Abstract 301: RUNX3 upregulates c-MYC via mR1ーan essential genomic element for p53-deficient osteosarcomagenesis
Abstract 301: RUNX3 upregulates c-MYC via mR1ーan essential genomic element for p53-deficient osteosarcomagenesis
复制标题
摘要 301：RUNX3 通过 mR1 上调 c-MYC，mR1 是 p53 缺陷型骨肉瘤发生的必需基因组元件
DOI：
10.1158/1538-7445.am2020-301
复制
发表时间：
2020
期刊：
影响因子：
11.2
通讯作者：
Ito Kosei
中科院分区：
文献类型：
--
作者：
Date Yuki;Otani Shohei;Ueno Tomoya;Ito Kosei
骨肉瘤(OS)是儿童和青少年最常见的骨恶性肿瘤。复发或转移的患者的5年存活率仍为20%，这表明需要新的治疗策略。该病的特征通常是反复出现的P53的躯体改变。成骨细胞特异性的p53基因敲除小鼠(SP7-CRE；p53F/F；这里的‘OS小鼠’)骨肉瘤的发病率很高，与人类的组织病理学相似。因此，OS小鼠可作为研究OS发生的分子机制的合理动物模型。RUNX3/Runx3在骨肉瘤的发生中被证明是致癌的。我们发现RUNX3在人和小鼠的OS组织中都有明显的上调，分析了人类OS病例和OS小鼠的基因表达谱，其中大多数病例具有基因失活的P53。人OS细胞系和从OS小鼠克隆的小鼠OS细胞在裸鼠体内的致瘤性均强烈依赖于RUNX3。Runx3杂合缺失可有效延长OS小鼠的寿命，c-myc/c-Myc被确定为Runx3的阳性靶点。结合基因芯片和芯片序列分析，我们发现c-Mycis在转录水平上受Runx3的上调。在人和小鼠OS细胞中，RUNX3和c-myc的表达水平相互之间存在很好的相关性，并且RUNX3的敲除大大降低了c-myc的表达和致瘤性。Fc-Myc杂合缺失和Runx3杂合缺失可阻止OS小鼠的骨肉瘤形成。在OS患者中，RUNX3和c-MYC的mRNA水平呈正相关，两者的高表达是预后不良的预测因素。此外，我们还定位了RUNX3诱导c-MYC所必需的基因组元件。评估小鼠OS细胞的芯片序列图谱，我们选择了几个候选的基因组元件，这些元件负责在其3兆碱基的拓扑关联域内上调FC-Myc。对这些候选基因在人和小鼠OS细胞中的表观基因组/基因组编辑显示，基因组元件‘MR1’，即c-myc/c-Myc启动子最近端的6个碱基的RUNX共识结合部位，对于RUNX3诱导c-myc和致瘤性是必不可少的。事实上，mR1的纯合破坏有效地抑制了OS小鼠的骨肉瘤形成，从而提高了它们的存活率。综上所述，我们认为RUNX3是p53缺陷的骨肉瘤发生中的一个中心致癌因子：RUNX3在p53失活后以某种方式上调，然后开始异常上调c-myc。此外，我们还提出R1是RUNX3过表达FC-MYC所必需的基因组元件。重要的是，mr1基因缺失的小鼠是有活力和生育能力的，而c-Myc基因缺失的小鼠则会导致胚胎死亡。这表明mR1不是FC-Mycin正常发育的生理表达所必需的，而是RUNX3在骨肉瘤形成中异常上调所必需的，这为将mR1作为OS的新疗法提供了理论基础。引用格式：Yuki Date，Shohei Otani，Tomoya Ueno，Kosei Ito。RUNX3上调c-MYCviamR1--p53缺陷性骨肉瘤发生的必需基因组元件[摘要]。见：2020年美国癌症研究协会年会论文集；2020年4月27日至28日和6月22日至24日。费城(宾夕法尼亚州)：AACR；癌症资源2020；80(16补充)：摘要编号301。
Osteosarcoma (OS) is the most common malignancy of bone in children and adolescents. The 5-year survival rate of patients with relapse or metastasis remain 20%, underscoring a need for new treatment strategies. The disease is generally characterized by recurrent somatic alterations ofp53. An osteoblast-specificp53-knockout mouse line (Sp7-Cre;p53F/F; ‘OS mouse' herein) has a high incidence of osteosarcoma with a close histopathological resemblance to that of human. Thus, the OS mouse serves as a rational animal model to study molecular mechanisms of OS development.RUNX3/Runx3 was proved oncogenic in osteosarcomagenesis. We found dominant upregulation of RUNX3 in both human and mouse OS tissues, analyzing gene expression profiles of human OS cases, most of which possess genetically inactivatedp53, and those of OS mice. Both human OS cell lines and mouse OS cells cloned from OS mice showed a strong dependency on RUNX3 for tumorigenicity in nude mice. Heterozygous deletion ofRunx3efficiently extended lifespans of OS mice.c-MYC/c-Mycwas identified as a positive target of RUNX3. Combining microarray and ChIP-seq analyses of mouse OS cells, we found thatc-Mycis transcriptionally upregulated by Runx3. In human and mouse OS cells, expression levels of RUNX3 and c-MYC correlated well with each other and knockdown ofRUNX3greatly reduced c-MYC expression and tumorigenicity. Heterozygous deletion ofc-Myc, as well as that ofRunx3, prevented osteosarcomagenesis of OS mice. In OS patients, mRNA levels ofRUNX3andc-MYCshowed a positive correlation and high expression of each was a predictor of poor prognosis.Furthermore, we located a requisite genomic element forc-MYCinduction by RUNX3. Assessing the ChIP-seq profiles of mouse OS cells, we selected several candidates of genomic elements responsible for upregulation ofc-Mycwithin its 3-megabase topological association domain. Epigenome/genome editing of these candidates in human and mouse OS cells revealed that a genomic element ‘mR1', the 6-bp RUNX consensus binding site most proximal to thec-MYC/c-Mycpromoter, is essential forc-MYCinduction by RUNX3 and tumorigenicity. Indeed, homozygous disruption ofmR1effectively suppressed osteosarcomagenesis of OS mice and thus improved their survivals.Taken together, we propose RUNX3 as a central oncogenic figure inp53-deficient osteosarcomagenesis: RUNX3 is somehow upregulated upon inactivation ofp53and then starts to aberrantly upregulatec-MYC. Moreover, we proposemR1as an essential genomic element for overexpression ofc-MYCby RUNX3. Importantly,mR1-null mice are viable and fertile whereasc-Myc-null mice result in embryonic lethality. This indicates thatmR1is required not for physiological expression ofc-MYCin normal development, but for its aberrant upregulation by RUNX3 in osteosarcomagenesis, providing a rationale for targetingmR1as a novel therapy of OS.Citation Format:Yuki Date, Shohei Otani, Tomoya Ueno, Kosei Ito. RUNX3 upregulatesc-MYCviamR1– an essential genomic element forp53-deficient osteosarcomagenesis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 301.