Reversed-phase gradient LC-MS was used to perform untargeted metabonomic 
analysis on extracts of human colorectal cancer (CRC) cell lines (COLO 205, 
HT-29, HCT 116 and SW620) subcutaneously implanted into age-matched athymic nude 
male mice to study small molecule metabolic profiles and examine possible 
correlations with human cancer biopsies. Following high mass accuracy data 
analysis using MS and MS/MS, metabolites were identified by searching against 
major metabolite databases including METLIN, MASSBANK, The Human Metabolome 
Database, PubChem, Biospider, LipidMaps and KEGG. HT-29 and COLO 205 tumor 
xenografts showed a distribution of metabolites that differed from SW620 and HCT 
116 xenografts (predominantly on the basis of relative differences in the 
amounts of amino acids and lipids detected). This finding is consistent with 
NMR-based analysis of human colorectal tissue, where the metabolite profiles of 
HT-29 tumors exhibit the greatest similarity to human rectal cancer tissue with 
respect to changes in the relative amounts of lipids and choline-containing 
compounds. As the metabolic signatures of cancer cells result from 
oncogene-directed metabolic reprogramming, the HT-29 xenografts in mice may 
prove to be a useful model to further study the tumor microenvironment and 
cancer biology.