title: Carcinogenic effects of MGP-7 and B[a]P on the hamster cheek pouch.
abstract: This study was performed to examine the carcinogenic effects of benzo[a]pyrene (B[a]P) and manufactured gas plant (MGP) residues on the hamster cheek pouch (HCP). Syrian hamsters were treated topically with a suspension of 2%, 10%, or 20% B[a]P or 50% or 100% MGP-7 (a mixture of residues from 7 MGP sites) in mineral oil for eight (short-term study) and sixteen, twenty, twenty-eight, and thirty-two weeks (long-term study). The short-term study showed that B[a]P induced p53 protein accumulation, indicative of genotoxic damage, as well as increased cell proliferation, hyperplasia, and inflammation, which is usually associated with promotional activity. In contrast, the MGP-7 presented only marginal p53 accumulation and induction of BrdU incorporation. In the long-term experiments, animals treated with 2% and 10% of B[a]P continued to show p53 protein accumulation as well as hyperplasia and increased cell proliferation and inflammation. By thirty weeks, all the animals treated with B[a]P had a 100% incidence of squamous cell carcinoma (SCC). Animals treated with 50% and 100% MGP-7 showed only weak hyperplasia and a low proliferation rate and accumulation of p53 protein through thirty-two weeks. Benzo[a]pyrene was highly carcinogenic when used at adequate doses. Manufactured gas plant residue, however, was not carcinogenic in this model.
authors.affiliation: The University of Texas M.D. Anderson Cancer Center, Department of Carcinogenesis, Smithville, TX 78957, USA.
authors.forename: Jimi Lynn
authors.initials: JL
authors.lastname: Brandon
authors.forename: Claudio J
authors.initials: CJ
authors.lastname: Conti
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Goldstein
authors.forename: John
authors.initials: J
authors.lastname: DiGiovanni
authors.forename: Irma B
authors.initials: IB
authors.lastname: Gimenez-Conti
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D015197:Carcinogenicity Tests / Q000379:methods; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D002610:Cheek / Q000473:pathology; D003033:Coal Tar / Q000633:toxicity*; D006224:Cricetinae; D004195:Disease Models, Animal; D006651:Histocytochemistry; D007220:Industrial Waste; D008297:Male; D008647:Mesocricetus; D009062:Mouth Neoplasms / Q000139:chemically induced* / Q000473:pathology; D012107:Research Design
chemical_list: D007220:Industrial Waste; D001564:Benzo(a)pyrene; D003033:Coal Tar