Sulforaphane inhibits damage‐induced poly (ADP‐ribosyl)ation via direct interaction of its cellular metabolites with PARP‐1

• Published in: Molecular nutrition & food research 2015-11, Vol.59 (11), p.2231-2242
• Main Authors: Piberger, Ann Liza, Keil, Claudia, Platz, Stefanie, Rohn, Sascha, Hartwig, Andrea
• Format: Article
• Language: English
• Subjects: Adenosine Diphosphate Ribose - metabolism; anticarcinogenic activity; broccoli; cell culture; DNA; DNA Breaks; DNA damage; DNA Repair; DNA single-strand break repair; enzymes; Erucin; fluorescent antibody technique; glucoraphanin; glutathione; HeLa Cells; Humans; Isothiocyanates - metabolism; Isothiocyanates - pharmacology; metabolites; PARP inhibition; Poly (ADP-Ribose) Polymerase-1 - metabolism; Poly(ADP-ribose) Polymerase Inhibitors - pharmacology; proteins; Sulfhydryl Compounds - metabolism; Sulforaphane; Thiol reactivity; thiols; zinc
• ISSN: 1613-4125; 1613-4133
• DOI: 10.1002/mnfr.201500457

SCOPE: The isothiocyanate sulforaphane, a major breakdown product of the broccoli glucosinolate glucoraphanin, has frequently been proposed to exert anticarcinogenic properties. Potential underlying mechanisms include a zinc release from Kelch‐like ECH‐associated protein 1 followed by the induction of detoxifying enzymes. This suggests that sulforaphane may also interfere with other zinc‐binding proteins, e.g. those essential for DNA repair. Therefore, we explored the impact of sulforaphane on poly (ADP‐ribose)polymerase‐1 (PARP‐1), poly (ADP‐ribosyl)ation (PARylation), and DNA single‐strand break repair (SSBR) in cell culture. METHODS AND RESULTS: Immunofluorescence analyses showed that sulforaphane diminished H₂O₂‐induced PARylation in HeLa S3 cells starting from 15 μM despite increased lesion induction under these conditions. Subcellular experiments quantifying the damage‐induced incorporation of ³²P‐ADP‐ribose by PARP‐1 displayed no direct impact of sulforaphane itself, but cellular metabolites, namely the glutathione conjugates of sulforaphane and its interconversion product erucin, reduced PARP‐1 activity concentration dependently. Interestingly, this sulforaphane metabolite‐induced PARP‐1 inhibition was prevented by thiol compounds. PARP‐1 is a stimulating factor for DNA SSBR‐rate and we further demonstrated that 25 μM sulforaphane also delayed the rejoining of H₂O₂‐induced DNA strand breaks, although this might be partly due to increased lesion frequencies. CONCLUSION: Sulforaphane interferes with damage‐induced PARylation and SSBR, which implies a sulforaphane‐dependent impairment of genomic stability.