Interaction between hepatitis C virus core protein and translin protein- a possible molecular mechanism for hepatocellular carcinoma and lymphoma caused by hepatitis C virus

Second malignant neoplasms in lymphomas, secondary lymphomas and lymphomas in metabolic disorders/diseases

With inconsistent findings, evidence has been obtained in recent years that metabolic disorders are closely associated with the development of lymphomas. Studies and multiple analyses have been published also indicating that some solid tumor survivors develop a secondary lymphoma, whereas some lymphoma survivors subsequently develop a second malignant neoplasm (SMN), particularly solid tumors. An interaction between the multiple etiologic factors such as genetic factors and late effects of cancer therapy may play an important role contributing to the carcinogenesis in patients with metabolic diseases or with a primary cancer. In this review, we summarize the current knowledge of the multiple etiologic factors for lymphomagenesis, focusing on the SMN in lymphoma, secondary lymphomas in primary cancers, and the lymphomas associated to metabolic disorders/diseases, which have been received less attention previously. Further, we also review the data of coexistence of lymphomas and hepatocellular carcinoma (HCC) in patients with infection of hepatitis C virus and hepatitis B virus.

Cloning and functions of the HBxAg-binding protein XBP1

In the present study the hepatitis B virus X antigen binding protein 1 (XBP1) was cloned by inducing its expression, and its subcellular localization and function were examined. Total RNA was extracted from HepG2 cells and XBP1 was amplified using reverse transcription polymerase chain reaction (RT-PCR), followed by restriction enzyme digestion of the pGBKT7 yeast plasmid and identification by enzyme digestion. The plasmid was transformed into AH109 yeast via the lithium acetate method and protein extracts were prepared. XBP1 protein expression in the eukaryotic cells was determined using polyacrylamide gel electrophoresis and western blot analysis. The gene encoding the XBP1-binding protein was screened in liver cells using yeast two-hybrid technology. We transfected a human hepatocellular carcinoma cell line and observed the intracellular localization of the gene expression protein using a fluorescence microscope, followed by prokaryotic expression and XBP1 gene identification. A 921-bp XBP1 gene fragment was obtained via RT-PCR amplification and 20 proteins with known functions that interact with XBP1 were screened, including metallothionein, smooth muscle cell-related protein, asialoglycoprotein receptor, pyruvate dehydrogenase kinase 1 and a sequence with unknown functions. A green fluorescent protein expression plasmid pEGFP-C1-XBP1 of XBP1 was constructed successfully and its expression protein was localized in the cytoplasm. A 56-kDa recombinant protein was successfully obtained via prokaryotic expression and was demonstrated to have good specificity using western blot analysis. The XBP1 gene, which expresses the XBP1 protein, is located in the cytoplasm and plays a role in the intracellular structure, cell growth, intracellular metabolism and signal transduction pathway, as well as DNA duplication, transcription, recombination and repair.

Screening and identification of interacting proteins with hepatitis B virus core protein in leukocytes and cloning of new gene C1

AIM: To investigate the biological function of HBcAg in pathogenesis of HBV replication in peripheral blood mononuclear cells (PBMCs).

METHODS: HBcAg region was amplified by polymerase chain reaction (PCR) and HBV HBcAg bait plasmid pGBKT7-HBcAg was constructed by routine molecular biological methods. Then the recombinant plasmid DNA was transformed into yeast AH109. After the HBV core protein was expressed in AH109 yeast strains (Western blot analysis), yeast-two hybrid screening was performed by mating AH109 with Y187 containing leukocyte cDNA library plasmid. Diploid yeast cells were plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) (QDO) and synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) (TDO). The second screening was performed with the LacZ report gene ( yeast cells were grown in QDO medium containing X-α-gal). The interaction between HBV core protein and the protein obtained from positive colonies was further confirmed by repeating yeast-two hybrid. After plasmid DNA was extracted from blue colonies and sequenced, the results were analyzed by bioinformatic methods.

RESULTS: Eighteen colonies were obtained and sequenced, including hypermethylated in cancer 2 (3 colones), eukaryotic translation elongation factor 2 (2 colones), acetyl-coenzyme A synthetase 3 (1 colone), DNA polymerase gamma (1 colone), putative translation initiation factor (1 colone), chemokine (C-C motif) receptor 5 (1 colone), mitochondrial ribosomal protein L41 (1 colone), kyot binding protein genes (1 colone), RanBPM (1 colone), HBeAg-binding protein 3 (1 colone), programmed cell death 2 (1 colone). Four new genes with unknown function were identified.

