Thiols can either enhance or suppress DNA damage induction by catecholestrogens

Paul A. Thibodeau, Suzanne Kocsis-Bédard, Josiane Courteau, Théophile Niyonsenga, Benoit Paquette

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


The estrogen metabolites catecholestrogens (or hydroxyestrogens) are involved in carcinogenesis and the development of resistance to methotrexate. This induction of drug resistance correlates with the relative efficiency of catecholestrogens in the generation of reactive oxygen species (ROS) and the induction of DNA strand breaks. Although antioxidants can neutralize ROS, the generation of these reactive species by catecholestrogens can be enhanced by electron donors like NADH. Therefore, this study was undertaken to determine the ability of different thiol agents (GSH, NAC, DTT, DHLA) to either inhibit or enhance the level of DNA damage induced by the H2O2 generating system 4-hydroxyestradiol/Cu(II). Our results show that GSH, DTT, and DHLA inhibited the induction of the 4-hydroxyestradiol/Cu(II)-mediated DNA damage, with GSH showing the best potential. In contrast, the GSH precursor NAC at low concentrations was able to enhance the level of oxidative damage, as observed with NADH. NAC can reduce Cu(II) to Cu(I) producing the radical NAC·, which can generate the superoxide anion. However, the importance of this pathway appears to be relatively minor since the addition of NAC to the 4-hydroxyestradiol/Cu(II) system generates about 15 times more DNA strand breaks than NAC and Cu(II) alone. We suggest that NAC can perpetuate the redox cycle between the quinone and the semiquinone forms of the catecholestrogens, thereby enhancing the production of ROS. In conclusion, this study demonstrates the crucial importance of the choice of antioxidant as potential therapy against the negative biological effects of estrogens.

Original languageEnglish
Pages (from-to)62-73
Number of pages12
JournalFree Radical Biology and Medicine
Issue number1
Publication statusPublished - 2001
Externally publishedYes


Dive into the research topics of 'Thiols can either enhance or suppress DNA damage induction by catecholestrogens'. Together they form a unique fingerprint.

Cite this