Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
J Cell Sci. 2013 Nov 1;126(Pt 21):4939-49. doi: 10.1242/jcs.130013. Epub 2013 Aug 28.
Various ion channels are expressed in human cancers where they are intimately involved in proliferation, angiogenesis, invasion and metastasis. Expression of functional voltage-gated Na(+) channels (Nav) is implicated in the metastatic potential of breast, prostate, lung and colon cancer cells. However, the cellular mechanisms that regulate Nav expression in cancer remain largely unknown. Growth factors are attractive candidates; they not only play crucial roles in cancer progression but are also key regulators of ion channel expression and activity in non-cancerous cells. Here, we examine the role of epidermal growth factor receptor (EGFR) signalling and Nav in non-small cell lung carcinoma (NSCLC) cell lines. We show unequivocally, that functional expression of the α subunit Nav1.7 promotes invasion in H460 NSCLC cells. Inhibition of Nav1.7 activity (using tetrodotoxin) or expression (by using small interfering RNA), reduces H460 cell invasion by up to 50%. Crucially, non-invasive wild type A549 cells lack functional Nav, whereas exogenous overexpression of the Nav1.7 α subunit is sufficient to promote TTX-sensitive invasion of these cells. EGF/EGFR signalling enhances proliferation, migration and invasion of H460 cells but we find that, specifically, EGFR-mediated upregulation of Nav1.7 is necessary for invasive behaviour in these cells. Examination of Nav1.7 expression at mRNA, protein and functional levels further reveals that EGF/EGFR signalling via the ERK1/2 pathway controls transcriptional regulation of channel expression to promote cellular invasion. Immunohistochemistry of patient biopsies confirms the clinical relevance of Nav1.7 expression in NSCLC. Thus, Nav1.7 has significant potential as a new target for therapeutic intervention and/or as a diagnostic or prognostic marker in NSCLC.
各种离子通道在人类癌症中表达，它们密切参与增殖、血管生成、侵袭和转移。功能性电压门控 Na(+) 通道 (Nav) 的表达与乳腺癌、前列腺癌、肺癌和结肠癌细胞的转移潜能有关。然而，调节癌症中 Nav 表达的细胞机制在很大程度上仍然未知。生长因子是有吸引力的候选者；它们不仅在癌症进展中发挥关键作用，而且还是非癌细胞中离子通道表达和活性的关键调节剂。在这里，我们研究了表皮生长因子受体 (EGFR) 信号转导和 Nav 在非小细胞肺癌 (NSCLC) 细胞系中的作用。我们明确地表明，α亚基 Nav1.7 的功能表达促进了 H460 NSCLC 细胞的侵袭。Nav1.7 活性的抑制（使用河豚毒素）或表达（使用小干扰 RNA）使 H460 细胞的侵袭减少了高达 50%。至关重要的是，非侵袭性野生型 A549 细胞缺乏功能性 Nav，而 Nav1.7 α亚基的外源性过表达足以促进这些细胞对 TTX 敏感的侵袭。EGF/EGFR 信号转导增强了 H460 细胞的增殖、迁移和侵袭，但我们发现，特别是 EGFR 介导的 Nav1.7 上调对于这些细胞的侵袭行为是必要的。对 Nav1.7 在 mRNA、蛋白质和功能水平上的表达的进一步检查表明，EGF/EGFR 信号转导通过 ERK1/2 途径控制通道表达的转录调节，以促进细胞侵袭。对患者活检的免疫组织化学证实了 Nav1.7 在 NSCLC 中的表达具有临床相关性。因此，Nav1.7 具有作为 NSCLC 治疗干预的新靶标以及作为诊断或预后标志物的巨大潜力。
