Background: Epoxyeicosatrienoic acids (EETs) are derived from arachidonic acid by cytochrome P450 (CYP) and metabolized by soluble epoxide hydrolase (sEH). EETs have been associated with cardiovascular disease, diabetes and several cancer diseases. However, the distribution in tissue and role of CYP2C8, 2C9, 2J2 and sEH in human breast carcinogenesis remains uncertain.
Methods: Breast cancer (BC) and adjacent noncancerous tissue was obtained from 40 breast cancer patients in the Chaoshan region in China from 2010 to 2012. The level of 14,15-EET/14,15-DHET in BC patients was detected by ELISA; the expression and distribution of CYP2C8, 2C9, 2J2 and sEH was determined by quantitative RT-PCR and immunohistochemical staining; and cell proliferation and migration was analyzed by MTT and transwell assays, respectively.
Results: The median 14,15-EET and 14,15-EET/DHET level was 2.5-fold higher in BC than noncancerous tissue. The mRNA and protein levels of CYP2C8, 2C9 and 2J2 were higher, and sEH was lower in BC than noncancerous tissue. Furthermore, CYP2C8 and 2C9 protein levels positively correlated with Ki67 status, and CYP2J2 levels positively correlated with histological grade and tumor size. The sEH protein level negatively correlated with tumor size, estrogen receptors and Ki67. In MDA-MB-231 cells, siRNA knockdown of CYP2C8, 2C9 or 2J2 reduced cell proliferation, by 24.5%, 29.13%, or 22.7% and decreased cell migration by 49.1%, 44.9%, and 50.9%, respectively. Similarly, with adenovirus overexpression of sEH, both cell proliferation and migration rates were reduced by 31.4% and 45.8%, respectively.
Conclusions: The present study shows that elevated EET levels in BC tissues are associated with upregulation of CYP2C8, 2C9, and 2J2, and downregulation of sEH, and are also associated with aggressive cell behavior in BC patients.