Biomedical subjects

Yan-jun Wen

Publications and source records attributed to Yan-jun Wen.

12 recordsLinked to original sources

PubMed2006

Prophylaxis against carcinogenesis in three kinds of unestablished tumor models via IL12-gene-engineered MSCs.

Mesenchymal stem cells (MSCs) were adenovirally engineered to secrete interleukin-12 (AdIL-12-MSCs) and evaluated for their anticarcinogenesis efficacy against three kinds of unestablished tumor models including B16 melanoma, LLC Lewis lung cancer and HCC hepatoma. Injection of AdIL-12-MSCs into protected mice before tumor inoculation prevented all of 12 mice in B16 preventive groups, 10 out of 12 in LLC lung cancer model and 11 out of 12 mice in HCC hepatoma model from developing tumors, whereas the control groups pre-receiving PBS were validated for 100% carcinogenesis; the tumor formation rates in free-AdIL-12 and vacant MSC groups were unveiled between approximately 83 and 100% even with plentiful angiogenesis and newborn lymphatic vessels, as well as distant metastases. As a novel approach, AdIL-12-MSC has revealed expected preventive effects on carcinogenesis (P<0.01) with low-toxic, broad-spectrum and long-range superiorities. In conclusion, our data indicate that AdIL-12-MSC possess the potential for tropism to preclinical tumor lesions and deprives surviving or hibernating tumor cells, which have escaped from conventional treatments, of revival and recurrence.

Animals↗

PubMed2006

Expression of extracellular domain of human vascular endothelial growth factor receptor-2 in Pichia pastoris.

OBJECTIVE: To investigate the feasibility of high expressing extracellular domain of human vascular endothelial growth factor receptor-2 (heVEGFR-2) with eukaryotic protein structure in Pichia pastoris. METHODS: We used PCR to amplify the DNA fragment encoding heVEGFR-2 from pORF-heVEGFR-2. The recombinant Pichia pastoris secretory expression vector(pPICZalphaA-heVEGFR-2)was constructed and transferred into Pichia pastoris X-33 by electroporation. The high expression transformnants were identified through its drug-resistant phenotype and methanol induction. RESULTS: As indicated by SDS-PAGE, the recombinant heVEGFR-2 protein with a molecular weight (MW) approximately 108 kDa, which reached 80 mg/L in the mass concentration, comprised 45% of the total expressed secreted proteins from Pichia pastoris X-33. The section of heVEGFR-2 had a MW approximately 106 kDa. The results of western blot analysis demonstrated that this protein could be specifically recognized by the rat monoclonal antibody against mouse VEGFR-2 (rat McAb against mVEGFR-2). CONCLUSION: The heVEGFR-2 with eukaryotic protein structure can get a high expression in Pichia pastoris.

Animals↗

PubMed2006

[Construction of mammalian co-expression plasmid pIRES -LMP1-HSP90 beta and its expression in vitro].

OBJECTIVE: This study sought to clone Epstein-Barr virus latent membrane protein 1 (LMP1) and heat shock protein 90 beta (HSP90 beta) of nasopharyngeal carcinoma (NPC), to construct the mammalian co-expression plasmid pIRES-LMP1-HSP90 beta, and to detect the expression of the plasmid in vitro. METHODS: Total RNA was isolated from human NPC by cloning technique, their cDNA fragments of LMP1 gene and HSP90 beta gene were gained by RT-PCR, and their cDNA fragments were constructed into the mammalian co-expression plasmid vector pIRES. The inserted target genes in the mammalian co-expression plasmid were verified by nucleotide sequencing. COS cell line was transfected with this mammalian co-expression plasmid using lipofectin reagent. The expression of LMP1 and HSP90 beta molecules were detected by RT-PCR and Western blot technique. RESULTS: The mammalian expression plasmid pIRES-LMP1-HSP90 beta was obtained by cloning technique. The nucleotide sequences of LMP1 gene and HSP90 beta gene in this mammalian co-expression plasmid had high homology with EBV-LMP1 (100%) and human HSP90 beta (100%) respectively. After transfection with this mammalian co-expression plasmid, the LMP1 and HSP90 beta molecules were expressed in COS cells. CONCLUSION: The constructed mammalian co-expression plasmid pIRES-LMP1-HSP90 beta can express LMP1 and HSP90 beta molecules in vitro at the same time.

