[Study on the status of methylation of Rb gene promoter in human esophageal cancer and effect of NMBzA on Rb gene promoter in monkey esophageal epithelium].
OBJECTIVE
To elucidate the cause of abnormal Rb expression in esophageal cancer (EC).


METHODS
Methylation of Rb gene promoter was examined with restriction endonuclease digestion and PCR amplification.


RESULTS
Of the 30 specimens of EC, 10 (33.3%) had Msp I type hypermethylation of the Rb gene promoter while 12 (40.0%) had Hpa II type hypermethylation and one had both type of hypermethylation. In monkey fed with a single dose of NMBzA (30 mg/kg) on day 0, increasing hypermethylation of both types of the Rb gene promoter in esophageal epithelium was found on day 1, 2 and 3 but reduced on day 5.


CONCLUSIONS
These data suggest that abnoromal expression of Rb gene may be related to hypermethylation of its promoter and carcinogen NMBzA can induce such hypermethylation in monkey esophageal epithelium.
Cancer Institute, Chinese Academy of Medical Science, Peking Union Medical College, Beijing.
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Fong
D000818:Animals; D004128:Dimethylnitrosamine / Q000031:analogs & derivatives / Q000494:pharmacology; D004848:Epithelium; D004938:Esophageal Neoplasms / Q000235:genetics*; D004947:Esophagus; D005786:Gene Expression Regulation / Q000187:drug effects; D016161:Genes, Retinoblastoma; D006801:Humans; D008253:Macaca mulatta; D008745:Methylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects*
C014707:nitrosobenzylmethylamine; D004128:Dimethylnitrosamine