Mahdloo Touba, Sahami Pantea, Ramezani Reihaneh, Jafarinia Mojtaba, Goudarzi Hamedreza, Babashah Sadegh
Department of Genetics, Faculty of Basic Sciences, Islamic Azad University, Marvdasht, Iran.
Department of Biomedical Sciences, Women Research Center, University of Alzahra, Tehran, Iran.
EXCLI J. 2021 Apr 15;20:748-763. doi: 10.17179/excli2021-3404. eCollection 2021.
microRNAs (miRNAs or miRs) play key roles in different stages of chronic myeloid leukemia (CML) pathogenesis. The present study aimed to demonstrate whether miR-155 enables CD34 CML cells to escape from the growth-inhibitory effects of TGF-β1 and bone morphogenetic protein (BMP) signaling. Among differentially expressed miRNAs in CD34 CML cells, miR-155 was highly up-regulated. QRT-PCR revealed an inverse correlation between miR-155 and two key members of the TGF-β pathway-TGF-βR2 and SMAD5. Results showed that SMAD5 is not only up-regulated through BMPs treatment, but recombinant TGF-β1 can also induce SMAD5 in CML cells. We also demonstrated that TGF-β1-mediated phosphorylation of SMAD1/5 was abolished by pre-treatment with the blocking TGF-βR2 antibody, suggesting a possible involvement of TGF-βR2. Additionally, overexpression of miR-155 significantly promoted the proliferation rate of CD34 CML cells. Results showed that siRNA-mediated knockdown of SMAD5 had a promoting effect on CD34 CML cell proliferation, suggesting that SMAD5 knock-down recapitulates the proliferative effects of miR-155. Importantly, TGF-β1 and BMP2/4 treatment had inhibitory effects on cell proliferation; however, miR-155 overexpression enabled CD34 CML cells to evade the anti-proliferative effects of TGF-β1 and BMPs. Consistently, down-regulation of miR-155 augmented the promoting effects of TGF-β1 and BMP signaling on inducing apoptosis in CD34 CML stem cells. Our findings demonstrated that targeting of SMAD5 and TGF-βR2 links miR-155 to TGF-β signaling in CML. Overexpression of miR-155 enables CD34 CML cells to evade growth-inhibitory effects of the TGF-β1 and BMP signaling, providing new perspectives for miR-155 as a therapeutic target for CML.
微小RNA（miRNA或miR）在慢性粒细胞白血病（CML）发病机制的不同阶段发挥关键作用。本研究旨在证明miR-155是否能使CD34⁺ CML细胞逃避转化生长因子-β1（TGF-β1）和骨形态发生蛋白（BMP）信号传导的生长抑制作用。在CD34⁺ CML细胞中差异表达的miRNA中，miR-155高度上调。定量逆转录聚合酶链反应（QRT-PCR）显示miR-155与TGF-β途径的两个关键成员——TGF-βR2和SMAD5呈负相关。结果表明，SMAD5不仅通过BMPs处理上调，而且重组TGF-β1也能在CML细胞中诱导SMAD5。我们还证明，用阻断TGF-βR2抗体预处理可消除TGF-β1介导的SMAD1/5磷酸化，提示TGF-βR2可能参与其中。此外，miR-155的过表达显著促进了CD34⁺ CML细胞的增殖率。结果表明，小干扰RNA（siRNA）介导的SMAD5敲低对CD34⁺ CML细胞增殖有促进作用，提示SMAD5敲低重现了miR-155的增殖效应。重要的是，TGF-β1和BMP2/4处理对细胞增殖有抑制作用；然而，miR-155过表达使CD34⁺ CML细胞能够逃避TGF-β1和BMPs的抗增殖作用。一致地，miR-155的下调增强了TGF-β1和BMP信号传导对诱导CD34⁺ CML干细胞凋亡的促进作用。我们的研究结果表明，靶向SMAD5和TGF-βR2将miR-155与CML中的TGF-β信号传导联系起来。miR-155的过表达使CD34⁺ CML细胞能够逃避TGF-β1和BMP信号传导的生长抑制作用，为miR-155作为CML的治疗靶点提供了新的视角。
