Feng Zuohua

The in vitro antitumor effect and in vivo tumor-specificity distribution of human-mouse chimeric antibody against transferrin receptor.

Transferrin receptor (TfR/CD71) deserves attention as a selective target for cancer therapy due to its higher expression in tumors versus normal tissues. Also, it has been shown the mouse-derived monoclonal antibody against TfR can significantly inhibit the proliferation of tumor cells. Through constructing the chimeric antibody against TfR, the antigenicity of antibody can be weakened, and most importantly, the antitumor effect of antibody can be strengthened by the introduction of the human Fc fragment. In previous studies, we successfully constructed the human-mouse chimeric antibody against TfR (D2C) and demonstrated that its Fab fragment could specially recognize the TfR on the surface of target cells. In this study, through labeling the chimeric antibody D2C with 125I, we calculated the affinity constant (Ka) of 9.34–9.62×109xa0l/mol for this antibody according to the Scatchard drawing method. Moreover, in vivo studies in nude mice-bearing human liver cancer (SMMC-7721) xenografts have shown that the radioactivity distribution ratio of 131I-D2C on T/NT was 2–14:1 or 3–21:1 on the seventh day after intraperitoneal or intratumoral injection of 131I-labeled D2C (131I-D2C). These evidences indicated that the in vivo distribution of D2C display the characteristics of certain tumor-specificity localization. In vitro studies, D2C can induce the apoptosis of K562 through the mitochondria death pathway and arrest the cell at G1 phase, as determined by cell cycle analysis. Using the human tumor cells (K562, CEM, and SMMC-7721) expressing TfR as target cells, and normal human PBMC as effector cells, Fc fragment of D2C can perform both the antibody-dependent cell-mediated cytotoxicity and the complement-dependent cytotoxicity. Together, it was demonstrated that the D2C display a tumor-specificity distribution, and has a strong antitumor effect. Thus, it has the potential therapeutic significance.

Construction and expression of eukaryotic expressing vector pCH510 of polypeptide CH50 and its chemotaxis and antitumor function by in vivo transfection.

SummaryTo construct an eukaryotic expressing vector that expresses CH50, a recombinant Cell I-Hep I bifunctional-domain polypeptide of human fibronectin, and to investigate the chemotaxis to immune cells and the inhibitory effect on the growth of tumor by the expression of the plasmidin vivo, the plasmid was constructed by DNA recombination. Gene transfection was performedin vitro andin vivo. The expressed product was identified by Western blot. The chemotaxis after gene transfectionin vivo was observed by histotomy and staining of muscle tissues. The inhibition of gene transfection on solid tumor was observed in mice. The results showed that plasmid pCH510 was constructed by the recombination of the 5′-terminal noncoding region and signal peptide coding region of human fibronectin cDNA and cDNA fragment coding CH50 polypeptide with a 3′-terminal noncoding region of human FN cDNA, and the insertion of the recombinated fragment into plasmid pcDNA3. 1. After transfection with plasmid pCH510, NIH3T3 cells could produce CH50 polypeptide. The transfection of plasmid pCH510 by the injection in muscle of mouse could produce the effects of chemotaxis on immune cells and the inhibition on the growth of solid tumor. It is concluded that plasmid pCH510 can express in cells andin vivo in mouse. The expression of the plasmidin vivo has a chemotactic effect on immune cells and can inhibit the growth of solid tumor.

Inhibitory effect of recombinant endostatin on angiogenesis and tumor growth of hepatoma

SummaryTo study the influence of recombinant endostatin on angiogenesis and tumor growth of mice H22 hepatoma, tumor models were constructed by injecting H22 hepatoma cells into the leg muscle of mice. Recombinant endostatin was produced by gene engineering in E. coli. The recombinant protein was injected subcutaneously to treat transplanted hepatoma faraway. The weight of tumors was measured, and the changes of necrosis of tumor cells and vessel density were observed by immunohistochemistry. The results suggested that the growth of hepatoma models transplanted in the muscle of legs was suppressed by recombinant endostatin. The density of vacularity was decreased, but the necrosis of tumor cells increased. The inhibitory effect of recombinant endostatin on angiogenesis and tumor growth of hepatoma was not affected after chemotherapy.

Investigation on the effects of soluble programmed death-1 (sPD-1) enhancing anti-tumor immune response.

