Liver hyperplasia is not necessarily associated with increased expression of c-fos and c-myc mRNA.

Abstract

Experiments were designed to investigate the expression of three cell-cycle-dependent proto-oncogenes in response to two different types of proliferative stimuli: compensatory cell proliferation after partial hepatectomy (PH) or CCl4 and liver hyperplasia induced by the mitogens ethylene dibromide (EDB) and cyproterone acetate (CPA). Steady-state levels of messenger RNAs for c-fos and c-myc were found to be elevated after PH or CCl4 with a maximum increase between 0.5 and 2 h for c-fos and at 2-3 h for c-myc and a rapid decline after 3 h. However, when liver cell proliferation was induced by mitogens, no increase in the expression of c-fos mRNA was observed with both EDB or CPA during the first 24 h. In addition, elevated expression of c-myc was found only in liver hyperplasia induced by EDB, but not with CPA. While the expression of c-myc mRNA and c-fos mRNA was different in the two types of proliferative stimuli, that of c-Ha-ras and c-Ki-ras was similar in all the experimental groups. Cell proliferation monitored by means of incorporation of labelled thymidine into DNA or mitotic index at 24 h following PH, EDB and CPA occurred at a similar extent in all the experimental groups. Our data indicate that the transient and sequential expression of cell-cycle-related genes may vary in response to proliferative stimuli of different nature and suggest that increased expression of cell-cycle-related genes may not be a necessary prerequisite for the entry of the cells into the cell cycle.

• Authors: P Coni, G Pichiri-Coni, G M Ledda-Columbano, P M Rao, S Rajalakshmi, D S Sarma, A Columbano
• Journal: Carcinogenesis (Carcinogenesis) Vol. 11 Issue 5 Pg. 835-9 (May 1990) ISSN: 0143-3334 [Print] England
• PMID: 2139817 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• RNA, Messenger
• Ethylene Dibromide
• Cyproterone Acetate
• Carbon Tetrachloride
• Cyproterone

Topics

• Animals
• Carbon Tetrachloride
• Cell Division (drug effects)
• Cyproterone (analogs & derivatives)
• Cyproterone Acetate
• Ethylene Dibromide
• Gene Expression (drug effects)
• Genes, ras (genetics)
• Hepatectomy
• Hyperplasia (chemically induced, genetics)
• Kinetics
• Liver (cytology, pathology)
• Male
• Proto-Oncogenes (genetics)
• RNA, Messenger (genetics)
• Rats
• Rats, Inbred Strains