Activity-de pendent regulation of voltage-gated Na+ channel expression in Mat-LyLu rat prostate cancer cell line
Activity-de pendent regulation of voltage-gated Na+ channel expression in Mat-LyLu rat prostate cancer cell line
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DOI：
10.1113/jphysiol.2006.106906
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发表时间：
2006-06-01
影响因子：
5.5
通讯作者：
Djamgoz, Mustafa B. A.
中科院分区：
文献类型：
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作者：
Brackenbury, William J.;Djamgoz, Mustafa B. A.
我们以前已经证明，电压门控Na+通道(VGSCs)在人类转移性疾病(前列腺癌、乳腺癌和小细胞肺癌)中上调，VGSC的活动增强了转移细胞的行为。然而，调控肿瘤细胞中功能性VGSC表达的机制(S)仍不清楚。我们研究了在大鼠前列腺癌强转移Mat-LyLu模型中VGSC功能表达的活性依赖(自动)调节的可能性。河豚毒素(TTX)可抑制VGSC的峰值电流密度，但不影响电压依赖性。假设VGSC的自动调节是通过VGSC介导的Na+内流和随后的蛋白激酶A(PKA)激活来实现的。确实，TTX预处理降低了磷酸化PKA的水平，PKA抑制剂KT5720减少，而腺苷环化酶激活剂Forsklin和Na+离子载体莫能菌素都增加了VGSC的峰值电流密度。TTX可降低VGSC在质膜上的蛋白表达，但不影响VGSC的总蛋白水平。在Transwell实验中，TTX预处理消除了细胞迁移中依赖VGSC的成分。结论：Mat-LyLu大鼠前列腺癌细胞VGSC活性通过PKA参与的正反馈机制稳态上调，从而增强了细胞的迁移能力。
We have shown previously that voltage-gated Na+ channels (VGSCs) are up-regulated in human metastatic disease (prostate, breast and small-cell lung cancers), and that VGSC activity potentiates metastatic cell behaviours. However, the mechanism(s) regulating functional VGSC expression in cancer cells remains unknown. We investigated the possibility of activity-dependent (auto) regulation of VGSC functional expression in the strongly metastatic Mat-LyLu model of rat prostate cancer. Pretreatment with tetrodotoxin (TTX) for 24-72 h subsequently suppressed peak VGSC current density without affecting voltage dependence. The hypothesis was tested that the VGSC auto-regulation occurred via VGSC-mediated Na+ influx and subsequent activation of protein kinase A (PKA). Indeed, TTX pretreatment reduced the level of phosphorylated PKA, and the PKA inhibitor KT5720 decreased, whilst the adenylate cyclase activator forskolin and the Na+ ionophore monensin both increased the peak VGSC current density. TTX reduced the mRNA level of Nav1.7, predominant in these cells, and VGSC protein expression at the plasma membrane, although the total VGSC protein level remained unchanged. TTX pretreatment eliminated the VGSC-dependent component of the cells' migration in Transwell assays. We concluded that the VGSC activity in Mat-LyLu rat prostate cancer cells was up-regulated in steady-state via a positive feedback mechanism involving PKA, and this enhanced the cells' migratory potential.