The Role And Biological Mechanism Of CircPGC In Regulating Proliferation And Migration Of Human Gastric Cancer Cells

Objects:Circular RNAs（circRNAs）are a class of RNA molecules that are widely found in mammals.They are closed loop structures and not easily degraded by RNA exonuclease.Recent studies have shown that circRNAs play an important role in the development of gastric cancer.In this study,the expression level of circPGC in gastric cancer was firstly tested,and then a series of western blot and other molecular biological experiments were carried out to study the role of circPGC in regulating the proliferation and migration of human gastric cancer cells and its biological mechanism.Methods:Firstly,Bioinformatics analysis was used to screen out the target circRNAs with differential expression in gastric cancer tissues in GSE100170 database and further verified by qRT-PCR.The target circRNAs overexpression vector was constructed using seamless cloning technology.Secondly,the effect of target circRNAs on the proliferation of AGS was detected by CCK8 cell proliferation assay and Cell colony formation assay.The effects of target circRNAs on the migration and invasion of AGS were detected by Wound Healing assay and Transwell assay.Finally,We used western blot to investigate the molecular mechanism that target circRNAs regulated cellular phenotypic changes.Results:Analysis by GSE100170 database showed that the expression levels of hsa_circ₀076305,hsa_circ₀076304 and hsa_circ₀000390 were significantly decreased in gastric cancer compared with normal gastric tissues.Among them,qRT-PCR assay of 9 gastric cancer tissues and 30 gastric cancer cDNA microarray confirmed that hsa_circ₀076305（named circPGC）was down-regulated in gastric cancer.Functional tests showed that overexpression of circPGC inhibited the proliferation and promoted the migration and invasion in gastric cancer cell AGS.Western blot analysis showed that overexpression of circPGC in AGS cell resulted in decreased expression of proto-oncogenes,PCNA,c-myc and EGFR.However,the expression level of epithelial characteristic protein,E-cadherin,was down-regulated,and the expression levels of mesenchymal characteristic proteins,Vimentin,(3-catenin,Snail,Twist,and migration-related proteins,Collagen I,MMP9,MMP14,were up-regulated.Conclusions:The expression level of circPGC is down-regulated in human gastric cancer tissues,which means that it has the potential to inhibit gastric cancer.It can inhibit cell proliferation by down-regulating the expression levels of proto-oncogene PCNA,c-myc and EGFR.CircPGC can degrade the extracellular matrix and basement membrane through MMP9 and MMP14,providing a microenvironment that facilitates cell migration.At the same time,the transcription factors Snail and Twist down-regulate the expression level of E-cadherin,inducing EMT,which promotes AGS cell migration and invasion.The role of circPGC in human gastric cancer presents a pattern of migration-proliferation dichotomy,and further studies will help reveal the role of circRNAs in the development of cancer.