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DNA adduct formation by hormonal steroids in vitro
M J Seraj1, A Umemoto, M Tanaka
1Second Department of Surgery, School of Medicine, University of Tokushima, Japan.
Mutation Research
|August 1, 1996
Summary
Certain steroid hormones can covalently bind to DNA, forming adducts primarily with guanine. This DNA binding was observed in vitro, with varying reactivity among different steroids, suggesting potential implications for cellular processes.
Area of Science:
- Biochemistry
- Molecular Biology
- Endocrinology
Background:
- Steroid hormones play crucial roles in various physiological processes.
- The interaction of steroid hormones with DNA is not fully understood.
- Previous research has not extensively explored the direct covalent binding of diverse steroid hormones to DNA.
Purpose of the Study:
- To investigate the in vitro binding of various steroid hormones to human liver DNA.
- To identify which steroid hormones form covalent adducts with DNA.
- To determine the primary DNA base targeted by reactive steroid hormones.
Main Methods:
- Incubation of seventeen steroid hormones and cholesterol with human liver DNA.
- Analysis of reaction mixtures using the nuclease P-1 version of 32P-postlabeling.
- Reaction of DNA-reactive steroids with individual DNA bases (mononucleotides) to identify the target base.
Main Results:
- Cortexolone, prednisolone, cortisone, cortisol, tetrahydrocortisol, corticosterone, 11-deoxycorticosterone, dexamethasone, dihydrocortisol, and aldosterone covalently bound to DNA.
- Progesterone, hydroxyprogesterone, estrone, estradiol, estriol, testosterone, cortol, and cholesterol did not form DNA adducts.
- Guanine was identified as the primary target base for DNA-reactive steroid hormones.
Conclusions:
- Specific steroid hormones can directly form covalent DNA adducts in vitro.
- The presence of a carbonyl group at carbon seventeen of the cholesterol skeleton appears crucial for DNA reactivity.
- While some steroids showed reactivity in vitro, their interaction with intracellular DNA in Hep G2 cells was limited under experimental conditions, suggesting complex in vivo dynamics.