Differences in the steady-state levels of c-fos, c-jun and c-myc messenger RNA during mitogen-induced liver growth and compensatory regeneration
✍ Scribed by Pierpaolo Coni; Gabriella Simbula; Alessandra Carcereri de Prati; Marta Menegazzi; Hisanori Suzuki; Dittakavi S. R. Sarma; Giovanna M. Ledda-Columbano; Amedeo Columbano
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 977 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0270-9139
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✦ Synopsis
The steady-state levels of c-fos, c-jun and c-myc messenger RNA were investigated in rat liver tissue after proliferative stimuli of different naturenamely, compensatory regeneration induced by partial hepatectomy or carbon tetrachloride administration-and direct hyperplasia induced by four different hepatomitogens: lead nitrate, ethylene dibromide, cyproterone acetate and nafenopin. We show here that whereas c-fos and c-jun expression increased soon after partial hepatectomy or carbon tetrachloride administration, an increased expression of c-jun in the absence of c-fos expression occurred during direct hyperplasia induced by lead nitrate and ethylene dibromide. When hyperplasia was induced by cyproterone acetate and nafenopin, the mitogenic response of the liver was not associated with an increased expression of c-jun or c-fos, despite the fact that the timing of the cell cycle was similar to that observed after partial hepatectomy. Finally, when c-myc expression was analyzed, it was found that proliferative conditions associated with an increased expression of this gene were characterized by an increased expression of c-jun. On the contrary, the hyperplasia induced by cyproterone acetate and nafenopin, which is characterized by a lack of increase in the expression of c-fos and c-jun, was also not associated with an increased c-myc expression. Similar results were obtained in these experiments with the mitogen nafenopin, a peroxisome proliferator. In fact, liver hyperplasia induced by this compound was not preceded or accompanied by an increased expression of c-fos and c-myc. This study suggests that depending on the nature of the proliferative stimulus, an increased expression of c-fos, c-jun and c-myc may not be necessary for in uiuo induction of liver cell prolifer-