胰岛素样生长因子结合蛋白7促进急性髓细胞白血病髓外浸润的信号通路研究

Extramedullary infiltration(EMI) is a poor marker in pediatric acute myeloid leukemia (AML). It has been reported that targeting invadosome was an effective treatment to protect EMI which would improve long-term survival for AML patients. As a result, it is very important to explore the mechanisms of regulating the process of EMI in the feild of AML research. Our previous study has found that IGFBP7 (Insulin-like growth factor binding protein 7) expressed at higher level in AML patients at first-diagnosis,reduced at remission and up-regulated again at relapse, and thus being considered a poor prognostic marker in AML. Further study indicated that IGFBP7 promoted AML cell proliferation and invasion in vitro. Microarray analysis on IGFBP7 overexpressed AML cells revealed multiple activated signal pathways such as PI3K/Akt and MAPK/ERK and the upregulated gene SELPLG, which is well known as a molecule involved in migration of neutrophils toward the inflammatory sites. Based on these findings we propose that IGFBP7 may upregulate the expression of SELPLG via sequential activiation of PI3K/Akt and MAPK/ERK signal pathways, which then promotes AML cell invasion. To validate this hypothesis, a number of techniques, such as gene transfection and overexpression, gene knockdown by RNA interference, inhibitors targeting key proteins and recombinant proteins will be used in vitro and in vivo. Our proposal will explore a novel pathway mediating the EMI in AML.IGFBP7 and SELPLG may be proved prognostic biomarkers for AML patients. Patients with higher expression of IGFBP7 and SELPLG will benefit from more intensive chemotherapy. Our study will reveal that EMI mediated by IGFBP7 promotes AML cells chemoresistance and relapse and may also help to find novel pathway and targets in AML treatment.

髓外浸润是儿童急性髓细胞白血病(AML)预后差的因素之一，研究发现靶向AML"侵略体"将有效防治髓外浸润，提高疗效，因此，非常有必要对髓外浸润形成方式和作用机制进行深入研究。我们小组研究胰岛素样生长因子结合蛋白7(IGFBP7)与AML相关性时，发现IGFBP7与预后相关；作用机制显示IGFBP7除了促进AML细胞增殖外，还赋予AML细胞浸润能力；全基因组芯片揭示IGFBP7可能活化PI3K/Akt和MAPK/ERK通路，促进细胞浸润，同时选择素P配体（SELPLG）基因明显上调。据此我们提出假说：IGFBP7通过活化上述信号通路，上调SELPLG表达，促进AML细胞髓外浸润。本课题拟应用基因转染过表达、RNA干扰、小分子抑制剂、重组蛋白等手段，从细胞水平和动物模型2个层面验证该假说。该课题将揭示由IGFBP7介导的促进AML细胞髓外浸润的新通路参与AML复发与耐药，为靶向治疗提供新靶点。

髓外浸润是儿童急性髓细胞白血病(AML)预后差的因素之一，研究发现靶向AML“侵略体”将有效防治髓外浸润，提高疗效，因此，非常有必要对髓外浸润形成方式和作用机制进行深入研究。我们小组研究胰岛素样生长因子结合蛋白7（IGFBP7）与AML相关性时，发现IGFBP7与预后相关，促进AML细胞的增殖，增强AML细胞的浸润能力，但其作用机制还不清楚。首先，我们建立IGFBP7过表达AML细胞株研究信号通路的变化，发现IGFBP7通过活化PI3K/AKT、JNK/MAPK信号通路促进细胞迁移；其次，利用Co-IP和LC-MS/MS技术发现IGFBP7与ANXA2相互作用，介导PI3K/AKT和JNK/MAPK的活化以及与细胞迁移、趋化和侵袭相关基因SELPLG等的表达；最后，建立小鼠细胞迁移模型，在体内证实IGFBP7对细胞具有促进迁移的作用。