ABSTRACT
This study is to optimize the preparation process of fusion protein Fv-LDP which was expressed in the form of inclusion body and consisted of lidamycin apoprotein LDP and single-chain Fv antibody (scFv) directed against type IV collagenase. The preparation and the dissolution of inclusion body, the immobilized metal affinity chromatography of the target protein and the renaturization by stepwise dialysis were optimized by single-factor analysis or orthogonal design. In addition, the refolded fusion protein Fv-LDP was refined by Sephadex G-75 chromatography followed by fluorescence-activated cell sorter (FACS)-based saturation binding assay to measure its antigen-binding activity. After optimization of the process, the purity of fusion protein Fv-LDP existed in the inclusion body was 63.9% and the corresponding solubility was 95.7%; Under denaturing conditions, the purity of fusion protein Fv-LDP was more than 95% after the purification process. The percentage of monomeric fusion protein Fv-LDP was 60% after the refolding process, while it was further refined to 85% which was 5.6-fold higher than that of the initial refolding condition. The refined fusion protein Fv-LDP could bind to human lung adenocarcinoma PAa cells and human hepatoma BEL-7402 cells with the dissociation constants (Kd) of 0.176 micromol x L(-1) and 0.904 micromol x L(-1), respectively. The preparation process of fusion protein Fv-LDP has been successfully optimized, which provides the experimental basis for the production and future development of fusion protein Fv-LDP, and might serve as a relatively practical system for the preparation of other scFv-based proteins expressed in the form of inclusion body.
Subject(s)
Humans , Adenocarcinoma , Metabolism , Pathology , Aminoglycosides , Chemistry , Metabolism , Antibiotics, Antineoplastic , Chemistry , Metabolism , Apoproteins , Chemistry , Metabolism , Carcinoma, Hepatocellular , Metabolism , Pathology , Cell Line, Tumor , Collagenases , Allergy and Immunology , Enediynes , Chemistry , Metabolism , Escherichia coli , Chemistry , Metabolism , Inclusion Bodies , Chemistry , Metabolism , Liver Neoplasms , Metabolism , Pathology , Lung Neoplasms , Metabolism , Pathology , Protein Binding , Recombinant Fusion Proteins , Chemistry , Metabolism , Single-Chain Antibodies , Chemistry , MetabolismABSTRACT
This study is to investigate the binding capability of lidamycin apoprotein (LDP), an enediyne-associated apoprotein of the chromoprotein antitumor antibiotic family, to human breast cancer and normal tissues, the correlation of LDP binding capability to human breast cancer tissues and the expression of tumor therapeutic targets such as VEGF and HER2. In this study, the binding capability of LDP to human breast cancer tissues was detected with tissue microarray. The correlation study of LDP binding capability to human breast tumor tissues and relevant therapeutic targets was performed on breast cancer tissue microarrays. Immunocytochemical examination was used to detect the binding capability of LDP to human breast carcinoma MCF-7 cells. As a result, tissue microarray showed that LDP staining of 73.2% (30/41) of breast cancer tissues was positive, whereas that of 48.3% (15/31) of the adjacent normal breast specimens was positive. The difference between the tumor and normal samples was significant (Chi2 = 4.63, P < 0.05). LDP immunoreactivity in breast cancer correlated significantly with the overexpression of VEGF and HER2 (P < 0.001 and < 0.01, r = 0.389 and 0.287, respectively). Determined with confocal immunofluorescent analysis, LDP showed the binding capability to mammary carcinoma MCF-7 cells. It is demonstrated that LDP can bind to human breast cancer tissues and there is significant difference between the breast cancer tissues and the corresponding normal tissues. Notably, the binding reactivity shows positive correlation with the expression of VEGF and HER2 in breast carcinoma tissues. The results imply that LDP may have a potential use as targeting drug carrier in the research and development of new anticancer therapeutics. This study may provide reference for drug combination of LDM and other therapeutic agents.