Animals↗

PubMed2006

[Construction of pORF-mIG and activity evaluation of MIG in vitro].

OBJECTIVE: To establish a transformant of monokine induced by interferon-gamma (MIG) with the eukaryotic expression vector for further investigating the efficacy of its use in antitumor gene therapy. METHODS: The MIG full-length cDNA was amplified from pBLAST-MIG and was cloned into the eukaryote expression vector pORF-mcs, and the resulted recombinant plasmid was named pORF-MIG. The recombinant pORF-MIG was determined with restriction enzyme and sequencing, and then it was transfected into COS-7 cells by Lipfectamin. Expression of the transformant was detected by immunoblot assay, and the bioactivity was assessed by chemotaxis assay. RESULTS: The restriction analysis and the sequence determination confirmed that the recombinant pORF-MIG contained the MIG full-length cDNA. And the transformants of pORF-MIG expressed the MIG protein which could apparently attract the activated lymphocytes. CONCLUSION: The recombinant pORF-MIG was constructed successfully, and this recombinant eukaryotic expression vector could be used in additional studies on the biological effect of MIG and its use in anti-tumor gene therapy.

Base Sequence↗

PubMed2005

[Expression of xenogeneic homologous epidermal growth factor receptor ectodomain in Pichia pastoris].

OBJECTIVE: To develop a secreted expression system of xenogeneic homologous epidermal growth factor receptor (EGFR) ectodomain using Pichia pastoris (P. pastoris), thus providing a basis for subsequent antitumor immunological researches on EGFR subunit protein vaccine. METHODS: In order to construct the secreted expression vector pPICZaA-mer and pPICZaA-her, we recombined the cDNA of xenogeneic (human) EGFR ectodomain (her) and the corresponding control mouse EGFR ectodomain (mer) with the empty plasmid pPICZaA, respectively. Then the recombinant plasmids were linearized by Sac I and transformed into P. pastoris strain GS115 by electroporation. The positive transformants were selected on YPDS plate including Zeocin and were induced to express by methanol. Consequently, the proteins in the culture supernatant were assayed with SDS-PAGE and Western-blot. So we could choose the high-level secreted expression recombinant strain to produce protein vaccine vastly. RESULTS: We got the secreted expression of mouse and human EGFR ectodomain in P. pastoris. The relative molecular mass of the two aimed proteins is about 95 x 10(3). The Western-blot analysis demonstrated that the expression proteins have much good antigenicity and specificity. CONCLUSION: The recombinant plasmids pPICZaA-mer and pPICZaA-her could be induced to express the EGFR aimed proteins by methanol in methanol-trophic yeast expression system.

Animals↗

PubMed2005

[Construction of the recombinant adenovirus vector expressing human CD40 ligand gene].

OBJECTIVE: To construct a recombinant adenovirus vector expressing hCD40L gene and explore it in the use of anti-tumor gene therapy. METHODS: 1,900 bp gene fragment was obtained form plasmid pORF-hCD40L by Xho I/Swa I cutting and then cloned directionally into the pShuttle plasmid, finally, the resultant plasmid was digested by restriction endonnuclease PmeI and subsequently cotransformtion into BJ5183 cells with the adenoviral backbone pAdEasy-1 to obtain the homologous recombinant and then the recombinant was packaged in the 293 cells. Some methods such as PCR and endonulease digestion were employed to identify the recombinant adenovirus. RESULTS: The evidences of endonulease digestion and PCR analysis confirmed that recombinant hCD40L gene was correctly inserted into adenovirus vector. CONCLUSION: The adenoviral vector which expressed hCD40L gene was constructed. It provides an experimental basis for studies on it expression in the mammalian cells and in tumor gene therapy.

Adenoviridae↗

PubMed2004

[Prokaryotic expression, purification and refolding of extracellular ligand binding domains of chick Tie-2 and its immunogenicity].

