Yonsei Med J.  1992 Sep;33(3):240-248. 10.3349/ymj.1992.33.3.240.

Expressions of c-fos and c-myc genes during 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB)-induced rat hepatocarcinoma

• Chai KJ
• Kim JS
• Lee HK

• KMID: 1120235
• DOI: http://doi.org/10.3349/ymj.1992.33.3.240

Abstract

We investigated the expression of the growth-related nuclear proto-oncogenes, c-fos and c-myc, in early preneoplastic regions and tumor nodules of 3'-MeDAB induced rat hepatocarcinoma. To amplify the levels of these transcripts, we gave cycloheximide (100 mg/kg B.W. i.p.) to each group of rats. The elevated levels of the 2.2 kb c-fos and 2.4 kb c-myc transcripts appeared as early as the 2nd week after feeding on the 3'-MeDAB diet and lasted through the 4th; 6th weeks and tumor. Southern blot analysis indicated that gross amplification or rearrangements were not observed in DNA of the preneoplastic livers and hepatoma nodules. We also measured the rate of the incorporation of [3H] thymidine into hepatic DNA in order to monitor the rate of cell proliferation occurring at the early preneoplastic periods. We have found that the rate of [3H] thymidine incorporation corresponds to the elevated levels of c-fos and c-myc transcripts in the precancerous stages. This finding suggests that the elevated expressions of c-fos and c-myc may result from the continuous cell proliferative stimuli generated in the carcinogen altered cells, which is essential to the initiation and promotion of chemical hepatocarcinogenesis.

Keyword

3'-methyl-4-dimethylaminoazobenzene(3'-MeDAB); c-fos; c-myc; Preneoplastic livers; cell proliferation

MeSH Terms

Animal
Blotting, Southern
DNA/biosynthesis
Female
*Gene Expression
*Genes, fos
*Genes, myc
Liver Neoplasms, Experimental/chemically induced/*genetics
Methyldimethylaminoazobenzene/*toxicity
Precancerous Conditions/chemically induced/*genetics
Rats
Rats, Sprague-Dawley
Support, Non-U.S. Gov't