CONCLUSION: Successful cloning of genes of HBV core protein interacting proteins in leukocytes may provide some new clues for studying the biological functions of HBV core protein.

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Identification and analysis of rat homologous gene to human HBV pre-S1 protein-binding protein

AIM: To identify and analyze rat homologous gene to human hepatitis B virus (HBV) pre-S1-binding protein (PS1BP) coding gene.

METHODS: The human PS1BP was screened and identified from a hepatocyte expressive cDNA library by phage display technique with purified recombinant pre-S1 protein of HBV as the solidified matrix. The nucleotide sequence database GenBank, established by National Center for Biotechnology Information (NCBI), National Library of Medicine (NLM), National Institute of Health (NIH), was searched for rat cDNA sequence homologous to human PS1BP cDNA by BLASTn tools online. A homologous cDNA sequence was identified as the rat PS1BP cDNA. The similarity and identity of rat PS1BP cDNA and amino acid (aa) sequences to human and mouse PS1BP genes were compared. The potential functional domains were predicted by online analysis tools.

RESULTS: The human PS1BP cDNA was identified by phage display technique. The rat PS1BP cDNA was identified by bioinformatics methods. The rat PS1BP cDNA consisted of 1 455 nt, and encoded a protein of 484 aa. The identity of rat PS1BP protein to human and mouse PS1BP proteins was 80.79% (391/484) and 92.98% (450/484), respectively. In the rat PS1BP protein sequence, several potential modification domains were identified.

CONCLUSION: Rat PS1BP cDNA and protein primary sequences are identified and analyzed.

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Development and application of a mixed microarray in detection of genes of HBV and HCV

AIM: To develop a DNA microarray to detect hepatitis virus B (HBV) DNA, hepatitis virus C (HCV) RNA, HBV YMDD mutant and HCV genotype simultaneously. At the same time, the chip was compared with other techniques to evaluate its prospect in clinical application.

METHODS: A set of probes was designed to detect HBV DNA, HCV RNA, HBV YMDD mutant and HCV genotype. The probes were synthesized by DNA synthesizer. The microarray was prepared by spotting the probes onto the specially treated glass sliders. Serum samples were collected from inpatients and outpatients at the Department of Infectious Diseases, the Third Affiliated Hospital of Zhongshan University. Among the samples, 20 were comfirmed HBV DNA positive by fluorescent quantitation PCR, 20 were HCV RNA positive, 20 were comfirmed YMDD mutant by mismatched PCR, 10 were HBV DNA and HCV RNA negative. HBV DNA and HCV RNA were extracted from the serum, then amplified by asymmetric PCR or RT-PCR in the presence of sense fluorescein labeled primers. The products of HBV YMDD and HCV NS-5 were purified and sequenced. Following the hybridization of amplified products on the microarrays, detection was carried out by the fluorescence scanner. The detection results were obtained by analyzing the intensity and ratio of the fluorescence signals using image analysis software.

RESULTS: For the HBV DNA positive samples and HCV RNA positive samples, an intensive signal was observed at the point of corresponding probes on the microarrays. In detection of YMDD mutant, the coincident rate of the microarray and the mismatched PCR was 75%, the coincident rate of microarray and sequencing was 95%. In detection of HCV genotype, the coincident rate of microarray and sequencing was 75%.

CONCLUSION: The technology of microarray appears to be versatile, with a great sensitivity and specifity in detection of HBV and HCV. Furthermore, it can find co-infection of different virus strains. But it has some false negative rate and false positive rate in HCV genotyping.

Effects of HCBP6 protein on transact-ivating function of HCV core protein

AIM: To study the inhibitory effects of HCBP6 on the transactivating effect of HCV core protein.

METHODS: The recombinant vectors expressive HCV core protein and HCBP6 protein were constructed, respectively, by routine molecular techniques. The hepatoblastoma cell line HepG2 were co-transfected. The chloramphenicol transferase (CAT) expressive levels under the SV40 early promoter were determined by an enzyme-linked immuno-sorbent assay (ELISA) kit.

