Perrais Michaël, Pigny Pascal, Copin Marie-Christine, Aubert Jean-Pierre, Van Seuningen Isabelle
Unité INSERM 560, Place de Verdun, 59045 Lille Cedex, France.
J Biol Chem. 2002 Aug 30;277(35):32258-67. doi: 10.1074/jbc.M204862200. Epub 2002 Jun 19.
The 11p15 mucin genes (MUC2, MUC5AC, MUC5B and MUC6) possess a cell-specific pattern of expression in normal lung that is altered during carcinogenesis. Growth factors of the epidermal growth factor family are known to target key genes that in turn may affect the homeostasis of lung mucosae. Our aim was to study the regulation of the 11p15 mucin genes both at the promoter and protein levels to assess whether their altered expression may represent a key event during lung carcinogenesis. Studies were performed in the mucoepidermoid NCI-H292 lung cancer cell line. Cell treatment with epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), or tumor necrosis factor alpha (TNF-alpha) resulted in a dramatic increase of MUC2 and MUC5AC mRNAs levels, promoter activity, and apomucin expression, whereas those of MUC5B and MUC6 were unchanged. pGL3 deletion mutants of MUC2, MUC5AC, and MUC5B promoters were constructed and used in transient transfection assays to characterize EGF- and TGF-alpha-responsive regulatory regions within the promoters. They were located in the -2627/-2097 and -202/-1 regions of MUC2 and MUC5AC promoters, respectively. Finally, we demonstrate that transcription factor Sp1 not only binds and activates MUC2 and MUC5AC promoters but also participates to their EGF- and TGF-alpha-mediated up-regulation. We also show that Sp3 is a strong inhibitor of 11p15 mucin gene transcription. In conclusion, MUC2 and MUC5AC are two target genes of EGFR ligands in lung cancer cells, and up-regulation of these two genes goes through concomitant activation of the EGFR/Ras/Raf/Extracellular Signal-regulated Kinase-signaling pathway and Sp1 binding to their promoters.
11p15粘蛋白基因（MUC2、MUC5AC、MUC5B和MUC6）在正常肺组织中具有细胞特异性表达模式，在癌变过程中会发生改变。已知表皮生长因子家族的生长因子靶向关键基因，这些基因进而可能影响肺黏膜的稳态。我们的目的是在启动子和蛋白质水平研究11p15粘蛋白基因的调控，以评估其表达改变是否可能是肺癌发生过程中的关键事件。研究在黏液表皮样NCI-H292肺癌细胞系中进行。用表皮生长因子（EGF）、转化生长因子α（TGF-α）或肿瘤坏死因子α（TNF-α）处理细胞，导致MUC2和MUC5AC mRNA水平、启动子活性和脱辅基粘蛋白表达显著增加，而MUC5B和MUC6的水平未改变。构建了MUC2、MUC5AC和MUC5B启动子的pGL3缺失突变体，并用于瞬时转染实验，以表征启动子内的EGF和TGF-α反应性调控区域。它们分别位于MUC2和MUC5AC启动子的-2627/-2097和-202/-1区域。最后，我们证明转录因子Sp1不仅结合并激活MUC2和MUC5AC启动子，还参与其EGF和TGF-α介导的上调。我们还表明Sp3是11p15粘蛋白基因转录的强抑制剂。总之，MUC2和MUC5AC是肺癌细胞中EGFR配体的两个靶基因，这两个基因的上调通过EGFR/Ras/Raf/细胞外信号调节激酶信号通路的同时激活以及Sp1与它们启动子的结合来实现。
