Liquid Chromatography-Tandem Mass Spectrometry-Based Targeted Lipidomic Analysis of Obesity-Related Colorectal Cancer: Potential Roles of the CYP Eicosanoid Pathway.

BACKGROUND: The mechanisms by which obesity increases colorectal cancer (CRC) risks are not well understood. Eicosanoids, lipid signaling molecules generated by cyclooxygenase (COX), lipoxygenase, and cytochrome P450 (CYP) enzymes, regulate inflammation, immune responses, and tumorigenesis. Although recent clinical studies support a role for the COX pathway in obesity-associated CRC, the roles of other pathways are unclear. OBJECTIVE: The mechanisms by which obesity increases colorectal cancer (CRC) risks are not well understood. Eicosanoids, lipid signaling molecules generated by cyclooxygenase (COX), lipoxygenase, and cytochrome P450 (CYP) enzymes, regulate inflammation, immune responses, and tumorigenesis. Although recent clinical studies support a role for the COX pathway in obesity-associated CRC, the roles of other pathways are unclear. METHODS: The mechanisms by which obesity increases colorectal cancer (CRC) risks are not well understood. Eicosanoids, lipid signaling molecules generated by cyclooxygenase (COX), lipoxygenase, and cytochrome P450 (CYP) enzymes, regulate inflammation, immune responses, and tumorigenesis. Although recent clinical studies support a role for the COX pathway in obesity-associated CRC, the roles of other pathways are unclear. RESULTS: Lipidomics identified changes in established CRC-associated eicosanoids, including increased COX-derived prostaglandin E(2) in obese CRC mice. Surprisingly, CYP-derived fatty acid epoxides were among the most markedly altered metabolites, exhibiting a 40%-76% reduction in obese CRC mice compared with lean controls. Gene-expression analysis supported the lipidomics results: CYP2C/2J isoforms responsible for epoxide production, such as Cyp2c38, Cyp2c39, Cyp2c65, Cyp2c70, and Cyp2j13, were reduced by ∼70% to 96%, whereas expression of soluble epoxide hydrolase, which degrades fatty acid epoxides, increased by ∼43% in the colons of obese CRC mice. CONCLUSIONS: These findings demonstrate that the CYP eicosanoid pathway is profoundly dysregulated in obesity-related CRC, providing a basis for exploring the roles of this pathway in the development of obesity-related CRC.