Overexpression of p28/gankyrin in human hepatocellular carcinoma and its clinical significance

AIM:To investigate the expression of p28/gankyringene and its role in the carcinogenetic process of humanhepatocellular carcinoma(HCC).METHODS:64 specimens of HCC and para-carcinomatissues,22 specimens of non-tumor liver tissues(7normal,15 cirrhosis),10 specimens of normal humantissues and 5 hepatoma cell lines were studied for theexpression of p28/gankyrin by Northern blot.Theexpression of p28/gankyrin protein was detectedimmunohistochemically by using the specificpolyclonal antibody.RESULTS:Northern blot analysis indicated that theexpression of p28/gankyrin mRNA was intensivelydistributed in brain and heart,weakly in lung,spleenand muscle,undetectable in digestive system includingliver,pancreas,stomach,small and large intestines.p28/gankyrin mRNA was absent in normal liver,weaklydetected in liver cirrhosis and in 18 of 64 para-carcinoma liver tissues.In contrast,the expression ofp28/gankyrin mRNA was intensively detected in all 5hepatoma cell lines tested,markedly increased in 57of 64 and moderately increased in 5 of 64 HCC samples.In comparison with liver cirrhosis and para-carcinomaliver tissues,the average expression of p28/gankyrin mRNA in HCC was increased 3.6-(2.901±0.507 vs 0.805±0.252,P<0.05)and 5.2-fold(2.901±0.507 vs 0.557±0.203,p<0.01),respectively.Inaddition,p28/gankyrin mRNA expression level washigher in HCC with portal vein tumor thrombus andmicroscopic hepatic vein involvement(P=0.021 andP=0.047,respectively).The overexpression of p28/gankyrin protein in HCC was targeted in hepatic tumorcells,not in bile duct cells and other interstitial cells.CONCLUSION:Overexpression of p28/gankyrin in HCC plays an important role and contributes to themetastasis potential in the process of carcinogenesis.p28/gankyrin may become a specific biological tissuemarker for the pathological diagnosis of HCC.