Deviation of the Expression Level in Genes Related to the Cell Cycle Regulation System in Liver of the Tumor-bearing Mice

Abstract

The expression level of genes related to the cell cycle regulation system were determined by a quantitative RT-PCR (QPCR) method in liver of the tumor-bearing mice transplanted with methylcholanthrene-induced fibrosarcoma. Effect of bleomycin administration was also studied in these genes in both animal groups. Results indicate that the expression level in all of the p53, p21, p16, p35, and cdk5 genes 2-5 times increased in tumor-bearing mouse liver than those found in normal liver. But K-ras level showed no difference between the two groups. Bleomycin induced, in normal mouse liver, a 3 to 4 fold increase in p53 and p21 expression level, but it decreased p16 level to one half of the initial level. While the level for p35 twice increased but, one for cdk5 did not show any change after the administration. The level of K-ras gradually increased 96h after the administration. On the other hand, tumor-bearing mouse liver showed slight increase (1.6 fold) in p53 expression, but no obvious changes in p21 and p16 expression by the stimulation of bleomycin. The agent induced a slight decrease (20%) in p35, no change in cdk5, and gradual increase in K-ras gene expression. These results suggest that the expression level in the genes related to the cell cycle regulation is altered in tumor-bearing animal leading the enhanced ytanscription rate in a certain enzyme system.