Lithium stimulates proliferation in cultured thyrocytes by activating Wnt/β-catenin signalling
Lithium stimulates proliferation in cultured thyrocytes by activating Wnt/β-catenin signalling
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DOI：
10.1530/eje.1.02038
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发表时间：
2005-12-01
影响因子：
5.8
通讯作者：
Brabant, G
中科院分区：
文献类型：
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作者：
Rao, AS;Kremenevskaja, N;Brabant, G
背景：锂，临床上用于治疗双相情感障碍，是众所周知的诱导甲状腺生长。然而，所涉及的机制只是不完全的特点。尽管传统上认为甲状腺增殖依赖于促甲状腺激素（TSH）/cAMP/cAMP反应元件结合蛋白（CREB）通路，但最近的数据表明Wnt/β-连环蛋白信号传导可能至关重要。在其它细胞类型中，锂通过GSK-3 β抑制激活经典Wnt信号传导，GSK-3 β抑制反过来稳定胞质游离β-连环蛋白。在这里，我们研究了锂处理下原发性和肿瘤性人甲状腺细胞中Wnt/β-连环蛋白信号传导的潜在调节。（NPA，FTC 133）甲状腺细胞用和不用LiCl处理，使用Western印迹、免疫沉淀、转录因子基因测定、MTT增殖测定和转染研究进行分析。LiCl剂量依赖性地抑制GSK-3 β，稳定游离β-连环蛋白并抑制β-连环蛋白降解。此外。氯化锂通过上调E-钙粘蛋白阻遏物Snail和下调E-钙粘蛋白表达改变了粘附连接的组装。在5 mM的剂量下，LiCl显著增加了甲状腺细胞的增殖能力，这似乎是由β-连环蛋白介导的，因为核β-连环蛋白刺激T细胞因子/淋巴增强因子（TCF/LEF）介导的转录并上调下游靶点，如细胞周期蛋白D1。为了表征Wnt/β-连环蛋白驱动的甲状腺细胞增殖的特异性，我们用显性负性TCF 4转染原代甲状腺细胞和FTC 133细胞以阻断Wnt依赖性途径或用显性负性CREB转染原代甲状腺细胞和FTC 133细胞以抑制TSH/cAMP级联反应。在用显性负性CREB转染的细胞中，锂刺激的增殖没有变化，而通过显性负性TCF 4阻断Wnt/β-连环蛋白使增殖降低约10%。结论：我们的数据表明Wnt/β-catenin信号在锂依赖性甲状腺细胞增殖的控制中具有重要意义。
Background: Lithium, clinically used in the treatment of bipolar disorders, is well known to induce thyroid growth. However, the mechanism involved is only incompletely characterized. Although it is conventionally believed that thyroid proliferation depends on the thyroid-stimulating hormone (TSH)/cAMP/cAMPresponseelementbinding protein (CREB) pathway, recent data indicate that Wnt/beta-catenin signalling may be of critical importance. in other cell types lithium activates canonical Wnt signalling by GSK-3 beta inhibition, which in turn stabilizes cytosolic free beta-catenin. Here we investigated the potential modulation of Wnt/beta-catenin signalling under lithium treatment in primary and neoplastic human thyrocytes.Methods: Primary (S18) and neoplastic (NPA, FTC133) thyrocytes treated with and without LiCI were analysed using Western blotting, immunoprecipitation, reporter-gene assay, MTT proliferation assay and transfection studies.Results: LiCl dose-dependently inhibited GSK-3 beta, stabilized free beta-catenin and inhibited beta-catenin degradation. Furthermore. LiCI altered the assembly of adherens junction by upregulating the E-cadherin repressor, Snail, and downregulated E-cadherin expression. At a dose of 5 mM, LiCl significantly increased the proliferative potency of thyrocytes, which appeared to be mediated by beta-catenin, since nuclear beta-catenin stimulated T-cell factor/lymphoid enhancer factor (TCF/LEF)-mediated transcription and upregulated downstream targets like cyclin D1. To characterize the specificity of Wnt/beta-catenin-driven thyrocyte proliferation, we transfected primary thyrocytes and FTC133 cells with dominant negative TCF4 to block Wnt-dependent pathways or with dominant negative CREB to inhibit the TSH/cAMP cascade. In cells transfected with dominant negative CREB lithium-stimulated proliferation was unchanged whereas blocking Wnt/beta-catenin by dominant negative TCF4 reduced proliferation by approx. 50%.Conclusion: Our data indicate that Wnt/beta-catenin signalling is of major importance in the control of lithium-dependent thyrocyte proliferation.