Nickel(II) interferes with the incision step in nucleotide excision repair in mammalian cells

• Published in: Cancer research (Chicago, Ill.) Vol. 54; no. 15; pp. 4045 - 4051
• Main Authors: HARTWIG, A, MULLENDERS, L. H. F, SCHLEPEGRELL, R, KASTEN, U, BEYERSMANN, D
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.08.1994
• Subjects: Biological and medical sciences; Carcinogenesis, carcinogens and anticarcinogens; Chemical agents; Colony-Forming Units Assay; DNA - chemistry; DNA - drug effects; DNA - radiation effects; DNA Damage; DNA Repair - drug effects; HeLa Cells - metabolism; HeLa Cells - radiation effects; Humans; Magnesium - pharmacology; Medical sciences; Nickel - antagonists & inhibitors; Nickel - pharmacokinetics; Nickel - toxicity; Nucleotides; Tumors; Ultraviolet Rays; Carcinogen; Nickel II; Toxicity; DNA; Inhibition; Mechanism of action; Repair; In vitro; Hela cell line; Tumor cell; Heavy metal
• ISSN: 0008-5472; 1538-7445

Nickel compounds are carcinogenic to humans and experimental animals. However, the mechanisms leading to tumor formation are still not understood since the mutagenic potential is rather weak. In contrast, nickel(II) enhances the cytotoxicity and genotoxicity in combination with several other DNA-damaging agents. To elucidate possible interactions with DNA repair processes, the effect of nickel(II) on the nucleotide excision repair pathway has been investigated after UV irradiation in HeLa cells. Nickel(II) blocks the removal of cyclobutane pyrimidine dimers as determined by T4 endonuclease V-sensitive sites. When the alkaline unwinding technique was applied, significantly less transient DNA strand breaks after UV irradiation were detected in the presence of nickel(II) compared to UV alone, suggesting an inhibition of the incision step of nucleotide excision repair. Once incisions are made, the ligation of repair patches is delayed as well in nickel-treated cells, as observed by the alkaline unwinding and nucleoid sedimentation techniques. This inhibition of DNA repair is partly reversible by the addition of magnesium(II), indicating that the competition between Ni2+ and Mg2+ may provide an important mechanism for the disturbance of DNA-protein interactions involved in the repair process. Since the repair inhibition is observed at noncytotoxic concentrations of nickel(II), it may well be relevant for its carcinogenic action.