Investigation of hypoxia/reoxygenation in spheroids following radiation and SN30000 treatment using a novel click chemistry based hypoxia probe

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dc.contributor.advisor Hicks, K en
dc.contributor.advisor Ross, J en
dc.contributor.advisor Amirapu, S en Patel, Priyanka en 2017-08-21T01:43:05Z en 2017 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Hypoxia is a significant issue in cancer therapy due to the resistance of hypoxic cells to radiation, therefore supporting the use of combination treatment to achieve greater tumour control by targeting these radioresistant cell populations. SN30000, is one of many hypoxia activated prodrugs developed to eliminate hypoxic cells in tumours, leading to spatial complementarity with radiation. Multicellular tumour spheroids are increasingly used in cancer pre-clinical pharmacology because they mimic tumour environments, including hypoxic gradients, and appear ideal for studying spatial complementarity. However, interpretation of results is often difficult. To address this, we have developed an agent based computational model of spheroid growth in response to drug and radiation therapy. Our model and others predict rapid reoxygenation of spheroids following radiation or combined radiation/SN30000 treatment. SN33267, a novel 2-nitroimidazole hypoxia marker based on click chemistry, developed at the ACSRC, does not require antibody conjugated fluorophores, thus enabling analysis of whole spheroids by confocal microscopy or widefield fluorescence imaging. However, comparison to histological section has highlighted the major obstacle of light penetration in thicker specimens in confocal microscopy. Methods were developed to optimize histological processing of spheroids to produce a reference set of images of hypoxia using EF5 and SN33267. Determination of the refractive index of spheroids with optical coherence tomography enabled selection of ScaleViewA2 as an immersion medium better matched to spheroids, thus achieving greater depths of imaging. Confocal and widefield microscopy were then used to investigate the effect of radiation and SN30000 in spheroids by imaging hypoxia using SN33267. Both modalities produced similar trends, demonstrating a clear delay in growth, with only a small decrease in hypoxia relative to spheroid size. This disagreed with the ABMs that assume cells apoptose rapidly or undergo reduced metabolic capacity after receiving lethal doses of radiation. This represents a failure of the model to adequately simulate radiation induced cell cycle growth delay. This study confirmed the utility of SN33267 to investigate hypoxia in whole spheroids. Further investigation of hypoxia/reoxygenation in spheroids is necessary to improve the ABM, and has relevance for assumptions about hypoxia/reoxygenation in dose scheduling experiments investigating fractionated radiation therapy in spheroids. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA99265046009302091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
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dc.title Investigation of hypoxia/reoxygenation in spheroids following radiation and SN30000 treatment using a novel click chemistry based hypoxia probe en
dc.type Thesis en Pharmacology en The University of Auckland en Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 650860 en Liggins Institute en
pubs.record-created-at-source-date 2017-08-21 en

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