骨髓微环境中的巨噬细胞及细胞因子网络在诱导骨髓瘤细胞DNA损伤/修复异常中的作用及其机制研究

It is well documented that the unbalance of bone marrow (BM) microenvironment acts as the exterior reason of the tumorgenesis and progression of multiple myeloma (MM).The network based by various kinds of immune cells and cytokines plays an important role in this process. Cytogenetic abnormality is one of the most related biological characteristics in MM, which mainly caused by the dysregulation of DNA damage and repair pathways. In previous study, we found that there was elevated infiltration of myeloma associated macrophages (mMΦs) in the bone marrow of MM patients and was closely related with the occurrence of MM chromosomal abnormalities. Meanwhile, mMΦs co-cultured with MM cells via the direct contact with MM cells and secreted numerous cytokines could up regulate the expression of DNA damage repair proteins in MM cells. We hypothesized that mMΦs and the cytokine network triggered by mMΦs in BM microenvironment may promote DNA mutation and chromosomal aberration by inducing dysregulation of DNA damage repair pathway to facilitate MM progression. Based on our previous studies, this project aims to explore the role of mMΦs and its related cytokine network in the induction of DNA damage and repair pathways via cell and molecular biology techniques, quantitative HR/NHEJ fluorescence reporting system, so as to provide new ideas to clarify the mechanism of MM development and progression, and new strategies for MM treatment.

骨髓（BM）微环境的紊乱是多发性骨髓瘤（MM）发生发展的重要外因，其中各种免疫细胞及其分泌的细胞因子形成的网络起到关键性的作用。MM细胞遗传学异常则是贯穿疾病演变过程中的重要病理生理特征。我们前期研究发现MM BM中存在骨髓瘤相关巨噬细胞（mMΦs）的大量浸润并与MM细胞中频发的染色体异常密切相关；mMΦs与MM细胞共培养，通过细胞间直接作用及分泌的诸多细胞因子可上调DNA损伤/修复相关蛋白在MM细胞中的表达。据此，我们推测BM微环境中mMΦs及其触发的细胞因子形成的网络可能通过调控DNA损伤/修复途径促使MM细胞发生基因突变与染色体畸变，推动疾病进展。本项目拟在前期研究基础上利用细胞、分子生物学技术、定量HR/NHEJ荧光报告系统进一步明确mMΦs及其相关炎症因子网络在诱导MM细胞DNA损伤/修复异常中的作用及机制，为阐明MM发生发展机制提供新思路，为探索MM治疗的新策略提供理论依据。

在多发性骨髓瘤患者的骨髓中，巨噬细胞的含量远高于正常对照，并且微环境中的巨噬细胞与MMCs的耐药相关，特别是偏M2型及肿瘤相关巨噬细胞。而其对MM的基因组不稳定性及遗传复杂性的作用却鲜有人知。我们的研究表明偏M2型的巨噬细胞保护MM细胞免于化疗药物引起的凋亡，在体内外均可降低MMCs基线及DNA损伤后的γH2AX，主要通过NHEJ方式修复MM细胞的DSB，而降低修复的精准度。进一步，MΦs促进MM细胞染色体易位的概率，与MM患者细胞遗传学复杂性密切相关。本研究从微环境巨噬细胞的角度对延缓临床多发性骨髓瘤克隆演变进程提供新的理论依据。