Metabolic profiling, a noninvasive approach for the detection of experimental colorectal neoplasia

Colorectal cancer is the second leading cause of cancer-related deaths in the United States. Although noninvasive stool-based screening tests are used for the early detection of colorectal neoplasia, concerns have been raised about their sensitivity and specificity. A metabolomics-based approach provides a potential noninvasive strategy to identify biomarkers of colorectal carcinogenesis including premalignant adenomas. Our primary objective was to determine whether a distinct metabolic profile could be found in both feces and plasma during experimental colorectal carcinogenesis. Feces, plasma as well as tumor tissue and normal colorectal mucosa were obtained from A/J mice at several time points following administration of azoxymethane or saline. Ultra-performance liquid chromatography tandem mass spectroscopy and gas chromatography mass spectroscopy were used to quantify metabolites in each of these matrices. Here, we show that colorectal carcinogenesis was associated with significant metabolic alterations in both the feces and plasma, some of which overlap with metabolic changes in the tumor tissue. These consisted of 33 shared changes between feces and tumor, 14 shared changes between plasma and tumor, and 3 shared changes across all 3 matrices. For example, elevated levels of sarcosine were found in both tumor and feces whereas increased levels of 2-hydroxyglutarate were found in both tumor and plasma. Collectively, these results provide evidence that metabolomics can be used to detect changes in feces and plasma during azoxymethane- induced colorectal carcinogenesis and thus provide a strong rationale for future studies in humans.