Neoplastic transformation and DNA-binding of 4,4'-methylenebis(2-chloroaniline) in SV40-immortalized human uroepithelial cell lines.

Abstract

The tumorigenic transformation of certain occupationally significant chemicals, such as N-hydroxy-4-4'-methylenebis[2-chloroaniline] (N-OH-MOCA), N-hydroxy-ortho-toluidine (N-OH-OT), 2-phenyl-1,4-benzoquinone (PBQ) and N-hydroxy-4-aminobiphenyl (N-OH-ABP) were tested in vitro using the well established SV40-immortalized human uroepithelial cell line SV-HUC.PC. SV-HUC cells were exposed in vitro to varying concentrations of N-OH-MOCA, N-OH-OT, N-OH-ABP and PBQ that caused approximately 25% and 75% cytotoxicity. The carcinogen treated cells were propagated in culture for about six weeks and subsequently injected subcutaneously into athymic nude mice. Two of the fourteen different groups of SV-HUC.PC treated with different concentrations of N-OH-MOCA, and one of the three groups exposed to N-OH-ABP, formed carcinomas in athymic nude mice. 32P-postlabeling analyses of DNA isolated from SV-HUC.PC after exposure to N-OH-MOCA revealed one major and one minor adduct. The major adduct has been identified as the N-(deoxyadenosin-3',5'-bisphospho-8-yl)-4-amino-3-chlorob enz yl alcohol (pdAp-ACBA) and the minor adduct as N-(deoxyadenosin-3',5'-bisphospho-8-yl)-4-amino-3-chlorot oluene (pdApACT). Furthermore, SV-HUC.PC cytosols catalyzed the binding of N-OH-MOCA to DNA, in the presence of acetyl-CoA, to yield similar adducts. The same adducts were also formed by chemical interaction of N-OH-MOCA with calf thymus DNA, suggesting that the aryl nitrenium ion may be the ultimate reactive species responsible for DNA binding. The tumorigenic activity of N-OH-MOCA in this highly relevant in vitro transformation model, coupled with the findings that SV-HUC.PC cells formed DNA-adducts in vitro and contained enzyme systems that activated N-OH-MOCA to reactive electrophilic species that bound to DNA, strongly suggest that MOCA could be a human bladder carcinogen. These findings are consistent with the International Agency for Research on Cancer's classification of MOCA as a probable human carcinogen.

• Authors: S Swaminathan, S M Frederickson, J F Hatcher, C A Reznikoff, M A Butler, K L Cheever, R E Savage Jr
• Journal: Carcinogenesis (Carcinogenesis) Vol. 17 Issue 4 Pg. 857-64 (Apr 1996) ISSN: 0143-3334 [Print] England
• PMID: 8625501 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Carcinogens
• Methylenebis(chloroaniline)
• DNA

Topics

• Animals
• Binding Sites
• Carcinogens (metabolism, toxicity)
• Cell Line, Transformed
• Cell Transformation, Neoplastic
• DNA (drug effects, metabolism)
• Female
• Humans
• Methylenebis(chloroaniline) (metabolism, toxicity)
• Mice
• Mice, Nude
• Simian virus 40 (physiology)
• Urinary Bladder Neoplasms (chemically induced)
• Urogenital System (cytology, drug effects)