Vandewalle B, Hornez L, Revillion F, Lefebvre J
Laboratoire d'Endocrinologie Expérimentale, Centre Oscar Lambret, Lille, France.
Cancer Lett. 1994 Sep 30;85(1):47-54. doi: 10.1016/0304-3835(94)90237-2.
We studied the effects of purine nucleotides and particularly adenosine triphosphate (ATP) in two (one hormonosensitive, MCF7 and one hormonoinsensitive, MDA-MB 231) human breast tumor cell lines. As described in other cells, we observed that purine nucleotides produced transient elevations in intracellular calcium ions, [Ca2+]i, in both types of cells as determined from Indo-1 fluorescence of loaded cells. In the absence of external calcium the [Ca2+]i transients consisted of single narrow peaks while an extension of peak duration along with a biphasic appearance were observed in the presence of external calcium. The potency of different purine nucleotides in elevating [Ca2+]i was ATP > ADP >> AMP > adenosine (which was inefficient) proving the presence of P2 purinergic receptor subtypes. Suramin, a compound known to compete with ATP for its binding sites, nearly abolished the effect of ATP on [Ca2+]i increase. while verapamil, a calcium channel blocker, was unable to abolish such an an ATP-induced [Ca2+]i increase. The concentrations of ATP required to increase [Ca2%bdi ranged from 10(-7) M to 10(-3) M, the maximal effect being obtained with 10(-4) M ATP. At this latter concentration, ATP induced cell growth inhibition which was dose-independent as triggered only when maximal elevation of [Ca2+]i was attained. This ATP concentration also induced maximal apoptotic features in both types of cells. Together, our results highlighted an 'all or none' effect of ATP on breast tumor cell growth mediated by its effect on [Ca2+]i liberation from intracellular stores, the first rise of [Ca2+]i being further amplified by an influx of calcium from extracellular space. The attainment of sufficient [Ca2+]i level then triggers cellular events.
我们研究了嘌呤核苷酸尤其是三磷酸腺苷（ATP）对两种人乳腺肿瘤细胞系（一种激素敏感型，MCF7；另一种激素不敏感型，MDA-MB 231）的影响。正如在其他细胞中所描述的那样，我们观察到嘌呤核苷酸会使两种细胞内的钙离子浓度（[Ca2+]i）出现短暂升高，这是通过负载细胞的Indo-1荧光测定得出的。在无细胞外钙的情况下，[Ca2+]i瞬变由单个窄峰组成，而在有细胞外钙存在时，则观察到峰持续时间延长以及双相出现。不同嘌呤核苷酸升高[Ca2+]i的效力为ATP > ADP >> AMP > 腺苷（腺苷效果不佳），这证明了P2嘌呤能受体亚型的存在。苏拉明是一种已知可与ATP竞争其结合位点的化合物，它几乎消除了ATP对[Ca2+]i升高的影响。而钙通道阻滞剂维拉帕米则无法消除ATP诱导的[Ca2+]i升高。使[Ca2+]i升高所需的ATP浓度范围为10^(-7) M至10^(-3) M，10^(-4) M ATP可获得最大效应。在这一浓度下，ATP诱导细胞生长抑制，这种抑制与剂量无关，只有在[Ca2+]i达到最大升高时才会触发。该ATP浓度还在两种细胞类型中诱导出最大的凋亡特征。总之，我们的结果突出了ATP对乳腺肿瘤细胞生长的“全或无”效应，这种效应是由其对细胞内储存库中[Ca2+]i释放的影响介导的，[Ca2+]i的首次升高会因细胞外空间钙的流入而进一步放大。足够的[Ca2+]i水平的达到随后触发细胞事件。
