Jankowski Kacper, Kucia Magda, Wysoczynski Marcin, Reca Ryan, Zhao Dongling, Trzyna Ela, Trent John, Peiper Stephen, Zembala Marek, Ratajczak Janina, Houghton Peter, Janowska-Wieczorek Anna, Ratajczak Mariusz Z
Stem Cell Biology Program, James Graham Brown Cancer Center, University of Louisville, 529 South Jackson Street, Louisville, KY 40202, USA.
Cancer Res. 2003 Nov 15;63(22):7926-35.
Rhabdomyosarcomas (RMSs) are frequently characterized by bone marrow involvement. Recently, we reported that human RMS cells express the CXC chemokine receptor-4 (CXCR4) and postulated a role for the CXCR4 stromal-derived factor (SDF)-1 axis in the metastasis of RMS cells to bone marrow. Because RMS cells also express the tyrosine kinase receptor c-MET, the specific ligand hepatocyte growth factor (HGF) that is secreted in bone marrow and lymph node stroma, we hypothesized that the c-MET-HGF axis modulates the metastatic behavior of RMS cells as well. Supporting this concept is our observation that conditioned media harvested from expanded ex vivo human bone marrow fibroblasts chemoattracted RMS cells in an HGF- and SDF-1-dependent manner. Six human alveolar and three embryonal RMS cell lines were examined. We found that although HGF, similar to SDF-1, did not affect the proliferation of RMS cells, it induced in several of them: (a) locomotion; (b) stress fiber formation; (c) chemotaxis; (d) adhesion to human umbilical vein endothelial cells; (e) trans-Matrigel invasion and matrix metalloproteinase secretion; and (f) phosphorylation of mitogen-activated protein kinase p42/44 and AKT. Moreover HGF, but not SDF-1, increased the survival of RMS cells exposed to radio- and chemotherapy. We also found that the more aggressive alveolar RMS cells express higher levels of c-MET than embryonal RMS cell lines and "home/seed" better into bone marrow after i.v. injection into immunocompromised mice. Because we could not find any activating mutations in the kinase region of c-MET or any evidence for HGF autocrine stimulation, we suggest that the increased response of RMS cell lines depends on overexpression of functional c-MET. We conclude that HGF regulates the metastatic behavior of c-MET-positive RMS cells, directing them to the bone marrow and lymph nodes. Signaling from the c-MET receptor may also contribute to the resistance of RMS cells to conventional treatment modalities.
横纹肌肉瘤（RMSs）常以骨髓受累为特征。最近，我们报道人类RMS细胞表达CXC趋化因子受体4（CXCR4），并推测CXCR4-基质衍生因子（SDF）-1轴在RMS细胞向骨髓转移中起作用。由于RMS细胞也表达酪氨酸激酶受体c-MET，其特异性配体肝细胞生长因子（HGF）在骨髓和淋巴结基质中分泌，我们假设c-MET-HGF轴也调节RMS细胞的转移行为。支持这一概念的是我们的观察结果，即从体外扩增的人骨髓成纤维细胞收获的条件培养基以HGF和SDF-1依赖的方式趋化RMS细胞。检测了6个人肺泡型和3个胚胎型RMS细胞系。我们发现，虽然HGF与SDF-1一样，不影响RMS细胞的增殖，但它在其中一些细胞中诱导了：（a）运动；（b）应力纤维形成；（c）趋化性；（d）与人脐静脉内皮细胞的黏附；（e）穿膜基质胶侵袭和基质金属蛋白酶分泌；以及（f）丝裂原活化蛋白激酶p42/44和AKT的磷酸化。此外，HGF而非SDF-1增加了接受放疗和化疗的RMS细胞的存活率。我们还发现，侵袭性更强的肺泡型RMS细胞比胚胎型RMS细胞系表达更高水平的c-MET，并且在静脉注射到免疫缺陷小鼠后能更好地“归巢/播种”到骨髓中。由于我们在c-MET的激酶区域未发现任何激活突变，也没有发现HGF自分泌刺激的任何证据，我们认为RMS细胞系反应性增加取决于功能性c-MET的过表达。我们得出结论，HGF调节c-MET阳性RMS细胞的转移行为，引导它们进入骨髓和淋巴结。来自c-MET受体的信号传导也可能导致RMS细胞对传统治疗方式产生抗性。
