Reduction of ornithine decarboxylase antizyme (ODC-Az) level in the 7,12-dimethylbenz(a)anthracene-induced hamster buccal pouch carcinogenesis model.
Ornithine decarboxylase (ODC) activity is elevated in and necessary for oral carcinogenesis, but the mechanism for its deregulation is unclear. Using subtractive hybridization, a 1029 bp full-length cDNA encoding a 222 amino acid open reading frame has been isolated from normal hamster oral keratinocytes. The hamster cDNA is homologous to the human, mouse and rat ornithine decarboxylase antizyme gene (ODC-Az). The hamster ODC-Az gene demonstrated a restriction fragment length polymorphism (RFLP) upon Southern blot analysis comparing normal and tumor hamster genomic DNA. Northern blot analysis revealed that normal hamster oral keratinocytes express readily detectable level of ODC-Az mRNA. Malignant oral keratinocytes demonstrate reduced expression of the ODC-Az mRNA. In contrast, malignant hamster oral keratinocytes have elevated ODC mRNA levels and lengthened ODC protein half-life when compared to the normal counterparts. This was corroborated by direct measurement of ODC enzymatic activity. These data support the hypothesis that the reduced and/or loss of expression and function of the ODC-Az gene is an important event for the early de-regulation of cellular proliferation during oral tumor development.
Tsuji
T
T
Department of Oral Medicine and Diagnostic Sciences, Harvard School of Dental Medicine, Boston, Massachusetts 02115, USA.
Todd
R
R
Meyer
C
C
McBride
J
J
Liao
P H
PH
Huang
M F
MF
Chou
M Y
MY
Donoff
R B
RB
Wong
D T
DT
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity*; D000818:Animals; D003001:Cloning, Molecular; D006224:Cricetinae; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors; D015972:Gene Expression Regulation, Neoplastic; D015603:Keratinocytes / Q000201:enzymology / Q000473:pathology; D008969:Molecular Sequence Data; D009062:Mouth Neoplasms / Q000139:chemically induced*; D009955:Ornithine Decarboxylase / Q000235:genetics; D065108:Ornithine Decarboxylase Inhibitors; D011506:Proteins / Q000032:analysis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D012334:RNA, Neoplasm / Q000032:analysis; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014407:Tumor Cells, Cultured / Q000201:enzymology
D004791:Enzyme Inhibitors; D065108:Ornithine Decarboxylase Inhibitors; D011506:Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; C031017:ornithine decarboxylase antizyme; D015127:9,10-Dimethyl-1,2-benzanthracene; D009955:Ornithine Decarboxylase