目的：探讨微小RNA（microRNA, miRNA）在结直肠癌（colorectal cancer, CRC）疾病进展中的作用及临床应用价值。方法：基于TCGA数据库，筛选分析人类结肠癌及癌旁组织的转录组差异表达miRNA，以miRNA-1229-3p作为研究对象，在GEO数据库与Starbase数据库中验证其表达水平。采用生物信息学方法对miR-1229-3p的生物功能特征进行分析，构建miR-1229-3p过表达细胞系及miR-1229-3p敲降细胞系，通过CCK-8实验、克隆形成实验、EdU实验、Transwell实验、流式细胞术实验在体外探究miR-1229-3p对CRC细胞增殖、转移、凋亡的影响，并通过裸鼠移植瘤试验探究miR-1229-3p对CRC细胞体内增殖的影响。通过DIANA 、TargetScan、miRDB数据库筛选miR-1229-3p的靶基因，并通过KEGG富集分析、GO分析靶基因的生物学功能。检测60例CRC患者及60例健康体检者血浆外泌体中的miR-1229-3p含量，采用受试者工作特征曲线（receiver operating characteristic curve, ROC）分析其对CRC患者的诊断效能。结果：数据分析显示，miR-1229-3p在CRC细胞和组织中表达下调。生物信息学方法预测结果显示，miR-1229-3p与肿瘤的进展途径（如上皮间质转化、血管形成等）呈显著负相关（R<0，P<0.05）。体内、外研究表明，过表达miR-1229-3p后，CRC细胞的增殖、迁移和侵袭能力受到抑制，且其潜在靶基因SETD7在细胞中的表达下调；而敲低miR-1229-3p后可抑制CRC细胞的凋亡。CRC患者血浆外泌体中的miR-1229-3p含量较健康体检者降低，ROC曲线分析显示，miR-1229-3p诊断CRC的约登指数最大值为0.586 8，曲线下面积为0.863 2（P<0.01）。结论：miR-1229-3p在CRC中表达下调，SETD7是其潜在的靶基因，miR-1229-3p可抑制CRC细胞增殖、迁移与侵袭，促进CRC细胞凋亡，有望作为诊断CRC的潜在生物标志物。

Objective: To investigate the role and clinical application of microRNA in the malignant progression of colorectal cancer (CRC). Methods: The transcriptome data of human colorectal cancer and adjacent tissues from TCGA database were analyzed to screen out the differentially expressed microRNAs (miRNAs), among which miR-1229-3p with the most significant difference was selected as the target miRNA, and furthermore the expression of miR-1229-3p was verified through GEO and Starbase databases. The biological functional characteristics of miR-1229-3p was analyzed through Bioinformatics. The miR-1229-3p overexpression cell line and miR-1229-3p knockdown cell line were constructed. The effect of miR-1229-3p on the proliferation, metastasis, and apoptosis of CRC cells was explored in vitro by CCK-8 experiment, cloning formation experiment, EdU experiment, transwell, and flow cytometry experiment. The effect of miR-1229-3p on the prolife-rative capacity of CRC in vivo was explored by nude mouse transplantation tumor experiment. The target genes of miR-1229-3p were screened out by DIANA, TargetScan, and miRDB databases. KEGG and GO were used to analyze the biological function of target genes. The expression of miR-1229-3p in plasma exosomes of 60 CRC patients and 60 healthy examiners obtained from Nanjing First Hospital were analyzed, and receiver operating characteristic curve (ROC) was used to distinguish its diagnostic efficacy for CRC patients. Results: The expression of miR-1229-3p was downregulated in CRC cells and tissues. Bioinformatics predicted a significant negative correlation between miR-1229-3p and tumor progression pathways, such as epithelial-mesenchymal transition and angiogenesis (R<0, P<0.05). In vitro and in vivo studies showed that after the overexpression of miR-1229-3p, the proliferation, migration and invasion of CRC cells were inhibited, and the potential target gene SETD7 was downregulated, while the apoptosis of CRC cells could be inhibited after downregulating miR-1229-3p. miR-1229-3p from plasma exosomes of CRC was downregulated, which could distinguish CRC patients from normal people. ROC curve showed that the optimal critical value of miR-1229-3p for diagnosing CRC was 0.586 8, and the area under the curve was 0.863 2 (P<0.01). Conclusions: The expression of miR-1229-3p is downregulated in CRC, and SETD7 is a potential target gene for miR-1229-3p. miR-1229-3p can inhibit the proliferation, migration and invasion of CRC cells, and promote apoptosis of CRC cells. miR-1229-3p can be served as a potential biomarker for CRC diagnosis.