SummaryBy using semi-quantitative RT-PCR method, it was found that PD-L1 mRNA but not PD-L2 mRNA was expressed in H22 hepatoma cells and both PD-L1 and PD-L2 mRNAs were expressed in tumor tissues of tumor-bearing mice and upregulated as compared with muscle tissues in normal mice and H22 hepatoma cells. PD-L1 and PD-L2 were also expressed on the surface of the activated T cells. The soluble recombinant sPD-1 expressed from the constructed eukaryotic expression vector could enhance the lysis of tumor cells by lymphocytes stimulated specifically with antigen. The expression of sPD-1 by local gene therapy on the inoculation site of H22 hepatoma cells could inhibit the growth of tumor. The results of this study indicate that expression of soluble receptor of negative costimulatory molecules could reduce the inhibitory effect on T cells in tumor microenvironment and enhance the cytotoxicity of T cells on tumor cells. This possibly provides a new method of improving efficacy of tumor gene therapy.

Inducement of antitumor-immunity by DC activated by Hsp70-H22 tumor antigen peptide

Objective: To investigate the feasibility of decreasing the dosage of tumor antigen peptides by dendritic cell (DC)-presenting and the characteristics of modification of DC by heat shock protein (Hsp70) and antigen peptides. Methods: Peptides were bound to Hsp70 and used to modify DCin vitro. The metabolism of the modified DC and the cytokines secreted by the modified DC were determined. The activation of lymphocytes by the modified DC and Hsp70-H22 peptides was tested. The cytotoxicity of the activated lymphocytes to H22 tumor cells was analyzed. The inhibitory effect of tumor in mice by the injection of DC and Hsp70-H22 peptides was tested. Results: 0.15 µ g of H22 peptides bound with Hsp70 could make 2 ×105 DC mature. 4×103 matured DC could activate 2×106 lymphocytes. The same amount of lymphocytes could be activated to produce similar cytotoxicity to tumor cells by either DC modified by 0.003µg of peptides bound with Hsp70 or by direct stimulation with 0.15 µg of peptides bound with Hsp70. The dosage of peptides could be reduced by about 50 folds if the modified DC was used for injection instead of Hsp70-peptides. Peptides from normal hepatocytes, bound with Hsp70, could not make DC mature, nor activate lymphocytes through DC. Conclusion: The dosage of Hsp70-H22 peptides can be reduced significantly by DC-presenting to activate lymphocytes. Peptides from normal cells could not activate lymphocytes by either Hsp70-presenting or DC-presenting and they have little chance to induce autoimmunity.

Effects of gene tranfection with CH50 polypeptide on the invasion ability of bladder cancer cell line BIU-87

SummaryThe expression of CH50 polypoptide in bladder cancer cell line BIU-87 and the effects on the invasion ability of BIU-87 were investigated. The eukaryotic expressing vector pCH510 of polypeptide CH50 was introduced into BIU-87 cells by gene transfectionin vitro. The expression of CH50 polypeptide was detected by using immunobistochemical S-P method. The expression of the transfected gene was identified by RT-PCR. Cell invasion assay kit was applied to detect the effect of CH50 polypeptide on the invasion ability of BIU-87. The results showed that the BIU-87 cells transfected with pCH510 could express the CH50 polypeptide, while in the control group, no CH50 polypeptide was detectable. In the transfection group, the invasion ability of BIU-87in vitro was lower than in control group (P<0.05). It was concluded that CH50 polypeptide was successfully expressed in BIU-87 cells by gene transfection, by which thein vitro invasion ability of BIU-87 was inhibited.The expression of CH50 polypoptide in bladder cancer cell line BIU-87 and the effects on the invasion ability of BIU-87 were investigated. The eukaryotic expressing vector pCH510 of polypeptide CH50 was introduced into BIU-87 cells by gene transfection in vitro. The expression of CH50 polypeptide was detected by using immunohistochemical S-P method. The expression of the transfected gene was identified by RT-PCR. Cell invasion assay kit was applied to detect the effect of CH50 polypeptide on the invasion ability of BIU-87. The results showed that the BIU-87 cells transfected with pCH510 could express the CH50 polypeptide, while in the control group, no CH50 polypeptide was detectable. In the transfection group, the invasion ability of BIU-87 in vitro was lower than in control group (P<0.05). It was concluded that CH50 polypeptide was successfully expressed in BIU-87 cells by gene transfection, by which the in vitro invasion ability of BIU-87 was inhibited.

