Rijksen G, Völler M C, Van Zoelen E J
Department of Hematology, University Hospital, Utrecht, The Netherlands.
J Cell Physiol. 1993 Feb;154(2):393-401. doi: 10.1002/jcp.1041540223.
Normal rat kidney [NRK] cells grown in the presence of epidermal growth factor (EGF) or platelet-derived growth factor (PDGF) have a normal phenotype and undergo density-dependent growth inhibition, whereas in the presence of multiple growth factors, density arrest is lost and the cells become phenotypically transformed. We studied the influence of the protein tyrosine phosphatase (PTPase) inhibitor sodium orthovanadate on the mitogenic stimulation of NRK cells by growth factors and on transformation-linked properties as loss of density-dependent growth inhibition and anchorage-independent growth. The fraction of cells in serum-deprived monolayer cultures that is induced to proliferate upon mitogenic stimulation by EGF or PDGF is only slightly enhanced upon addition of low concentrations (25-50 microM) of vanadate. Addition of vanadate per se induces proliferation of only a very limited amount of cells, but results in a shift of the dose-response curves for other growth factors to lower concentrations. Vanadate added in combination with EGF or PDGF is able to mimic the effect of transforming growth factor beta (TGF beta) in inducing phenotypic transformation. In monolayer cultures density-dependent growth inhibition is lost and anchorage-independent proliferation is observed on dishes coated with poly(2-hydroxy-ethyl methacrylate) (polyHEMA). The extent of these changes is similar to that induced by TGF beta. However, the morphology of the obtained colonies in polyHEMA-coated dishes is quite different. Cells transformed by TGF beta in the presence of EGF form rather amorphous colonies, whereas in the presence of orthovanadate colonies are formed that tend to fall apart in loose cells. The effect of vanadate on cell transformation is dependent on the growth factor conditions in a bimodal way. When a suboptimal dose of growth factor(s) is used, 25 microM vanadate is very effective in preventing density-induced growth inhibition and stimulating anchorage-independent proliferation. However, the same concentration of vanadate is inhibitory when cells are maximally stimulated and antagonizes the transforming effect of TGF beta added in combination with other growth factors. It is hypothesized that vanadate acts on a set of different protein tyrosine phosphatases. Some of these are positive and others negative regulators of growth.
在表皮生长因子（EGF）或血小板衍生生长因子（PDGF）存在的情况下培养的正常大鼠肾[NRK]细胞具有正常表型，并经历密度依赖性生长抑制，而在多种生长因子存在的情况下，密度停滞消失，细胞发生表型转化。我们研究了蛋白质酪氨酸磷酸酶（PTPase）抑制剂原钒酸钠对生长因子对NRK细胞的促有丝分裂刺激以及对与转化相关特性（如密度依赖性生长抑制的丧失和不依赖贴壁生长）的影响。在血清饥饿的单层培养物中，经EGF或PDGF有丝分裂刺激后诱导增殖的细胞比例，在添加低浓度（25 - 50 microM）钒酸盐时仅略有增加。单独添加钒酸盐仅诱导极少量细胞增殖，但会导致其他生长因子的剂量反应曲线向较低浓度偏移。与EGF或PDGF联合添加的钒酸盐能够模拟转化生长因子β（TGFβ）诱导表型转化的作用。在单层培养中，密度依赖性生长抑制丧失，并且在涂有聚（甲基丙烯酸2 - 羟乙酯）（聚HEMA）的培养皿上观察到不依赖贴壁的增殖。这些变化的程度与TGFβ诱导的相似。然而，在聚HEMA包被的培养皿中获得的集落形态有很大不同。在EGF存在下被TGFβ转化的细胞形成相当无定形的集落，而在原钒酸盐存在下形成的集落倾向于在松散的细胞中散开。钒酸盐对细胞转化的影响以双峰方式依赖于生长因子条件。当使用次优剂量的生长因子时，25 microM钒酸盐在防止密度诱导的生长抑制和刺激不依赖贴壁增殖方面非常有效。然而，当细胞受到最大刺激时，相同浓度的钒酸盐具有抑制作用，并拮抗与其他生长因子联合添加的TGFβ的转化作用。据推测，钒酸盐作用于一组不同的蛋白质酪氨酸磷酸酶。其中一些是生长促进因子，而另一些是生长负调节因子。