RESULTS: The recombinant vectors of pcDNA3.1(-)-HCBP6 and pcDNA3.1(-)-core were constructed, and demonstrated correctly by restriction enzyme digestion and sequencing analysis. The hepatoblastoma cell line HepG2 was transfected with the vector alone or combined, respectively. The expression level of CAT indicated that the inhibitory rate was 40.4%-62.3%.

CONCLUSION: The expression of HCBP6 has inhibitory effects on the transacting activity of HCV core protein.

Expression of HSP 70 and caspase 3 and their significance in hepatocellular carcinoma tissues

AIM: To investigate the expression of heat shock protein 70 (HSP70) and caspase 3 protein and their clinical significance in hepatocellular carcinomas and surrounding liver tissues.

METHODS: The expression of HSP70 and caspase 3 protein were detected by immunohistochemistry in hepatocellular carcinomas (HCC) and their surrounding liver tissues.

RESULTS: The positive rate and intensity of HSP70 in HCCs were significantly higher than those in pericarcinomatous liver tissues (68.6% vs 31.4%, P < 0.01), and these of caspase protein were significantly lower (17.1% vs 35.7%, P < 0.01). The expression level of HSP70 and caspase protein in HCCs was remarkably related to differentiation degree and tumor size of HCCs, and the poorer differentiation, the stronger the expression of HSP70 (F = 5.219 and 5.421 respectively, P < 0.01), the weaker the expression of caspase 3 protein (F = 5.944 and 4.571 respectively, P < 0.01). The correlation analysis indicated that there was a negative relationship between expression of HSP70 and caspase protein in HCC and their surrounding liver tissues (r = 0.4 126 and 0.5 237 respectively, P < 0.01).

CONCLUSION: The expression of HSP70 may make uncontrolled growth and unceasingly increased malignant degree of HCC by accelerating cell transformation and proliferation and inhibiting apoptosis. HSP70 may be an important marker for evaluation of prognosis in patients with HCC.

Identification and characterization of retinol dehydrogenase 11 as a hepatitis C virus core protein-binding protein by yeast-two hybrid technique

AIM: To screen the hepatocyte protein interacting with HCV core protein.

METHODS: By using HCV core protein as a bait, yeast-two hybrid system 3 was employed for screening and identification of HCV core protein-binding proteins from a hepatocyte cDNA library expressed in yeast cells. The protein-protein interaction was confirmed by back-cross experiment, and the inserts of the expressive vectors were sequenced and analyzed by bioinformatics methods.

RESULTS: Among them we identified retinol dehydrogenase 11(RDH11/androgen- regulated short-chain dehydrogenase/reductase 1 (ARSDR1) as a HCV core protein-interacting protein. This is the first time, to the best of our knowledge, to know the fact that there are interactions of HCV core protein-retinol dehydrogenase 11.

CONCLUSION: The identification of retinol dehydrogenase 11 as the HCV core protein binding partner paves a new way for further understanding of the pathogenesis of HCV infection.

Identification and sequence analysis of mouse homologous gene coding for hepatitis C virus non-structural protein 5A-binding protein 37

AIM: To clone murine homologous gene to human NS5ABP37 gene, and to elucidate its biological functions and the possible effects in the pathogenesis of hepatitis C virus (HCV) infection.

METHODS: Yeast-two hybrid system was employed to screen the human liver cDNA library by using non-structural protein 5A (NS5A) of hepatitis C virus (HCV) as the bait. According to the homologous role between the species, a murine NS5ABP37 homologous to human NS5ABP37 was deduced by bioinformatics methods. The primary sequence of murine NS5ABP37 was searched for conserved domains by online tools of GeneBank.

RESULTS: Human NS5ABP37 was screened and cloned from human liver cDNA library by yeast-two hybrid system 3. The murine NS5ABP37 was deduced by bioinformatics methods. The open reading frame (ORF) of murine NS5ABP37 consisted of 1 488 nt encoding a protein of 495 amino acids. Calculated molecular weight was 54 583.67 dalton and predicted pI was 4.70. From the homologous protein search, murine NS5ABP37 was demonstrated homologous to leukocyte antigen related (LAR) protein precursor. The sequence of murine NS5ABP37 was deposited into GenBank, and the accession number was AY234860.

