Roger Sébastien, Rollin Jérôme, Barascu Aurélia, Besson Pierre, Raynal Pierre-Ivan, Iochmann Sophie, Lei Ming, Bougnoux Philippe, Gruel Yves, Le Guennec Jean-Yves
INSERM, E0211, Tours, F-37000, France.
Int J Biochem Cell Biol. 2007;39(4):774-86. doi: 10.1016/j.biocel.2006.12.007. Epub 2007 Jan 20.
Ionic channel activity is involved in fundamental cellular behaviour and participates in cancerous features such as proliferation, migration and invasion which in turn contribute to the metastatic process. In this study, we investigated the expression and role of voltage-gated sodium channels in non-small-cell lung cancer cell lines. Functional voltage-gated sodium channels expression was investigated in normal and non-small-cell lung cancer cell lines. The measurement, in patch-clamp conditions, of tetrodotoxin-inhibitable sodium currents indicated that the strongly metastatic cancerous cell lines H23, H460 and Calu-1 possess functional sodium channels while normal and weakly metastatic cell lines do not. While all the cell lines expressed mRNA for numerous sodium channel isoforms, only H23, H460 and Calu-1 cells had a 250 kDa protein corresponding to the functional channel. The other cell lines also had another protein of 230 kDa which is not addressed to the membrane and might act as a dominant negative isoform to prevent channel activation. At the membrane potential of these cells, channels are partially open. This leads to a continuous entry of sodium, disrupting sodium homeostasis and down-stream signaling pathways. Inhibition of the channels by tetrodotoxin was responsible for a 40-50% reduction of in vitro invasion. These experiments suggest that the functional expression of voltage-gated sodium channels might be an integral component of the metastatic process in non-small-cell lung cancer cells probably through its involvement in the regulation of intracellular sodium homeostasis. These channels could serve both as novel markers of the metastatic phenotype and as potential new therapeutic targets.
离子通道活性参与基本的细胞行为，并参与增殖、迁移和侵袭等癌性特征，而这些特征反过来又有助于转移过程。在本研究中，我们调查了电压门控钠通道在非小细胞肺癌细胞系中的表达及作用。在正常和非小细胞肺癌细胞系中研究了功能性电压门控钠通道的表达。在膜片钳条件下，对河豚毒素可抑制的钠电流进行测量，结果表明高转移性癌细胞系H23、H460和Calu-1具有功能性钠通道，而正常和低转移性细胞系则没有。虽然所有细胞系都表达多种钠通道亚型的mRNA，但只有H23、H460和Calu-1细胞有一个与功能性通道相对应的250 kDa蛋白。其他细胞系也有一种230 kDa的蛋白，该蛋白不会定位于细胞膜，可能作为一种显性负性亚型来阻止通道激活。在这些细胞的膜电位下，通道部分开放。这导致钠持续内流，破坏钠稳态和下游信号通路。河豚毒素对通道的抑制导致体外侵袭减少40 - 50%。这些实验表明，电压门控钠通道的功能性表达可能是非小细胞肺癌细胞转移过程的一个组成部分，可能是通过其参与细胞内钠稳态的调节。这些通道既可以作为转移表型的新标志物，也可以作为潜在的新治疗靶点。
