Different alterations of cytochrome P450 3A4 isoform and its gene expression in livers of patients with chronic liver diseases

Abstract

Aim: To determine whether parenchymal cells or hepatic cytochrome P450 protein was changed in chronic liver diseases, and to compare the difference of CYP3A4 enzyme and its gene expression between patients with hepatic cirrhosis and obstructive jaundice, and to investigate the pharmacologic significance behind this difference.

Methods: Liver samples were obtained from patients undergoing hepatic surgery with hepatic cirrhosis (n=6) and obstructive jaundice (n=6) and hepatic angeioma (controls, n=6). CYP3A4 activity and protein were determined by Nash and western blotting using specific polychonal antibody, respectively. Total hepatic RNA was extracted and CYP3A4cDNA probe was prepared according the method of random primer marking, and difference of cyp3a4 expression was compared among those patients by Northern blotting.

Results: Compared to control group, the CYP3A4 activity and protein in liver tissue among patients with cirrhosis were evidently reduced. (P<0.01) Northern blot showed the same change in its mRNA levels. In contrast, the isoenzyme and its gene expression were not changed among patients with obstructive jaundice.

Conclusion: Hepatic levels of P450s and its CYP3A4 isoform activity were selectively changed in different chronic liver diseases. CYP3A4 isoenzyme and its activity declined among patients with hepatic cirrhosis as expression of cyp3a4 gene was significantly reduced. Liver's ability to eliminate many clinical therapeutic drug substrates would decline consequently. These findings may have practical implications for the use of drugs in patients with cirrhosis and emphasize the need to understand the metabolic fate of therapeutic compounds. Elucidation of the reasons for these different changes in hepatic CYP3A4 may provide insight into more fundamental aspects and mechanisms of imparied liver function.

Figure 1

Western Blot analysis of CYP3A4 isoform protein among three groups, compared with controls (tagged by “C_1-6”) . CYP3A4 protein content in liver tissues among patients with cirrhosis (tagged by “H_1-6”) reduced. but in obstructive jaundice (tagged by “O_1-6”) , There was no change of CYP3A4 protein expression.

Figure 2

The results of substratum electrophoresis in pBS M13 CYP3A4 plasmid. Lane 1: pBS M13 CYP3A4 (Hind III), Lane 2: Marker (1kb DNA ladder).

Figure 3

Northern blot analysis mRNA expression of CYP3A4 isoform in liver tissues among three groups. Total RNA was isolated without degradation and each bottom panel showed an equal amount of total RNA loading as indicated in 28 s and 18 s rRNA. CYP3A4mRNA was expressed well in human liver tissues, of patients with cirrhosis (tagged by “H”) , CYP3 A4mRNA was reduced significantly compared with control (tagged by “C”) , but no decline happened in jaundice group (tagged by “O”) .