Cyclin D1 is a mediator of gastrointestinal stromal tumor KIT-independence
Cyclin D1 is a mediator of gastrointestinal stromal tumor KIT-independence
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Cyclin D1 是胃肠道间质瘤 KIT 依赖性的介质
DOI：
10.1038/s41388-019-0894-3
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发表时间：
2019-09-26
期刊：
影响因子：
8
通讯作者：
Fletcher, Jonathan A.
中科院分区：
文献类型：
--
作者：
Ou, Wen-Bin;Ni, Nan;Fletcher, Jonathan A.
致癌试剂盒或PDGFRA酪氨酸激酶突变是大多数胃肠道间质瘤(GIST)的引人注目的治疗靶点，因此KIT抑制剂伊马替尼是转移性GIST患者的标准护理。然而，一些GIST失去了KIT癌蛋白的表达，因此变得不依赖KIT，因此对KIT抑制药物具有耐药性。我们确定了不依赖试剂盒的、对伊马替尼耐药的GIST的独特生物学特征，作为在这些鲜为人知的肿瘤中识别药物靶点的一步。我们建立了等基因的GIST系，其中亲本形式依赖KIT癌蛋白，而亚系KIT癌蛋白表达缺失，伴随着GIST生物标记物蛋白激酶C-theta(PRKCQ)的显著下调。通过转录组测序、qRT-PCR、免疫印迹、蛋白质相互作用研究、基因敲除和表达分析以及双荧光素酶分析，确定了非试剂盒依赖的GIST独特的生物学机制。转录组测序显示，在三个依赖于试剂盒的GIST细胞系中，有两个细胞周期蛋白D1的表达极低，而在每个非试剂盒依赖的GIST亚系中，细胞周期蛋白D1的表达都很高。在非KIT依赖的GIST中抑制细胞周期蛋白D1具有抗增殖和促凋亡作用，并与Rb激活和p27上调有关。PRKCQ而不是KIT是细胞周期蛋白D1表达的负调控因子，而Jun和Hippo通路效应分子YAP和TAZ则是细胞周期蛋白D1表达的正调控因子。PRKCQ、JUN和河马途径协同调节GIST细胞周期蛋白D1的表达。这些发现突出了PRKCQ、JUN、HIPPO和细胞周期蛋白D1在GIST中作为致癌介质的作用，GIST在TKI治疗期间已经转化为非试剂盒状态。这些途径的抑制剂对这些现在无法治疗的肿瘤可能是有效的治疗方法。
Oncogenic KIT or PDGFRA tyrosine kinase mutations are compelling therapeutic targets in most gastrointestinal stromal tumors (GISTs), and the KIT inhibitor, imatinib, is therefore standard of care for patients with metastatic GIST. However, some GISTs lose expression of KIT oncoproteins, and therefore become KIT-independent and are consequently resistant to KIT-inhibitor drugs. We identified distinctive biologic features in KIT-independent, imatinib-resistant GISTs as a step towards identifying drug targets in these poorly understood tumors. We developed isogenic GIST lines in which the parental forms were KIT oncoprotein-dependent, whereas sublines had loss of KIT oncoprotein expression, accompanied by markedly downregulated expression of the GIST biomarker, protein kinase C-theta (PRKCQ). Biologic mechanisms unique to KIT-independent GISTs were identified by transcriptome sequencing, qRT-PCR, immunoblotting, protein interaction studies, knockdown and expression assays, and dual-luciferase assays. Transcriptome sequencing showed that cyclin D1 expression was extremely low in two of three parental KIT-dependent GIST lines, whereas cyclin D1 expression was high in each of the KIT-independent GIST sublines. Cyclin D1 inhibition in KIT-independent GISTs had anti-proliferative and pro-apoptotic effects, associated with Rb activation and p27 upregulation. PRKCQ, but not KIT, was a negative regulator of cyclin D1 expression, whereas JUN and Hippo pathway effectors YAP and TAZ were positive regulators of cyclin D1 expression. PRKCQ, JUN, and the Hippo pathway coordinately regulate GIST cyclin D1 expression. These findings highlight the roles of PRKCQ, JUN, Hippo, and cyclin D1 as oncogenic mediators in GISTs that have converted, during TKI-therapy, to a KIT-independent state. Inhibitors of these pathways could be effective therapeutically for these now untreatable tumors.