CONCLUSION: Successful identification and cloning of murine NS5ABP37, which is homologous to LAR protein precursor, paves a way for elucidating the biological function of murine NS5ABP37 and pathogenesis of hepatitis C virus infection.

Comparisons of differentially expressed genes transactivated by hepatitis B and C viral proteins using suppression subtractive hybridization and cDNA micro-array techniques

AIM: To clone and identify human genes transactivated by hepatitis B and C viral proteins via construction of a cDNA subtractive library with suppression subtractive hybridization (SSH) technique and cDNA microarray techniques.

METHODS: Suppression subtractive hybridization (SSH) and cDNA microarray techniques were used for screening and cloning of the target genes transactivated by hepatitis B and C viral proteins. The mRNA was isolated from HepG2 cells transfected recombinant vector expressing hepatitis B and C viral proteins and pcDNA3.1(-) empty vector,respectively. SSH and cDNA microarray were employed to analyze the differentially expressed DNA sequence between the two groups. In SSH assay, after restriction enzyme Rsa I digestion, small sizes of cDNAs were obtained. Then tester cDNA was divided into two groups and ligated to the specific adaptor 1 and adaptor 2, respectively. After tester cDNA was hybridized with driver cDNA twice and underwent two times of nested PCR and then was subcloned into T/A plasmid vectors to set up the subtractive library. Amplification of the library was carried out with E. coli strain JM109. The cDNA was sequenced and analyzed in GenBank with Blast search after PCR.

RESULTS: The subtractive library of genes transactivated by hepatitis B and C viral proteins was constructed successfully. The up-regulated and down-regulated genes from cDNA microarray assay was conducted for each of the hepatitis B and C viral proteins. The results were compared.

CONCLUSION: The obtained sequences may be target genes transactivated by hepatitis B and C viral proteins, among which some genes coding proteins involve cell cycle regulation, signal transduction, tumor immunity and development, and apoptosis.

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Screening of the genes of HCV core interacting proteins from human leucocyte cDNA library by yeast two-hybrid system

AIM: To investigate the binding protein of hepatitis C virus core protein (HCVcore).

METHODS: The HCVcore gene was amplified by polymerase chain reaction (PCR) and HCVcore bait plasmid was constructed by using yeast-two hybrid system 3, then transformed into yeast AH109. The transformed yeast mated with yeast Y187 containing leucocyte cDNA library plasmid in 2×YPDA medium. Diploid yeast was plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) and synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing x-α-gal for selecting two times and screening. After extracting and sequencing of plasmid from blue colonies, we underwent analysis by bioinformatics.

RESULTS: Six colonies were sequenced, among which,two colonies were golgi complex associated protein 1 (GOCAP1), one colony was Ran binding protein M (RanBPM), one colony was pellino homolog 2 (PELI2), and two colonies were KIAA1949 protein (KIAA1949).

CONCLUSION: Genes of HCV core interacting proteins in leucocyte are successfully cloned and the results bring some new clues for studying the biological functions of HCVcore and associated proteins.

Bioinformatics analysis of human hepatitis C virus core protein-binding protein 6 gene and protein

AIM

To investigate the structure and function of gene encoding human hepatitis C virus core protein-binding protein 6 (HCBP6) with yeast two-hybrid technique and bioinformatics methods.

METHODS

Yeast two-hybrid technique and bioinformatics method were used to screen and identify the human HCBP6 gene and its amino acid sequences.

RESULTS

Human HCBP6 cDNA and genomic DNA sequences were identified. Human HCBP6 coded for 456 nt and corresponding protein was composed of 152 amino acids. The promoter sequence of HCBP6 gene was identified and promoter motif was predicted by 3 different bioinformatics methods. No intron in HCBP6 gene was identified by homologous search of cDNA and genomic DNA sequence database. The hydrophilic domain was predicted by bioinformatics methods, and the functional domains were determined with online search tools. Mouse HCBP6 gene was identified on the basis of the mouse homologous DNA sequence database. However, all data obtained from bioinformatics analysis were preliminary and further study is required for confirmation.

CONCLUSION

The bioinformatics is a powerful method for the analysis and prediction of a new gene and corresponding protein. Although the predicted result is not accurate, it provides valuable information for further study.