Biomedical subjects

Bei-fen Shen

Publications and source records attributed to Bei-fen Shen.

11 recordsLinked to original sources

PubMed2006

[The expression, renaturation, purification and preliminary identification of human IgE Cepsilon3-Cepsilon4].

AIM: To gain recombinant protein Cepsilon3-Cepsilon4 of IgE Fc (E34). METHODS: We cloned the gene coding human IgE Cepsilon3-Cepsilon4 (E34) and constructed an expression vector pET28a(+)-E34. The target protein was expressed as inclusion body in E.coli BL-21. Following renaturation and purification through a CM sephorose FF column, the soluble protein was acquired, and its binding ability to murine anti-hIgE mAb was identified by Western blot and ELISA. RESULTS: The cloned E34 gene was sequenced and proved by SDS-PAGE to be the same as reported sequence. SDS-PAGE analysis showed the relative molecular mass of E34 protein obtained was correct as predicted. Western blot and ELISA data revealed that it owned the epitope of binding to murine anti-hIgE mAb. CONCLUSION: The expression vector pET28a(+)-E34 has been successfully constructed and the target protein E34 recognized specifically by murine anti-hIgE mAb is obtained.

Antibodies, Monoclonal↗

PubMed2006

[Construction and expression of chimeric anti-human CD20 monoclonal antibody].

AIM: To construct the eukaryotic expression vector of chimeric anti-human CD20 monoclonal antibody (mAb) and realize its expression. METHODS: The light- and heavy-chain genes were amplified from hybridoma cell line 1-28 secreting anti-human CD20 mAb by RT-PCR and were cloned to T vector and sequenced. Proteins of mAb 1-28 were separated by reducing SDS-PAGE. Light- and heavy-chain bands were excised from preparative gel, digested by trypsin, and subjected to peptide mass fingerprinting. Software Biolynx and pepeseq were used to evaluate the score of probability. Correctness of the light- and heavy-chain DNA sequences was verified by their protein sequences. Genes of V(H) and V(L) were amplified from T vector and cloned into chimeric antibody expression vector (pCMV-V(H) and pCMV-V(L)), generating the expression vectors of chimeric anti-human CD20 mAb (C1-28) including light chain expression vector C1-28L and heavy chain expression vector C1-28H. The two plasmids were co-transfected into 293T cells with Lipofectamine 2000. RT-PCR was used to detect the transcription at mRNA level. C1-28 expression was detected by Sandwich ELISA and Western blot methods. RESULTS: mAb 1-28's genes were successfully cloned and verified by peptide mass fingerprinting. Eukaryotic expression vectors of anti-human CD20 mAb were constructed and expressed in 293T cells with the expression amount reaching 257 mg/L and the molecular weight consistent with that of human IgG. CONCLUSION: These experiments lay solid foundation for further study on the role of chimeric CD20 antibody in the treatment of non-Hodgkin's lymphoma.

Antibodies, Monoclonal↗

PubMed2005

Proteomics-based identification of human acute leukemia antigens that induce humoral immune response.

The identification of panels of tumor antigens that elicit an antibody response may have utility in cancer screening, diagnosis, and establishing prognosis. Until now, autoimmunity in cancer has been mainly revealed in solid tumors. The aim of this study was to apply the proteomic approach to the identification of proteins that commonly elicit a humoral response in acute leukemia (AL). Sera from 21 newly diagnosed patients with AL, 20 patients with solid tumors, and 22 noncancer controls were analyzed for antibody-based reactivity against AL proteins resolved by two-dimensional electrophoresis. As a result, autoantibody against a protein identified by mass spectrometry as Rho GDP dissociation inhibitor 2 was detected in sera from 15 of 21 patients with AL (71%). By contrast, such antibody was detected in sera from one of 20 patients with solid tumors (5%) and one of 22 noncancer controls (4.5%). Five other protein autoantibodies were also found in AL patients with a high frequency and constituted the major target antigens of the AL autoimmune response. The findings of autoantibodies against Rho GDP dissociation inhibitor 2 and other proteins in sera of patients with AL suggest that the proteomic approach we have implemented may have utility for the development of a serum-based assay for AL screening and diagnosis.

Adolescent↗

PubMed2005

[Experimental study of adoptive immunotherapy using CD3AK cells].

