Modulation of DNA repair processes by arsenic and selenium compounds.

Area of Science:

• Environmental Toxicology
• Molecular Biology
• Carcinogenesis

Background:

• Nickel, cadmium, cobalt, and arsenic compounds are established human carcinogens.
• These metals induce oxidative DNA damage and interfere with DNA repair pathways like base excision repair (BER) at non-cytotoxic levels.
• Arsenic metabolites, particularly MMA(III) and DMA(III), also inactivate DNA repair mechanisms.

Purpose of the Study:

• To investigate the molecular targets of carcinogenic metal compounds and their metabolites on DNA repair and damage signaling pathways.
• To elucidate the interaction of these compounds with zinc finger proteins crucial for DNA repair.
• To explore the potential dual role of selenium compounds in genetic stability.

Main Methods:

• Investigated the effects of nickel, cadmium, cobalt, and arsenic compounds on DNA repair processes.
• Examined the inactivation of specific DNA repair enzymes (Fpg, XPA) and signaling pathways (poly(ADP-ribosyl)ation) by arsenic and its metabolites.
• Assessed the interaction of metal compounds with zinc finger proteins involved in DNA repair.

Main Results:

• Arsenic, MMA(III), and DMA(III) were found to inactivate DNA repair proteins, including Fpg (BER) and XPA (NER).
• Arsenite suppressed poly(ADP-ribosyl)ation, a key DNA damage signaling pathway, at environmentally relevant concentrations.
• Interactions with zinc finger structures of DNA repair proteins were identified as a potential molecular mechanism.

Conclusions:

• Carcinogenic metals and their metabolites disrupt critical DNA repair pathways, contributing to their genotoxicity.
• Zinc finger proteins are likely molecular targets for these metal-induced DNA repair interferences.
• Essential trace elements like selenium can also interact with DNA repair proteins, exhibiting concentration-dependent effects on genetic stability.