Subject(s)
Female , Humans , Aminoglycosides , Metabolism , Antibiotics, Antineoplastic , Metabolism , Apoproteins , Metabolism , Breast Neoplasms , Metabolism , Pathology , Cell Line, Tumor , Enediynes , Metabolism , Protein Binding , Receptor, ErbB-2 , Metabolism , Tissue Array Analysis , Methods , Vascular Endothelial Growth Factor A , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To study the effect of co-blockage of vascular endothelial growth factor (VEGF) and its receptor (KDR) on growth of bladder carcinoma T24 cells and nude mice xenograft.</p><p><b>METHODS</b>T24 cell line co-transfected with VEGF siRNA and sKDR expression plasmids was developed and its proliferation was assayed by MTT and apoptosis by FCM. The nude mice model bearing bladder carcinoma xenograft was established. The tumor cell VEGF expression, stroma microvessel density (MVD) and tumor cell topoisomerase II alpha (Topo II alpha) expression were detected by immunohistochemistry. Cell apoptosis was estimated by TUNEL assay.</p><p><b>RESULTS</b>MTT assay showed that cell proliferation in VEGF siRNA, sKDR and combination groups was 56.3% +/- 8.3%, 42.6% +/- 13.8% and 32.5% +/- 4.3%, respectively, significantly lower than that in the scramble control (97.3% +/- 11.6%, P < 0.0001). FCM showed there were sub-diploid apoptotic peaks before G1 phase in VEGF siRNA, sKDR and combination groups, and apoptosis ratio was 5.1% +/- 0.9%, 4.2% +/- 0.5% and 8.8% +/- 0.7%, respectively, all of which were higher than that in the scramble control (0.9% +/- 0.4%, P < 0.05), and the combination group had even more higher apoptosis than the two singlely treated groups (P < 0.01). In vivo test showed that tumor growth was inhibited in VEGF siRNA, sKDR and combination groups, and from day 16 the tumor volume in combination group was significantly smaller than that in scramble control (P < 0.05), and from day 28 the tumor almost lost the ability to further growth. Immunohistochemistry revealed VEGF expression in combination group was 54.37 +/- 5.28, significantly lower than that in the scramble control (141.66 +/- 8.59, P < 0.0001). MVD number was only 8.22 +/- 3.79, much less compared with that in the scramble control (61.76 +/- 5.28, P < 0.0001) or sKDR group (19.46 +/- 4.16, P = 0.0089). Tumor cell proliferation index in the combination group (1.5% +/- 0.7%) was significantly decreased compared with that in the scramble control (11.8% +/- 5.2%, P < 0.0001), and apoptosis index (67.2% +/- 8.5%) was much higher than that in the scramble control (8.7% +/- 2.7%, P < 0.0001), VEGF siRNA group (54.3% +/- 4.8%, P = 0.0492) or sKDR group (52.3% +/- 6.4%, P = 0.0293).</p><p><b>CONCLUSION</b>VEGF siRNA or sKDR alone can inhibit tumor cell proliferation and induce cell apoptosis, but co-blockage of VEGF and KDR by their combination shows more significant therapeutic efficacy.</p>
Subject(s)
Animals , Humans , Male , Mice , Apoptosis , Cell Line, Tumor , Cell Proliferation , Gene Expression Regulation, Neoplastic , Mice, Inbred BALB C , Mice, Nude , Neoplasm Transplantation , Neovascularization, Pathologic , Plasmids , RNA Interference , RNA, Small Interfering , Genetics , Transfection , Tumor Burden , Urinary Bladder Neoplasms , Metabolism , Pathology , Vascular Endothelial Growth Factor A , Genetics , Metabolism , Vascular Endothelial Growth Factor Receptor-2 , Genetics , Metabolism , Xenograft Model Antitumor AssaysABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of lidamycin (LDM) on telomerase activity in human hepatoma BEL-7402 cells under the condition of LDM inducing mitotic cell death and senescence.</p><p><b>METHODS</b>Chromatin condensation was detected by co-staining with Hoechst 33342 and PI. Cell multinucleation was observed by Giemsa staining and genomic DNA was separated by agarose gel electrophoresis. Fluorescent intensity of Rho123 was determined for mitochondrial membrane potential. MTT assay and SA-beta-gal staining were employed to analyze the senescence-like phenotype. The expression of proteins was analyzed by Western blot. Telomerase activity was assayed by telomerase PCR-ELISA.</p><p><b>RESULTS</b>Mitotic cell death occurred in LDM-treated cells characterized by unique and atypical chromatin condensation, multinucleation and increased mitochondrial membrane potential. However, no apoptotic bodies or DNA ladders were found. In addition, apoptosis-related proteins remained nearly unaltered. Senescence-like phenotype was identified by increased and elongated size of cells, growth retardation, enhanced SA-beta-gal activity and the changes of senescence-related protein expression. Telomerase activity markedly decreased (P<0.01) in LDM-treated hepatoma BEL-7402 cells.</p><p><b>CONCLUSION</b>Mitotic cell death and senescence could be triggered simultaneously or sequentially after exposure of hepatoma BEL-7402 cells to LDM. The decrease in telomerase activity may play a key role in the defective mitosis and aging morphology. Further investigation of detailed mechanism is needed.</p>