The critical role that STAT3 plays in glioma-initiating cells: STAT3 addiction in glioma.
The critical role that STAT3 plays in glioma-initiating cells: STAT3 addiction in glioma.
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DOI：
10.18632/oncotarget.25188
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发表时间：
2018-04-24
期刊：
影响因子：
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通讯作者：
Pfeffer LM
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文献类型：
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作者：
Ganguly D;Fan M;Yang CH;Zbytek B;Finkelstein D;Roussel MF;Pfeffer LM
胶质瘤起始细胞（GIC）被认为是胶质母细胞瘤（GBM）肿瘤发生、进展和复发的原因。在之前的研究中，我们报道了来自 GBM 患者异种移植物的 GIC 中 STAT3 转录因子的组成型磷酸化，并且 STAT3 在 GBM 肿瘤发生中发挥着关键作用。在这项研究中，我们发现，在已建立的 GBM 细胞系中，CRISPR/Cas9 介导的 STAT3 缺失通过颅内注射显着抑制了肿瘤发生，但对体外细胞增殖影响不大。通过在缺乏 STAT3 的细胞中强制表达野生型 STAT3，可以挽救肿瘤发生。相比之下，GIC 对 STAT3 高度依赖，并且在 STAT3 缺失后，GIC 无法存活。此外，我们发现 STAT3 在 GIC 中通过酪氨酸 (Y705) 和丝氨酸 (S727) 残基的磷酸化而被组成型激活。因此，为了研究 GIC 中 STAT3 的功能，我们建立了一个敲低 STAT3 表达的诱导系统 (iSTAT3-KD)。使用这种方法，我们证明了 Y705-STAT3 磷酸化对于 GIC 诱导的肿瘤形成至关重要且不可或缺。 STAT3 中的两个磷酸化位点均促进 GIC 体外增殖。我们进一步表明 S727-STAT3 磷酸化是 Y705 依赖性的。靶向微阵列和RNA测序显示，STAT3激活细胞周期调节基因，并下调参与干扰素反应、缺氧反应、TGFβ途径和细胞外基质重塑的基因。由于 STAT3 是 GBM 的重要致癌驱动因素，因此鉴定 GIC 中的这些 STAT3 调节途径将为针对 GBM 和其他癌症中的 STAT3 开发更好的靶向疗法提供信息。
Glioma-Initiating Cells (GICs) are thought to be responsible for tumor initiation, progression and recurrence in glioblastoma (GBM). In previous studies, we reported the constitutive phosphorylation of the STAT3 transcription factor in GICs derived from GBM patient-derived xenografts, and that STAT3 played a critical role in GBM tumorigenesis. In this study, we show that CRISPR/Cas9-mediated deletion of STAT3 in an established GBM cell line markedly inhibited tumorigenesis by intracranial injection but had little effect on cell proliferation in vitro. Tumorigenesis was rescued by the enforced expression of wild-type STAT3 in cells lacking STAT3. In contrast, GICs were highly addicted to STAT3 and upon STAT3 deletion GICs were non-viable. Moreover, we found that STAT3 was constitutively activated in GICs by phosphorylation on both tyrosine (Y705) and serine (S727) residues. Therefore, to study STAT3 function in GICs we established an inducible system to knockdown STAT3 expression (iSTAT3-KD). Using this approach, we demonstrated that Y705-STAT3 phosphorylation was critical and indispensable for GIC-induced tumor formation. Both phosphorylation sites in STAT3 promoted GIC proliferation in vitro. We further showed that S727-STAT3 phosphorylation was Y705-dependent. Targeted microarray and RNA sequencing revealed that STAT3 activated cell-cycle regulator genes, and downregulated genes involved in the interferon response, the hypoxia response, the TGFβ pathway, and remodeling of the extracellular matrix. Since STAT3 is an important oncogenic driver of GBM, the identification of these STAT3 regulated pathways in GICs will inform the development of better targeted therapies against STAT3 in GBM and other cancers.