Enhanced expression of human vimentin intermediate filaments in hepatocellular carcinoma cells decreases their proliferative and invasive abilities in vitro / 中华肿瘤杂志

<p><b>OBJECTIVE</b>Expression of vimentin in carcinoma cells is a marker for poor prognosis in patients. The aim of this investigation was to assess the influence of vimentin on the characteristics of carcinoma cells.</p><p><b>METHODS</b>The full-length vimentin gene open reading frame (1401 base pairs) was cloned into the plasmid vector pcDNA 3.1 (+), and these vectors were used to stably transfect the human hepatocellular carcinoma HepG2 cell line. Vimentin gene expression was evaluated by RT-PCR and Western blot. Proliferative activity and invasive potential of tumor cells were determined by the CellTiter 96 aqueous one solution cell proliferation assay and BioCoat GFR Matrigel invasion chamber, respectively.</p><p><b>RESULTS</b>DNA sequencing and restriction endonuclease digestion analysis demonstrated that the recombinant vector was correctly cloned. The stable cell line demonstrated a higher vimentin RNA and protein expression. However, both proliferative and invasive abilities of the cells were reduced in vitro ( P < 0.05).</p><p><b>CONCLUSION</b>A recombinant plasmid pcDNA3. 1-VIM is successfully constructed and a carcinoma cell line HepG2-pV highly expressing vimentin is obtained. Recombinant vimentin protein suppresses the proliferative and invasive abilities of HepG2 cells, suggesting that it might decrease malignant phenotype of tumor cells in vitro. This work makes a foundation for further study on the relationship between vimentin and biological phenotype of carcinoma cells.</p>

Construction and expression of a novel bisbicistronic expression vector: pCMV-Myc-IRES-EGFP / 生物工程学报

It is often necessary to construct more than one recombinant plasmids when investigating the characteristics, physchemical features and functional mechanisms of genes or proteins. Repeated sub-cloning procedures including design of primers, enzyme digestion, ligation and verification of recombinant plasmids, have to be involved with. For this reason, it has become a tendency to developing new genetic vectors which can be used in multitude of experiments. Therefore, by using pIRES vector as a backbone, here we reported the construction of a mammalian expression vector: pCMV-Myc-IRES-EGFP which contains the N-terminal c-Myc epitope tag and the enhanced green fluorescent protein (EGFP) translated in an IRES-dependent manner. This novel vector can be used to testify the efficiency of cell transfection, to collect successfully transfected cell population via cytometry, to conduct transcription and translation in vitro, to purify target proteins or to trap their interactional proteins. The availability of this vector can facilitate function study of genes.

Searching for genes interacting with human PCIA1 gene by using the bacterial two-hybrid system / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To search for the genes which could interact with newly found homo sapiens cross-immune reaction antigen (PCIA1) gene and accordingly to provide insights into the study of the gene function.</p><p><b>METHODS</b>The Stratagene's BacterioMatch Two-Hybrid System and BacterioMatch Fetal Kidney Library were adopted and the recombinant bait plasmid pBT-PCIA1 was cotransformated with the target plasmid pTRG-cDNA library DNA into the reporter stain. After screening and isolation of positive pTRG clones, the target genes were identified by DNA sequencing and bioinformation analysis.</p><p><b>RESULTS</b>Among all the seven detected target genes, three genes' function were not known, the other four genes had important functions. Their mutations or abberant expression resulted in severe diseases and overexpression of ACTN4 (actinin, alpha 4), PSAP (prosaposin) or EIF3S10 (eukaryotic translation initiation factor 3, subunit 10 theta) could promote tumor development and progression.</p><p><b>CONCLUSION</b>The bacterial two-hybrid system technique is an efficient method, which can provides insights into the study of novel genes' function by detecting protein-protein interactions. This study indicates that PCIA1 gene expression correlates with tumor formation, invasion and metastasis.</p>

Prokaryotic expression of extracellular ligand binding domains of chick tie-2 and its anti-angiogenesis effect / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>