Cho Rong Hong1, Sunali Y Mehta2,3, H D Sarath Liyanage1, Sarah P McManaway1, Ho H Lee1, Jagdish K Jaiswal1,3, Gib Bogle4,3, Moana Tercel1,3, Frederik B Pruijn1,3, William R Wilson5,6, Kevin O Hicks1,3. 1. Auckland Cancer Society Research Centre, University of Auckland, 85 Park Rd, Grafton, Auckland, 1023, New Zealand. 2. Department of Pathology, Otago University, Dunedin, New Zealand. 3. Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand. 4. Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand. 5. Auckland Cancer Society Research Centre, University of Auckland, 85 Park Rd, Grafton, Auckland, 1023, New Zealand. wr.wilson@auckland.ac.nz. 6. Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand. wr.wilson@auckland.ac.nz.
Abstract
PURPOSE: Hypoxia-activated prodrugs (HAPs) have the potential for eliminating chemo- and radiation-resistant hypoxic tumour cells, but their activity is often compromised by limited penetration into hypoxic zones. Nitrochloromethylbenzindoline (nitroCBI) HAPs are reduced in hypoxic cells to highly cytotoxic DNA minor groove alkylating aminoCBI metabolites. In this study, we investigate whether a lead nitroCBI, SN30548, generates a significant bystander effect through the diffusion of its aminoCBI metabolite and whether this compensates for any diffusion limitations of the prodrug in tumour tissue. METHODS: Metabolism and uptake of the nitroCBI in oxic and anoxic cells, and diffusion through multicellular layer cultures, was characterised by LC-MS/MS. To quantify bystander effects, clonogenic cell killing of HCT116 cells was assessed in multicellular spheroid co-cultures comprising cells transfected with cytochrome P450 oxidoreductase (POR) or E. coli nitroreductase NfsA. Spatially-resolved pharmacokinetic/pharmacodynamic (PK/PD) models, parameterised by the above measurements, were developed for spheroids and tumours using agent-based and Green's function modelling, respectively. RESULTS: NitroCBI was reduced to aminoCBI by POR under anoxia and by NfsA under oxia, and was the only significant cytotoxic metabolite in both cases. In spheroid co-cultures comprising 30% NfsA-expressing cells, non-metabolising cells were as sensitive as the NfsA cells, demonstrating a marked bystander effect. Agent-based PK/PD models provided good prediction of cytotoxicity in spheroids, while use of the same parameters in a Green's function model for a tumour microregion demonstrated that local diffusion of aminoCBI overcomes the penetration limitation of the prodrug. CONCLUSIONS: The nitroCBI HAP SN30548 generates a highly efficient bystander effect through local diffusion of its active metabolite in tumour tissue.
PURPOSE:Hypoxia-activated prodrugs (HAPs) have the potential for eliminating chemo- and radiation-resistant hypoxic tumour cells, but their activity is often compromised by limited penetration into hypoxic zones. Nitrochloromethylbenzindoline (nitroCBI) HAPs are reduced in hypoxic cells to highly cytotoxic DNA minor groove alkylating aminoCBI metabolites. In this study, we investigate whether a lead nitroCBI, SN30548, generates a significant bystander effect through the diffusion of its aminoCBI metabolite and whether this compensates for any diffusion limitations of the prodrug in tumour tissue. METHODS: Metabolism and uptake of the nitroCBI in oxic and anoxic cells, and diffusion through multicellular layer cultures, was characterised by LC-MS/MS. To quantify bystander effects, clonogenic cell killing of HCT116 cells was assessed in multicellular spheroid co-cultures comprising cells transfected with cytochrome P450 oxidoreductase (POR) or E. coli nitroreductase NfsA. Spatially-resolved pharmacokinetic/pharmacodynamic (PK/PD) models, parameterised by the above measurements, were developed for spheroids and tumours using agent-based and Green's function modelling, respectively. RESULTS:NitroCBI was reduced to aminoCBI by POR under anoxia and by NfsA under oxia, and was the only significant cytotoxic metabolite in both cases. In spheroid co-cultures comprising 30% NfsA-expressing cells, non-metabolising cells were as sensitive as the NfsA cells, demonstrating a marked bystander effect. Agent-based PK/PD models provided good prediction of cytotoxicity in spheroids, while use of the same parameters in a Green's function model for a tumour microregion demonstrated that local diffusion of aminoCBI overcomes the penetration limitation of the prodrug. CONCLUSIONS: The nitroCBI HAP SN30548 generates a highly efficient bystander effect through local diffusion of its active metabolite in tumour tissue.
Authors: Ishna N Mistry; Matthew Thomas; Ewen D D Calder; Stuart J Conway; Ester M Hammond Journal: Int J Radiat Oncol Biol Phys Date: 2017-03-22 Impact factor: 7.038
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Authors: L H Li; T F DeKoning; R C Kelly; W C Krueger; J P McGovren; G E Padbury; G L Petzold; T L Wallace; R J Ouding; M D Prairie Journal: Cancer Res Date: 1992-09-15 Impact factor: 12.701