The CXCR4-SDF-1 Axis in Metastatic Rhabdomyosarcoma

横纹肌肉瘤（RMS）是儿童中最常见的肉瘤，经常浸润骨髓（BM）。 我们最近发表的数据表明，基质衍生因子-1（SDF-1），这是分泌在BM微环境中，可能发挥了至关重要的作用，在指导骨髓的RMS细胞表达SDF-1受体，CXCR 4。 为了研究RMS转移的机制，并开发一种新的治疗方法来阻断RMS中SDF-1-CXCR 4轴，我们提出了三个目标。 目标1。阐明CXCR 4启动的分子机制。 由于我们观察到散射因子（SF）增加/引发CXCR 4 + RMS细胞对SDF-1梯度的趋化反应，我们将关注RMS转移中SDF-1-CXCR 4和SF-c-Met轴之间串扰的分子机制。 我们将研究SDF-1介导的转移步骤受到SF的影响，并根据我们的初步数据，我们将测试SF通过增加CXCR 4进入膜脂筏调节RMS细胞对SDF-1梯度的反应性的假设。 目标2。确定PAX基因是否调节CXCR 4的表达。 由于在RMS细胞系中，CXCR 4的表达与肺泡RMS以及PAX 3-FKHR和PAX 7-FKHR基因的表达相关，因此我们将研究PAX基因是否直接调节RMS细胞中CXCR 4的表达。 我们将测试从RMS患者分离的细胞中CXCR 4表达是否也与RMS的肺泡类型相关，以及与PAX-3和PAX-7-FKHR融合和/或PAX-3和PAX-7野生型基因的过表达相关。 目标3。评估通过靶向SDF-1-CXCR 4轴阻断RMS细胞转移行为的治疗策略。 我们注意到，放疗/化疗诱导SDF-1在各种器官中分泌，并创造了一个“转移允许”的环境。 因此，我们推测SDF-1-CXCR 4轴可能在逃避治疗的肿瘤细胞的扩散中起作用。 为了控制RMS细胞在体内的自发和放射/化疗诱导的转移行为，我们将在人RMS异种移植免疫缺陷小鼠模型中采用新合成的CXCR 4受体小分子抑制剂（TE 14013）。 这项工作将与设计阻断SDF-1-CXCR 4轴以治疗CXCR 4阳性癌症的策略相关。

DESCRIPTION (provided by applicant): Rhabdomyosarcoma (RMS) is the most common sarcoma in children and very often infiltrates the bone marrow (BM). Our recently published data show that stromal derived factor-1 (SDF-1), which is secreted within the BM microenvironment, may play a crucial role in directing to the BM the RMS cells that express the receptor for SDF-1, CXCR4. To investigate the mechanisms operating in the metastasis of RMS and develop a new therapeutic approach to blocking the SDF-1-CXCR4 axis in RMS, we propose three aims. Aim #1. To elucidate the molecular mechanisms of CXCR4 priming. Since we observed that scatter factor (SF) increases/primes the chemotactic response of CXCR4+ RMS cells to an SDF-1 gradient, we will focus on molecular mechanisms of crosstalk between the SDF-1-CXCR4 and SF-c-Met axes in RMS metastasis. We will investigate which SDF-1-mediated steps in metastasis are influenced by SF and, based on our preliminary data, we will test the hypothesis that SF by increasing inclusion of CXCR4 into membrane lipid rafts modulates the responsiveness of RMS cells to SDF-1 gradient. Aim #2. To determine whether PAX genes regulate the expression of CXCR4. Since in RMS cell lines the expression of CXCR4 correlates with alveolar RMS and expression of the PAX3-FKHR and PAX7-FKHR genes, we will investigate whether PAX genes directly regulate CXCR4 expression in RMS cells. We will test whether CXCR4 expression in cells isolated from RMS patients also correlates with the alveolar type of RMS, and with PAX3- and PAX7-FKHR fusion and/or overexpression of PAX-3 and PAX-7 wild-type genes. Aim # 3. To assess therapeutic strategies to block the metastatic behavior of RMS cells by targeting the SDF-1-CXCR4 axis. We noticed that radio-/chemotherapy induces SDF-1 secretion in various organs and creates a "metastasis-permissive" environment. Thus we hypothesize that the SDF-1-CXCR4 axis may play a role in the spread of tumor cells that have escaped therapy. To control the spontaneous and radio-/chemotherapy-induced metastatic behavior of RMS cells in vivo, we will employ the newly synthesized small-molecular inhibitor of the CXCR4 receptor (TE14013) in a human RMS xenotransplant-immunodeficient mouse model. This work will be of relevance for designing strategies to block the SDF-1-CXCR4 axis to treat CXCR4-positive cancers.