Humez S, Monet M, Legrand G, Lepage G, Delcourt P, Prevarskaya N
Laboratoire de Physiologie Cellulaire, INSERM EMI 0228, USTL, Batiment SN3, 59655 Villeneuve d'Ascq Cedex, France.
Endocr Relat Cancer. 2006 Mar;13(1):181-95. doi: 10.1677/erc.1.01079.
Neuroendocrine differentiation (NED) has been implicated in prostate cancer progression and hormone-therapy failure. Neuroendocrine cells are non-proliferating and escape apoptotic cell death, although their origin and the causes of their apoptotic resistance have as yet been poorly elucidated. This study demonstrates a new mechanism involved in controlling NED. We report that epidermal growth factor (5-50 ng/ml) promotes neuroendocrine-like differentiation of androgen-independent DU145 prostate cancer cells. This differentiation is associated with an increase in the expression of Neuron Specific Enolase (NSE) and a reduction in cell proliferation and is blocked by inhibiting tyrosine kinase activity with genistein and with compound 56 (C56). An increase in the cAMP level, using dibutryl cAMP (db-cAMP) (1 mM) and isobutylmethylxanthine (100 microM), does not promote NED by itself, but does increase the effect of EGF on NED. In addition, EGF-induced NED protects cells from apoptosis induced with thapsigargin (1 microM) by reducing the thapsigargin-induced cytosolic calcium overload. In order to describe how EGF-induced NED protects cells against thapigargin-induced calcium overload we investigated the spatiotemporal calcium signalling linked to apoptosis. By using thapsigargin in various conditions on DU145 cells and using micro-fluorimetric calcium measurements, we show that depletion of intracellular calcium store induces apoptosis and that the amplitude and duration of the capacitive calcium entry are two apoptosis-modulating parameters. We show that protection against thapsigargin-induced apoptosis conferred by NED is achieved by reducing the amount and the speed of calcium that can be released from calcium pools, as well as modulating the amplitude of the subsequent calcium entry.
神经内分泌分化（NED）与前列腺癌进展及激素治疗失败有关。神经内分泌细胞不增殖且逃避凋亡性细胞死亡，尽管它们的起源及其凋亡抗性的原因尚未完全阐明。本研究揭示了一种参与控制NED的新机制。我们报告表皮生长因子（5 - 50 ng/ml）可促进雄激素非依赖性DU145前列腺癌细胞向神经内分泌样分化。这种分化与神经元特异性烯醇化酶（NSE）表达增加、细胞增殖减少相关，并被染料木黄酮和化合物56（C56）抑制酪氨酸激酶活性所阻断。使用二丁酰环磷腺苷（db - cAMP）（1 mM）和异丁基甲基黄嘌呤（100 microM）提高cAMP水平本身并不促进NED，但会增强表皮生长因子对NED的作用。此外，表皮生长因子诱导的NED通过减少毒胡萝卜素（1 microM）诱导的细胞溶质钙超载来保护细胞免受其诱导的凋亡。为了描述表皮生长因子诱导的NED如何保护细胞免受毒胡萝卜素诱导的钙超载，我们研究了与凋亡相关的时空钙信号传导。通过在不同条件下对DU145细胞使用毒胡萝卜素并进行微量荧光钙测量，我们表明细胞内钙库的耗竭诱导凋亡，且电容性钙内流的幅度和持续时间是两个凋亡调节参数。我们表明，NED赋予的对毒胡萝卜素诱导凋亡的保护作用是通过减少可从钙库释放的钙量和速度，以及调节随后钙内流的幅度来实现的。
