EFFECTS OF ANTISENSE EPIDERMAL GROWTH FACTOR AND ITSRECEPTOR RETROVIRAL EXPRESSION VECTORS ON CELLGROWTH OF HUMAN PANCREATIC CARCINOMA CELL LINE

A 150 bp epidermal growth factor (EGF) cDNA fragment and a 1024 bp epidermal growth factor receptor (EGFR) cDNA fragment were inserted into 5.05 kb pBabe-puro retroviral vectors between BamH I and EcoR I sites in 3'-5' and / or 5'-3' orientation. The vectors were ligated with EGF and EGFR fragments by T-4 Ligase. The recombinant retroviral vectors were then packaged with packaging cell line PA317 through calcium phosphate mediated transfection. The viral supernatant of transfected PA317 cell lines were used to infect the human pancreatic carcinoma cell line PC-7. The resultant transformant cell lines: PC-7 / AS-EGF, PC-7 / S-EGFR, PC-7 / AS-EGFR and PC-7 / pBabe were tested for their endogenous EGF and EGFR mRNA expressions, cell growth rate, 3H-TdR incorporation rate, soft agar colony formation and tumorigenicity in nude mice. The results showed that there were noticeable inhibitions of cell growth, 3H-TdR incorporation rate, soft agar colony formation and tumorigenicity in nude mice in PC-7 / AS-EGF and PC-7 / AS-EGFR transformant cell lines. The endogenous EGF mRNA expression was blocked in PC-7 / AS-EGF cell line and the endogenous EGFR mRNA was significantly down-regulated in PC-7 / AS-EGFR cell line.

Construction of Recombinant Retroviral Vector Containing HIV-1 Tat Gene and Functional Detection of Expressed Tat in Target Cells

Objective: To construct recombinant retroviral vector containing HIV-1 Tatgene and evaluate the junction of the expressed Tat in target cells. Methods: HIV-1 Tat_(101) genewas recovered from pEV plasmid by Hind Ⅲ digestion and cloned into expression plasmid LZESpBMN-Z toconstruct recombinant retroviral expression plasmid named LZRS-Tat_(101). Using the method ofcalcium phosphate, the construct of LZRS-Tat_(101) was then transfected into packaging cell linesPhoenix (ΦNX) which contained env and gal genes encoding structural proteins and pol gene codingfor 3 enzymes ( reverse transcriptase, protease and integrate) essential for retroviral integrationand replication . The stable transfected cell lines was obtained using puromycin to screen for morethan 3 days. Then, immunohistochemical (IHC ) staining was carried out to detect the expressionlevel of Tat_(101) protein in both transiently and stably trancfected ΦNX, respectively. Thesupematants containing recombinant virus collected from transient and stable transfected cells wereemployed to infect 293 cells, respectively, and the expressed Tat in 293 cells was tested by Westernblot. Meantime, the supematants of infected 293 cells was further added to HL3T1 cells which wereHela cell lines containing an HIV-1-LTR/CAT reporter construct to establish a co-culture system.After co-culture for 72 hours, the protein was extracted from HL3T1 cells and used for CAT activityassay. Results: After LZRS- Tat_(101) was transfected into ΦNX, the amount of expressed Tat intransient transfection cells was significantly higher than that in stable transfection cells; Tatcould be detected not only in 293 cells but also in the supematants from 293 cells culture, and Tatin the supematants could activate HIV-1 LTR promoter in HL3T1, resulting in high 'expression of CATlocated at the downstream of LTR. Conclusion: The construct of recombinant retrovirus LZRS-Tat_(101) could express Tat protein in target cells and the expressed Tat was functionally activeand can really exhibit the ability to activate transcription.

High level expression of human Factor Ⅷ in mammalian cells after retroviral-mediated gene transfer

Abstract:Objective To develop a retroviral-mediated high efficient expression system of human coagulation factor Ⅷ. Methods The LNC-FⅧBD retroviral vector was generated by cloning a human B-domain-deleted (760aa～1639aa) Factor Ⅷ (FⅧ) cDNA (FⅧ cDNA BD) into the retroviral vector pLNCX. Several mammalian cell lines, including NIH3T3, CHO, Cos-7 and human hepatic cell line, L-02, were transduced with viral supernatant from the highest virus-producing PA317 clone. Antigen and coagulant activity of human FⅧ in cell culture medium were measured by ELISA and a one-stage method, respectively. RT-PCR was performed for the detection of FⅧBD mRNA. Results Human FⅧ was expressed in all four target cells, with the highest FⅧ expression observed in NIH3T3. The coagulant activity of secreted FⅧ was up to 1.6U/106 cells*24?hrs-1, and the FⅧ antigen was 500?ng/106 cells*24?hrs-1. FⅧ coagulant activity and antigen expressed by transduced CHO cells were 0.12?U/106 cells*24?hrs-1 and 62.4?ng/106 cells*24?hrs-1, respectively. Human FⅧ expression was relatively low in Cos-7 and L-02 cells. RT-PCR results demonstrated transcription of FⅧcDNA BD in the target cells.Conclusions The constructed retroviral vector was able to direct high level expression of human FⅧ in various mammalian cell lines. It has potential utility in the future gene therapy for Hemophilia A.