一种新的抗肿瘤靶点—CD47

肿瘤细胞可以通过多种途径逃避机体免疫系统的识别和清除，如诱导免疫抑制的肿瘤微环境，降低肿瘤细胞的免疫原性等；其中，肿瘤细胞逃避天然免疫系统如巨噬细胞等吞噬细胞清除的机制之一是上调细胞表面“别吃我”（don't eat me）信号的表达。整合素相关蛋白（IAP，即CD47）便是一种重要的自我信号，它通过与巨噬细胞上的配体信号调节蛋白α（SIRPα）结合，进而抑制巨噬细胞对肿瘤细胞的吞噬；此外，在天然免疫细胞如树突状细胞等向适应性免疫T细胞提呈抗原的过程中，CD47也发挥着抑制作用。因此，CD47在肿瘤免疫中发挥着重要的调节作用，靶向CD47是一个潜在的抗肿瘤方向。本文对CD47的抗肿瘤作用进行了详述，包括分子结构、信号转导、调节吞噬与促凋亡作用及成药性考虑等。

Tumor cells can escape the recognition and clearance of immune system through a variety of ways,such as inducing immunosuppressive microenvironment,reducing the immunogenicity of tumor cells,etc.. One of the mechanisms by which tumor cells escape the phagocytic removal from the innate immune system such as macrophages,is to up-regulate the expression of "don't eat me" signal on the cell surface. Integrin-associated protein(IAP,also named CD47) is an important self-signal. It inhibits the phagocytosis of tumor cells by being bound to the ligand signal regulatory protein α(SIRPα) on macrophages. Besides,in the process of presenting antigens to adaptive immune T cells by natural immune cells such as dendritic cells,it also plays an inhibitory role. Therefore,CD47 plays an important role in the regulation of tumor immunity. Targeting CD47 is a potential anti-tumor direction. In this paper,the anti-tumor effects of CD47,including molecular structure,signal transduction,regulation of phagocytosis and apoptosis as well as considerations for drug development,are reviewed.