Berghuis Dagmar, Schilham Marco W, Santos Susy J, Savola Suvi, Knowles Helen J, Dirksen Uta, Schaefer Karl-Ludwig, Vakkila Jukka, Hogendoorn Pancras Cw, Lankester Arjan C
Department of Pediatrics, Leiden University Medical Center, Albinusdreef 2, 2300, RC, Leiden, the Netherlands.
Clin Sarcoma Res. 2012 Dec 18;2(1):24. doi: 10.1186/2045-3329-2-24.
Chemokine receptor CXCR4, together with its ligand CXCL12, plays critical roles in cancer progression, including growth, metastasis and angiogenesis. Ewing sarcoma is a sarcoma with poor prognosis despite current therapies, particularly for patients with advanced-stage disease. Lungs and bone (marrow), organs of predilection for (primary/metastatic) Ewing sarcoma, represent predominant CXCL12 sources.
To gain insight into the role of the CXCR4-CXCL12 axis in Ewing sarcoma, CXCR4, CXCL12 and hypoxia-inducible factor-1α protein expression was studied in therapy-naïve and metastatic tumors by immunohistochemistry. CXCR4 function was assessed in vitro, by flow cytometry and proliferation/ cell viability assays, in the presence of recombinant CXCL12 and/or CXCR4-antagonist AMD3100 or under hypoxic conditions.
Whereas CXCR4 was predominantly expressed by tumor cells, CXCL12 was observed in both tumor and stromal areas. Survival analysis revealed an (expression level-dependent) negative impact of CXCR4 expression (p < 0.04). A role for the CXCR4-CXCL12 axis in Ewing sarcoma growth was suggested by our observations that i) CXCR4 expression correlated positively with tumor volume at diagnosis (p = 0.013), ii) CXCL12 was present within the microenvironment of virtually all cases, iii) CXCL12 induced proliferation of CXCR4-positive Ewing sarcoma cell lines, which could be abrogated by AMD3100. CXCR4 expression was not correlated with occurrence of metastatic disease. Also, therapy-naïve tumors demonstrated higher CXCR4 expression as compared to metastases (p = 0.027). Evaluation of in vivo hypoxia-inducible factor-1α expression and culture of cells under hypoxic conditions revealed no role for hypoxia in CXCR4 expression.
Together, our results imply a crucial role for the CXCR4-CXCL12 axis in auto- and/or paracrine growth stimulation. Integration of CXCR4-targeting strategies into first- and/or second-line treatment regimens may represent a promising treatment option for Ewing sarcoma.
趋化因子受体CXCR4与其配体CXCL12在癌症进展（包括生长、转移和血管生成）中发挥关键作用。尤因肉瘤是一种尽管有现有治疗手段但预后仍较差的肉瘤，对于晚期疾病患者尤为如此。肺和骨（骨髓）是（原发性/转移性）尤因肉瘤的偏好器官，是主要的CXCL12来源。
为深入了解CXCR4 - CXCL12轴在尤因肉瘤中的作用，通过免疫组织化学研究了初治肿瘤和转移性肿瘤中CXCR4、CXCL12和缺氧诱导因子 - 1α蛋白的表达。在重组CXCL12和/或CXCR4拮抗剂AMD3100存在的情况下，或在缺氧条件下，通过流式细胞术以及增殖/细胞活力测定，在体外评估CXCR4的功能。
CXCR4主要由肿瘤细胞表达，而CXCL12在肿瘤和基质区域均有观察到。生存分析显示CXCR（4表达水平依赖性）的负面影响（p < 0.04）。我们的观察结果提示CXCR4 - CXCL12轴在尤因肉瘤生长中起作用，即：i）CXCR4表达与诊断时的肿瘤体积呈正相关（p = 0.013），ii）几乎所有病例的微环境中都存在CXCL12，iii）CXCL12诱导CXCR4阳性尤因肉瘤细胞系增殖，而AMD3100可消除这种增殖。CXCR4表达与转移性疾病的发生无关。此外，与转移灶相比，初治肿瘤显示出更高的CXCR4表达（p = 0.027）。对体内缺氧诱导因子 - 1α表达的评估以及在缺氧条件下细胞培养表明缺氧在CXCR4表达中不起作用。
总之，我们的结果表明CXCR4 - CXCL12轴在自分泌和/或旁分泌生长刺激中起关键作用。将靶向CXCR4的策略纳入一线和/或二线治疗方案可能是尤因肉瘤一种有前景的治疗选择。
