大肠癌（CRC）被认为是全球第二致命和第三最常见的恶性肿瘤。研究细菌的致癌机制或其在癌症恶化中的作用是非常宝贵的。核酸梭菌核酸（F. nucleatum）是大肠癌发生和扩散中重要的细菌之一。在本研究中，我们调查了CRC患者活检样本中miR-21、miR-17-5P、miR-155的表达水平和F. nucleatum的相对频率。使用组织提取试剂盒提取DNA和RNA样本，然后使用相关试剂盒合成cDNA。根据miR-17-5P、miR-21和miR-155基因的序列选择F. nucleatum专属16srRNA和细菌universal16srRNA特异性引物，利用实时PCR方法分析目标基因的表达水平。在癌组中miR-21、miR-17-5P和miR-155基因的表达水平明显增加。同时，所提到的miRNA在F. nucleatum阳性样本中的表达也显著提高。与对照组相比，癌组中F. nucleatum的相对频率明显增加。由于F. nucleatum存在时可能造成CRC的基因表达变化，通过研究患者的微生物组相关性和不同选择基因的表达变化，可以促进疾病的识别和治疗解决方案的提供。©2023. 作者。

Colorectal cancer (CRC) is considered the second-deadliest and third-most common malignancy worldwide. Studying the carcinogenic mechanism of bacteria or their role in aggravating cancer can be precious. Fusobacterium nucleatum (F. nucleatum) is one of the important bacteria in the occurrence and spread of CRC. In this study, we investigated the expression levels of miR-21, miR-17-5P, miR-155, and the relative frequency of F. nucleatum in biopsy samples from patients with CRC.DNA and RNA samples were extracted using a tissue extraction kit, and then cDNAs were synthesized using a related kit. Based on the sequence of miR-17-5P, miR-21, and miR-155 genes, F. nucleatum specific 16srRNA and bacterial universal16srRNA specific primers were selected, and the expression levels of the target genes were analyzed using the Real-Time PCR method.The expression level of miR-21, miR-17-5P, and miR-155 genes showed a significant increase in the cancer group. Also, the expression of the mentioned miRNAs was significantly raised in the positive samples for F. nucleatum presence. The relative frequency of F. nucleatum in the cancer group was significantly increased compared to the control group.Due to the changes in the expression of genes involved in causing CRC in the presence of F. nucleatum, it is possible to prompt identification and provide therapeutic solutions to cancer patients by studying their microbial profiles and the expression changes of different selected genes.© 2023. The Author(s).