Todo T, Adams E F, Fahlbusch R, Dingermann T, Werner H
Department of Neurosurgery, University of Tokyo, Japan.
J Neurosurg. 1996 May;84(5):852-8; discussion 858-9. doi: 10.3171/jns.1996.84.5.0852.
The authors have previously shown that meningioma-derived conditioned medium profoundly stimulates the in vitro proliferation of meningioma cells. In this paper, self mitogenic agents found in the conditioned medium-autocrine growth-stimulatory factors actually secreted by human meningioma cells-are characterized as proteins related to the B chain of platelet-derived growth factor (PDGF) and possibly to the A chain of PDGF as well. The addition to conditioned medium of a neutralizing antibody against PDGF-BB caused a significant inhibition of the conditioned medium-stimulated DNA synthesis in all three meningioma cultures studied. A similar neutralizing effect was observed with an anti-PDGF-AA antibody in one meningioma culture studied. Gel filtration chromatography of concentrated conditioned medium from two different meningiomas using a Sephadex G-100 column revealed similar profiles from both conditioned media with a major peak of mitogenic activity against meningioma cells at a molecular weight (M(r)) of approximately 32 to 36 kD, accompanied by a minor peak at approximately 22 kD. The major peak mitogenic activity was significantly reduced by addition of an anti-PDGF-BB antibody. Western blot analysis of protein extracts from five meningioma specimens was performed using a monoclonal antibody against the B chain of PGDF, and a major band of PDGF-B immunoreactivity was detected at an M(r) of approximately 19 kD in all five meningiomas under both reducing and nonreducing conditions. Exogenous human and porcine PDGFs both exhibited a significant dose-dependent stimulation of DNA synthesis in two of three and three of five meningioma cultures examined, respectively. Although not all meningiomas investigated proved to share the biological activity associated with PDGF and these results may be preliminary, it seems that the autocrine growth-stimulatory loop established by PDGF-B-related molecules plays an important functional role in meningioma cell proliferation.
作者先前已表明，脑膜瘤来源的条件培养基能显著刺激脑膜瘤细胞的体外增殖。在本文中，在条件培养基中发现的自身促有丝分裂因子——实际上由人脑膜瘤细胞分泌的自分泌生长刺激因子——被鉴定为与血小板衍生生长因子（PDGF）B链相关的蛋白质，可能也与PDGF A链相关。在所研究的三种脑膜瘤培养物中，向条件培养基中添加抗PDGF - BB中和抗体均显著抑制了条件培养基刺激的DNA合成。在一种所研究的脑膜瘤培养物中，抗PDGF - AA抗体也观察到了类似的中和作用。使用Sephadex G - 100柱对来自两种不同脑膜瘤的浓缩条件培养基进行凝胶过滤层析，结果显示两种条件培养基的图谱相似，在分子量（M(r)）约为32至36 kD处有一个针对脑膜瘤细胞的促有丝分裂活性主峰，同时在约22 kD处有一个小峰。添加抗PDGF - BB抗体后，主要的促有丝分裂活性峰显著降低。使用抗PGDF B链的单克隆抗体对五个脑膜瘤标本的蛋白质提取物进行蛋白质印迹分析，在还原和非还原条件下，所有五个脑膜瘤中均在M(r)约为19 kD处检测到一条主要的PDGF - B免疫反应性条带。在所检测的三种脑膜瘤培养物中的两种以及五种脑膜瘤培养物中的三种中，外源性人和猪的PDGF均分别表现出显著的剂量依赖性DNA合成刺激作用。尽管并非所有研究的脑膜瘤都被证明具有与PDGF相关的生物活性，且这些结果可能是初步的，但似乎由PDGF - B相关分子建立的自分泌生长刺激环在脑膜瘤细胞增殖中发挥着重要的功能作用。
