Juarez Julius, Baraz Rana, Gaundar Shivashni, Bradstock Kenneth, Bendall Linda
Westmead Institute for Cancer Research, Westmead Millennium Institute, University of Sydney, Westmead, NSW, Australia.
Haematologica. 2007 Apr;92(4):450-9. doi: 10.3324/haematol.10621.
The chemokine stroma-derived factor 1a (SDF-1a or CXCL12) is essential for proliferation of B lineage acute lymphoblastic leukemia (ALL) cells in their physiological microenvironment, bone marrow stroma. CXCL12 synergizes with cytokines that stimulate myeloid cells, but its interaction with cytokines affecting lymphoid cells has not been examined. We investigated whether interleukin (IL)-7 and IL-3 interact with CXCL12 to regulate ALL proliferation.
The survival of ALL cells in serum-free cultures, with or without stromal support and cytokines, was assessed by flow cytometry, and proliferation by 3H-thymidine incorporation. Signaling mechanisms were assessed by western blotting of phosphorylated forms of signaling molecules and by the use of specific inhibitors.
CXCL12, IL-3, and IL-7 had only marginal effects on ALL cell survival under serum-free conditions. However, these molecules individually induced significant proliferative responses in stromal cultures of 11 cases of ALL. The combination of CXCL12 with IL-7 or IL-3 produced a variety of responses, with clear synergistic or additive interactions observed in four cases. Synergistic proliferation in response to CXCL12 plus IL-7 was associated with enhanced phosphorylation of the mitogen-activated protein kinases, ERK-1/2 and p38, and AKT, and was partially inhibited by pretreatment of cells with inhibitors for p38 MAPK and phosphatidylinositol 3-kinase, implicating these pathways in the proliferation in response to IL-7 plus CXCL12.
These findings indicate a complex interaction between signaling from the CXCR4 receptor on ALL cells with those initiated by the cytokines IL-7 and IL-3, suggesting that CXCL12 may facilitate ALL proliferation by enhancing cytokine-signaling pathways in responsive cases.
趋化因子基质衍生因子1a（SDF-1a或CXCL12）对于B系急性淋巴细胞白血病（ALL）细胞在其生理微环境骨髓基质中的增殖至关重要。CXCL12与刺激髓系细胞的细胞因子协同作用，但其与影响淋巴细胞的细胞因子之间的相互作用尚未得到研究。我们研究了白细胞介素（IL）-7和IL-3是否与CXCL12相互作用以调节ALL的增殖。
通过流式细胞术评估ALL细胞在无血清培养中、有无基质支持和细胞因子情况下的存活率，通过3H-胸腺嘧啶核苷掺入法评估增殖情况。通过对信号分子磷酸化形式进行蛋白质印迹分析以及使用特异性抑制剂来评估信号传导机制。
在无血清条件下，CXCL12、IL-3和IL-7对ALL细胞存活仅有轻微影响。然而，这些分子各自在11例ALL的基质培养中诱导了显著的增殖反应。CXCL12与IL-7或IL-3联合产生了多种反应，在4例中观察到明显的协同或相加相互作用。对CXCL12加IL-7的协同增殖与丝裂原活化蛋白激酶ERK-1/2、p38和AKT的磷酸化增强相关，并且在用p38丝裂原活化蛋白激酶和磷脂酰肌醇3-激酶抑制剂预处理细胞后受到部分抑制，提示这些途径参与了对IL-7加CXCL12的增殖反应。
这些发现表明ALL细胞上CXCR4受体的信号传导与细胞因子IL-7和IL-3启动的信号传导之间存在复杂的相互作用，提示CXCL12可能通过增强反应性病例中的细胞因子信号传导途径促进ALL的增殖。
