A New Approach Of Targeting Treatment In Human Gastric Carcinoma By SiRNA Delivery In Vivo.

Gastric cancer is a malignant tumor originating from the epithelium of the gastric mucosa.gastric cancer is one of the leading causes of cancer-related death worldwide.many patients found unsuitable for surgery at diagnosis or repeated recurrence after resection of cancer tissue.Gastric cancer is anatomically divided into gastric adenocarcinoma and gastroesophageal junction adenocarcinoma,and histologically divided into intestinal type and gastric type(diffuse type).Surgery is the only treatment so far.For local advanced gastric cancer,surgery can be co mbined with other auxiliary measures for treatment.but the treatment effect is poor in metastatic gastric cancer,and the median survival time is only about 1 year.With the study of targeted therapy,targeted drugs have entered the field of vision.The abnormal high expression of vascular endothelial growth factor(vascular endothelial growth factor,VEGF)has been reported to be an important feature of most tumors,including gastric cancer,which induces angiogenesis mainly through receptor Fit-1(fms-like tyrosine kinase-1,VEGFR-1)and KDR(kinase insert domains-containing receptor,VEGFR-2)acting on the surface of vascular endothelial cells.During tumor progression and metastasis,angiogenesis is a basic step,which is regulated by a series of factors in vivo,among which VEGF is the most important.recent studies have shown that VEGF receptors are not specifically expressed in vascular endothelial cells and tumor cells can also be expressed.RNA interference technique is a technique that initiates cell RNA induced silencing complexes(RNA-induced silencing complex,RISC)mediated by small molecular RNA,thereby specifically targeting and silencing specific genes.We use small interfering RNA(si RNA)to construct interfering plasmids,introduce plasmids into experimental animals,secrete corresponding small RNA,through their own tissues and organs into target cells through exocrine bodies,and play the role of targeted therapy.This study focused on gastric cancer to explore whether VEGFR-si plasmids can inhibit tumor angiogenesis by interfering with vegf signaling pathways,thereby inhibiting tumor growth and metastasis.The work includes the following parts:Firstly,we designed si-RNA sequences for VEGFR gene and integrated them onto pc DNA6.2 plasmid.We used low differentiation cell lines MKN-45 gastric cancer to verify the VEGFR plasmid interference effect,the plasmid was transfected 24 hours after receiving total RNA and total protein,the VEGFR protein expression was detected by Western Blotting technique,and the most effective plasmid was selected;Besides,we verified the effects of VEGFR plasmid down-regulation VEGFR expression on the proliferation,migration and apoptosis function of gastric cancer cells in MKN-45 cell lines.we verified that this plasmid can effectively inhibit the migration and proliferation of MKN-45 cell lines and promote the apoptosis of gastric cancer cells by cell proliferation experiments and migration experiments.At last,we constructed an in situ model of gastric cancer in mice.the caudal vein administration VEGFR plasmid,was performed every two days.after one month of administration,we evaluated VEGFR plasmid inhibition of tumor growth.The results showed that the tumor growth rate of VEGFR plasmid 20mg/kg group decreased compared with Control plasmid group,and the survival time was prolonged.In summary,based on our novel small RNA carrier delivery system,we injected the rat tail vein VEGFR plasmid,used the animal liver as the bioreactor processing expression VEGFR si RNA,and through the liver cell-derived exosomes secreted secretes the VEGFR si RNA to the blood circulation system,transports to other tissues and organs,exerts the interference receptor cell VEGFR the gene expression function,provides the new thought for the gastric cancer clinical treatment and the target drug development.