Ducret Thomas, Boudina Sihem, Sorin Bruno, Vacher Anne Marie, Gourdou Isabelle, Liguoro Dominique, Guerin Jean, Bresson-Bepoldin Laurence, Vacher Pierre
Laboratoire de Neurophysiologie, Centre National de la Recherche Scientifique UMR 5543, Université de Bordeaux 2, France.
Glia. 2002 May;38(3):200-14. doi: 10.1002/glia.10056.
Prolactin (PRL) has several physiological effects on peripheral tissues and the brain. This hormone acts via its membrane receptor (PRL-R) to induce cell differentiation or proliferation. Using reverse transcription-polymerase chain reaction (RT-PCR) combined with Southern blot analysis, we detected PRL-R transcripts in a human glioma cell line (U87-MG) and in primary cultured human glioblastoma cells. These transcripts were deleted or not in their extracellular domains. We examined the effects of PRL on intracellular free Ca2+ concentration (Ca2+) in these cells in order to improve our understanding of the PRL transduction mechanism, which is still poorly documented. Ca2+ was measured by microspectrofluorimetry using indo-1 as the Ca2+ fluorescent probe. Spatiotemporal aspects of PRL-induced Ca2+ signals were investigated using high-speed fluo-3 confocal imaging. We found that physiological concentrations (0.4-4 nM) of PRL-stimulated Ca2+ entry and intracellular Ca2+ mobilization via a tyrosine kinase-dependent mechanism. The two types of Ca2+ responses observed were distinguishable by their kinetics: one showing a slow (type I) and the other a fast (type II) increase in Ca2+. The amplitude of PRL-induced Ca2+ increases may be sufficient to provoke several physiological responses, such as stimulating proliferation. Furthermore, PRL induced a dose-dependent increase in [3H]thymidine incorporation levels and in cellular growth and survival, detected by the MTT method. These data indicate that PRL induced mitogenesis of human glioma cells.
催乳素（PRL）对周围组织和大脑具有多种生理作用。这种激素通过其膜受体（PRL-R）发挥作用，诱导细胞分化或增殖。我们采用逆转录聚合酶链反应（RT-PCR）结合Southern印迹分析，在人胶质瘤细胞系（U87-MG）和原代培养的人胶质母细胞瘤细胞中检测到PRL-R转录本。这些转录本在其细胞外结构域存在缺失或无缺失情况。为了更好地理解仍知之甚少的PRL转导机制，我们研究了PRL对这些细胞内游离Ca2+浓度（[Ca2+]i）的影响。使用indo-1作为Ca2+荧光探针，通过显微荧光测定法测量[Ca2+]i。利用高速fluo-3共聚焦成像研究PRL诱导的Ca2+信号的时空特征。我们发现，生理浓度（0.4 - 4 nM）的PRL通过酪氨酸激酶依赖性机制刺激Ca2+内流和细胞内Ca2+释放。观察到的两种类型的Ca2+反应在动力学上可区分：一种显示[Ca2+]i缓慢升高（I型），另一种显示快速升高（II型）。PRL诱导的Ca2+升高幅度可能足以引发多种生理反应，如刺激增殖。此外，PRL诱导[3H]胸苷掺入水平以及通过MTT法检测到的细胞生长和存活呈剂量依赖性增加。这些数据表明PRL诱导人胶质瘤细胞发生有丝分裂。
