血管内皮细胞生长因子影响难治性急性髓系白血病发生发展的作用研究

Role of Vascular Endothelial Growth Factor (VEGF) in Development and Progress of Refractory Acute Myeloid Leukemia

背景和目的:难治性白血病的发生发展机制非常复杂,近年来发现白血病患者骨髓过度表达血管内皮细胞生长因子(vascularendothelialgrowthfactor,VEGF),但VEGF如何影响难治性白血病尚未明确。本研究探讨高表达VEGF对人急性髓系白血病细胞株HL-60增殖及三尖杉酯碱诱导HL-60细胞凋亡影响;观察难治性急性髓系白血病(acutemyeloidleukemia,AML)中VEGF蛋白表达与疾病发展的相关性。方法:采用脂质体转染VEGF165cDNA入HL-60细胞,通过RT-PCR及ELISA方法鉴定转染克隆HL-60/VEGF165细胞中VEGFmRNA及蛋白的表达,MTT法、集落形成实验比较HL-60/VEGF165及转染pcDNA3.1-neo空载体的HL-60/neo细胞增殖活性,流式细胞仪观察三尖杉酯碱诱导的细胞凋亡。用ELISA法检测难治性与非难治性AML患者血浆中VEGF蛋白浓度。结果:HL-60/VEGF165细胞培养上清中VEGF蛋白浓度为(399.07±12.45)ng/L,高于HL-60/neo细胞(184.45±10.53)ng/L(P<0.01)。HL-60/VEGF165细胞与HL-60/neo细胞相比生长速度明显加快,集落形成能力明显增加,集落数分别为(157.00±17.00)/500细胞和(110.00±12.90)/500细胞(P<0.05);而细胞凋亡率减少,分别为(3.18±0.33)%和(6.61±0.50)%,三尖杉酯碱诱导HL-60/VEGF165细胞凋亡率低于HL-60/neo细胞。

BACKGROUND &OBJECTIVE:The mechanism of refractory leukemia is very complex. Recent studies have shown that overexpression of vascular endothelial growth factor (VEGF) was detected in bone marrow from acute myeloid leukemia (AML) patients, suggesting it may play an important role in AML. However,the effect of VEGF in the development of refractory leukemia is not clear. The current study was designed to explore the effect of overexpression of VEGF on the abnormal proliferation and harringtonine induced apoptosis of HL 60 cells and to observe VEGF expression in the progression of refractory AML. METHODS: HL 60 cells were transfected with the VEGF165cDNA sense vector (HL 60/VEGF165) and with the pcDNA3.1 vector (HL 60/neo) as the control using lipofectamine. Reverse transcription polymerase chain reaction (RT PCR) was used to determine VEGF mRNA. VEGF concentrations in the cell cultural supernatant were determined by enzyme linked immunosorbent assay (ELISA). 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 VEGF165 cDNA transfection on harringtonine induced apoptosis of HL 60 cells. ELISA was used to detect VEGF concentrations in the plasma from refractory and non refractory AML patient. RESULTS: The mean VEGF concentration in the cell cultural supernatant of HL 60/VEGF165 cells (399.07±12.45 ng/L) was 2 folds higher than that in HL 60/neo cells (184.45±10.53 ng/L)(P< 0.01). The VEGF165cDNA sense vector transfected HL 60 exhibited a 2 fold increase in VEGF secretion. The growth rate of HL 60/VEGF165 cells was significantly higher than those of the controls, and colony formation capacity of HL 60/VEGF165 increased significantly(P< 0.05);the colony numbers were (157.00±17.00)/500 cells and (110±12.90)/500 cells for HL 60/VEGF165 and HL 60/neo, respectively. HL 60/VEGF165 had less apoptotic cells than HL 60/neo in the same culture condition. High expression of VEGF could reduce the harringtonine induced apoptosis of HL 60 cells. Refractory AML patients had higher mean plasma VEGF levels (558.90±271.25 ng/L) than non refractory patients(392.54±217.82 ng/L), and significant difference was observed between them (P< 0.05). CONCLUSION: VEGF expression in refractory AML patients is higher than that in non refractory AML patients. VEGF plays an important role in the abnormal proliferation and apoptosis of AML cells. High expression of VEGF could reduce the harringtonine induced apoptosis of HL 60 cells.