In order to obtain three isoforms of apolipoprotein E (apoE), the cDNA encoding apoE3 was obtained by RT-PCR from normal human liver tissue. Site-directed mutagenesis was used to obtain the cDNAs encoding apoE2 and apoE4 isoforms. The 3 cDNAs were subcloned into vector pGEM-3Z and verified by DNA sequencing. The expression recombinant which can express the target protein as a (His) 6-tagged fusion was constructed by subcloning apoE cDNA into vector pT7-PL. The purified proteins were gained by Ni-NTA column. The SDS-PAGE results revealed the 6 His fusion proteins (apoE2, apoE3 and apoE4) were correctly expressed and purified successfully.

The inhibition of metastatic progression of Somatostatin receptor type 2 (SSTR2) gene transfection mediated by adenovirus in human pancreatic carcinoma cells and the mechanism involved in this effect were studied. The full-length human SSTR2 cDNA was introduced into the pancreatic cancer cell line BXPC-3 by adenovirus-mediated transfection. Stable expression of mRNAs and protein of SSTR2 was detected by RT-PCR and Western-blot. The Matrigel-coated Transwell was used to detect the migratory and invasive ability of SSTR2-expressing cells, Adv-GFP control cells and mock control cells. Furthermore, the expression of matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) was detected by RT-PCR in these cells. The stable expression of SSTR2 was detected in BXPC-3 transfected by Adv-GFP-SSTR2. A dramatic decrease of BXPC-3 expressing sst2 cells migrating through a Matrigel-coated filter was observed, as compared with Adv-GFP control and mock control cells (P<0.01). Moreover, the expression of MMP-2 mRNA was significantly reduced in the SSTR2-expressing cells and conversely the expression of TIMP-2 mRNA was significantly increased in the SSTR2-expressing cells when compared with the Adv-GFP control and mock control (P<0.01). The expression of reintroduced human SSTR2 gene in BXPC-3 cells by Adv-GFP-SSTR2 had the anti-migratory and anti-invasive effects, and the mechanisms involved in this effect may be due to the down-regulated expression of MMP-2 and up-regulated expression of TIMP-2.

In order to construct recombinant baculovirus carryingSchistosoma japonicum 26 ku glutathione S-transferase gene (Sj26), and observe the expression ofSj26 in mammalian cells, theSj26 gene was amplified with plasmid pGEX-3X as template by PCR, and then recombined into T vector for sequencing.Sj26 gene was inserted into the downstream of CMV promoter of donor plasmid pFBDGC, and the recombinant donor plasmid pFBDGC-Sj26 transformed into DH10Bac, then the recombinant bacmid AcCMVSj26 was isolated and transfected into Sf9 cells. The recombinant baculovirus was harvested and final titer of vAcCMVSj26 was measured. BHK cells were transducted with recombinant baculovirusin vitro. By using Western blot, the expression of 26 ku glutathione S-transferase (GST) was detected. The results showed that after enzyme digestion and sequencing, the donor plasmid was successfully constructed. PCR confirmed that pFBDGC-Sj26 and Bacmid homologous recombination occurred inE. coli. After transfection of Sf9 cells with recombinant Bacmid, recombinant baculovirus was replicated in Sf9 cells and expressed green fluorescent protein. PCR further revealed recombinant baculovirus containedSj26. The titer of the harvested baculovirus was 1.24×10⁸. Western blot demonstrated that recombinant baculovirus could express 26 ku GST in BHK cells. It was concluded thatSj26 recombinant baculovirus was successfully constructed, and the 26 ku GST was expressed in mammalian cells.