Tumor-associated APE1 variant exhibits reduced complementation efficiency but does not promote cancer cell phenotypes.
Base excision repair (BER) is the major pathway for coping with most forms of endogenous DNA damage, and defects in the process have been associated with carcinogenesis. Apurinic/apyrimidinic endonuclease 1 (APE1) is a central participant in BER, functioning as a critical endonuclease in the processing of noncoding abasic sites in DNA. Evidence has suggested that APE1 missense mutants, as well as altered expression or localization of the protein, can contribute to disease manifestation. We report herein that the tumor-associated APE1 variant, R237C, shows reduced complementation efficiency of the methyl methanesulfonate hypersensitivity and impaired cell growth exhibited by APE1-deficient mouse embryonic fibroblasts. Overexpression of wild-type APE1 or the R237C variant in the nontransformed C127I mouse cell line had no effect on proliferation, cell cycle status, steady-state DNA damage levels, mitochondrial function, or cellular transformation. A human cell line heterozygous for an APE1 knockout allele had lower levels of endogenous APE1, increased cellular sensitivity to DNA-damaging agents, impaired proliferation with time, and a distinct global gene expression pattern consistent with a stress phenotype. Our results indicate that: (i) the tumor-associated R237C variant is a possible susceptibility factor, but not likely a driver of cancer cell phenotypes, (ii) overexpression of APE1 does not readily promote cellular transformation, and (iii) haploinsufficiency at the APE1 locus can have profound cellular consequences, consistent with BER playing a critical role in proliferating cells. Environ. Mol. Mutagen. 58:84-98, 2017. © 2017 Wiley Periodicals, Inc.
Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, Maryland.
Jennifer L
JL
Illuzzi
Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, Maryland.
Daniel R
DR
McNeill
Laboratory of Genetics, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, Maryland.
Paul
P
Bastian
Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, Maryland.
Boris
B
Brenerman
Flow Cytometry Unit, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, Maryland.
Robert
R
Wersto
Genetics Department, St. Jude Children's Research Hospital, Memphis, Tennessee.
Helen R
HR
Russell
Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland.
Fred
F
Bunz
Genetics Department, St. Jude Children's Research Hospital, Memphis, Tennessee.
Peter J
PJ
McKinnon
Laboratory of Genetics, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, Maryland.
Kevin G
KG
Becker
Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, Maryland.
David M
DM
Wilson
D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D004249:DNA Damage / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000235:genetics* / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D045325:HCT116 Cells; D006801:Humans; D008698:Mesylates / Q000494:pharmacology; D008822:Mice, Transgenic; D013629:Tamoxifen / Q000494:pharmacology
D008698:Mesylates; D013629:Tamoxifen; C045880:methanesulfonic acid; C085108:APEX1 protein, human; C486216:Apex1 protein, mouse; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase
APE1/APEX1; base excision repair; cancer susceptibility; haploinsufficiency; transformation