title: Site-specific mutagenesis in human cells by bulky exocyclic amino-substituted guanine and adenine derivatives.
abstract: OBJECTIVE
  7-Bromomethylbenz[a]anthracene is a well-known mutagen and carcinogen. The aim of this study is to determine the mutagenic potency of its two major DNA adducts [N(2)-(benz[a]anthracen-7-ylmethyl)-2'-deoxyguanosine (b[a]a(2)G) and N(6)-(benz[a]anthracen-7-ylmethyl)-2'-deoxyadenosine (b[a]a(6)A)] and the simpler benzylated analogs [N(2)-benzyl-2'-deoxyguanosine (bn(2)G) and N(6)-benzyl-2'-deoxyadenosine (bn(6)A)] in Ad293 human cells and to compare to their mutagenicity in human cells and E. coli.
  
  
  METHODS
  The shuttle vector pGP50 is capable of replicating in E. coli and human cells. Modified nucleotides were positioned in the plasmid pGP50 in a manner similar to pGP10 as described (8). Adenovirus transformed human embryonic kidney cells (line 293) were transfected with a shuttle vector containing an adduct. Two days later, the plasmids were recovered and treated with DpnI to remove unreplicated DNA. DH10B E. coli were transformed with the plasmids. Bacteria were cultured with the media containing X-gal, IPTG and ampicillin. Bacteria transformed by the plasmid with the adduct-induced mutation in the initiation codon of lacZ' form white colonies whereas bacteria transformed by the plasmid without mutation form blue colonies.
  
  
  RESULTS
  In the human cell site-specific mutagenesis system, bn(2)G exhibited weak mutagenicity and bn(6)A was not mutagenic, although b[a]a(2)G or b[a]a(6)A produced 8% and 7% mutant colonies, respectively. At the site of the adduct, b[a]a(2)G induced the G-->T transversion mutation while b[a]a(6)A produced the A-->G transition mutation.
  
  
  CONCLUSIONS
  These data indicate that bulkier b[a]a(2)G and b[a]a(6)A exhibit significantly greater mutagenicity in human cells than in E. coli.
authors.affiliation: Department of Clinical Pathology, and Bioindustry and Technology Research Institute, Kwangju Health College, Gwangju, Korea. kmoon@www.kjhc.ac.kr
authors.forename: Ki-Young
authors.initials: KY
authors.lastname: Moon
references.citation: Chem Res Toxicol. 1988 Jan-Feb;1(1):1-18
references.pmid: 2979705
references.citation: Proc Natl Acad Sci U S A. 1994 Dec 6;91(25):11899-903
references.pmid: 7991554
references.citation: Biochemistry. 1991 Dec 17;30(50):11700-6
references.pmid: 1751489
references.citation: Carcinogenesis. 1997 Aug;18(8):1609-15
references.pmid: 9276637
references.citation: J Gen Virol. 1977 Jul;36(1):59-74
references.pmid: 886304
references.citation: Carcinogenesis. 1993 Mar;14(3):373-83
references.pmid: 8453713
references.citation: Mutat Res. 2000 Feb 16;465(1-2):39-44
references.pmid: 10708967
references.citation: Eur J Cancer (1965). 1971 Oct;7(5):473-6
references.pmid: 5159876
references.citation: Biochemistry. 1999 Jan 19;38(3):1144-52
references.pmid: 9894012
references.citation: Arch Pharm Res. 2000 Apr;23(2):139-46
references.pmid: 10836739
references.citation: Carcinogenesis. 1996 Feb;17(2):283-8
references.pmid: 8625451
references.citation: Eur J Cancer (1965). 1970 Oct;6(5):417-23
references.pmid: 5500708
references.citation: IARC Sci Publ. 1994;(125):25-36
references.pmid: 7806317
references.citation: Chem Res Toxicol. 1990 Jul-Aug;3(4):292-5
references.pmid: 2133074
references.citation: Biochemistry. 1994 Aug 9;33(31):9169-77
references.pmid: 8049220
references.citation: Cancer Res Treat. 2003 Feb;35(1):75-80
references.pmid: 26680918
references.citation: Biochemistry. 1971 Nov;10(23):4323-30
references.pmid: 5126943
references.citation: Chem Res Toxicol. 2002 Feb;15(2):165-9
references.pmid: 11849042
references.citation: Biochemistry. 1996 Dec 24;35(51):16646-51
references.pmid: 8988000
references.citation: Biochemistry. 1996 Sep 3;35(35):11487-92
references.pmid: 8784204
references.citation: Chem Res Toxicol. 1988 Nov-Dec;1(6):391-7
references.pmid: 2979756
references.citation: Carcinogenesis. 1998 Mar;19(3):457-61
references.pmid: 9525280
references.citation: Biochemistry. 1973 Mar 13;12(6):1202-7
references.pmid: 4734662
references.citation: Biochemistry. 1995 Jul 11;34(27):8924-30
references.pmid: 7612634