determined using flow cytometry and by measuring caspase-3 activation. A syngeneic murine tumour model was used to determine bacterial accumulation and the response to expressed TRAIL.Results: After irradiation, engineered S. typhimurium secreted TRAIL, which caused caspase-3-mediated apoptosis and death in 4T1 mammary carcinoma cells in culture. Systemic injection of Salmonella and induction of TRAIL expression using 2 Gy γ-irradiation caused a significant delay in mammary tumour growth and reduced the risk of death by 76% when compared with irradiated controls. Repeated dosing with TRAIL-bearing Salmonella in conjunction with radiation improved the 30-day survival from 0 to 100%.Conclusion: These results show the pre-clinical utility of S. typhimurium as a TRAIL expression vector that effectively reduces tumour growth and extends host survival. |
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Keywords: | targeted cancer therapy spatiotemporal controlled delivery attenuated Salmonella typhimurium TRAIL RecA |
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