Epoxyeicosatrienoic acids (EETs) form adducts with DNA in vitro

Area of Science:

• Lipid biochemistry
• Molecular toxicology
• Genetics

Background:

• Epoxyeicosatrienoic acids (EETs) are lipid mediators derived from arachidonic acid.
• EETs exist as four distinct regioisomers: 5,6-, 8,9-, 11,12-, and 14,15-EET.

Purpose of the Study:

• To investigate the potential of EETs to form covalent DNA adducts in vitro.
• To determine if EET regioisomers exhibit differential reactivity with DNA.

Main Methods:

• Utilized the (32)P-postlabelling assay for sensitive DNA adduct detection.
• Examined the reaction of individual deoxynucleoside 3'-monophosphates and calf thymus DNA with racemic EETs.
• Tested EET reactivity under physiological (pH 7.4) and acidic (pH 4) conditions.

Main Results:

• At neutral pH, only ±11,12-EET formed detectable DNA adducts.
• Pre-incubation at acidic pH enabled all four racemic EETs to form multiple DNA adducts.
• DNA adduct levels were significantly higher (up to two orders of magnitude) under acidic conditions compared to neutral pH for 11,12-EET.
• Adducts primarily formed with deoxyguanosine and deoxyadenosine.

Conclusions:

• All four EET regioisomers can form DNA adducts in vitro following activation by acidic pH.
• ±11,12-EET is capable of forming DNA adducts at neutral pH.
• These findings suggest that EETs may function as endogenous genotoxic agents.