SEMIQUANTITATION OF INTRAHEPATIC MDR3 MESSENGER-RNA LEVELS BY REVERSETRANSCRIPTION COMPETITIVE POLYMERASE CHAIN-REACTION

Background/Aims: Knockout mice lacking mdr2, the murine analogue of hu man MDR3 P-glycoprotein, develop chronic non-suppurative cholangitis, Recently, a deficiency in MDR3 messenger RNA (mRNA) has been reported in a subtype of progressive familial intrahepatic cholestasis. Thus, r educed MDR3 gene expression could be involved in human cholestatic liv er diseases, Methods: We developed a sensitive and specific reverse tr anscription/competitive polymerase chain reaction for the semiquantita tion of intrahepatic MDR3 mRNA levels, Using this method we determined the MDR3 mRNA levels in 52 liver specimens from primary biliary cirrh osis (n=11), chronic hepatitis B (n=5), chronic hepatitis C (n=14), no n-cholestatic cirrhosis (n=9) and controls (n=13), Results: MDR3 mRNA was detected in all specimens with some variation in mRNA levels, No s ignificant differences in the mean MDR3 mRNA levels were present betwe en the groups studied, including normal controls, Conclusions: We foun d no evidence for deficient or severely reduced intrahepatic MDR3 mRNA in primary biliary cirrhosis, nor were mRNA levels altered significan tly by virus-induced inflammation or by cirrhosis, The reverse transcr iption/competitive polymerase chain reaction assay described here shou ld be a useful tool in the semiquantitative study of MDR3 mRNA levels in small tissue specimens.