lncRNA MALAT1在结直肠癌中的表达、生物学功能及其与患者预后的关系

目的:探讨lncRNA MALAT1在结直肠癌（colorectal cancer，CRC）中的表达、生物学功能及其与患者预后的关系。方法:采用生物信息方法在TCGA数据库和Oncomine数据库中分析比较MALAT1在CRC患者癌组织和癌旁组织中的差异表达情况，并比较高低表达组患者总生存期（OS）和无病生存期（DFS）是否存在差异。采用cBioPortal在线分析TCGA数据库中MALAT1突变种类及频率。采用实时荧光定量聚合酶链反应(real-time PCR)技术检测我院收治并手术治疗的30例CRC患者手术切除标本的癌组织、癌旁组织、肠癌细胞系(SW620、LOVO、HCT116)及正常人肠上皮细胞(NCM460)中MALAT1的相对表达水平。小干扰RNA敲低SW620细胞中MALAT1表达后观察MALAT1细胞迁移和侵袭能力改变情况。siRNA下调SW620细胞MALAT1，利用免疫印迹实验检测上皮间质化标志物E-cadherin、N-cadherin和Vimentin的表达水平。结果:Oncomine数据库中，CRC患者癌组织中高表达MALAT1的研究有6项；30对人配对CRC组织标本中，相比癌旁组织，MALAT1 在46.7%（14/30）的CRC患者组织中表达增高（P＜0.05）；Real-time PCR结果显示，肠癌细胞系(SW620、LOVO、HCT116)中MALAT1的相对表达量显著高于正常人肠上皮细胞(NCM460)，差异有统计学意义（P＜0.05）。MALAT1基因突变类型主要为融合突变、扩增突变及深度缺失突变，其在各种肿瘤中的总体突变率为1.1%，在CRC组织中的突变率为0.34%。小干扰RNA抑制MALAT1表达可明显抑制SW620细胞的划痕迁移与小室侵袭能力。抑制MALAT1表达后，SW620细胞中E-cadherin的表达水平升高，同时N-cadherin和Vimentin的表达水平明显降低，表明上皮间质化过程受到明显抑制。MALAT1表达水平与结肠癌患者DFS存在明显的关系，高表达患者DFS显著低于低表达患者（HR=1.6,P=0.044）。结论:lncRNA MALAT1在肠癌中表达上调，并通过抑制上皮间质化抑制细胞迁移和侵袭能力。MALAT1高表达结肠癌患者预后不良，可能成为结肠癌预后分子标志物。

Expression and biological function analysis of lncRNA MALAT1 in colorectal cancer and its correlation with prognosis

Objective:To investigate the expression and biological function analysis of lncRNA MALAT1 in colorectal cancer (CRC) and its correlation with prognosis.Methods:The differential expression of lncRNA MALAT1 in cancer tissues and adjacent tissues of CRC patients was analyzed by bioinformatics analysis in TCGA database and Oncomine database,and the difference of overall survival (OS) and disease-free survival (DFS) between high and low expression groups was compared.cBioPortal was used to analyze the mutation types and frequency of MALAT1 in TCGA database.Real-time PCR was used to detect the relative expression of MALAT1 in cancer cell lines (SW620,LOVO,HCT116),normal human intestinal epithelial cells (NCM460),tumor tissues,adjacent tissues from 30 patients with CRC treated our hospital.After knockdown of MALAT1 expression in SW620 cells,the changes of migration and invasion ability of MALAT1 cells were observed.The expression of E-cadherin,N-cadherin and Vimentin was detected by Western blot.Results:In Oncomine database,there were 6 studies on high expression of MALAT1 in CRC tissues.In 30 pairs of paired human CRC tissues,the expression of MALAT1 in 46.7%(14/30) CRC patients tissues was higher than that in adjacent tissues (P＜0.05).Real-time PCR results showed that the expression of MALAT1 in CRC cell lines (SW620,LOVO,HCT116) was significantly higher than normal human intestinal epithelial cells (NCM460)(P＜0.05).The main types of MALAT1 gene mutation were fusion mutation,amplification mutation and deep deletion mutation.The overall mutation rate of MALAT1 in various tumors was 1.1%,and the mutation rate in CRC tissues was 0.34%.Inhibition of MALAT1 expression by siRNA could significantly inhibit the scratch migration and cell invasion ability of SW620 cells,and enhance the expression of E-cadherin,but reduce the expression of N-cadherin and Vimentin in SW620 cells,indicating that epithelial mesenchymal process was significantly inhibited.There was a significant correlation between MALAT1 expression and DFS in colon cancer patients.The DFS of MALAT1 high expression patients was significantly lower than MALAT1 low expression (HR=1.6,P=0.044).Conclusion:The expression of lncRNA MALAT1 is up-regulated in CRC and inhibits cell migration and invasion by inhibiting epithelial mesenchymal transition.The prognosis of colon cancer with high expression of MALAT1 is poor which may be a potential molecular marker of colon cancer prognosis.