Hsieh Joseph, Danis Etienne P, Owens Charles R, Parrish Janet K, Nowling Nathan L, Wolin Arthur R, Purdy Stephen Connor, Rosenbaum Sheera R, Ivancevic Atma M, Chuong Edward B, Ford Heide L, Jedlicka Paul
Medical Scientist Training Program, University of Colorado Anschutz Medical Campus (UC-AMC), Aurora, CO, USA.
Cancer Biology Graduate Training Program, UC-AMC, Aurora, CO, USA.
Oncogene. 2025 Jan;44(1):19-29. doi: 10.1038/s41388-024-03201-2. Epub 2024 Oct 24.
Rhabdomyosarcoma (RMS), a malignancy of impaired myogenic differentiation, is the most common soft tissue pediatric cancer. PAX3-FOXO1 oncofusions drive the majority of the clinically more aggressive fusion-positive rhabdomyosarcoma (FP-RMS). Recent studies have established an epigenetic basis for PAX3-FOXO1-driven oncogenic processes. However, details of PAX3-FOXO1 epigenetic mechanisms, including interactions with, and dependence on, other chromatin and transcription factors, are incompletely understood. We previously identified a novel disease-promoting epigenetic axis in RMS, involving the histone demethylase KDM3A and the ETS1 transcription factor, and demonstrated that this epigenetic axis interfaces with PAX3-FOXO1 both phenotypically and transcriptomically, including co-regulation of biological processes and genes important to FP-RMS progression. In this study, we demonstrate that KDM3A and ETS1 colocalize with PAX3-FOXO1 to enhancers of important disease-promoting genes in FP-RMS, including FGF8, IL4R, and MEST, as well as PODXL, which we define herein as a new FP-RMS-promoting gene. We show that ETS1, which is induced by both PAX3-FOXO1 and KDM3A, exists in complex with PAX3-FOXO1, and augments PAX3-FOXO1 chromatin occupancy. We further show that the PAX3-FOXO1/ETS1 complex can be disrupted by the clinically relevant small molecule inhibitor YK-4-279. YK-4-279 displaces PAX3-FOXO1 from chromatin and interferes with PAX3-FOXO1-dependent gene regulation, resulting in potent inhibition of growth and invasive properties in FP-RMS, along with downregulation of FGF8, IL4R, MEST and PODXL expression. We additionally show that, in some FP-RMS, KDM3A also increases PAX3-FOXO1 levels. Together, our studies illuminate mechanisms of action of the KDM3A/ETS1 regulatory module, and reveal novel targetable mechanisms of PAX3-FOXO1 chromatin complex regulation, in FP-RMS.
横纹肌肉瘤（RMS）是一种肌源性分化受损的恶性肿瘤，是儿童最常见的软组织癌症。PAX3-FOXO1致癌融合基因驱动了临床上侵袭性更强的大多数融合阳性横纹肌肉瘤（FP-RMS）。最近的研究为PAX3-FOXO1驱动的致癌过程奠定了表观遗传基础。然而，PAX3-FOXO1表观遗传机制的细节，包括与其他染色质和转录因子的相互作用及依赖性，仍未完全了解。我们之前在RMS中鉴定出一种新的促进疾病的表观遗传轴，涉及组蛋白去甲基化酶KDM3A和ETS1转录因子，并证明该表观遗传轴在表型和转录组水平上与PAX3-FOXO1相互作用，包括对FP-RMS进展重要的生物学过程和基因的共同调控。在本研究中，我们证明KDM3A和ETS1与PAX3-FOXO1共定位于FP-RMS中重要的促进疾病基因的增强子上，包括FGF8、IL4R和MEST，以及PODXL，我们在此将其定义为一个新的促进FP-RMS的基因。我们发现，由PAX3-FOXO1和KDM3A共同诱导的ETS1与PAX3-FOXO1形成复合物，并增加PAX3-FOXO1在染色质上的占据率。我们进一步表明，临床相关的小分子抑制剂YK-4-279可破坏PAX3-FOXO1/ETS1复合物。YK-4-279将PAX3-FOXO1从染色质上置换下来，并干扰PAX3-FOXO1依赖性基因调控，从而有效抑制FP-RMS的生长和侵袭特性，同时下调FGF8、IL4R、MEST和PODXL的表达。我们还表明，在一些FP-RMS中，KDM3A也会增加PAX3-FOXO1的水平。总之，我们的研究阐明了KDM3A/ETS1调控模块的作用机制，并揭示了FP-RMS中PAX3-FOXO1染色质复合物调控的新的可靶向机制。
