Mutagenicity of N-hydroxy-4-aminobiphenyl in human TP53 knock-in (Hupki) mouse embryo fibroblasts

TY - JOUR

T1 - Mutagenicity of N-hydroxy-4-aminobiphenyl in human TP53 knock-in (Hupki) mouse embryo fibroblasts

AU - Hölzl-Armstrong, Lisa

AU - Kucab, Jill E.

AU - Zwart, Edwin P.

AU - Luijten, Mirjam

AU - Phillips, David H.

AU - Arlt, Volker M.

N1 - Funding Information: Lisa H?lzl-Armstrong was supported by a PhD studentship from the MRC Centre for Environment and Health. Work at King's College London was supported by the Cancer Research UK Grand Challenge Award ?Mutographs of Cancer? (grant C98/A24032). Publisher Copyright: © 2021 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals LLC on behalf of Environmental Mutagen Society. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/4

Y1 - 2021/4

N2 - TP53 harbors somatic mutations in more than half of human tumors with some showing characteristic mutation spectra that have been linked to environmental exposures. In bladder cancer, a unique distribution of mutations amongst several codons of TP53 has been hypothesized to be caused by environmental carcinogens including 4-aminobiphenyl (4-ABP). 4-ABP undergoes metabolic activation to N-hydroxy-4-aminobiphenyl (N-OH-4-ABP) and forms pre-mutagenic adducts in DNA, of which N-(deoxyguanosin-8-yl)-4-ABP (dG-C8-4-ABP) is the major one. Human TP53 knock-in mouse embryo fibroblasts (HUFs) are a useful model to study the influence of environmental carcinogens on TP53-mutagenesis. By performing the HUF immortalization assay (HIMA) TP53-mutant HUFs are generated and mutations can be identified by sequencing. Here we studied the induction of mutations in human TP53 after treatment of primary HUFs with N-OH-4-ABP. In addition, mutagenicity in the bacterial lacZ reporter gene and the formation of dG-C8-4-ABP, measured by 32P-postlabelling analysis, were determined in N-OH-4-ABP-treated primary HUFs. A total of 6% TP53-mutants were identified after treatment with 40 μM N-OH-4-ABP for 24 hr (n = 150) with G>C/C>G transversion being the main mutation type. The mutation spectrum found in the TP53 gene of immortalized N-OH-4-ABP-treated HUFs was unlike the one found in human bladder cancer. DNA adduct formation (~40 adducts/108 nucleotides) was detected after 24 hr treatment with 40 μM N-OH-4-ABP, but lacZ mutagenicity was not observed. Adduct levels decreased substantially (sixfold) after a 24 hr recovery period indicating that primary HUFs can efficiently repair the dG-C8-4-ABP adduct possibly before mutations are fixed. In conclusion, the observed difference in the N-OH-4-ABP-induced TP53 mutation spectrum to that observed in human bladder tumors do not support a role of 4-ABP in human bladder cancer development.

AB - TP53 harbors somatic mutations in more than half of human tumors with some showing characteristic mutation spectra that have been linked to environmental exposures. In bladder cancer, a unique distribution of mutations amongst several codons of TP53 has been hypothesized to be caused by environmental carcinogens including 4-aminobiphenyl (4-ABP). 4-ABP undergoes metabolic activation to N-hydroxy-4-aminobiphenyl (N-OH-4-ABP) and forms pre-mutagenic adducts in DNA, of which N-(deoxyguanosin-8-yl)-4-ABP (dG-C8-4-ABP) is the major one. Human TP53 knock-in mouse embryo fibroblasts (HUFs) are a useful model to study the influence of environmental carcinogens on TP53-mutagenesis. By performing the HUF immortalization assay (HIMA) TP53-mutant HUFs are generated and mutations can be identified by sequencing. Here we studied the induction of mutations in human TP53 after treatment of primary HUFs with N-OH-4-ABP. In addition, mutagenicity in the bacterial lacZ reporter gene and the formation of dG-C8-4-ABP, measured by 32P-postlabelling analysis, were determined in N-OH-4-ABP-treated primary HUFs. A total of 6% TP53-mutants were identified after treatment with 40 μM N-OH-4-ABP for 24 hr (n = 150) with G>C/C>G transversion being the main mutation type. The mutation spectrum found in the TP53 gene of immortalized N-OH-4-ABP-treated HUFs was unlike the one found in human bladder cancer. DNA adduct formation (~40 adducts/108 nucleotides) was detected after 24 hr treatment with 40 μM N-OH-4-ABP, but lacZ mutagenicity was not observed. Adduct levels decreased substantially (sixfold) after a 24 hr recovery period indicating that primary HUFs can efficiently repair the dG-C8-4-ABP adduct possibly before mutations are fixed. In conclusion, the observed difference in the N-OH-4-ABP-induced TP53 mutation spectrum to that observed in human bladder tumors do not support a role of 4-ABP in human bladder cancer development.

KW - 4-aminobiphenyl

KW - bladder carcinogen

KW - DNA adducts

KW - mutation

KW - TP53

UR - http://www.scopus.com/inward/record.url?scp=85102466358&partnerID=8YFLogxK

U2 - 10.1002/em.22429

DO - 10.1002/em.22429

M3 - Article

C2 - 33620775

AN - SCOPUS:85102466358

SN - 0893-6692

VL - 62

SP - 252

EP - 264

JO - Environmental and Molecular Mutagenesis

JF - Environmental and Molecular Mutagenesis

IS - 4

ER -