OBJECTIVE: To study the prokaryotic expression of extracellular ligand binding domains of chick Tie-2, the purification and refolding conditions of the recombinant protein, and to observe its immunogenicity in mouse. METHODS: A DNA fragment encoding extracellular ligand binding domains of chick Tie-2 was obtained by PCR from a previous constructed plasmid as a template. The amplified fragment was then inserted into prokaryotic expression vector PQE30, and was expressed in E. coli XL-1 blue by adding isopropyl-beta-D-thiogalactoside(IPTG). The recombinant protein in inclusion bodies was purified by nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography under denatured conditions. Then the refolding of the purified protein was performed with gradient dialysis. The target protein was injected into mouse subcutaneously, and the antiserum of the mouse was analyzed by ELISA and Western blot analysis. RESULTS: The recombinant protein was highly expressed in E. coli XL-1 blue, and in mouse it produced the antibody which could specifically recognize the recombinant protein. CONCLUSION: The protein of extracellular ligand binding domains of chick Tie-2 can be highly expressed in prokaryotic expression system, and the expressed protein can induce immune response in mouse. These findings are very important for the further study of this protein in anti-angiogenesis and immunotherapy research.

Animals↗

PubMed2004

[Prokaryotic expression of extracellular ligand binding domains of chick tie-2 and its anti-angiogenesis effect].

OBJECTIVE: To study the prokaryotic expression of extracellular ligand binding domains of chick tie-2, the purification, refolding conditions of the recombinant protein, and its anti-angiogeneic effect. METHODS: A DNA fragment encoding extracellular ligand binding domains of chick tie-2 was obtained by PCR amplification using a previous constructed plasmid as a template. The amplified fragment was then inserted into prokaryotic expression vector pQE30, and was expressed in E.Coli XL-1 blue by adding isopropyl-beta-D-thiogalactoside(IPTG). The recombinant protein in inclusion bodies was purified by nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography under denatured conditions. Then the refolding of the purified protein was performed with gradient dialysis. The target protein was injected s.c. into mouse, and the antibody was detected by ELISA and Western blot analysis. The antibody was purified from the antiserum and then incubated with human umbilical endothelial vein cell (HUEVC) to find its anti-angiogenesis in vitro by using propidium iodide(PI) dying through FACS. Alginate encapsulated tumor cell assays were performed and micro-vessel density was determined by counting per high power field in the sections stained with an antibody reactive to CD31 to test its inhibition of angiogenesis. RESULTS: The recombinant protein was highly expressed in E.Coli XL-1 blue, and the antibody produced in mouse could specifically recognize the recombinant protein. The purified antibody could induce apoptosis of HUEVC in vitro. The anti-angiogenic effect of the antibody could also be found in alginate-encapsulate tumor cell assay and by counting micro-vessel density. CONCLUSION: The protein of extracellular ligand binding domains of chick tie-2 can be expressed at high level in the prokaryotic expression system, and the expressed protein can induce immune response in mouse. Furthermore, the antibody can induce the anti-angiogenic effect.

Angiogenesis Inhibitors↗

PubMed2004

[Construction of pcDNA-BLC and expression of BLC in tumor cells].

OBJECTIVE: To establish a stable transformants of B-lymphocyte chemoattractant (BLC) with the eukaryotic expression vector for investigation of its anti-tumor function further. METHODS: The BLC full-length cDNA was amplified by RT-PCR from the total RNA isolated from the spleen of mouse. After sequence determination, the BLC full-length cDNA was cloned into the eukaryote expression vector pcDNA3.1 (+), the resulted recombinant was designated as pcDNA-BLC. Then pcDNA-BLC was transfected into murine tumor cell line colon 26 by LIPOFECTIN. The stable transformants were selected by G418 and identified by immunoblot assay. The bioactivity of BLC was confirmed by chemotaxis assay. RESULTS: The recombinant pcDNA-BLC was successfully constructed. The stable transformants of BLC can express the bioactive BLC in tumor cell lines. CONCLUSION: The stable transformants can stably express BLC in tumor cell lines. These stable transformants will be useful for further study of the BLC biological effect on tumor and for the development of cancer vaccine.

Adenocarcinoma↗

PubMed2004

[Construction of eukaryotic expression plasmid pSecTag2B-msBlyS expressing mouse soluble B lymphocyte stimulator].

