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Increased DNA Damage and Decreased DNA Repair Following Poly(ADP‐ribose) Glycohydrolase Inhibition and Chemotherapy
Author(s) -
KOH DAVID W,
Zhou Yiran,
Feng Xiaoxing,
Garcia Katherine D.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.878.3
Subject(s) - dna damage , dna repair , chromatin , dna , microbiology and biotechnology , comet assay , biology , histone , poly adp ribose polymerase , chemistry , biochemistry , polymerase
The synthesis of poly(ADP‐ribose) (PAR) is an immediate response to DNA damage. We reported previously that the failure to degrade PAR by inhibiting PAR glycohydrolase (PARG) leads to hypersensitivity to DNA damage. OBJECTIVE To investigate the ability of PARG inhibition to increase the effectiveness of DNA‐damaging agents. METHODS Utilizing PARG null trophoblast stem cells, chromatin structure was analyzed by the detection of PAR‐modified nuclear proteins, DNA damage and repair were analyzed by Comet assay after treatment with N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG), and cell death was measured by FACS. RESULTS PARG null cells displayed high levels of PAR‐modified histones, suggesting chromatin structural change. Low‐dose MNNG led to high levels of DNA damage, which suggests greater DNA access due to PARG inhibition. Further, this DNA damage was not repaired after 12 hr, which suggests unrepairable levels of DNA damage or decreased DNA repair. Finally, treatment of PARG null cells with current chemotherapeutic agents led to increased cell death. CONCLUSION The results show that PARG inhibition enhances the efficacy of DNA‐damaging agents by inducing greater amounts of DNA damage and decreasing DNA repair. Therefore, targeting PARG is expected to enhance the effectiveness of DNA‐modifying anti‐cancer agents. Support was provided by ASPET, ACS, and the PhRMA Foundation.