AIM: To analyze the immunological properties and biological activity of a monoclonal antibody (mAb) against CD3 molecule(yCD3), and to observe the tumor-suppressive activity of CD3AK cells in vitro and in vivo. METHODS: FCM was used to test the specificity of yCD3 and the immunological phenotype and cytokine production of CD3AK. 3H-TdR assay was used to measure the transformation of lymphocytes activated by yCD3. LDH assay was used to analyze the cytotoxic activity of CD3AK in vitro. Mice bearing tumors were used to observe the anti-tumor effect of CD3AK cells. RESULTS: yCD3 could bind specifically to T cells. 5 microg yCD3 could competitively inhibit 70% of standard anti-CD3 antibody to bind with CD3 molecules on cell membrane. 8 microg/L of yCD3 stimulated the proliferation of peripheral blood lymphocytes, which could be further boosted by IL-2 or anti-CD28 antibodies. Among activated CD3AK cells, CD3+, CD8+, and CD25+ cells increased. IL-2 and IFN-gamma producing CD3+ cells were also increased, to 3.29- and 2.47- fold, respectively, under the co-stimulation of anti-CD28 antibody. When the ratio of effective cells and target cells was 80:1, 57.54% target cells were killed. As compared with control, the percent of tumor inhibition in CD3AK cells treated tumor-bearing mice was 33.17%, and the inhibition rate of lung metastasis was 39.70%. The CD3AK cells treatment was more effective when combined with LAK cells. CONCLUSION: yCD3 could activate T cells and significantly induce the tumor-suppressive activity of CD3AK cells in vitro and in vivo, which lays a foundation for adoptive immunotherapy against tumors in clinical medicine.

Animals↗

PubMed2005

[Cloning of variable region and signal peptide genes of anti-CD20 monoclonal antibody by RLM-RACE].

AIM: To seek a good method for simultaneous cloning V(L), V(H) and signal peptide genes of anti-CD20 monoclonal antibody (mAb) from hybridoma cells 1-28. METHODS: Total RNA was prepared from hybridoma cells 1-28 by Trizol. Two methods were used to clone the target genes. One was traditional rapid amplification of 5' cDNA end (T-5' RACE), and the other was RNA ligase-mediated rapid amplification of 5' cDNA end (RLM-RACE). The PCR products were then cloned into pGEM-T Easy vector, sequenced and analyzed with Blast method using Kabat and GenBank Databases. RESULTS: The target genes of L chain and H chain were both successfully cloned by RLM-RACE, while only V(L) gene and its signal peptide genes were obtained by T-5' RACE. CONCLUSION: RLM-RACE is a good method for cloning antibody's V gene and signal peptide genes.

5' Untranslated Regions↗

PubMed2004

[Mannosylation of ligand binding domain 2 of HER-2/neu].

AIM: To establish a new method for protein mannosylation, which will facilitate the study of antigen presentation mediated by mannose receptor. METHODS: Recombinant HER-2/neu ligand binding domain 2 (LBD2) was purified through DEAE sepharose FF column and cobalt-based affinity resins. LBD2 protein was mannosylated in-vitro,and then analyzed by MALDI-TOF-MS and resorcinol-sulfuric acid method. RESULTS: The purity of LBD2 obtained was 90%. Analysis of MALDI-TOF-MS and resorcinol-sulfuric acid method suggested LBD2 was mannosylated. CONCLUSION: LBD2 neoglycoprotein has been obtained, which lays the foundation for the study of antigen uptake and presentation mediated by mannose receptor and the development of tumor vaccine.

Binding Sites↗

PubMed2004

[Expression of antibody Fab against platelet IIb/IIIa in E.coli and characterization of its biological activity].

AIM: To develop a Fab antibody against platelet GPIIb/IIIa. METHODS: A mouse anti-human GPIIb/IIIa monoclonal antibody (mAb) P140 was selected by the indirect immunofluorescence assay (IFA) and platelet aggregation inhibition test. The Fd and light chain genes were cloned from the hybridoma cells secreting the mAb P140. The genes of P140 Fab were inserted into plasmid p3MH to construct recombinant expression plasmid p3MH/P140kappa-Fd. After digestion with the restriction enzyme, the recombinant plasmid was transformed into E.coli XLI-Blue. The expressed product was purified by TALON metal affinity resin. Purified P140 Fab was characterized by SDS-PAGE, ELISA, Western blot and platelet aggregation inhibition test. RESULTS: SDS-PAGE analysis showed that relative molecular mass (M(r)) of P140 Fab was 47x10(3). The results of ELISA, Western blot and platelet aggragation inhibition test indicated that P140 Fab could specifically bind to platelet and inhibit platelet aggragation in dose-dependent manner. The mean value of IC(50) was 16.85 mg/L. CONCLUSION: A soluble anti-platelet GPIIb/IIIa antibody P140 Fab was prepared successfully, which lays the foundation for further clinical application.

