Construction Of An Oral DNA Vaccine PcDNA3.1+/flk-1_n1-7 And Its Inhibitory Effect On Gastric Cancer

Background and Objective Angiogenesis is plays an important role in the growth, invason and metastasis of most solid tumors. Vascular endothelial growth factor (VEGF) and its receptor fik-1 play a key role in tumor angiogenesis. Blocking VEGF-fik-1 pathway may inhibit tumor growth. The study was to construct an oral DNA vaccine pcDNA3.1+/flk-1(n1-7) against tumor angiogenesis and investigate the effects and mechanism of the vaccine on tumor development and metastasis in vivo.Methods l.Total RNA was extracted from C57BL/6J mice embryo. Extracellular domain of flk-1 was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). After confirmed by DNA sequence analysis, flk-1(n1-7)cDNA was inserted into eucaryotic expression vector pcDNA3.1+ containing CMV promoter. The recombinant plasmids pcDNA3.1+/flk-1(n1-7) was constructed and transfected into eucaryotic expression system COS-7 cells by lipofectamine. Then detecting protein expression of flk-l(n1-7) by Western blot. 2.The recombinant plasmid pcDNA3.1+/ flk-1(n1-7) was transformed into attenuated Salmonella typhimurium SL3261 to develop an oral DNA vaccine against the extracellular domain of flk-1. 3.Mice were divided into 3 groups (DNA vaccine group, vector group and saline group) and wereorally immunized with SL3261 transformed with the recombinant plasmid, pcDNA3.1 (+), or saline respectively 3 times at 2-wk intervals. Then mice were challenged by subcutaneous (s.c) injection of gastrc cancer cells (MFC) into the right armpit 2 weeks after the last immunization and survival time of the animals was...