Regulation of mutational load by chemopreventive agents and implications for molecular pathogenesis of colorectal cancer

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In Australia colorectal cancer is the second most common cause of cancer death, however the morbidity and mortality of colorectal cancer is currently not under control. Identification of safe and practical preventive agents should aid control. There is increasing evidence that colorectal cancer is associated with endogenous (internall) and exogenous (external) factors. They cause damage to DNA which might lead to tumour development if the damage is not repaired. This study will first identify the ability of preventive agents (aspirin-like drugs, fish oil, and antioxidants) to regulate DNA damage, then examine the effect of combination of the agents. It will finally determine the ability of agents, or combination of agents, to prevent development of colorectal cancer using two animal models. Prevention of human CRC by such a strategy should be feasible. First, evidence indicates that DNA damage is important in tumour initiation. Second, exogenous regulation of DNA damage, repair and removal seems possible. Epidemiological studies have suggested that that 30-70% of cancer can potentially be prevented with proper adjustment of diets (fat, fibre, resistant starch) and supplements of drugs (NSAIDs) or antioxidants (Vitamin, Selenium). Third, preventive strategies are likely to be feasible. At the population level, they would need to be safe and manageable in the context of dietary lifestyle, but this can be achieved through a range of food technology developments. In individuals at high risk, personalised preventive strategies become feasible through doctor-patient contact. This study focuses on regulation of DNA damage, and its repair and removal during the early stage of tumour development. The study will provide information if preventive agents, alone or in combination, provide a promising strategy for colorectal cancer through reduction of genetic damage. They might also identify new biomarkers that facilitate testing in humans.