TGF-β1 modulates temozolomide resistance in glioblastoma via altered microRNA processing and elevated MGMT.
TGF-β1 modulates temozolomide resistance in glioblastoma via altered microRNA processing and elevated MGMT.
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TGF-β1 通过改变 microRNA 处理和升高 MGMT 调节胶质母细胞瘤中的替莫唑胺耐药性。
DOI：
10.1093/neuonc/noaa198
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发表时间：
2021-03-25
期刊：
影响因子：
15.9
通讯作者：
You Y
中科院分区：
文献类型：
--
作者：
Nie E;Jin X;Miao F;Yu T;Zhi T;Shi Z;Wang Y;Zhang J;Xie M;You Y
我们以前的研究表明，miR-198降低细胞甲基鸟嘌呤DNA甲基转移酶（MGMT）水平，以增强替莫唑胺的敏感性。转化生长因子β 1（TGF-β1）通过抑制表皮角质形成细胞中K同源剪接调节蛋白（KSRP）的表达来关闭miR-198的表达。然而，TGF-β1在替莫唑胺耐药中的潜在作用仍然未知。采用免疫印迹法和免疫荧光法检测KSRP的分布。微阵列分析用于比较TGF-β1处理和未处理的细胞之间的长非编码RNA（lncRNA）的水平。RNA免疫沉淀法验证RNA与KSRP的关系。采用流式细胞术和原位及皮下移植瘤模型检测TGF-β1在替莫唑胺耐药中的作用。TGF-β1的过表达促进了MGMT启动子低甲基化胶质母细胞瘤细胞对替莫唑胺的耐药。TGF-β1处理通过抑制miR-198的表达降低细胞MGMT水平。然而，TGF-β1上调并不影响胶质瘤细胞中KSRP的表达。我们鉴定并表征了2个lncRNA（H19和HOXD-AS 2），它们通过Smad信号被TGF-β1上调。H19和HOXD-AS 2与KSRP竞争性结合，阻止KSRP与原代miR-198结合，从而降低miR-198的表达。HOXD-AS 2或H19上调强烈促进替莫唑胺耐药和MGMT表达。此外，KSRP耗竭消除了TGF-β1和lncRNA对miR-198和MGMT的影响。最后，我们发现TGF-β1或lncRNA表达水平低的患者从替莫唑胺治疗中获益。我们的研究结果揭示了TGF-β1赋予替莫唑胺耐药的潜在机制。此外，我们的研究结果表明，替莫唑胺与TGF-β抑制剂的新型组合可能是胶质母细胞瘤的有效治疗方法。
Our previous studies have indicated that miR-198 reduces cellular methylguanine DNA methyltransferase (MGMT) levels to enhance temozolomide sensitivity. Transforming growth factor beta 1 (TGF-β1) switches off miR-198 expression by repressing K-homology splicing regulatory protein (KSRP) expression in epidermal keratinocytes. However, the underlying role of TGF-β1 in temozolomide resistance has remained unknown. The distribution of KSRP was detected by western blotting and immunofluorescence. Microarray analysis was used to compare the levels of long noncoding RNAs (lncRNAs) between TGF-β1–treated and untreated cells. RNA immunoprecipitation was performed to verify the relationship between RNAs and KSRP. Flow cytometry and orthotopic and subcutaneous xenograft tumor models were used to determine the function of TGF-β1 in temozolomide resistance. Overexpression of TGF-β1 contributed to temozolomide resistance in MGMT promoter hypomethylated glioblastoma cells in vitro and in vivo. TGF-β1 treatment reduced cellular MGMT levels through suppressing the expression of miR-198. However, TGF-β1 upregulation did not affect KSRP expression in glioma cells. We identified and characterized 2 lncRNAs (H19 and HOXD-AS2) that were upregulated by TGF-β1 through Smad signaling. H19 and HOXD-AS2 exhibited competitive binding to KSRP and prevented KSRP from binding to primary miR-198, thus decreasing miR-198 expression. HOXD-AS2 or H19 upregulation strongly promoted temozolomide resistance and MGMT expression. Moreover, KSRP depletion abrogated the effects of TGF-β1 and lncRNAs on miR-198 and MGMT. Finally, we found that patients with low levels of TGF-β1 or lncRNA expression benefited from temozolomide therapy. Our results reveal an underlying mechanism by which TGF-β1 confers temozolomide resistance. Furthermore, our findings suggest that a novel combination of temozolomide with a TGF-β inhibitor may serve as an effective therapy for glioblastomas.
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