Mendes Elizabeth A, Munshi Aanandi, Singh Archana, Evans Maisie D, Chou Hsien-Chao, Kim Yong Yean, Song Young, Jo Ara, Lee Daniel, Ciampi Jaida, Chambers Audrey, Weitzel Samantha, Deel Michael, Bentley Rex C, Khan Javed, Green Darrell, Linardic Corinne M
Division of Pediatric Hematology-Oncology, Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA.
Department of Pharmacology & Cancer Biology, Duke University School of Medicine, Durham, NC, USA.
bioRxiv. 2025 Jul 24:2025.07.21.665972. doi: 10.1101/2025.07.21.665972.
Fusion-positive rhabdomyosarcoma is an aggressive pediatric cancer of skeletal muscle lineage, with a 5-year overall survival of <30% for high-risk disease, and <8% when metastatic. The fusion gene, resulting from (2:13), is a signature driver of fusion-positive rhabdomyosarcoma, but similar to other transcription-factor based fusion genes in other cancers, not currently pharmacologically tractable. To identify novel druggable proteins in fusion-positive rhabdomyosarcoma tumor tissue and cell lines, we performed mRNA-seq of RMS patient tumors and utilizing the human FP-RMS cell lines Rh30 and Rh4, found that the RUNX2 transcription factor was the top druggable dependency. loss of function studies using genetic (RNAi) or pharmacologic (small molecule CADD522) inhibition showed that RUNX2 suppression inhibited FP-RMS cell growth, induced myogenic differentiation and apoptosis, and phenocopied PAX3::FOXO1 suppression. loss of function studies using conditional (dox-inducible) or pharmacologic (small molecule CADD522) blockade of tumor growth in a xenograft model system showed that RUNX2 suppression inhibited tumor growth. Mechanistically, we identify a PAX3::FOXO1 feed-forward loop whereby PAX3::FOXO1 binds a enhancer to upregulate gene expression alongside MYOD1, while RUNX2 expression supports the expression of PAX3::FOXO1 at the mRNA and protein level.
融合阳性横纹肌肉瘤是一种侵袭性的源自骨骼肌谱系的儿童癌症,高危疾病的5年总生存率小于30%,发生转移时则小于8%。由(2:13)产生的融合基因是融合阳性横纹肌肉瘤的标志性驱动因素,但与其他癌症中基于转录因子的融合基因类似,目前在药理学上难以处理。为了在融合阳性横纹肌肉瘤肿瘤组织和细胞系中鉴定新的可药物化蛋白,我们对横纹肌肉瘤患者肿瘤进行了mRNA测序,并利用人融合阳性横纹肌肉瘤细胞系Rh30和Rh4,发现RUNX2转录因子是首要的可药物化依赖性因素。使用基因(RNA干扰)或药理学(小分子CADD522)抑制进行的功能丧失研究表明,RUNX2抑制可抑制融合阳性横纹肌肉瘤细胞生长,诱导肌源性分化和凋亡,并模拟PAX3::FOXO1抑制的表型。在异种移植模型系统中使用条件性(多西环素诱导)或药理学(小分子CADD522)阻断肿瘤生长的功能丧失研究表明,RUNX2抑制可抑制肿瘤生长。从机制上讲,我们鉴定出一个PAX3::FOXO1前馈环,其中PAX3::FOXO1结合一个增强子以与MYOD1一起上调基因表达,而RUNX2表达在mRNA和蛋白质水平上支持PAX3::FOXO1的表达。
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