| Objective:Gastric cancer is the fifth most common cancer and accounts for 8.2% of all cancer mortality,which makes it the third leading cause of cancer death worldwide.The process of tumor metastasis is essentially Epithelial-Mesenchymal Transition(EMT).EMT is a complex process involving multiple genes,multiple steps and many stages,in which the tight junctions of epithelial cells are disrupted under specific conditions,resulting in the loss of the original polarity of the cells,along with the loss of order and coherence.At present,the process of gastric cancer development is not fully understood,therefore,it is meaningful to deeply investigate the molecular mechanisms regulating its malignant biological behavior,which can also provide new directions for thinking about the search of genetic markers for early diagnosis and new targets for interventional therapy.The human homolog of the Drosophila double-tailed C gene,BICC1,it can influence the malignant biological behavior of tumor cells by regulating cellular signaling pathways.However,the biological function of BICC1 in gastric carcinogenesis development is not clear.The aim of this study was to verify the expression of BICC1 gene in clinical gastric cancer tissues as well as cell lines,and to explore the effect of BICC1 gene on the proliferation,invasion and metastasis process of gastric cancer cells by participating in the TGF-β signaling pathway.Methods : 1.The data on gastric cancer available in the TCGA database were analyzed to determine the expression of BICC1 gene in gastric cancer tissues and control paraneoplastic tissues.The expression levels of BICC1 protein and BICC1 mRNA in clinical gastric cancer tissues and paired paraneoplastic tissues were detected by immunohistochemical assay,protein blotting assay(WB,Western blot),and real-time quantitative PCR(qRT-PCR).The association between abnormal BICC1 gene expression and pathological features of clinical gastric cancer patients was analyzed by statistical immunohistochemical experiments,PCR,and WB results.Gastric cancer cell lines: SGC-7901,BGC-823,and normal gastric mucosa cell line:GES-1 were cultured,and the expression of BICC1 gene in the cells was detected by qRT-PCR and Western blot.2.The BICC1 gene was knocked down in gastric cancer cells by transfection of small interfering RNA(siRNA),and the gastric cancer cell lines were divided into knockdown and control groups,and the knockdown status of BICC1 gene was detected by PCR assay and WB assay.CCK8 assay,scratch assay and Transwell assay were used to detect the biological functions of the cells,including cell proliferation viability,migration ability and invasion ability,and the expression of BICC1 protein and EMT-related protein were detected by WB assay,and then TGF-β signaling pathway inhibitor BIO-013-077 was added to the knockdown group by WB assay to detect the TGF-β signaling pathway protein smad2/3 expression changes.Results:1.Bioinformatics analysis revealed that BICC1 gene was highly expressed in gastric cancer tissues,and immunohistochemical staining results showed that the positive expression rate of BICC1 protein in gastric cancer tissues was much higher than that in paracancerous tissues,and WB and PCR results showed that the relative expression of BICC1 protein and BICC1 mRNA in gastric cancer tissues was significantly higher than that in paracancerous tissues.The expression levels of BICC1 protein and BICC1 mRNA in gastric cancer cell lines SGC-7901 and BGC-823 were significantly higher than those in normal gastric mucosal cell line GES-1.2.CCK-8 assay showed that knockdown of BICC1 gene inhibited the proliferation of gastric cancer cells,and scratch assay showed that the wound healing rate of BICC1 knockdown group was significantly Transwell experiments showed that knockdown of BICC1 gene significantly reduced the invasive ability of cells,and the expression of EMT-related proteins and signaling pathway proteins in the knockdown group decreased compared with the control group,and after the addition of the signaling pathway inhibitor BIO-013-077 in the knockdown group,the expression of TGF-β signaling pathway protein smad2/3 was significantly decreased in the knockdown group compared with the control group.Conclusion:1.The expression levels of BICC1 protein and BICC1 mRNA in gastric cancer tissues were significantly higher than those in paracancerous tissues,and the expression levels of BICC1 protein and BICC1 mRNA in gastric cancer cell lines were significantly higher than those in normal gastric mucosal cell lines.2.The BICC1 gene could enhance the proliferation viability,migration and invasion ability of gastric cancer cells,and these abilities were inhibited by down-regulation of BICC1.BICC1 gene may be involved in regulating the malignant biological behavior of gastric cancer cells by regulating the TGF-β pathway. |
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