PR3通过IκBα蛋白剪切促进急性髓系白血病细胞增殖的分子机制研究

NF-κB通路的持续激活是维持急性髓白血病（AML）细胞增殖的重要原因，该通路主要受IκBα蛋白调控。除经典降解途径外，IκBα蛋白可以通过被酶异常剪切的方式参与肿瘤的发生发展。我们率先发现：在AML细胞中参与细胞增殖的蛋白酶3（PR3）对IκBα蛋白有剪切活性，且剪切片段有一定的生物学功能，从而提出“PR3通过剪切IκBα蛋白促进AML细胞增殖”的假说。本课题拟采用氨基酸蛋白质谱分析明确PR3对IκBα蛋白的剪切位点，继而采用沉默PR3，体内外过表达截短型IκBα蛋白片段等实验明确该剪切片段在NF-κB通路中的调控作用。进一步检测AML患者初发时和疾病进展复发时骨髓样本中PR3和剪切型IκBα蛋白片段的表达水平，分析PR3对κBα蛋白的剪切作用在AML疾病发生发展中的意义。本课题将从IκBα蛋白剪切的新的角度阐释AML细胞中NF-κB信号的激活途径，为AML发病机制的研究提供新思路。

It has been reported that the continuous activation of NF-κB signaling pathway, which is mainly regulated by IκBα protein, is the important cause in maintaining the proliferation of AML cells. In addition to the classical degradation pathway, IκBα protein could also be abnormally cleaved by enzymes to involve in tumor genesis and development in many cancers. Recently, we found an unreported form of IκBα protein in AML cells cleaved by the enzyme protease 3(PR3) which was related to AML cells proliferation. The cleaved IκBα fragment exhibited biological functions in NF-κB pathway regulation. In this project, based on our previous works, we speculated that PR3 could promote the AML cells proliferation through the novel cleaved IκBα protein in NF-κB signaling pathway regulation. The IκBα protein cleavage sites were identified by amino acids analysis. The roles of the cleaved IκBα protein in NF-κB pathway regulation were explored by gene editing techniques for PR3 silence and truncated IκBα protein over-expression through in vivo and in vitro researches. We also further verified the correlation between PR3 and the novel IκBα cleavage in AML patients’ bone marrow cells in disease progression. Our study will furnish a new experimental and theoretical basis in NF-κB signaling activation regulation mechanism in AML via a novel IκBα cleavage perspective, and also provide new ideas for the study in AML pathogenesis.