title: Morphological changes of the nucleolar organizer regions induced by 7,12-dimethylbenz[a]anthracene in the hamster cheek pouch.
abstract: The staining of nucleolar organizer regions (NORs), which equate to rDNA transcription, was applied to chemically induced-lesions of the hamster cheek pouch. The cheek pouches of 16 male golden Syrian hamsters were treated three times a week with 0.5% 7,12-dimethylbenz[a]anthracene (DMBA) in mineral oil for 16 weeks. The percentage of gathered-type NORs with high activity nucleoli increased in the pouch epithelium during DMBA treatment and reached the highest values in malignant tumors. The percentage of dispersed-type NORs also increased in the malignant lesions. However, the absolute number of NORs was not affected by DMBA treatment. These results suggest that DMBA induces modification of NOR activity at the early stages of carcinogenesis and shows the potential of this model for studying NOR alterations in neoplasia.
authors.affiliation: University of Texas M. D. Anderson Cancer Center, Science Park Research Division, Smithville.
authors.forename: N
authors.initials: N
authors.lastname: Yoshimi
authors.forename: I B
authors.initials: IB
authors.lastname: Gimenez-Conti
authors.forename: T J
authors.initials: TJ
authors.lastname: Slaga
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000494:pharmacology*; D000818:Animals; D001585:Benzoyl Peroxide / Q000494:pharmacology; D002610:Cheek; D006224:Cricetinae; D006965:Hyperplasia; D008297:Male; D008647:Mesocricetus; D009061:Mouth Mucosa / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000473:pathology; D009697:Nucleolus Organizer Region / Q000187:drug effects* / Q000648:ultrastructure; D011230:Precancerous Conditions / Q000139:chemically induced / Q000473:pathology; D013194:Staining and Labeling; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene; D013755:Tetradecanoylphorbol Acetate; D001585:Benzoyl Peroxide