Carcinogen-induced amplification of SV40 DNA inserted at 9q12-21.1 associated with chromosome breakage, deletions, and translocations in human uroepithelial cell transformation in vitro.
The fate of integrated SV40 viral genome in SV40-immortalized human uroepithelial cells (SV-HUC) during multistep chemical transformation in vitro was studied. We previously reported that exposure of SV-HUC at passage (P) 15 to the chemical carcinogens 3-methylcholanthrene (MCA), 4-aminobiphenyl (ABP), or the N-hydroxy metabolites of ABP causes tumorigenic transformation and/or neoplastic progression. We report now that these same chemical carcinogens induce amplification of SV40 DNA in SV-HUC. We used fluorescence in situ hybridization (FISH) to show that this amplification occurs at the SV40 integration site, which was mapped near a common fragile site at 9q12-21.1 on the der(9)t(8;9) chromosome that is present in all SV-HUC at the earliest passage studied. Karyotypic analysis, along with FISH, also revealed that all carcinogen-induced tumors (T-SV-HUCs) had breaks at 9q12-21.1, deletions of 9q12-21.1-->pter, and new derivative chromosomes containing SV40 in the segment 9q12-21.1-->9q34::8q22-->8qter. Southern blot analysis, along with FISH, confirmed SV40 genome rearrangements in T-SV-HUCs. In contrast, no 9q12-21.1 breaks were observed in control SV-HUC. Thus, these results associate 9q12-21.1-->pter alterations with HUC tumorigenic transformation. In addition, these results indicate for the first time that (carcinogen-induced) amplification of chromosome-integrated viral genes may create sites that are prone to breakage, deletions, and translocations. These results suggest a new mechanism by which chemical carcinogens in synergy with a DNA tumor virus could initiate a cascade of events that contribute to the genomic instability associated with tumorigenesis.
Kao
C
C
University of Wisconsin Comprehensive Clinical Cancer Center, Department of Human Oncology, Madison 53792.
Wu
S Q
SQ
DeVries
S
S
Reznikoff
W S
WS
Waldman
F M
FM
Reznikoff
C A
CA
D002273:Carcinogens / Q000494:pharmacology*; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D002869:Chromosome Aberrations; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D002906:Chromosomes, Human, 6-12 and X; D002899:Chromosomes, Human, Pair 9; D004279:DNA, Viral / Q000032:analysis; D005784:Gene Amplification / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D015321:Gene Rearrangement; D005814:Genes, Viral / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D015336:Molecular Probe Techniques; D013539:Simian virus 40 / Q000187:drug effects / Q000235:genetics*; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured; D016662:Virus Integration
D002273:Carcinogens; D004279:DNA, Viral