In US, there are ~130,000 new cases and ~50,000 deaths resulted from colorectal cancer (CRC) every year, making CRC the second leading cause of cancer‐related deaths. There is an urgent need to identify novel biomarkers and/or therapeutic targets of CRC, in order to reduce the risks of CRC. Here we report that the expressions of cytochrome P450 (CYP) epoxygenases and their eicosanoid metabolites (fatty acid epoxides) are dramatically increased in cell culture model, animal model, and human cancer patients of CRC; in addition, pharmacological inhibition or genetic ablation of CYP epoxygenases suppresses development of CRC in mice, illustrating that the previously unappreciated CYP epoxygenase pathway could serve as novel biomarkers and/or therapeutic targets of CRC. In a well‐established azoxymethane (AOM)/dextran sulfate sodium (DSS)‐induced CRC model in C57BL/6 mice, LC‐MS/MS showed that CYP‐derived fatty acid epoxides were the only eicosanoid metabolites which were significantly increased in both plasma and colon tissues of tumor‐bearing mice. RT‐PCR and immunoblotting analysis demonstrated that the expressions of CYP (including CYP2C38, 2C39, 2C50, 2C65, 2C70, and 2J6) were significantly increased in colon tumors. Consistent with the animal results, LC‐MS/MS showed that the serum levels of CYP‐derived fatty acid epoxides were significantly increased in patients clinically diagnosed with CRC. To study the functional roles of CYP in CRC, we tested whether pharmacological inhibition or genetic ablation of CYP affects CRC development in mice. We found that treatment with SKF‐525A and clotrimazole, which are two different inhibitors of CYP epoxygenases, suppressed AOM/DSS‐induced CRC in mice. We further showed that compared with wild‐type (WT) control mice, the AOM/DSS‐induced CRC was reduced in Cyp2c gene cluster knockout mice. To elucidate the specific metabolites involved in the pro‐CRC effects of CYP, we treated mice with epoxyoctadecenoic acids (EpOMEs) which are metabolites of linoleic acid produced by CYP, and found that EpOMEs promoted development of colonic inflammation in mice. Together, our studies showed that the previously unappreciated CYP epoxygenase pathway plays critical roles in promoting progression of CRC, in part through formation of pro‐inflammatory EpOMEs. These results suggest that the circulating levels of CYP‐derived fatty acid epoxides could serve as novel diagnostic biomarkers of CRC, and the CYP enzymes could be promising therapeutic targets of CRC.Support or Funding InformationThis work was supported by USDA NIFA 2016‐67017‐24423 (to G.Z.). In addition, the research is supported in part by NIEHS R01 ES002710 and Superfund Research Program P42 ES04699.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.