SPARC在结直肠癌中的表达及其对细胞侵袭能力影响的机制

Expression of SPARC in colorectal cancer and mechanisms of its effects on cancer cell invasion

目的·分析富含半胱氨酸的酸性蛋白(SPARC)在结直肠癌中的表达,并探讨其对结直肠癌细胞侵袭能力的影响及机制。方法·从GEO数据库中提取GSE9348数据集的生物信息学资料,分析SPARC在结直肠癌和正常结直肠组织中的表达差异。在CEO数据库中提取具有患者临床信息及预后资料的GSE12945数据集,分析SPARC表达水平与结直肠癌患者生存期的关系,并对影响患者预后的危险因素进行单因素Cox生存分析。运用GSEA分析探讨SPARC与结直肠癌进程中生物学通路的关系。运用侵袭实验观察在结直肠癌细胞HT29中下调SPARC后,细胞侵袭能力的改变。采用real-time PCR、Western blotting检测在HT29、HCT116细胞中下调SPARC后上皮间质转化(EMT)相关基因的表达水平。结果·SPARC在结直肠癌组织中的表达显著高于正常结直肠组织(P=0.000)。SPARC高表达患者生存期显著短于低表达患者(P=0.029)。淋巴结转移、远处转移、低分化程度、肿瘤复发以及SPARC高表达是结直肠癌患者生存期的危险因素。GSEA分析显示结直肠癌细胞迁移和创伤愈合通路相关基因在SPARC高表达患者中富集。结直肠癌细胞中下调SPARC能降低细胞侵袭能力并能抑制N-cadherin、TWIST1、SNAIL2等表达。结论·SPARC在结直肠癌中表达增高,且与患者预后呈负相关。SPARC能增强结直肠癌细胞的侵袭能力,可能与SPARC参与细胞间质化改变有关。

Objective · To analyze the expression of secreted protein acidic and rich in cysteine （SPARC） in colorectal cancer （CRC） and investigate the role of SPARC in CRC cell invasion and relevant mechanisms. Methods · Bioinformatics data in microarray dataset GSE9348 from Gene Expression Omnibus （GEO） were collected for analyzing the difference in SPARC expression between CRC tissues and normal colorectal tissues. Clinical and prognostic data in microarray dataset GSE12945 from GEO were collected for analyzing the correlation between the expression level of SPARC and the survival time of CRC patients. Univariate Cox survival analysis was used to screen out risk factors influencing the prognosis of CRC patients. Gene set enrichment analysis （GSEA） was performed to gain further insight into the biological pathways involved in CRC progression related to SPARC. Changes in the invasion ability of CRC cell HT29 were observed with Transwell assay after down-regulation of SPARC. Real-time PCR and Western blotting were used to detect the levels of EMT-related genes in HT29 and HCT116 cells after down-regulation of SPARC. Results · The expression of SPARC in CRC tissues was significantly elevated compared with normal colorectal tissues （P = 0.000）. The overall survival time was significantly shorter in patients with high expression of SPARC than in patients with low expression of SPARC （P = 0.029）. The univariate analysis indicated that lymph node metastasis, distant metastasis, poor histological differentiation, recurrence, and high expression of SPARC were risk factors for the survival time in CRC patients. GSEA analysis showed that genes related to cell migration and wound-healing pathways were enriched in patients with high expression of SPARC. The down-regulation of SPARC in CRC cells could decrease the invasion ability and inhibit the expressions of N-cadherin, TWIST1, and SNAIL2. Conclusion · SPARC is up-regulated in CRC and negatively correlated to the prognosis of patients. SPARC can promote the invasion ability of CRC cells, which may be related to the involvement of SPARC in mesenchymal transition of cells.