Molecular Characterization of Sporadic Colorectal Cancer in the Young from India

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DESCRIPTION (provided by applicant): The main aim of the proposed work is to understand the biology of tumors occurring in young sporadic colorectal cancer (CRC) patients. Colorectal cancer (CRC) is one of the most common lethal cancers in USA and Europe. Studies on CRCs have mainly focused on either older patients (above 50 years) or younger patients (below 50 years) with a familial predisposition. Two major forms of familial cancer syndromes have been well studied viz. the Hereditary Non-polyposis Colorectal Cancer (HNPCC) caused mainly due to germline inactivation of mismatch repair genes and the Familial Adenomatous Polyposis (FAP) caused mainly due to the germline inactivation of the Adenomatous Polyposis Coli tumor suppressor gene. Studies on sporadic CRCs occurring in the young have however been limited. Several recent reports have indicated an increase in the proportion of young sporadic CRC patients in developing countries in Africa and Asia, including India, as compared to USA and Europe. These patients account for almost 1/4th of the total CRC patients and often succumb to aggressive metastatic disease. Moreover, the tumor in these patients is usually localized to the rectum, as against similar young patients from the USA and Europe, in which case the tumor is predominantly localized to the colon. There are therefore several indications that suggest that the tumors occurring in the young may be distinct from similar tumors occurring in the elderly. In the present grant application, we propose a comprehensive comparative characterization of sporadic CRCs occurring in the young with those occurring in the elderly, from India. A multi-pronged strategy would be used including 1) screening for mutations in the Adenomatous Polyposis Coli (APC) tumor suppressor gene, 2) determination of status of Wnt signaling through studies on beta-catenin and transcript profiling of Wnt target genes, 3) screening for microsatellite instability, 4) identification of recurrent DNA copy number alterations and 5) analyses of genome-wide gene expression profiles. The present study therefore is not only expected to yield valuable insights into the molecular basis for young sporadic CRC but may also provide inputs into cellular pathways governing tumor initiation and progression in general. Public Health Relevance: Colorectal cancer (CRC) is one of the most common and lethal cancers in the USA. Non-hereditary young CRC patients often are ill fated, and this type of cancer is not understood well. In our present study, we expect to define the detailed behavior of this class of tumors, which is expected to aid in designing more efficient therapies in the future.