Effects of chemopreventive natural products on non-homologous end-joining DNA double-strand break repair.
Double-strand breaks (DSBs) may result from endogenous (e.g., reactive oxygen species, variable (diversity) joining, meiotic exchanges, collapsed replication forks, nucleases) or exogenous (e.g., ionizing radiation, chemotherapeutic agents, radiomimetic compounds) events. DSBs disrupt the integrity of DNA and failed or improper DSBs repair may lead to genomic instability and, eventually, mutations, cancer, or cell death. Non-homologous end-joining (NHEJ) is the major pathway used by higher eukaryotic cells to repair these lesions. Given the complexity of NHEJ and the number of proteins and cofactors involved, secondary metabolites from medicinal or food plants might interfere with the process, activating or inhibiting repair. Twelve natural products, arbutin, curcumin, indole-3-carbinol, and nine flavonoids (apigenin, baicalein, chalcone, epicatechin, genistein, myricetin, naringenin, quercetin, sakuranetin) were chosen for their postulated roles in cancer chemoprevention and/or treatment. The effects of these compounds on NHEJ were investigated with an in vitro protocol based on plasmid substrates. Plasmids were linearized by a restriction enzyme, generating cohesive ends, or by a combination of enzymes, generating incompatible ends; plasmids were then incubated with a nuclear extract prepared from normal human small-intestinal cells (FHS 74 Int), either treated with these natural products or untreated (controls). The NHEJ repair complex from nuclear extracts ligates linearized plasmids, resulting in plasmid oligomers that can be separated and quantified by on-chip microelectrophoresis. Some compounds (chalcone, epicatechin, myricetin, sakuranetin and arbutin) clearly activated NHEJ, whereas others (apigenin, baicalein and curcumin) significantly reduced the repair rate of both types of plasmid substrates. Although this in vitro protocol is only partly representative of the in vivo situation, the natural products appear to interfere with NHEJ repair and warrant further investigation.
Université de Mons (UMONS), Department of Therapeutic Chemistry and Pharmacognosy, Institute of Health Sciences and Technology, Bât. Mendeleiev, Av. Maistriau, 7000 Mons, Belgium.
Catherine
C
Charles
Université de Mons (UMONS), Department of Therapeutic Chemistry and Pharmacognosy, Institute of Health Sciences and Technology, Bât. Mendeleiev, Av. Maistriau, 7000 Mons, Belgium.
Amandine
A
Nachtergael
Université de Ouagadougou, Laboratory of Pharmacology and Toxicology, Health Sciences Faculty, 03 BP 7021 Ouagadougou 03, Burkina Faso.
Moustapha
M
Ouedraogo
Université de Mons (UMONS), Laboratory of Molecular Biology, Institute of Health Sciences and Technology, Av. du Champ de Mars, 7000 Mons, Belgium.
Alexandra
A
Belayew
Université de Mons (UMONS), Department of Therapeutic Chemistry and Pharmacognosy, Institute of Health Sciences and Technology, Bât. Mendeleiev, Av. Maistriau, 7000 Mons, Belgium; Université Libre de Bruxelles (ULB), Laboratory of Pharmacognosy, Bromatology and Human Nutrition, Faculty of Pharmacy, CP 205-9, B-1050 Brussels, Belgium. Electronic address: pierre.duez@umons.ac.be.
Pierre
P
Duez
D016587:Antimutagenic Agents / Q000494:pharmacology*; D002460:Cell Line; D059766:DNA End-Joining Repair / Q000187:drug effects*; D004260:DNA Repair / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D010957:Plasmids / Q000235:genetics / Q000378:metabolism*
D016587:Antimutagenic Agents; D005419:Flavonoids
Arbutin; Chemoprevention; Curcumin; Flavonoids; Indole-3-carbinol; Microelectrophoresis