卵泡抑素样蛋白1在胃间质瘤生长和凋亡中的作用

Role of follistatin-like protein 1 (FSTL1) in gastric stromal tumor cell growth and apoptosis

目的研究卵泡抑素样蛋白1(FSTL1)在胃间质瘤中的表达及其功能。方法采用ELISA法检测27例胃间质瘤患者手术前后和32名健康志愿者血清中FSTL1的表达。Western印迹法检测FSTL1在胃间质瘤组织、正常胃黏膜上皮组织、胃间质瘤细胞株GIST882和人正常胃黏膜上皮细胞株RGM-1中的含量。以FSTL1 mimic或FSTL1小干扰RNA(siRNA)瞬时转染GIST882细胞上调或抑制FSTL1蛋白质的表达,并设立各自阴性对照(NC)和空白对照(BC)组。细胞计数试剂盒-8(CCK-8)法检测各组细胞,以及加入伊马替尼后各组细胞的活力;平板克隆形成实验观察GIST882细胞形成细胞克隆的能力。流式细胞术检测FSTL1 siRNA及其对照组的细胞周期和早期凋亡率;Western印迹法检测细胞周期相关蛋白,包括周期素E(Cyclin E)、E2F-1、p-Rb、p53和p73;细胞凋亡相关蛋白,包括细胞色素C、Bax、bcl-2、半胱天冬酶(caspase)-3和多聚二磷酸腺苷核糖聚合酶(PARP);细胞通路蛋白,包括磷酸化的细胞外信号调节激酶(p-ERK)、磷酸化的c-Jun氨基末端激酶(p-JNK)、磷酸化的蛋白激酶B(p-AKT)和NF-κB抑制蛋白(IκB)的表达。结果胃间质瘤患者术前血清FSTL1相对表达量(27.3±3.4)显著高于健康志愿者(19.5±3.2,P<0.01);在接受胃间质瘤手术后,患者血清中FSTL1相对表达量(14.6±2.6)较术前显著下调(P<0.01)。FSTL1蛋白的表达水平在胃间质瘤组织中显著高于正常胃黏膜上皮组织,在GIST882细胞中显著高于RGM-1细胞(P值均<0.01)。抑制FSTL1表达可抑制GIST882细胞活力,而上调FSTL1表达可提高GIST882细胞活力。抑制FSTL1表达可使GIST882细胞生长和增殖受到抑制;GIST882细胞周期停滞在G1期;同时下调Cyclin E、E2F-1和p-Rb的表达,上调p53和p73的表达;并诱导GIST882细胞发生凋亡,同时促进细胞中细胞色素C、Bax、裂解的PARP和裂解的caspase-3的表达,并抑制bcl-2的表达;FSTL1 siRNA组GIST882细胞中p-ERK和p-AKT表达下调,与siRNA NC和siRNA BC组比较,差异均有统计学意义(P值均<0.01)。加入伊马替尼后,FSTL1 siRNA组细胞活力显著低于siRNA NC组(0.622±0.134比1.121±0.189,P<0.01)。结论FSTL1在胃间质瘤中表达显著上调,FSTL1与胃间质瘤细胞生长和凋亡相关。抑制FSTL1的表达可增加GIST882细胞对伊马替尼的敏感性。

Objective To investigate the expression and role of follistatin-like protein 1(FSTL1)in gastric stromal tumor(GST).Methods Enzyme-linked immunosorbent assay(ELISA)was used to detect the level of FSTL1 in the serum of 27 GST patients and 32 healthy persons.Western blot was employed to analyze the translational level of FSTL1 in GST specimens and normal gastric epithelium tissues,and the expression of FSTL1 in GST cell line GIST882 and normal gastric epithelial cell line RGM-1.The expression of FSTL1 was deregulated in GIST882 cells by transfection of FSTL1 mimic or FSTL1 siRNA.And a negative control group and a blank control group were set up.CCK-8 and cell clone formation assays were employed to detect the cell viability and proliferation before and after imatinib was added in vitro.The cell cycle was analyzed by flow cytometry.Annexin V/PI apoptosis assay was utilized to explore the apoptosis of GIST882 cells.The cell cycle regulating proteins(Cyclin E,E2 F-1,p-Rb,p53 and p73),cell apoptosis related factors(Cytochrome C,Bax,bcl-2,caspase-3 and PARP)as well as cell signaling pathway factors(p-ERK,p-JNK,p-AKT and IκB)were determined by western blot.Results There was a significant promotion of FSTL1 level in GST patients in comparison with healthy persons(27.3±3.4 vs.19.5±3.2,P<0.01),and the translational level of FSTL1 was promoted in GST tissues than that in normal gastric epithelium samples.After surgery,the level of FSTL1 in serum was significantly down-regulated in GST patients(14.6±2.6,P<0.01).The protein level of FSTL1 was significantly higher in GIST882 cells than that in RGM-1 cells(all P<0.01).Compared to the control groups,knockdown of FSTL1 suppressed the viability and proliferation of GIST882 cells,and the down-regulation of FSTL1 also increased cell arrest in the G1 phase by decreasing Cyclin E,E2 F-1 and p-Rb as well as up-regulating p53 and p73(all P<0.01).Silencing of FSTL1 induced GIST882 cell apoptosis through the up-regulation of Cytochrome C and Bax,the proteolysis of PARP and caspase 3,and the inhibition of bcl-2(all P<0.01).Knockout of FSTL1 deceased the levels of p-ERK and p-AKT in GIST882 cells(P<0.01).Moreover,after imatinib was added,the cell activity of FSTL1 siRNA group was lower than that of the negative control group(0.622±0.134 vs.1.121±0.189,P<0.01).Conclusion The expression of FSTL1 is notably increased in GST and clearly associated with the growth and apoptosis of GST cells.Knockdown of FSTL1 can make GIST882 cells more susceptible to imatinib-induced cell death.