WNT11调控急性髓系白血病骨髓脂肪细胞异常分化的作用及机制研究

Lipid metabolism dysregulation has been proposed to be a contributing factor toward leukemia resistance to chemotherapy. Nevertheless, little research has been performed to illustrate the role of adipocyte alterations within hematopoietic microenvironment in the initiation of chemoresistance. In our series of clinical observations and in vitro experiments, it has been reported that adipocytes from bone marrow in patients with acute myeloid leukemia (AML) were unable to differentiate normally and thought to confer chemoresistance. Remarkably, the level of WNT11, an early expressed gene in the regulation of adipocytes differentiation, was found to be lower in cells from patients with AML. Furthemore, it has been reported that WNT11 has a critical role in adipocytes development and differentiation from bone marrow mesenchymal stem cells. Given no experiments being performed to show the role of WNT11 on abnormal differentiation of adipocytes derived from bone marrow in patients with AML, we proposed that WNT11 act in concert with its downstream effectors to induce abnormal differentiation of adipocytes and participate in microenvironment-influenced chemoresistance. This project intends to definitively address the role of WNT 11 in abnormal differentiation of adipocytes from AML hematopoietic microenvironment through clinical observation and in vitro experiments. Meanwhile, it is also aimed to screen major downstream effectors modulated by WNT11 through systemically analyzing protein expression profiles before and after WNT11 gene silence using protein array chips. These works will gain a deeper insight into the molecular mechanism of WNT11 involved in AML microenvironment-induced chemoresistance, which will provide novel therapeutic targets for chemoresistance or refractory AML.

体脂代谢异常与白血病化疗抵抗密切相关，但针对造血微环境重要成分的原位脂肪细胞诱导白血病细胞耐药的相关研究较少。本课题组前期体外实验及临床研究发现，急性髓系白血病（AML）患者骨髓脂肪细胞异常分化，并参与化疗抵抗。WNT11是正常脂肪细胞分化早期高表达的基因，但在AML患者骨髓细胞中异常低表达；进一步研究显示，WNT11显著影响骨髓间充质干细胞成脂分化。鉴于此，我们提出假说：WNT11调变下游信号通路介导AML骨髓脂肪细胞异常分化，促使其参与化疗抵抗。本项目拟以WNT11信号通路为切入点，通过临床相关性分析和体外功能验证实验，探究WNT11在AML骨髓脂肪细胞异常分化中的作用；同时采用蛋白芯片技术检测并系统分析WNT11基因沉默前后其下游信号蛋白表达谱的变化，并进一步筛查关键靶分子，从而阐明WNT11诱导AML骨髓脂肪细胞异常分化的分子机制，为难治性白血病治疗提供靶标。

脂肪细胞是骨髓重要微环境之一，在急性髓系白血病（AML）发生发展中发挥重要作用。我们前期研究发现，WNT11是骨髓间充质干细胞（MSC）成脂分化的关键基因。本项目结合分子生物及免疫组化等技术明确了WNT11在AML骨髓MSC中表达减低，致使其成脂分化异常，进一步协助白血病细胞抵抗化疗，参与复发。同时，我们发现AML骨髓单个核细胞中WNT11表达异常增高，沉默其表达可有效抑制AML细胞有丝分裂，减慢其增殖，并协助对抗化疗。下游信号通路的检测提示Ca2+介导的PKC/TRPV4信号通路可能是WNT11调控AML骨髓脂肪细胞异常分化，协助AML细胞化疗抵抗的主要机制。本研究证实WNT11通过直接参与或间接诱导成脂分化异常的方式协助AML化疗抵抗，为难治性AML治疗提供了新的研究方向。