Targeting EWS-ATF1 Fusion in Clear Cell Sarcoma of Soft Tissue

项目摘要/摘要 这项应用的目标是开发针对软组织透明细胞肉瘤的新的靶向疗法。 (CCSST)，并了解它们的作用机制。CCSST是一种罕见的侵袭性软组织肉瘤， 通常发生在靠近肌腱和腱膜的青少年和青壮年的下肢。它 是一种目前无法治愈的孤儿疾病。转移性病例的5年生存率仅为20%。这个 目前的治疗选择是进行广泛的局部手术切除或截肢，试图移除所有 癌细胞。然而，在转移性病例中，完全移除癌细胞变得不可能，并且 全身辅助治疗是控制本病的关键。不幸的是，这种疾病因其 对现有化疗不敏感，强调迫切需要开发新的靶向治疗 对于CCSST。CCSST的特点是t(12；22)(q13；q12)染色体平衡 易位，导致尤文氏肉瘤基因EWSR1(EWS RNA结合蛋白1)与 激活转录因子1(Atf1)以产生癌基因EWS-atf1。ATF1是阵营的一员- 反应元件结合蛋白(CREB)家族转录因子。EWS-atf1在结构上对 驱动通常由CREB/atf1调控的靶基因的表达。除atf1外，EWS- 在CCSST患者中也检测到CREB融合，进一步支持了CREB/ATF1‘S的关键作用 转录活性在推动CCSST发育中的作用。不同类型CCSST的体内外研究 模型已经令人信服地表明，CCSST细胞依赖于ews-atf1介导的基因转录。 为继续生存而进行的活动。这些结果表明，靶向EWS-atf1是一种强大的、有前途的 为CCSST开发新的靶向治疗药物的途径。作为一种转录因子，EWS-atf1已经成为一种 开发小分子抑制剂具有挑战性的目标。此外，EWS-atf1通过哪些机制 激活基因转录的机制还不是很清楚。我们最近开发了一种名为666-15的小分子， CREB/atf1介导的基因转录的第一个有效抑制剂。666-15在体内耐受性良好。在这 应用，我们将研究666-15在各种CCSST模型中的活性及其作用机制 (目标1)。我们将进一步研究EWS-atf1如何激活基因转录(目标2)。在目标3中，我们将确定 CCSST的综合治疗策略。

PROJECT SUMMARY/ABSTRACT The goals of this application are to develop novel targeted therapies for clear cell sarcoma of soft tissue (CCSST) and understand their mechanism of action. CCSST is a rare and aggressive soft tissue sarcoma that typically develops in the lower extremity close to tendons and aponeuroses of adolescents and young adults. It is an orphan disease presently with no cure. The 5-year survival rate is only 20% for metastatic cases. The current treatment option is to perform wide local surgical resection or amputation attempting to remove all the cancer cells. However, in metastatic cases, complete removal of cancer cells becomes impossible and systemic adjuvant therapy is the key to control this disease. Unfortunately, this disease is notorious for its insensitivity to existing chemotherapies, underscoring an urgent need for developing novel targeted therapies for CCSST. The hallmark of CCSST is characterized by a balanced t(12;22) (q13;q12) chromosomal translocation, which results in a fusion of the Ewing's sarcoma gene EWSR1 (EWS RNA-bind protein 1) with activating transcription factor 1 (ATF1) to generate an oncogene EWS-ATF1. ATF1 is a member of the cAMP- responsive element binding protein (CREB) family transcription factor. EWS-ATF1 is constitutively active to drive the expression of target genes that are normally regulated by CREB/ATF1. In addition to ATF1, EWS- CREB fusion has also been detected in CCSST patients, further supporting a critical role of CREB/ATF1's transcription activity in driving the development of CCSST. In vitro and in vivo studies in various CCSST models have convincingly shown that CCSST cells depend on the EWS-ATF1-mediated gene transcription activity for continued survival. These results suggest that targeting EWS-ATF1 is a powerful and promising approach to develop novel targeted therapeutics for CCSST. As a transcription factor, EWS-ATF1 has been a challenging target for developing small molecule inhibitors. In addition, the mechanisms by which EWS-ATF1 activates gene transcription are not well-understood. We recently developed a small molecule called 666-15 as the first potent inhibitor of CREB/ATF1-mediated gene transcription. 666-15 is well-tolerated in vivo. In this application, we will investigate the activity of 666-15 in various CCSST models and its mechanism of action (Aim 1). We will further study how EWS-ATF1 activates gene transcription (Aim 2). In Aim 3, we will identify combination treatment strategies for CCSST.