基质细胞衍生因子在不同的急性髓系白血病细胞系的迁移、黏附和细胞凋亡中的生物学作用

本研究探讨基质细胞衍生因子（stromal cell derived factor 1，SDF-1）在急性髓系白血病（AML）细胞的迁移、黏附和细胞凋亡中的生物学作用及有关的信号转导。采用流式细胞术检测AML的细胞系KG1a、ML1、U937细胞表面标记物的表达；以免疫荧光技术检测SDF-1对肿瘤细胞膜表面分子的影响；通过微孔细胞转移实验检测SDF-1对AML细胞的趋化作用及磷脂酰肌醇3激酶（P13K）在趋化过程中的作用；用蛋白免疫印记技术检测P13K信号途径有关的细胞凋亡分子BCL—XL在SDF-1活化此途径后的变化。结果表明：3种AML细胞系不同程度表达CD34（KG1a=95．6％、ML1=4．6％、U937=4．8％）、CD45（KG1a=98．3％、U937=97．5％、NIL1=17．8％）、CXCR4（ML1=85．4％、U937=43.6％、KG1a=3．8％）、ICAM（KG1a=75．8％、U937=41．8％、ML1：46.3％）。SDF-1能促进CXCR4高表达的ML1和U937细胞在基质细胞的黏附并能够诱导此类细胞的迁移，上述作用被G蛋白抑制剂pertussistoxin（PTX）、P13K抑制剂渥曼青霉素（wortmannin）明显抑制；而对CXCR4低表达的KG1a细胞则无上述作用。SDF通过此途径还促进肿瘤细胞存活；此作用同样可被P13K抑制剂明显抑制，加用wortman—nin后促肿瘤细胞调亡显著增加。蛋白免疫印记检测phospho—AKT、BCL—XL显示，在SDF组明显增强，加用PTX、wortmannin组则减弱。结论：SDF-1能触发CXCR4高表达的ML1和U937细胞的极化形态的建立及诱导黏附分子的重新分布，从而通过P13K信号途径促进此类AML细胞的迁移，减少肿瘤细胞的调亡，而对CXCR4低表达的KG1a细胞则无上述作用。上述作用可以被P13K信号途径阻断剂和G蛋白抑制剂所阻断。

Biological Behavior of Stromal Cell-derived Factor-1 on Migration, Adhesion and Apoptosis in Different Kinds of AML Cell Lines

The study was aimed to investigate the biological behavior of stromal cell-derived factor-1 (SDF-1) in migration, adhesion and apoptosis as well as the related signaling transduction pathways in different kinds of acute myeloid leukemia (AML) cell lines. The expression of surface molecules on AML (KG1a, ML1 and U937) cells were analyzed by flow cytometry. The cell adhesion was detected by MTT assay. The cell migration was checked by transwell assay. Bcl-xl was checked by immunoblotting after activation of phosphionositide-3 kinase (PI3K) in AML cells treated with SDF-1. The results indicated that the expressions of the surface molecules on AML (KG1a, ML1 and U937) cells were different. The list of the expression showed CD34 (KG1a = 95.6%, ML1 = 4.6%, U937 = 4.8%), CD45 (KG1a = 98.3%, U937 = 97.5%, ML1 = 17.8%), CXCR4 (ML1 = 85.4%, U937 = 43.6%, KG1a = 3.8%), ICAM (KG1a = 75.8%, U937 = 41.8% and ML1 = 46.3%). SDF-1 could not upregulate their expression, but could trigger the establishment of polarized morphology of the cells which expressed CXCR4 high. SDF-1 promoted ML1 and U937 cell adhesion to the stroma cells (HS5, HS27), stimulated PI3K in the cells. It was also confirmed that SDF-1 could increase the leukemic cell survival by stimulate this pathway. After addition of wortmaninn or PTX, the cell death increased. It is concluded that the SDF-1 increases the leukemic cell adhesion, migration and survival by stimulating the PI3K pathway. These functions can be depressed by the PI3K inhibitor and also the inhibitor of G protein as well.