Mitochondrial genomic and proteomic analysis in colorectal tumor progression

1254 Adenomatous changes in the polyps are associated with the overwhelming majority of colorectal cancer. These adenomas are the precursor lesions of colon cancer. Our rationale for initiating this study is based upon the fact that typically, the clinical management of individuals with colorectal polyps is guided by the histology of the lesions. Yet, early staging of colorectal tumor progression continues to confound clinical pathologists as well as surgeons. Most recent studies suggest an involvement of the mitochondrial defects in many early stage diseases including Alzheimer, Parkinson, and some malignant tumors. Although much progress has been made in identifying mitochondrial defects associated with diseases, the protein expression patterns that are associated with colorectal tumors progressive stages have yet to be established. This may prove to be a useful prognostic tool and reduce the need for surgery. Here we use both High-resolution restriction endonucleases and SELDI-TOF MS techniques to describe mitochondrial DNA mutations and protein expression patterns associated with colorectal tumors progressive stages. Highly purified mitochondrial DNA and protein extracts were obtained from cancerous tissues as well as adenomas of three histological Colorectal Cancer (CRC) subtypes : (1) tubular (T), (2) tubulo-villous (TV), (3) villous (V) and Adjacent normal surrounding tissues (NST). High-resolution restriction analyses and SELDI-TOF MS techniques were used to identify mitochondrial biomarkers among the CRC adenomatous subtypes. A total of100 samples were used in this study (T= 8, TV=9, V=8, CRC=27, and NST=52). Nine overlapping primer sets were used to PCR amplified the entire mitochondrial genome of each sample, analyzed with restriction mapping and subsequently sequenced. These analyses resulted in a trend of 38 cumulative frequencies of mtDNA mutations and and 16 SNPs. For protein analysis study, extracted mitochondrial proteins from the samples were subjected to anion exchange fractionation and the patterns of protein express were detected by SELDI-TOF-MS. Protein expression patterns were compared between the three CRC adenomatous subtypes and the NST. A three-to-five significant differentially expressed protein peaks were observed between the three CRC, T, TV, V and NST (p-value from 0.005-0.02). However, protein profiles of the NST of the three Adenomatous subtypes were very similar. Most of the observed peaks masses ranged from 10 to 80 kDa. To further correlate these peaks with three CRC adenomatous subtypes, we are currently analyzing more number of specimens. Taken together, these data upon confirmation may be useful as predictors of colorectal tumor progression.