Objective To construct the responsive plasmid PTRE-HIF-1αof Tet-on gene expression system and examine its expression. Methods RT-nested PCR was performed on the total RNA extracted from hypoxia HepG2 cells to obtain the cDNA of HIF-1α, which was inserted into the responsive plasmid PTRE2hyg. DNA sequencing was performed after the recombinant of responsive plasmid PTRE-HIF-1α was identified by endonuclease digestion. This recombinant vector was transfected into HepG2Tet-on cells by means of liposome and its expression was examined by RT-PCR and Western blot under the control of deoxycycline. Results The amplified products were confirmed as the cDNA of HIF-1α by DNA sequencing. The responsive plasmid PTRE-HIF-1α verified by edonuclease digestion, was capable of expression in HepG2Tet-on cells and could be controlled by deoxycycline. Conclusion The responsive plasmid PTRE-HIF-1α of Tet-on expression system is constructed successfully, and it can express under the regulation of deoxycycline in the HepG2Tet-on cells.
Objective To be expressed human vascular endothelial growth factor (VEGF) recombinant protein in Escherichia Coli in high level. Methods VEGF was amplified from human fetal brain cDNA library, the amplified fragment was inserted into M13mP18 and confirmed to be VEGF165cDNA by restriction mapping and DNA sequencing, then it was combined with an expression vector PRL621. This recombinant plasmid overexpressed a 20kd recombinant protein in E.Coli(TG1), the protein was isolated and purifed from E.Coli, and initially renatured. Results The overexpressed recombinant protein was 35% of the total cell protein, the sequence of its first 15-N terminal amino acid was identrical to that of the human natural VEGF protein, Chorioallantoic membrane(CAM) assay showed that the rhVEGF promated new capillary vessels formation. Conclusion The genetic engineering Escherichia Coli can express human vascular endothelial growth factor in high level.
Objective To detect the expression of forkhead box P3 （FOXP3 ）gene in esophageal squamous cell carcinoma(ESCC) and provide a new basis for immunotherapy of esophageal cancer. Methods Based on fluorescent TaqMan methodology, a realtime quantitative reverse transcription polymerase chain reaction (RT-PCR) for detecting the expression of FOXP3 was set up. In this method, a cloning vector pMD 18-T-FOXP3 was constructed as a standard plasmid. The specific expression of FOXP3 in 42 patients with ESCC and 30 healthy controls were measured by using GeneAmp 7500 Sequence Detection Systems. Results FOXP3 mRNA copy number in ESCC was significantly higher than that in healthy control tissue ［(72.20±23.10)×104copy/μg RNA vs.(0.68±0.34)×104 copy/μg RNA；Plt;0.05］. Conclusion A realtime quantitative RT-PCR method for detecting the expression of FOXP3 gene in ESCC has been successfully established. The expression level of FOXP3 is increased in ESCC compare with healthy controls.
Objective To obtain the full-length gene and functional domains of FXYD6 gene which is a cholangiocarcinoma related gene. Methods A new strategy with the integration of bioinformatics and molecular biology was used. Bioinformatical methods were used to analyze the full-length sequence, and to predict the functional domains of its protein. And the full-length sequence of FXYD6 was isolated by polymerase chain reaction from fetal hepatic, brain and spleen cDNA libraries, and then cloned in pGEM-T vector for sequence analyzing. Goldkey Sequence Analyzing Software was used to analyze the sequence of candidate domain without signal peptide.Results The full-length sequence of FXYD6 was isolated by Touch-down PCR from fetal hepatic and brain cDNA library, but was not from spleen cDNA library. The open reading frame Finder software was used in the National Center for Biotechnology Information website to find the most probable encoding regions of FXYD6 gene. And the +1 phase was selected as the template sequence, from 67 bp to 354 bp, to predict the functional domains by Goldkey Sequence Analyzing Software. The signal peptide was located from 1 amino acid (aa) to 17 aa， and the main domain was composed from 18 aa to 34 aa. The region between 35 aa and 57 aa was the transmembrane region. The FHYD peptide chain was highly conserved amino acids. Conclusion The study of full-length cDNA cloning of FXYD6 gene and its functional domains provides the basis for understanding the relationship between the structure and function of FXYD6. More work shall be performed on FXYD6 protein and its influence on the mechanism of cholangiocarcinoma.
Objective To identify and isolate the variant gene associated with gastric adenocarcinoma and clone the fragment of variant gene.Methods By arbitrarily primer polymerase chain reaction (AP-PCR), DNA samples from 5 matched gastric adenocarcinoma and non-tumor gastric tissues were analysed. Results The produced AP-PCR profiles were different in each matched gastric adenocarcinoma and non-tumor gastric tissue. One differentiated amplified DNA fragments PW2.2 from a matched gastric adenocarcinoma were cloned. The result of Southern blot hybridization with PW2.2 as a probe showing that this fragment was also found in some other gastric adenocarcinoma samples. Conclusion AP-PCR fingerprinting assay can be used to identify and clone the variant genes associated with gastric adenocarcinoma.