INVESTIGATION OF INDUCING EFFECT OF SPECIFIC CYTOTOXICITY OF CTLS BY ANTIGEN PEPTIDES FROM T LYMPHOCYTIC LEUKEMIA CELLS

Objective: To investigate the characteristics of specific antitumor immunity induced by antigen peptides mixture from T lymphocytic leukemia cells. Method: Antigen peptides mixtures were prepared from different leukemia cell lines and then bound with Hsp70in vitro. Human peripheral blood mononuclear cells (PBMC) were culturedin vitro, and activated with Hsp70-antigen peptides. The activated PBMC was cultured continuouslyin vitro, and used as effector cellsin vitro test of cytotoxicity to different target cells. Results: The antigen peptides from different leukemia cell lines were peptides mixture and could activate PBMC effectively if they were presented by Hsp70. The activated PBMC could proliferate in the presence of IL-2 and Hsp70-antigen peptides. The proliferative PBMC had specific cytotoxicity to leukemia cells corresponding to the antigen peptides. PBMC activated by antigen peptides from T lymphocytic leukemia cell lines could effectively kill T lymphocytic leukemia cells, and the cytotoxicity of these PBMC to T lymphocytic leukemia cells was significantly stronger than that of PBMC activated by antigen peptides from other leukemia cells (P<0.05). PBMC activated by either Hut78-peptides or Molt 4-peptides could effectively kill Jurkat cells. And the cytotoxicity of PBMC activated by Hut78/Molt-4-peptides to Jurkat cells was significantly stronger than that of PBMC activated by either Hut78-peptides or Molt-4-peptides alone (P<0.05). Conclusion: Antigen peptides mixture from T lymphocytic leukemia cell lines can induce specific cytotoxic effect to T lymphocytic leukemia cells. There exists cross-reactivity among antigen peptides mixture from different T lymphocytic leukemia cell lines. The cross-reactivity could be amplified by blending of different antigen peptides from different T lymphocytic leukemia cell lines, suggesting that it is possible to prepare broad-spectrum antigen peptide vaccine against T lymphocytic leukemia by using multiple leukemia cell lines.

Investigation of the therapeutic effect of expression of trailin vivo on mouse hepatocellular carcinoma

Objective: To construct an eukaryotic expressing plasmid of mouse TRAIL (mTRAIL), and investigate its ability to induce the apoptosis of hepatocellular carcinoma cellsin vitro and in vivo, its inhibitory effect on the growth of hepatocellular carcinoma, and its synergism with pCH510, an eukaryotic expressing plasmid of recombinant human FN polypeptide. Methods: The eukaryotic expressing plasmid of mTRAIL was constructed by RT-PCR and DNA recombination techniques. Gene transfection was performedin vitro and in vivo. The apoptosis rate of hepatocellular carcinoma cells was measured by Flow Cytometry. The apoptosis of hepatocellular carcinoma cells was detected by TdT-mediated dUTP nick end labeling (TUNEL) and histochemistry techniques. The inhibitory effect of gene transfection on solid tumor was observed in mice. Results: The cDNA of mTRAIL was amplified by RT-PCR from the RNA of mouse spleen cells, and cloned into the eukaryotic expressing vector pcDNA3.1. The recombinant plasmid was designated as pXl. The BHK cells transfected with plasmid pXl could attack H22 hepatocellular carcinoma cells and induce the apoptosis of them. The transfection of plasmid pX1 through injection into mouse muscles could inhibit the growth of hepatocellular carcinoma by inducing the apoptosis of tumor cells. Plasmid pX1 and pCH510 had a synergistic inhibitory effect on the hepatocellular carcinoma growth. Conclusion: Plamid pX1 could be expressed in cells andin vivo in mouse. The expression of pX1in vivo andin vitro could induce the apoptosis of hepatocellular carcinoma cells and inhibit the growth of hepatocellular carcinoma. Plasmid pX1 and pCH510 had a synergistic inhibitory effect on the hepatocellular carcinoma growth.

Study on the preparation of recombinant human HSP70 and its presenting-antigen function

SummaryThe preparation of recombinant human HSP70 and its presenting-antigen function were investigated. Cultured in glucose-free M9ZB medium and induced with IPTG and lactose at a final concentration of 0. 02 mmol/L and 5 mmol/L respectively, the engineered bacteria carrying expression vector of human HSP70 gene expressed rHSP70 at an efficiency of 60 %. After the purification with DEAE ion-exchange chromatography, HSP70 with a purity of higher than 90 % was obtained. The purified product could bind tumor-antigen peptidein vitro, and the binding was identified by native PAGE containing 5 % glycerol. HSP70-peptide complex could activate lymphocytes to produce specific cytotoxicity to tumor cells, suggesting that the recombinant human HSP70 could be used as an antigen-presenting reagent in tumor therapy.