Lethiferous effects of a recombinant vector carrying thymidine kinase suicide gene on 2.2.15 cells via a self-modulating mechanism

Construction of two vectors harboring PNP gene under control of two different promoters and their expression

AIM: To construct two expression vectors carrying PNP gene under a cytomegalovirus (CMV) promoter and a hybrid a-fetoprotein (AFP) tissue-specific promoter, and to detect and analyze their expression in different cell lines.

METHODS: [HRE]AF promoter was inserted into pcDNA3.0 vector, and a recombinant vector controlled by the hybrid AFP promoter, p[HRE]AF, was constructed. Inserting PNP gene into pcDNA3.0 and p[HRE]AF vectors separately, two PNP gene expression vectors driven by two different promoters, pcDNA3.0/PNP and p[HRE]AF /PNP, were constructed by using recombinant DNA techniques. The recombinants were analyzed and identified by restriction enzymes, PCR and sequencing. pcDNA3.0/PNP and p[HRE]AF/PNP were transfected into human hepatocellular carcinoma cell lines by liposome-mediated method. The expression of PNP gene in four different cell lines was detected by RT-PCR method.

RESULTS: All target fragments were separately cloned into corresponding vectors. We detected the expression of PNP gene under the control of CMV promoter in all cell lines, and the tissue-specific expression of PNP gene under the control of [HRE]AF promoter in AFP positive and negative hepatocellular carcinoma cell line was positive.

CONCLUSION: Two expression vectors harboring PNP gene are novel effective vectors for human hepatocellular carcinoma gene therapy, and p[HRE]AF/PNP is a target-expressing vector in AFP positive, especially in AFP negative hepatocellular carcinoma cells.

Construction of human CD81 eukaryotic expression vector and expression of the gene segment in COS-7 cell line

AIM: To construct a human CD81 eukaryotic expression vector and to analyze the expression of CD81 in COS-7 cells.

METHODS: CD81 gene from the pMD18-T-CD81 vector with double-enzyme digestion was cloned into the pVAX1 eukaryotic expression vector, named pVAX1-CD81. The recombinant vector pVAX1-CD81 and pVAX1 as controls were transfected into COS-7 cells by lipofectamine, and the transient expression product on the transfected cells was analyzed with anti-CD81 monoclonal antibody by indirect immunofluorescence assay (IFA).

RESULTS: The identification of the eukaryotic expression vector pVAX1-CD81 by PCR and restriction enzyme analysis showed that CD81 gene was rightly inserted into the vector; and the product of the CD81 gene was successfully expressed on surface of COS-7 cells.

CONCLUSION: The eukaryotic expression vector with CD81 gene is constructed and efficiently expressed in COS-7 cells. The results indicate that the transfected CD81 cells will need to further studies on the roles of CD81 in the process of HCV infection and entrance to cells.