You are here:
FORMATION OF 7-(2-0XOETHYL)GUANINE FROM LIPID PEROXIDATION AND VINYL CHLORIDE EXPOSURE IN MALE SPRAGUE DAWLEY RATS
Citation:
Mutlu, E., Y. Jeong, L. Collins, A. Harn, P. Upton, G. E. HATCH, D. W. WINSETT, P. A. EVANSKY, AND J. A. SWENBERG. FORMATION OF 7-(2-0XOETHYL)GUANINE FROM LIPID PEROXIDATION AND VINYL CHLORIDE EXPOSURE IN MALE SPRAGUE DAWLEY RATS. Presented at Society of Toxicology (SOT) Annual Meeting, San Francisco, CA, March 11 - 15, 2012.
Impact/Purpose:
Vinyl Chloride (VC) is a known human and animal -carcinogen that induces hepatic angiosarcomas. Other than occupational exposure and smoking, VC is also found in Superfund sites at ppb concentrations
Description:
Vinyl Chloride (VC) is a known human and animal carcinogen that induces hepatic angiosarcomas. Other than occupational exposure and smoking, VC is also found in Superfund sites at ppb concentrations. VC is metabolized to chloroethylene oxide by CYP450 2E1 to induce four major DNA adducts, including 7-(2-oxoethyl)guanine (7-0EG). Using a new sensitive method, we analyzed 7-0EG formation in tissue DNA from adult and weanling rats exposed to 1100 ppm [13C2]-VC for 5 days. After the neutral thermal hydrolysis of sample DNA, 7-0EG was derivatized with o-tbutylhydroxylamine and analyzed by LC-MS/MS. The limit of detection was 1 fmol and the limit of quantitation was 1.5 fmol on column. By using stable isotope VC, we discerned VC-induced, exogenous (exo) 7-0EG from endogenous (endo) 7-0EG for the first time. The number of endo 7-0EG in tissue DNA from adult and weanling rats was 0.1-1.0 adducts/105 guanine (add/105G). The number of exo 7-0EG in liver DNA of exposed adult rats was 10.4±2.3 add/105G (n=4) with other tissues ranging from 0.1-3.9 add/105G (n=4). While adult and weanling rats displayed similar endo 7-0EG concentrations, exo 7-0EG concentrations were higher in weanlings with liver averaging 30 add/lO5G. Studies on the persistence of [13C2]7- 0EG in adult rats sacrificed 2,4, or 8 wks post exposure to [13C2]-VC determined the half-life of 7-0EG in liver and lung to be 4 days. We hypothesized that [13C2]-7-0 EG would form from lipidperoxidationandtestedthisbyreacting calfthymus DNAwith [13CI8]-ethyllinoleateunder peroxidizing conditions and demonstrating that it was readily formed. Our additional finding that endo 7-0EG is present in amounts similar to 8-0HdG in unexposed rat tissue further emphasizes the importance of understanding the role of endogenous DNA damage in disease. Abstract does not reflect EPA policy