OBJECTIVE: The purpose of this study was to clone the soluble form of the mouse BlyS (msBlyS) and insert it into a eukaryotic expression vector pSecTag2B in order to further elucidat the antitumor activity induced by msBlyS expressed by the recombined plasmid pSecTag2B-msBlyS. METHODS: Full length cDNA of mouse soluble BlyS (msBlyS) was amplified by reverse transcription-PCR from total RNA of mouse spleen. The PCR product was ligated directly with linearized vector pCR2.1 supplied in the TA cloning kit. The recombined plasmid pCR2.1-msBlyS which was selected and identified using blue-white screening method and restriction map analysis and the purified original plasmid pSecTag2B were both cut by HindIII and EcoR I. The digested fragments were extracted and purified from low-melting temperature agarose and ligated by T4DNA ligase. The recombined plasmid pSecTag2B-msBlyS were isolated and identified by restricted endonuclease cutting and Sanger dideoxy DNA sequencing. RESULTS: The sequencing data indicated that inserted msBlyS gene had correct DNA sequence and orientation. CONCLUSION: Eukaryotic expression vector pSecTag2B. Expressing mouse BlyS have successfully been cloned. This will provide us an opportunity to do further research work on BlyS.

Animals↗

PubMed2003

Inhibition of tumor growth with a vaccine based on xenogeneic homologous fibroblast growth factor receptor-1 in mice.

Angiogenesis is important for the growth of solid tumors. The breaking of the immune tolerance against the molecule associated with angiogenesis should be a useful approach for cancer therapy. However, the immunity to self-molecules is difficult to elicit by a vaccine based on autologous or syngeneic molecules due to immune tolerance. Basic fibroblast growth factor (bFGF) is a specific and potent angiogenic factor implicated in tumor growth. The biological activity of bFGF is mediated through interaction with its high-affinity receptor, fibroblast growth factor receptor-1 (FGFR-1). In this study, we selected Xenopus FGFR-1 as a model antigen by the breaking of immune tolerance to explore the feasibility of cancer therapy in murine tumor models. We show here that vaccination with Xenopus FGFR-1 (pxFR1) is effective at antitumor immunity in three murine models. FGFR-1-specific autoantibodies in sera of pxFR1-immunized mice could be found in Western blotting analysis. The purified immunoglobulins were effective at the inhibition of endothelial cell proliferation in vitro and at the antitumor activity in vivo. The antitumor activity and production of FGFR-1-specific autoantibodies could be abrogated by depletion of CD4+ T lymphocytes. Histological examination revealed that the autoantibody was deposited on the endothelial cells within tumor tissues from pxFR1-immunized mice, and intratumoral angiogenesis was significantly suppressed. Furthermore, the inhibition of angiogenesis could also be found in alginate-encapsulate tumor cell assay. These observations may provide a new vaccine strategy for cancer therapy through the induction of autoimmunity against FGFR-1 associated with angiogenesis in a cross-reaction.

Alginates↗

PubMed2003

Immunogene therapy of tumors with vaccine based on xenogeneic epidermal growth factor receptor.

The breaking of immune tolerance against self epidermal growth factor receptor (EGFr) should be a useful approach for the treatment of receptor-positive tumors with active immunization. To test this concept, we constructed a plasmid DNA encoding extracellular domain of xenogeneic (human) EGFr (hEe-p) or corresponding control mouse EGFr (mEe-p) and empty vector (c-p). Mice immunized with hEe-p showed both protective and therapeutic antitumor activity against EGFr-positive tumor. Sera isolated from the hEe-p-immunized mice exhibited positive staining for EGFr-positive tumor cells in flow cytometric analysis and recognized a single 170-kDa band in Western blot analysis. Ig subclasses responded to rEGFr proteins were elevated in IgG1, Ig2a, and Ig2b. There was the deposition of IgG on the tumor cells. Adoptive transfer of the purified Igs showed the antitumor activity. The increased killing activity of CTL against EGFr-positive tumor cells could be blocked by anti-CD8 or anti-MHC class I mAb. In vivo depletion of CD4(+) T lymphocytes could completely abrogate the antitumor activity, whereas the depletion of CD8(+) cells showed partial abrogation. The adoptive transfer of CD4-depleted (CD8(+)) or CD8-depleted (CD4(+)) T lymphocytes isolated from mice immunized with hEe-p vaccine showed the antitumor activity. In addition, the increase in level of both IFN-gamma and IL-4 was found. Taken together, these findings may provide a new vaccine strategy for the treatment of EGFr-positive tumors through the induction of the autoimmune response against EGFr in a cross-reaction between the xenogeneic homologous and self EGFr.

Adoptive Transfer↗