TRAIL Therapy for Rhabdomyosacrcoma

描述(由申请人提供)：出现转移性儿科RMS的患者和携带PAX3/FOXO1a基因产物的患者的预后仍然很差。这一续订申请探索了专门应用于儿科RMS的开发治疗方法。11个RMS细胞系中有5个对细胞毒配体TRAIL敏感。当FOXO1a被转导时，选择性地诱导TRAIL耐药臂中caspase-3的激活和凋亡，并使Rh30臂细胞对TRAIL敏感。假设这些事件是通过FADD、Bim或caspase-3介导的选择性调控，并可能涉及p38MAPK、DR5或TRAIL的激活。总体目标是阐明FOXO1a的下游靶点，它可能选择性地调节TRAIL耐药臂的细胞凋亡，并可能用于治疗。SphK在所有RMS细胞系中都升高，它抑制促凋亡的Sh向Sp的转化(参与转化和增殖)。Sph和SphK抑制剂DHSph诱导所有细胞系的凋亡，不依赖TRAIL、FADD、caspase-8、Bcl2或Bclxl，而Cer以FADD和caspase-8不依赖的方式诱导细胞凋亡，但可被Bcl2或Bclxl抑制。Sph和DHSph也可增强TRAIL诱导的细胞凋亡。假设Sph或DHSph诱导的细胞凋亡受墨水激活、Bcl2的磷酸化或孤儿核受体Nur77的调节。总体目标是阐明SphK作为ERMS和ARM的治疗靶点的作用。除TRAIL外，在儿科RMS细胞系中，细胞溶解抗体HGS-ETR2(人类基因组科学；抗DR5)而不是HGS-ETR1(抗DR4)具有活性，并且DR5高水平表达。HGS-ETR2表现出1)高于TRAIL的活性，2)形成一个大的死亡诱导信号复合体，3)减少核因子-KB的激活，以及4)在TRAIL抗性的JR1 ERMS细胞中具有极高的敏感性。假设HGS-ETR2靶向RMS的范围比TRAIL更广，这是因为DR5结合的差异或生存信号通路的影响较小，并且无论是在单独使用FOXO1a转导的手臂中，还是与DHSph联合使用时，HGS-ETR2的活性都优于TRAIL。总体目标是开发利用TRAIL信号通路的ERMS和ARM的治疗方法。长期目标是通过了解参与细胞死亡调控的特定信号通路，识别新的分子靶点，并根据特定的分子特征开发新的治疗策略，开发高效的转移性RMS治疗方法。

DESCRIPTION (provided by applicant): The prognosis for patients presenting with metastatic pediatric RMS and for those patients with ARMS harboring the PAX3/FOXO1a gene product remains poor. This renewal application explores developmental therapeutic approaches specifically for application to pediatric RMS. Five of eleven RMS cell lines are sensitive to the cytotoxic ligand TRAIL. FOXO1a, when transduced, selectively induces caspase-3 activation and apoptosis in TRAIL-resistant ARMS, and sensitizes Rh30 ARMS cells to TRAIL. The hypothesis is that these events are mediated by selective regulation via FADD, Bim or caspase-3, and may involve activation of p38 MAPK, DR5 or TRAIL. The overall goal is to elucidate downstream targets of FOXO1a that may selectively regulate apoptosis in TRAIL-resistant ARMS and may be exploitable therapeutically. SphK, which inhibits the conversion of proapoptotic Sph to SIP (involved in transformation and proliferation), is elevated in all RMS cell lines. Sph, and the SphK inhibitor, DHSph, induce apoptosis in all cell lines, independent of TRAIL, FADD, caspase-8, Bcl-2 or Bcl-xL, in contrast to Cer, which induces apoptosis in a FADD- and caspase-8-independent manner, but is inhibited by Bcl-2 or Bcl-xL. Sph and DHSph also potentiate TRAIL-induced apoptosis. The hypothesis is that Sph- or DHSph-induced apoptosis are regulated by INK activation, phosphorylation of Bcl-2, or the orphan nuclear receptor Nur77. The overall goal is to elucidate the role of SphK as a therapeutic target in both ERMS and ARMS. In addition to TRAIL, the cytolytic antibody HGS-ETR2 (Human Genome Sciences; anti-DR5) but not HGS-ETR1 (anti-DR4) is active in pediatric RMS cell lines, and DR5 is expressed at high levels. HGS-ETR2 demonstrates 1) activity superior to TRAIL, 2) formation of a large death-inducing signaling complex, 3) reduced activation of NF-KB, and 4) exquisite sensitivity in TRAIL-resistant JR1 ERMS cells. The hypothesis is that HGS-ETR2 targets a broader spectrum of RMS than TRAIL due to differences in DR5 binding or reduced influence of survival signaling pathways, and has superior activity over TRAIL either alone, in FOXO1a-transduced ARMS, or in combination with DHSph. The overall goal is to develop therapeutic approaches for both ERMS and ARMS that exploit the TRAIL signaling pathway. The long-term objectives are to develop highly effective therapy for metastatic RMS from understanding specific signaling pathways involved in the regulation of cell death, the identification of new molecular targets, and developing new therapeutic strategies based upon specific molecular characteristics.