Analysis of Gene Expression in Primary Hepatocellular Carcinoma Using Differentially Displayed Reverse Transcriptase Polymerase Chain Reaction / 대한소화기학회지

BACKGROUND/AIMS: The investigation of a specific tumor marker for hepatocellular carcinoma (HCC) is needed to examine the carcinogenesis and to select the patients for treatment options. The aim of this study was to find the genes related to HCC. We also examined the expression level of these genes in cancer cell lines and tissue specimens. METHODS: Three pairs of HCC tissue and non-neoplastic hepatic tissue around the HCC were collected from three patients who underwent resection for HCC. Differential display reverse transcriptase-PCR (DD RT-PCR) using GeneFishing (TM) PCR was used to detect the differences in the gene expression between in HCC tissue and non-neoplatic tissue. Up- or down-regulated genes in HCC tissue were identified through BLAST searches after cloning and sequencing assays. Real-time RT-PCR assay was employed to detect the expression rate in 11 HCC tissues and human cancer cell lines. RESULTS: Differentially expressed 21 genes were identified, and they were classified as genes involved in protein metabolism, ubiquitin-dependent protein catabolism, carbohydrate metabolism, lipid metabolism, DNA repair, and inflammatory response. CONCLUSIONS: We identified differentially expressed genes in HCC, and these genes may play an important role in the study of hepatocarcinogenesis, development of biomarker, and target therapy for HCC.

Functional characterization of human oncoprotein gankyrin in Zebrafish

Gankyrin is an oncoprotein containing seven ankyrin repeats that is overexpressed in hepatocellular carcinoma (HCC). Gankyrin binds to Mdm2, which results in accelerated ubiquitylation via degradation of p53, and it also plays an important role in cell proliferation. However, little is known about the relationships between p53 levels, cell proliferation, and gankyrin over-expression. In order to investigate the influence of gankyrin protein on p53 and Mdm2 in a zebrafish model, we injected human gankyrin (hgankyrin) containing expression vectors (pCS2-hgankyrin, pCS2-hgankyrin-EGFP) into zebrafish embryos. To measure p53 and Mdm2 expression in hgankyrin-injected embryos, RT-PCR, Northern blot and in-situ hybridization and BrdU immunostaining were used. In addition, to know the effect of hgankyrin on cell proliferation in vitro, cell viability assays such as MTT, trypan blue staining and RT-PCR following transfection of hgankyrin-containing vector into HEK 293 cell line were performed. In vivo results indicated that p53 mRNA levels decreased but those of Mdm2 were not decreased in the presence of hgankyrin. These results suggest that gankyrin downregulates p53 expression and not Mdm2 expression. In the study of cell proliferation, BrdU-positive cells were predominantly increased in the head and tail regions in hgankyrin-injected zebrafish. Additional in vitro studies using trypan blue staining and MTT assay showed that gankyrin-expressing HEK 293 cells proliferated at a faster rate, indicating that gankyrin promotes cell proliferation. Our results demonstrate that hgankyrin overexpression downregulates p53 expression and promotes cell proliferation in zebrafish. Gankyrin may play an important role in tumorigenesis via its effects on p53 and cell proliferation.

In vitro Culture of Hepatitis C Virus (HCV) Using Immortalized Hepatocyte / 대한소화기학회지

BACKGROUND/AIMS: It is essential to develop an in vitro culture model of primary hepatocytes for the study of hepatocellular function and the pathogenesis of hepatitis C virus (HCV) infection. In this study, we have established the immortalized primary human hepatocyte (IPHH) and performed in vitro culture of HCV derived from human patient. METHODS: Primary human hepatocytes were isolated from surgically resected liver tissue and then were immortalized by transfection with the SV40 large T antigen. The characterization of the IPHH during culture was analyzed by immunocytochemistry, RT-PCR, Western blot, ELISA, and soft agar assay. Next, sera and/or liver tissue homogenates from surgically resected liver tissues of patients with HCV infection were inoculated for the culture of HCV in IPHH. After HCV RNA extraction from IPHH and culture media, positive or negative stranded HCV RNA was examined by specific nest RT-PCR. RESULTS: IPHH expressed liver-associated proteins but did not express alpha-fetoprotein. Also IPHH showed ammonia removal activity. With regard to its malignant potential, colony formation in soft agar assay was not observed. Next, positive and negative stranded HCV RNAs in IPHH infected with patient's sera plus liver tissue homogenates were clearly detected whereas those in IPHH infected with only patient's sera were not detected. CONCLUSIONS: These results demonstrated the phenotypic characteristics of IPHH and the feasibility in vitro culture system of HCV infected human samples. This system might be useful for study of pathogenesis of HCV infection or hepatocyte-based applications.