DNA repair mechanisms in the pathogenesis of hepatocellular carcinoma

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Hepatocellular carcinoma (HCC) or cancer originating in the liver ranks 5th in worldwide frequency among tumours, and is the 3rd highest cause of cancer in our region. The incidence is increasing in most countries including Australia, Japan and USA. The overall prognosis is poor, with >80% affected persons dying from this disorder. The risk factors for HCC are well known and include chronic hepatitis B or C virus infection, alcoholism and liver iron accumulation. Despite the vast amount of information available regarding these risk factors, the way in which they alter normal liver cells to make them cancerous remains undefined. The majority of liver cancers, regardless of cause, develop in severely scarred, or cirrhotic liver in the presence of chronic liver inflammation. Such an environment causes liver cells, which are usually stable and not dividing, to continue replicating in response to injury; such continued cell division can lead to damaged genetic information in the DNA of these cells. Many cancers are associated with chromosomal damage, including broken ends and deleted genetic material. The main focus of this project to investigate how defective repair of disrupted genetic information contained in DNA of chromosomes in damaged liver cells contributes to the development of liver cancer. Using mice lacking specific genetic information to repair DNA double strand breaks, we plan to investigate whether abnormalities in DNA repair mechanisms in liver cells damaged by diethylnitrosamine (DEN) predisposes liver cells to regenerate abnormally thereby progressing to cancer. We have clues that 7 specific sites in chromosomes where loss of key genes may promote HCC formation. These studies will greatly enhance our understanding of the molecular basis by which HCC develops. The ultimate goal of this research is to develop effective screening and treatment strategies to prevent or interrupt the process of liver cancer development in at-risk individuals.