PO.TB05.01 · 肿瘤生物学
探索与上皮样肉瘤中SMARCB1缺陷相关的可靶向治疗靶点
Exploring actionable therapeutic targets associated with SMARCB1 deficiency in Epithelioid sarcoma
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
上皮样肉瘤（EPS）是一种罕见、生长缓慢但高度转移的间叶性肿瘤，以SMARCB1失活为特征。尽管EZH2抑制剂Tazemetostat已被批准用于EPS患者，但临床结局仍然不佳。在本研究中，我们进行了功能基因组学研究，以识别EPS的治疗弱点并阐明其潜在机制。使用靶向约2,700个可成药基因的sgRNA文库进行CRISPR筛选，鉴定出EPS细胞对以下基因的依赖性：BAF复合体亚基（SMARCA4、SMARCC2和SMARCD1）、整合素通路基因（ITGAV、PTK2、PTPN11）以及细胞周期蛋白依赖性激酶（CDK4和CDK6）。临床可用的CDK4/6双重抑制剂Palbociclib在体外有效抑制EPS细胞增殖，并在人EPS细胞系来源的异种移植模型中显著延缓肿瘤生长。此外，CDK4选择性抑制剂Atirmociclib在CDK6低表达的细胞系中表现出显著的细胞毒性，提示可根据CDK6表达水平定制CDK4/6靶向疗法的可行性。使用Tet-ON条件表达系统重新表达SMARCB1诱导了生长停滞，伴随RB磷酸化减少和细胞周期蛋白A2（CCNA2）表达降低。SMARCB1的重新表达还上调了CDK抑制剂p21和p27，表明细胞周期控制受损。EPS对p21/p27-CDK4/6轴的强烈依赖性支持将CDK4/6抑制作为一种治疗策略。我们的CRISPR筛选和体外活力实验表明，EPS细胞系对Tazemetostat具有内在耐药性，p16的遗传学和表观遗传学沉默成为该耐药性背后的潜在机制。综上所述，功能基因组学筛选界定了EPS的关键治疗弱点，提示CDK4/6抑制剂作为EPS患者有前景的治疗选择。我们提出，CDK6和p16的表达水平可能作为对EZH2和CDK4/6抑制剂反应的预测性生物标志物，从而为患者分层提供依据并改善临床结局。
查看英文原文 English abstract
Epithelioid sarcoma (EPS) is a rare, slow-growing yet highly metastatic mesenchymal neoplasm characterized by inactivation of SMARCB1. Although the EZH2 inhibitor Tazemetostat has been approved for EPS patients, clinical outcomes remain poor. In this study, we performed functional genomic studies to identify therapeutic vulnerabilities of EPS and to elucidate their underlying mechanisms.CRISPR screening using an sgRNA library targeting ~2,700 druggable genes identified dependencies of EPS cells on; BAF complex subunits (SMARCA4, SMARCC2 and SMARCD1), integrin pathway genes (ITGAV, PTK2, PTPN11) and the cyclin-dependent kinases (CDK4 and CDK6). A clinically available CDK4/6 dual inhibitor Palbociclib effectively inhibited EPS cell proliferation in vitro and significantly delayed tumor growth in human EPS cell line-derived xenograft models. Moreover, the CDK4-selective inhibitor Atirmociclib showed profound cytotoxicity in cell lines with low CDK6 expression, suggesting the feasibility of tailoring CDK4/6-targeted therapy based on CDK6 expression levels.Re-expression of SMARCB1 using a Tet-ON conditional expression system induced growth arrest, accompanied by reduced RB phosphorylation and decreased cyclin A2 (CCNA2) expression. SMARCB1 re-expression also upregulated the CDK inhibitors, p21 and p27, indicating compromised cell cycle control. The strong dependency of EPS on p21/p27-CDK4/6 axis supports CDK4/6 inhibition as a therapeutic strategy. Our CRISPR screen and in vitro viability assays demonstrated that EPS cell lines are intrinsically resistant to Tazemetostat, with genetic and epigenetic silencing of p16 emerging as a potential mechanism underlying this resistance.Together, functional genomic screens define key therapeutic vulnerabilities in EPS, suggesting CDK4/6 inhibitors as a promising treatment option for EPS patients. We propose that expression levels of CDK6 and p16 may serve as predictive biomarkers for response to EZH2 and CDK4/6 inhibitors, thereby informing patient stratification and improving clinical outcomes.
利益披露 Disclosure
J. Park, None..
R. Miyamoto, None..
D. G. Kirsch, None.