miR-29b induces SOCS-1 expression by promoter demethylation and negatively regulates migration of multiple myeloma and endothelial cells
miR-29b induces SOCS-1 expression by promoter demethylation and negatively regulates migration of multiple myeloma and endothelial cells
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DOI：
10.4161/cc.26585
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发表时间：
2013-12-01
期刊：
影响因子：
4.3
通讯作者：
Tassone, Pierfrancesco
中科院分区：
文献类型：
--
作者：
Amodio, Nicola;Bellizzi, Dina;Tassone, Pierfrancesco
肿瘤抑制基因的表观遗传学沉默经常发生，并且可能是它们在癌细胞中失活的原因。我们先前证明miR-29 b是一种肿瘤抑制microRNA（miRNA），靶向从头DNA甲基转移酶，并减少多发性骨髓瘤（MM）细胞的整体DNA甲基化。在这里，我们提供的证据表明，miR-29 b的表观遗传活性导致启动子去甲基化的抑制细胞因子信号传导-1（SoCS-1），一个高甲基化的肿瘤抑制基因。如通过Sequenom MassARRAY epitYpeR分析所评估的，在MM细胞系中合成的miR-29 b模拟物的强制表达导致SOCS-1基因启动子去甲基化和SoCS-1蛋白上调。miR-29 b诱导的SOCS-1去甲基化与StAt 3磷酸化减少和NF-κ B活性受损相关。在用miR-29 b模拟物转染的MM细胞以及用来自miR-29 b转染的MM细胞的条件培养基处理的内皮（HUVec）或基质（HS-5）细胞中可以检测到VeGF-A和IL-8 mRNA的下调。值得注意的是，miR-29 b模拟物的增强表达增加了MM细胞对HS-5的粘附，并减少了MM和HUVec细胞的迁移。这些发现表明miR-29 b是MM或内皮细胞迁移的负调节因子。最后，蛋白酶体抑制剂硼替佐米可诱导miR-29 b的表达，通过miR-29 b依赖性机制降低整体DNA甲基化，并诱导SOCS-1启动子去甲基化和蛋白质上调。总之，我们的数据表明，miR-29 b具有表观遗传活性，并介导硼替佐米在MM细胞中的先前未知功能。
epigenetic silencing of tumor suppressor genes frequently occurs and may account for their inactivation in cancer cells. We previously demonstrated that miR-29b is a tumor suppressor microRNA (miRNA) that targets de novo DNA methyltransferases and reduces the global DNA methylation of multiple myeloma (MM) cells. Here, we provide evidence that epigenetic activity of miR-29b leads to promoter demethylation of suppressor of cytokine signaling-1 (SoCS-1), a hypermethylated tumor suppressor gene. enforced expression of synthetic miR-29b mimics in MM cell lines resulted in SOCS-1 gene promoter demethylation, as assessed by Sequenom MassARRAY epitYpeR analysis, and SoCS-1 protein upregulation. miR-29b-induced SOCS-1 demethylation was associated with reduced StAt3 phosphorylation and impaired NF-kappa B activity. Downregulation of VeGF-A and IL-8 mRNAs could be detected in MM cells transfected with miR-29b mimics as well as in endothelial (HUVeC) or stromal (HS-5) cells treated with conditioned medium from miR-29b-transfected MM cells. Notably, enforced expression of miR-29b mimics increased adhesion of MM cells to HS-5 and reduced migration of both MM and HUVeC cells. these findings suggest that miR-29b is a negative regulator of either MM or endothelial cell migration. Finally, the proteasome inhibitor bortezomib, which induces the expression of miR-29b, decreased global DNA methylation by a miR-29b-dependent mechanism and induced SOCS-1 promoter demethylation and protein upregulation. In conclusion, our data indicate that miR-29b is endowed with epigenetic activity and mediates previously unknown functions of bortezomib in MM cells.