Department of Biochemistry, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran.
Cellular and Molecular Research Center, Urmia University of Medical Sciences, Urmia, Iran.
J Cell Physiol. 2021 Oct;236(10):7071-7087. doi: 10.1002/jcp.30378. Epub 2021 Apr 5.
Programmed death ligand 1 (PD-L1) plays a significant role in colorectal tumorigenesis through induction of regulatory T cells (Tregs) and suppression of antitumor immunity. Furthermore, microRNAs (miRNAs) as the posttranscriptional regulators of gene expression show considerable promise as a therapeutic target for colorectal cancer (CRC) treatment. Considering this, in vitro effects of miRNA-124 (miR-124-3p) on CRC cell tumorigenesis and Tregs differentiation via targeting PD-L1 were investigated in the current study. Functional analysis showed that miR-124 is significantly downregulated in CRC tissues as compared with marginal normal samples (p < .0001), and its downregulation was negatively correlated with PD-L1 expression. Moreover, a specific region in PD-L1 3'-untranslated region was predicted as the miR-124 target and validated using the luciferase assay. Further investigation showed that transfection of HT29 and SW480 cells with miR-124 mimics significantly reduced PD-L1 mRNA, protein, and cell surface expression, and inhibited Tregs in coculture models via modulating interleukin [IL]-10, IL-2, tumor necrosis factor α, transforming growth factor beta, and interferon gamma expression levels. Besides, miR-124 overexpression decreased CRC cell proliferation and arrested cell cycle at the G1 phase through downregulation of c-Myc and induced apoptosis in CRC cells via upregulation of both intrinsic and extrinsic pathways. Also, miR-124 exogenous overexpression could reduce colony and spheroid formation ability of CRC cells via downregulating CD44 mRNA expression. miR-124 also diminished MMP-9 expression and subsequently suppressed cell migration and invasion. We also illustrated that STAT3 signaling was repressed by miR-124 in CRC cells. Taken together, our findings imply that considering the involvement of miR-124 in the regulation of PD-L1 through colorectal tumorigenesis and its remarkable antitumor effects, this miRNA could be regarded as the promising target for the development of therapeutic approaches for colorectal cancer.
程序性死亡配体 1（PD-L1）通过诱导调节性 T 细胞（Tregs）和抑制抗肿瘤免疫，在结直肠肿瘤发生中发挥重要作用。此外，作为基因表达的转录后调节剂的 microRNAs（miRNAs）作为结直肠癌（CRC）治疗的治疗靶点显示出很大的希望。有鉴于此，本研究旨在研究 miRNA-124（miR-124-3p）通过靶向 PD-L1 对 CRC 细胞肿瘤发生和 Tregs 分化的体外作用。功能分析显示，miR-124 在 CRC 组织中的表达明显低于边缘正常样本（p<0.0001），并且其下调与 PD-L1 表达呈负相关。此外，PD-L1 3'-非翻译区的特定区域被预测为 miR-124 的靶标，并通过荧光素酶测定进行验证。进一步的研究表明，miR-124 模拟物转染 HT29 和 SW480 细胞可显著降低 PD-L1 mRNA、蛋白和细胞表面表达，并通过调节白细胞介素[IL]-10、IL-2、肿瘤坏死因子-α、转化生长因子-β和干扰素-γ的表达水平抑制共培养模型中的 Tregs。此外，miR-124 过表达通过下调 c-Myc 降低 CRC 细胞增殖并将细胞周期阻滞在 G1 期，并通过上调内在和外在途径诱导 CRC 细胞凋亡。此外，miR-124 外源性过表达可通过下调 CD44 mRNA 表达降低 CRC 细胞集落和球体形成能力。miR-124 还降低 MMP-9 的表达，从而抑制细胞迁移和侵袭。我们还表明，miR-124 抑制 CRC 细胞中的 STAT3 信号转导。总之，我们的研究结果表明，鉴于 miR-124 在调节结直肠肿瘤发生过程中的 PD-L1 参与及其显著的抗肿瘤作用，该 miRNA 可作为开发结直肠癌治疗方法的有前途的靶点。
