自分泌VEGF对人慢性髓性白血病细胞系K562的作用

血管内皮细胞生长因子（VEGF）是血管内皮细胞特异性的丝裂原，与实体肿瘤的血管生成、生长、转移及不良预后密切相关。最近的报送表明，慢性髓性白血病（CML）病人骨髓过度表达VEGF。然而，VEGF在CML细胞异常增殖中的作用还不清楚。为了探讨自分泌VEGF对CML细胞系K562增殖与凋亡的影响，本研究首次采用正义和反义VEGF121cDNA转染K562细胞，通过RT-PCR及ELISA方法鉴定各转染克隆VEGF mRNA及蛋白的表达。结果显示，转染反义VEGF121 cDNA可以降低K562细胞VEGF的表达，而转染正义VEGF121 cDNA可使VEGF的表达提高3倍以上。MTT，集落形成试验及细胞凋亡检测试验观察：反义VEGF121 cDNA转染可以抑制K562细胞的增殖及其集落形成，而促进其凋亡；正义VEGF121 cDNA转染与其结果相反。本研究结果说明自分泌VEGF在CML细胞系K562的增殖与凋亡起重要作用。

Effect of Autocrine VEGF on Chronic Myeloid Leukemia Cell Line K562

Vascular endothelial growth factor (VEGF) is a specific mitogen for vascular endothelial cells. It has been associated with angiogenesis, growth, metastasis and poor prognosis in solid tumors. Lately, it has been known that VEGF expression is higher in bone marrow from chronic myeloid leukemia (CML) patients than that in normal subjects. However, it is not clarified that the effect of VEGF on the abnormal proliferation of CML cells. In order to explore the effect of autocrine VEGF on CML cells, K562 cells were transfected with the VEGF 121 cDNA sense vector(K562/S) or with the VEGF 121 cDNA antisense vector(K562/As). K562 cells were transfected with the pcDNA 3 vector (K562/V) as the control. Cell proliferation was determined by MTT and colony forming assay in vitro. Flow cytometric Annexin-V-FITC/PI dual labeling technique was performed to observe the effect of VEGF 121 cDNA transfection on apoptosis of K562 cells. Results indicated that K562/S transfectants exhibited a 3-fold increase in VEGF secretion, and K562/As transfectants exhibited a 49% reduction in VEGF secretion. K562/As showed a reduced growth rate and colony forming efficiency as compared to K562/V. K562/S showed an increasing growth rate and colony forming efficiency as compared to K562/V. K562/As had more apoptotic cells than K562/V and K562/S in the same culture condition. These data suggest that VEGF plays an important role in the abnormal proliferation and apoptosis in CML cells through an autocrine mechanism.