Hematology Unit, Department of Oncology and Hematology, University of Modena and Reggio Emilia, Modena, Italy.
Leuk Res. 2010 Mar;34(3):312-21. doi: 10.1016/j.leukres.2009.06.023. Epub 2009 Jul 18.
Emerging evidence suggests that angiogenic signalling pathways play important role in the patho-biology of chronic lymphocytic leukemia (CLL). Our goal was to investigate: (i) the spontaneous and hypoxia-induced production of pro-angiogenic factors, VEGF and Ang2, by Real-time PCR and ELISA, (ii) the degree of vascularization in CLL-infiltrated bone marrow (BM) compartment by CD34 immunohistochemical staining of microvessels and (iii) the direct angiogenic effect of CLL-derived VEGF and Ang2 by function-blocking experiments in Matrigel assays. The results demonstrated that CLL cells spontaneously express both VEGF and Ang2 and are able to secrete these factors in surrounding microenvironment. Full-length Ang2 mRNA and truncated form Ang2(443) were detectable. Moreover, CLL cells were shown to enhance secretion of both VEGF and Ang2 proteins when subjected to hypoxic condition. Furthermore, increased in vivo and in vitro angiogenesis was induced by CLL cells. Enhanced BM vascularity correlated with Ig-unmutated CLL subset and increased expression of Ang2. Then, we demonstrated that supernatants obtained from CLL cells significantly increase the HUVEC tube formation in Matrigel assays and that this enhanced angiogenic capacity is mediated by both CLL-derived VEGF and Ang2. Taken together, these results suggest that several simultaneous mechanisms may be involved in the CLL capacity to induce the disruption of pre-existing vessel structures to give rise to tumor neoangiogenesis. The preliminary studies in solid tumors, showing that the disruption of Ang2 function can inhibit tumor vessel density and growth, are encouraging and suggest the possibility of new future therapeutic options targeting CLL microenvironment.
新出现的证据表明，血管生成信号通路在慢性淋巴细胞白血病 (CLL) 的病理生物学中发挥着重要作用。我们的目标是研究：（i）通过实时 PCR 和 ELISA 检测 CLL 细胞自发和缺氧诱导产生的促血管生成因子 VEGF 和 Ang2；（ii）通过 CD34 免疫组化染色检测 CLL 浸润骨髓 (BM) 中血管的程度；（iii）通过 Matrigel 实验中的功能阻断实验研究 CLL 来源的 VEGF 和 Ang2 的直接血管生成作用。结果表明，CLL 细胞自发表达 VEGF 和 Ang2，并能够在周围微环境中分泌这些因子。全长 Ang2 mRNA 和截断形式 Ang2(443) 均可检测到。此外，当 CLL 细胞处于缺氧状态时，其 VEGF 和 Ang2 蛋白的分泌也会增加。此外，CLL 细胞可诱导体内和体外血管生成增加。增强的 BM 血管生成与 Ig 未突变的 CLL 亚群和 Ang2 的表达增加相关。然后，我们证明来自 CLL 细胞的上清液可显著增加 Matrigel 实验中 HUVEC 的管形成，并且这种增强的血管生成能力是由 CLL 来源的 VEGF 和 Ang2 介导的。总之，这些结果表明，几种同时发生的机制可能参与了 CLL 诱导破坏现有血管结构以产生肿瘤新生血管的能力。在实体瘤中的初步研究表明，Ang2 功能的破坏可以抑制肿瘤血管密度和生长，这令人鼓舞，并表明针对 CLL 微环境的新未来治疗选择的可能性。
