Department of Critical Care Medicine, Henan Key Laboratory for Critical Care Medicine, Zhengzhou Key Laboratory for Critical Care Medicine, Henan Provincial People's Hospital, Zhengzhou, 450003, Henan, China.
Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, 450003, Henan, China.
Clin Transl Oncol. 2022 Oct;24(10):1940-1953. doi: 10.1007/s12094-022-02845-4. Epub 2022 May 19.
Distal metastases are a major cause of poor prognosis in colorectal cancer patients. Approximately 95% of metastatic colorectal cancers are defined as DNA mismatch repair proficient (pMMR). Our previous study found that miR-6511b-5p was downregulated in pMMR colorectal cancer. However, the mechanism of miR-6511b-5p in pMMR colorectal cancer metastases remain unclear.
We first used quantitative real-time PCR to evaluate the role of miR-6511b-5p in colorectal cancer. Second, we conducted invasion assays and wound healing assays to investigate the role of miR-6511b-5p and CD44 in colorectal cancer cells metastases. Third, luciferase reporter assay, in situ hybridization (ISH), and immunohistochemistry assays were performed to study the relationship between miR-6511b-5p and BRG1. Finally, real-time quantitative PCR, immunohistochemistry, and chromatin immunoprecipitation (ChIP) assays were performed to analyze the relationship between BRG1 and CD44 in colorectal cancer.
We found that lower expression of miR-6511b-5p appeared more often in pMMR colorectal cancer patients compared with dMMR (mismatch repair deficient) cases, and was positively correlated with metastases. In vitro, overexpression of miR-6511b-5p inhibited metastasis by decreasing CD44 expression via directly targeting BRG1 in colorectal cancer. Furthermore, BRG1 knockdown decreased the expression of CD44 by promoting CD44 methylation in colorectal cancer cells.
Our data suggest that miR-6511b-5p may act as a promising biomarker and treatment target for pMMR colorectal cancer, particularly in metastatic patients. Mechanistically, miR-6511b-5p suppresses invasion and migration of colorectal cancer cells through methylation of CD44 via directly targeting BRG1.
远处转移是结直肠癌患者预后不良的主要原因。大约 95%的转移性结直肠癌被定义为 DNA 错配修复功能正常（pMMR）。我们之前的研究发现 miR-6511b-5p 在 pMMR 结直肠癌中下调。然而，miR-6511b-5p 在 pMMR 结直肠癌转移中的机制尚不清楚。
我们首先使用定量实时 PCR 评估 miR-6511b-5p 在结直肠癌中的作用。其次，我们进行了侵袭实验和划痕愈合实验，以研究 miR-6511b-5p 和 CD44 在结直肠癌细胞转移中的作用。第三，进行了荧光素酶报告基因实验、原位杂交（ISH）和免疫组织化学实验，以研究 miR-6511b-5p 与 BRG1 之间的关系。最后，进行了实时定量 PCR、免疫组织化学和染色质免疫沉淀（ChIP）实验，以分析 BRG1 与 CD44 在结直肠癌中的关系。
我们发现与 dMMR（错配修复缺陷）病例相比，pMMR 结直肠癌患者 miR-6511b-5p 的表达水平较低，且与转移呈正相关。在体外，miR-6511b-5p 的过表达通过直接靶向 BRG1 降低 CD44 表达从而抑制结直肠癌细胞的转移。此外，BRG1 的敲低通过促进结直肠癌细胞中 CD44 的甲基化降低了 CD44 的表达。
我们的数据表明，miR-6511b-5p 可能作为 pMMR 结直肠癌，特别是转移性患者有前途的生物标志物和治疗靶点。从机制上讲，miR-6511b-5p 通过直接靶向 BRG1 抑制 CD44 的甲基化，从而抑制结直肠癌细胞的侵袭和迁移。
