TY - JOUR T1 - Expression and functional characterization of breast cancer-associated cytochrome P450 4Z1 in <em>Saccharomyces cerevisiae</em> JF - Drug Metabolism and Disposition JO - Drug Metab Dispos DO - 10.1124/dmd.117.078188 SP - dmd.117.078188 AU - Matthew G McDonald AU - Sutapa Ray AU - Clara J. Amorosi AU - Katherine A. Sitko AU - John P. Kowalski AU - Lorela Paco AU - Abhinav Nath AU - Byron M. Gallis AU - Rheem A. Totah AU - Maitreya J. Dunham AU - Douglas M. Fowler AU - Allan E. Rettie Y1 - 2017/01/01 UR - http://dmd.aspetjournals.org/content/early/2017/10/10/dmd.117.078188.abstract N2 - CYP4Z1 is an 'orphan' P450 enzyme that has provoked interest because of its hypothesized role in breast cancer through formation of the signaling molecule 20-HETE. We expressed human CYP4Z1 in Saccharomyces cerevisiae and evaluated its catalytic capabilities towards arachidonic and lauric acids (AA and LA). Specific and sensitive mass spectrometry assays enabled discrimination of the regioselectivity of hydroxylation of these two fatty acids. CYP4Z1 generated 7-, 8-, 9-, 10- and 11-hydroxy LA, while the 12-hydroxy metabolite was not detected. HET0016, the prototypic CYP4 inhibitor, only weakly inhibited laurate metabolite formation (IC50 ~15 µM). CYP4Z1 preferentially oxidized AA to the 14(S),15(R)-epoxide with high regio- and stereoselectivity, a reaction that was also insensitive to HET0016, but neither 20-HETE nor 20-carboxy-AA were detectable metabolites. Docking of LA and AA into a CYP4Z1 homology model was consistent with this preference for internal fatty acid oxidation. Thus, human CYP4Z1 has an inhibitor profile and product regioselectivity distinct from most other CYP4 enzymes, consistent with CYP4Z1's lack of a covalently-linked heme. These data suggest that, if CYP4Z1 modulates breast cancer progression, it does so by a mechanism other than direct production of 20-HETE. ER -