Cytochrome P450 2J2 metabolizes the endocannabinoid, anandamide

Abstract

Cytochrome P450 2J2 (CYP2J2) is a heme containing monooxygenase that is highly expressed in hematologic malignant diseases and in several human tumor tissues and cell lines. CYP2J2 metabolizes arachidonic acid (AA) to four epoxyeicosatrienoic acids (EETs) which promote tumor cell growth by increasing cell proliferation and inhibiting apoptosis. Studies show that the concentration of anandamide (AEA), an endogenous cannabinoid related to AA, can be increased, decreased, or unchanged in cancer cells. Conflicting reports exist regarding AEA effects on cancer cell proliferation. Moreover, AEA has been shown to induce apoptosis in certain cancer cells and it is involved in the metastatic processes of migration, invasion, and angiogenesis. In addition, anandamide is metabolized by several P450s, including CYP3A4, CYP2D6, and CYP2B6. The objective of this study is to determine if CYP2J2 expressed in leukemia cells can metabolize AEA and to investigate the effects of any metabolites formed by CYP2J2 on cell proliferation and survival. LC/MS was used to identify the metabolites formed during the metabolism of AEA by CYP2J2. Studies using purified protein in the reconstituted system showed that CYP2J2 formed the 20‐hydroxyeicosatetraenoic acid ethanolamide (HETE‐EA) and several epoxygenated products, including 8,9‐, 11,12‐, and 14,15‐epoxyeicosatrienoic acid ethanolamides (EET‐EAs). The leukemia cell line, K562, metabolizes AEA to 5,6‐, 8,9‐, 11,12‐, and 14,15‐EET‐EA, in addition to 19‐HETE‐EA. Future studies utilizing CYP2J2 specific siRNA will be used to determine if the metabolites formed by the K562 cells are dependent on CYP2J2 activity. In addition, experiments will be performed to observe the effects of anandamide and its metabolites on the proliferation and apoptosis of the K562 cells. This research was supported in part by NIH grant CA16954.