转录因子JunB/AP-1在多发性骨髓瘤血管生成中的作用及机制研究

In multiple myeloma (MM), angiogenesis significantly influences disease progression and is correlated with adverse prognosis. The increase in vascular density within the bone marrow (BM) microenvironment is triggered by oncogene-mediated expression of pro-angiogenic factors. Members of the AP-1 family of transcription factors have emerged as actively pursued therapeutic targets over the past years. Specifically, in MM it has been shown that c-Maf acts as a proto-oncogene, while c-Jun is involved in drug-induced cell apoptosis. Our previous studies showed the AP-1 family member JunB expression in MM cells was induced by co-culture of BM stromal cells (BMSCs) and demonstrated a critical role for JunB in MM cell proliferation, survival and drug resistance. Whether JunB also contributes to MM BM angiogenesis is currently unknown. Our preliminary data identified correlative expression patterns of JUNB and pro-angiogenic factors using the Oncomine software. Similar to JUNB, our data identified significant induction of VEGF, VEGFB, IGF-1, PlGF, HGF and CD138, progressing from normal plasma cells to cells from patients with monoclonal gammopathy of undetermined significance (MGUS) and MM in the gene expression profiling data set. These results were then verified in vitro by qRT-PCR. Therefore, this project intends to uncover: 1) the functional role of JunB on BM angiogenesis in vitro and in vivo; 2) whether bone marrow cell-mediated production of pro-angiogenic factors is mediated via JunB in MM cells; 3) the mechanisms underlying the regulation of the angiogenic factors by JunB; 4) the signaling pathways and gene network involved in the regulation of BM angiogenesis by JunB.

多发性骨髓瘤（MM）骨髓血管生成由癌基因介导的促血管生成因子的表达所引发，对MM患者的疾病进展有显著影响，并与预后不良相关。近年来研究显示AP-1转录因子家族可能是MM潜在的治疗靶点。我们前期研究表明骨髓基质细胞共培养能诱导MM细胞中JunB的表达，并证明JunB在MM细胞增殖、生存和耐药性中起关键作用。而JunB是否有助于MM骨髓血管生成仍然未知。基因表达谱数据集分析发现，从正常浆细胞发展至MM细胞，VEGF，VEGFB，IGF-1和PlGF等基因的表达显著增加，和JUNB基因存在相关性。定量PCR实验初步验证了MM细胞中JunB和上述促血管生成因子的关联。因此，本课题将进一步确认MM细胞中JunB蛋白对骨髓细胞介导的促血管生成因子表达的调控，探索潜在的分子机制；在体外和体内阐明JunB对骨髓血管新生的功能作用，并探讨涉及的信号通路和分子网络以及临床意义，为MM新的治疗方案提供理论依据。

骨髓血管生成显著影响多发性骨髓瘤（MM）患者的疾病进程并与不良预后相关。我们的这项研究第一次阐述了转录因子AP-1家族成员JunB在促血管生成因子的转录调控中发挥关键性作用，从而促进MM的骨髓血管生成。我们发现，在MM患者的肿瘤细胞中，JunB的表达水平与促血管生成因子VEGF，VEGFB以及IGF1显著相关。在MM人源细胞系中诱导敲减或者激活JunB的表达，证实JunB在功能上能够调控促血管生成因子的表达和分泌；因而从诱导敲减或者激活JunB表达的MM人源细胞系培养中得到的条件性培养基，能够相应的显著抑制或促进人脐静脉内皮细胞的体外血管生成能力。ChIP-seq实验证实VEGF及IGF1为JunB直接的转录调控靶基因。我们进一步在免疫缺陷小鼠皮下异植瘤中验证了JunB在MM血管生成中的作用。最后，在MM患者骨髓组织样本中，JunB的表达水平和骨髓血管生成水平显著相关。综上所述，我们的研究阐明了JunB对MM骨髓血管生成的作用及机制。结合我们之前的研究发现：JunB调控MM细胞的增殖、生存和耐药性，均揭示了JunB在MM病理发生中的关键致癌作用。因此，我们的发现凸显了对于癌症、特别是MM的治疗，靶向特定的致病性转录因子在未来是一个很有前途的策略。