高表达CAMSAP2通过上调TGF-β信号促进胃癌细胞的侵袭和转移

High expression of CAMSAP2 promotes invasion and metastasis of gastric cancer cells by upregulating TGF-βsignaling

目的阐明钙调蛋白调控的光谱相关蛋白2(CAMSAP2)在胃癌中的表达及其对疾病进展和预后的影响,并分析可能的机制。方法利用公共癌症数据初步分析CAMSAP2的表达和胃癌进展及预后的关系,另纳入2013年10月~2017年10月在我院完成胃癌根治术的106例患者进行验证。利用生物信息学预测CAMSAP2的生物学功能。采用CAMSAP2过表达质粒、特异性干扰分别处理胃癌细胞系(MGC803)分为CAMSAP2上调组、CAMSAP2下调组,将未经处理的MGC803设为空白对照组,体外观察CAMSAP2对胃癌细胞上皮-间质转化(EMT)和侵袭的影响,并建立裸鼠胃原位种植瘤模型进行在体验证,同时分析CAMSAP2调控胃癌的分子机制。结果CAMSAP2在胃癌组织中的表达显著高于癌旁组织(P<0.05),并和外周血CEA、CA19-9水平正相关(P<0.001)。Cox回归分析显示CAMSAP2高表达是影响胃癌患者术后5年生存率的独立危险因素(HR:2.969;95%CI:1.031-8.548)。富集分析提示CAMSAP2的作用可能与EMT和TGF-β信号有关。免疫印迹、划痕和Transwell实验发现:体外上调CAMSAP2可促进胃癌细胞表达Vimentin和N-cadherin,同时抑制E-cadherin的表达,并促进胃癌细胞迁移和侵袭(P<0.05);下调CAMSAP2则结果相反(P<0.05)。在体上调CAMSAP2可促进裸鼠胃原位种植瘤的转移(P<0.05),促进胃癌组织中Vimentin和N-cadherin的表达,同时抑制E-cadherin的表达(P<0.05);下调CAMSAP2则结果相反(P<0.05)。体内外实验中,上调CAMSAP2可升高胃癌组织或胃癌细胞中TGF-β和p-Smad2/3的水平(P<0.05),而下调CAMSAP2则结果相反(P<0.05)。结论CAMSAP2在胃癌中高表达并和肿瘤恶性进展以及预后不良相关,其可能通过上调TGF-β信号参与了胃癌的EMT过程。

Objective To investigate the expression of calmodulin-regulated spectrin-associated protein 2(CAMSAP2)in gastric cancer and its effect on gastric cancer cell invasion and metastasis.Methods The association of CAMSAP2 expression levels with progression and prognosis of gastric cancer was analyzed using public cancer data and in 106 patients receiving radical gastrectomy in our hospital from October,2013 to October,2017.The biological functions of CAMSAP2 were predicted using bioinformatics analysis.Gastric cancer MGC803 cells with CAMSAP2 overexpression and knockdown were observed for epithelial-mesenchymal transition(EMT),migration and invasion.A nude mouse model bearing orthotopic gastric cancer cell xenografts was established for verifying the results and exploring the underlying molecular mechanism.Results Gastric cancer tissues expressed high levels of CAMSAP2,which were positively correlated with CEA and CA19-9(P<0.001).Cox regression analysis showed that CAMSAP2 expression level was an independent risk factor affecting the 5-year survival rate of gastric cancer patients(HR=2.969,95%CI:1.031-8.548).Enrichment analysis suggested that CAMSAP2 was involved in epithelial-mesenchymal transition(EMT)and TGF-βsignaling.In gastric cancer cells,CAMSAP2 overexpression significantly increased the expressions of vimentin and N-cadherin,inhibited the expression of E-cadherin,and enhanced cell migration and invasion(P<0.05);CAMSAP2 knockdown produced the opposite effects in the cells(P<0.05).In the tumor-bearing mice,xenografts overexpressing CAMSAP2 showed enhanced metastasis(P<0.05),increased vimentin and N-cadherin expressions and lowered E-cadherin expression(P<0.05),and the xenografts with CAMSAP2 knockdown showed the opposite changes(P<0.05).Both the in vivo and in vitro experiments showed that CAMSAP2 overexpression increased and CAMSAP2 knockdown lowered the levels of TGF-βand p-Smad2/3 in the gastric cancer cells(P<0.05).Conclusion The high expression of CAMSAP2 contributes to disease progression and poor prognosis of gastric cancer possibly by upregulating TGF-βsignaling to promote EMT.