Proudfit Austin, Bhunia Nabanita, Pore Debasis, Parker Yvonne, Lindner Daniel, Gupta Neetu
Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
Department of Pediatric Hematology-Oncology & Bone Marrow Transplantation, Cleveland Clinic, Cleveland, OH, USA.
Sarcoma. 2020 Sep 9;2020:9010496. doi: 10.1155/2020/9010496. eCollection 2020.
Intermediate and high-risk rhabdomyosarcoma (RMS) patients have poor prognosis with available treatment options, highlighting a clear unmet need for identification of novel therapeutic strategies. Ezrin-radixin-moesin (ERM) family members are membrane-cytoskeleton linker proteins with well-defined roles in tumor metastasis, growth, and survival. ERM protein activity is regulated by dynamic changes in the phosphorylation at a conserved threonine residue in their C-terminal actin-binding domain. Interestingly, ERM family member, ezrin, has elevated expression in the RMS tissue. Despite this, the translational scope of targeting ERM family proteins in these tumors through pharmacological inhibition has never been considered. This study investigates the inhibition of ERM phosphorylation using a small molecule pharmacophore NSC668394 as a potential strategy against RMS. Upon in vitro treatment with NSC668394, RMS cells exhibit a dose-dependent decrease in cell viability and proliferation, with induction of caspase-3 cleavage and apoptosis. siRNA-mediated knockdown of individual ERM protein expression revealed that each regulates RMS survival to a different degree. In vivo administration of NSC668394 in RMS xenografts causes significant decrease in tumor growth, with no adverse effect on body weight. Collectively, this study highlights the importance of the active conformation of ERM proteins in RMS progression and survival and supports pharmacologic inhibition of these proteins as a novel therapeutic approach.
中高危横纹肌肉瘤（RMS）患者采用现有治疗方案时预后较差，这凸显了明确的未满足需求，即需要确定新的治疗策略。埃兹蛋白-根蛋白-膜突蛋白（ERM）家族成员是膜细胞骨架连接蛋白，在肿瘤转移、生长和存活中具有明确作用。ERM蛋白活性受其C末端肌动蛋白结合域中保守苏氨酸残基磷酸化动态变化的调节。有趣的是，ERM家族成员埃兹蛋白在RMS组织中的表达升高。尽管如此，通过药物抑制在这些肿瘤中靶向ERM家族蛋白的转化应用范围从未被考虑过。本研究调查了使用小分子药效团NSC668394抑制ERM磷酸化作为针对RMS的潜在策略。在用NSC668394进行体外处理后，RMS细胞的细胞活力和增殖呈剂量依赖性下降，并诱导半胱天冬酶-3裂解和凋亡。siRNA介导的单个ERM蛋白表达敲低显示，每种蛋白对RMS存活的调节程度不同。在RMS异种移植瘤中体内给予NSC668394可导致肿瘤生长显著降低，且对体重无不良影响。总体而言，本研究突出了ERM蛋白活性构象在RMS进展和存活中的重要性，并支持将这些蛋白作为一种新的治疗方法进行药物抑制。
