TY - JOUR
T1 - Evidence that error-prone DNA repair converts dibenzo[a,l]pyrene-induced depurinating lesions into mutations
T2 - Formation, clonal proliferation and regression of initiated cells carrying H-ras oncogene mutations in early preneoplasia
AU - Chakravarti, Dhrubajyoti
AU - Mailander, Paula C.
AU - Cavalieri, Ercole L.
AU - Rogan, Eleanor G.
N1 - Funding Information:
We gratefully acknowledge the efforts of Dr. Kai-Ming Li in preparing solutions of DB[a,l]P and anti-DB[a,l]PDE for these studies and Dr. Robert Lahue for very helpful discussions. This research was supported by US Public Health Service grant P01 CA49210 and NRSA fellowship F32 CA68761 (DC), from the National Cancer Institute. Core support at the Eppley Institute was funded by NCI Laboratory Cancer Research Support (Core) grant CA 36727.
PY - 2000/11/30
Y1 - 2000/11/30
N2 - Initiation of skin tumors in mice is associated with the formation of oncogenic mutations in the H-ras gene. Mice treated on the dorsal skin with the potent polycyclic aromatic hydrocarbon (PAH) carcinogen dibenzo[a,l]pyrene (DB[a,l]P) form papillomas carrying the H-ras codon 61 (CAA to CTA) mutations. These mutations are induced in early preneoplastic skin within 1 day after DB[a,l]P treatment (Oncogene 16 (1998) 3203-3210) and appear to be related to DB[a,l]P-Ade-depurinating adducts (Proc. Natl. Acad. Sci. U. S. A. 92 (1995) 10422-10426). The rapid kinetics of mutation induction suggests that abasic sites generated from base depurination may undergo error-prone excision repair in pre-S-phase cells to induce these mutations. Analysis of mutations in the H-ras exon 1 and 2 region in DB[a,l]P-treated early preneoplastic skin indicated great changes in mutation spectra in the preneoplastic period. The initial spectra contained abundant A→G mutations, which frequently occurred 3' to a putative conserved sequence (TGN-doublet). These mutations appeared to be induced initially as mismatched (G.T) heteroduplexes and then converted into double-stranded mutations by one round of replication. Unlike the A→G mutations found in DB[a,l]P-treated skin (which forms 99% depurinating adducts), A→G mutations found in anti-DB[a,l]P-diol epoxide-treated skin (forms 97% stable adducts) did not appear to be G.T heteroduplexes. These results, therefore, suggest that under these conditions, the repair errors occurred only from abasic sites but not from stable adducts. Initiated cells carrying specific oncogenic mutations, formed presumably by misrepair, underwent rapid clonal expansion and regression (transient clonoplasia). The multiplication of initiated stem cells during transient clonoplasia may be a factor determining the tumor-initiating potential of some PAH carcinogens. Copyright (C) 2000 Elsevier Science B.V.
AB - Initiation of skin tumors in mice is associated with the formation of oncogenic mutations in the H-ras gene. Mice treated on the dorsal skin with the potent polycyclic aromatic hydrocarbon (PAH) carcinogen dibenzo[a,l]pyrene (DB[a,l]P) form papillomas carrying the H-ras codon 61 (CAA to CTA) mutations. These mutations are induced in early preneoplastic skin within 1 day after DB[a,l]P treatment (Oncogene 16 (1998) 3203-3210) and appear to be related to DB[a,l]P-Ade-depurinating adducts (Proc. Natl. Acad. Sci. U. S. A. 92 (1995) 10422-10426). The rapid kinetics of mutation induction suggests that abasic sites generated from base depurination may undergo error-prone excision repair in pre-S-phase cells to induce these mutations. Analysis of mutations in the H-ras exon 1 and 2 region in DB[a,l]P-treated early preneoplastic skin indicated great changes in mutation spectra in the preneoplastic period. The initial spectra contained abundant A→G mutations, which frequently occurred 3' to a putative conserved sequence (TGN-doublet). These mutations appeared to be induced initially as mismatched (G.T) heteroduplexes and then converted into double-stranded mutations by one round of replication. Unlike the A→G mutations found in DB[a,l]P-treated skin (which forms 99% depurinating adducts), A→G mutations found in anti-DB[a,l]P-diol epoxide-treated skin (forms 97% stable adducts) did not appear to be G.T heteroduplexes. These results, therefore, suggest that under these conditions, the repair errors occurred only from abasic sites but not from stable adducts. Initiated cells carrying specific oncogenic mutations, formed presumably by misrepair, underwent rapid clonal expansion and regression (transient clonoplasia). The multiplication of initiated stem cells during transient clonoplasia may be a factor determining the tumor-initiating potential of some PAH carcinogens. Copyright (C) 2000 Elsevier Science B.V.
KW - Anti-dibenzo[a,l]pyrene-diol epoxide
KW - DNA repair
KW - Dibenzo[a,l]pyrene
KW - H-ras mutation
KW - Mismatched heteroduplex
KW - SENCAR mouse
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U2 - 10.1016/S0027-5107(00)00102-0
DO - 10.1016/S0027-5107(00)00102-0
M3 - Article
C2 - 11087892
AN - SCOPUS:0034736284
SN - 0027-5107
VL - 456
SP - 17
EP - 32
JO - Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
JF - Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
IS - 1-2
ER -