Amino Acid Sequence↗

PubMed2004

[Nano-ESI-MS/MS identification on differentiation-associated proteins in M1 mouse myeloid leukemia cells induced by IL-6].

OBJECTIVE: To identify two differentiation-associated proteins induced by rhIL-6 in M1 mouse myeloid leukemia cells. METHODS: Protein spots were excised from 2-D gels and digested in-gel with trypsin. The trypsin lysis products were first analyzed by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) through peptide mass fingerprinting and then performed peptide sequencing by nano-electrospray ionization mass spectrometry/mass spectrometry (nano-ESI-MS/MS). The database search was finished with the Mascot search engine (http://www.matrixscience.co.uk) using the data processed through MaxEnt3 and MasSeq. RESULTS: The two proteins were not revealed by peptide mass fingerprint using MALDI-TOF-MS, while they were respectively identified as Destrin and Putative protein after the sequence of their trypic peptides were obtained by the nano-ESI-MS/MS techniques. CONCLUSION: Nano-ESI-MS/MS technique can successfully identify the two differentiation-associated proteins induced by rhIL-6 and has great advantage in protein analysis.

Actin Depolymerizing Factors↗

PubMed2003

[Biological analysis of a novel gene related with interleukin-6].

OBJECTIVE: To understand the action mechanism of interleukin (IL)-6 through investigation of its related genes. METHODS: Using electronic cloning with IL-6-related expressed sequence tags (ESTs), a novel gene at its full length of 924 bp was acquired. Reverse transcriptase-PCR method was subsequently employed to amplify the cDNA of this gene from the total RNA of human U937 cells, which were previously activated with 100 ng/ml IL-6 for 8 h. The fragment was then ligated into the pGEM-Teasy vector and sequence analysis was conducted. RESULT: The whole cDNA gene was successfully fished. CONCLUSION: Electronic cloning technology can be instrumental in identifying novel genes.

Amino Acid Sequence↗

PubMed2003

[Identification of HCV antigen epitopes from a random 15-peptide library by anti-HCV polycloral antibody].

AIM: To analyze epitope recognized by anti-HCV antibodies; patients suffered from hepatitis C. METHODS: Anti-HCV Abs were purified from the patients serum through an affinity chromatography column which was prepared with sepharose 4B coupled with protein A. These Abs were used for biopanning of a phage-displayed random 15-peptide library. RESULTS: After 3 rounds of biopanning, the ratio of output to input increased to 3.3 x 10(3) and the false positive rate reduced to 0.2%, suggesting that the enrichment was effective. After the third round of biopanning, sixteen clones were selected to conduct binding test to Abs from the patients and normal person's sera. Nine of them were proved to react specifically to the sera from the patients. From the deduced insert sequence in the coat protein VIII, the core sequence of WPWS was found in 8 clones. The positive phage clones could react to different patients' and not react to normal person's sera. CONCLUSION: These findings indicate that WPWS motif in the short peptide may mimic the HCV epitope recognized by anti-HCV Abs.

Amino Acid Sequence↗

PubMed2002

IL-6 inhibits apoptosis of human myeloma cell line XG-7 through activation of JAK/STAT pathway and up-regulation of Mcl-1.

BACKGROUND & OBJECTIVE: IL-6 can protect myeloma cells from apoptosis induced by various stimuli. A series of intracellular molecules might participate in this process. Our aim in this study is to investigate which anti-apoptotic Bcl-2 family proteins (Bcl-2, Bcl-XL, Mcl-1) and which signal transduction pathway(JAK/STAT, Ras/MAPK, PI-3K/Akt) can mediate the anti-apoptotic effect of IL-6 on a human myeloma cell line XG-7. METHODS: Apoptosis of XG-7 cells was analyzed by flow cytometry with propidium iodide(PI) staining of nuclei. The expression of three Bcl-2 family proteins in XG-7 cells were monitored by immunoblot assay. AG490, PD98059, and LY294002, three specific antagonists for JAK/STAT, Ras/MAPK, and PI-3K/Akt signal transduction pathways respectively, were used to determine which signal transduction pathway was responsible for the effect of IL-6 on XG-7 cells. RESULTS: IL-6 inhibited the apoptosis of XG-7 cells and up-regulated the expression of only one of the three anti-apoptotic Bcl-2 family proteins-Mcl-1. In addition, up-regulation of Mcl-1 expression induced by IL-6 was significantly inhibited in the presence of AG490, while not of PD98059 and LY294002. CONCLUSIONS: IL-6 inhibited apoptosis of XG-7 cells through up-regulation of Mcl-1 and the activation of JAK/STAT rather than Ras/MAPK nor PI-3K/Akt signal transduction pathway.

Apoptosis↗