PTEN对婴幼儿血管瘤内皮细胞VEGF-A/VEGFR-2自分泌环的调控作用

目的 研究PTEN在婴幼儿血管瘤(infantile hemangioma,IH)中的表达,探讨其对血管瘤内皮细胞(HemEC)中VEGF-A/VEGFR-2自分泌环的影响与意义.方法 应用Real-time PCR检测增殖期IH组织与正常皮肤组织中PTEN基因表达差异,Western blot检测HemEC与正常血管内皮细胞中PTEN蛋白水平.采用腺病毒瞬时转染构建立PTEN高表达HemEC模型,观察PTEN表达变化对HemEC中VEGF-A、VEGFR-2与磷酸化VEGFR-2表达水平的影响,分析PTEN表达变化对HemEC增殖与凋亡的影响.结果 PTEN基因在IH微血管组织中的表达较正常皮肤血管组织出现显著的下调.通过对HemEC中PTEN蛋白表达量进行检测发现,与异常活化的VEGF-A/VEGFR-2信号通路相反,HemEC中PTEN蛋白表达较正常血管内皮细胞低(0.08±0.02比1.86±0.41).PTEN高表达可显著抑制VEGF的表达,并抑制VEGF-A对VEGFR-2磷酸化的激活(1.27±0.25比0.09±0.03),但对VEGFR-2蛋白表达水平无显著作用(2.32±0.51比2.35±0.42).上调PTEN后HemEC增殖能力显著降低、凋亡率显著升高.结论 PTEN通过对HemEC中VEGF-A/VEGFR-2自分泌环的调控,从而影响HemEC的增殖和凋亡状态.

Modulating effects of PTEN in the loop of autocrine VEGF-A/VEGFR-2 in hemangioma-derived cells

Objective To explore the expression of PTEN in infantile hemangioma (IH) and determine its involvement in the regulation of VEGF-A/VEGFR-2 loop of hemangioma-derived endothelial cells (HemECs).Methods Real-time polymerase chain reaction (PCR) was performed for evaluating the expression of PTEN in proliferating IH tissues and normal skin.Protein expressions of PTEN in HemECs and normal endothelial cells (ECs) were assayed by Western blot.And the effects of PTEN were also analyzed in regulating HemEC proliferation and apoptosis.Results The expression of tumor suppressor PTEN decreased in proliferating IH tissues as compared with normal skin.As compared with normal'endothelial cells (HUVECs),HemECs showed a down-regulation of PTEN protein (0.08 ± 0.02 vs 1.86 ± 0.41).The expression of endogenous VEGF and activation of VEGFR2 decreased markedly in PTEN-transfected HemECs as compared with control cells (1.27 ± 0.25 vs 0.09 ± 0.03).In contrast,there was no significant effect of PTEN on VEGFR-2 expression (2.32 ± 0.51 vs 2.35 ± 0.42).An up-regulation of PTEN decreased HemEC proliferation and caused heightened sensitivity to apoptosis in HemEcs.Conclusions PTEN prevents the activation of VEGFA/VEGFR-2 loop in HemECs.Also it is capable of inhibiting HemECs proliferation and inducing HemECs apoptosis in vitro.