Epigenetic regulation of the human mucin gene MUC4 in epithelial cancer cell lines involves both DNA methylation and histone modifications mediated by DNA methyltransferases and histone deacetylases
Epigenetic regulation of the human mucin gene MUC4 in epithelial cancer cell lines involves both DNA methylation and histone modifications mediated by DNA methyltransferases and histone deacetylases
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DOI：
10.1096/fj.07-103390
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发表时间：
2008-08-01
期刊：
影响因子：
4.8
通讯作者：
Van Seuningen, Isabelle
中科院分区：
文献类型：
--
作者：
Vincent, Audrey;Ducourouble, Marie-Paule;Van Seuningen, Isabelle
人类基因MUC4编码一种跨膜粘蛋白，ErbB2的配体，与胰腺肿瘤的进展有关。在正常胰腺中，MUC4不表达，而在胰腺癌变的早期观察到其表达的激活。然而，导致MUC4基因激活的分子机制仍不清楚。MUC45‘-侧翼区富含GC，包括两个CpG岛，我们假设可能涉及表观遗传调控，并承诺破译所暗示的分子现象。通过用5-氮杂-2‘-脱氧胞苷(5-aza)和曲古抑素A(TSA)处理癌细胞，我们能够以细胞特异性的方式恢复MUC4的表达。我们通过亚硫酸氢盐处理的基因组DNA测序和染色质免疫沉淀表明，5个CpG位点的甲基化和5‘-非翻译区抑制性组蛋白密码的建立与MUC4沉默有关，并削弱了Sp1对MUC4的激活。通过RNA干扰和染色质免疫沉淀证实了DNMT3A、DNMT3b、HDAC1和HDAC3的直接参与。此外，TSA对组蛋白去乙酰化的抑制与高表达细胞中MUC4的强烈抑制有关。总之，这项工作首次显示了表观遗传学在调节MUC4表达中的重要性，并可能代表一种抑制其在上皮性肿瘤中表达的新策略。
The human gene MUC4 encodes a transmembrane mucin, ligand of ErbB2, that is associated with pancreatic tumor progression. In the normal pancreas, MUC4 is not expressed, whereas activation of its expression is observed in the early steps of pancreatic carcinogenesis. The molecular mechanisms responsible for MUC4 gene activation are however still unknown. The MUC4 5'-flanking region being GC-rich and including two CpG islands, we hypothesized that epigenetic regulation may be involved and undertook to decipher the molecular phenomenons implied. By treating cancer cell lines with 5-aza-2'-deoxycytidine (5-aza) and trichostatin A (TSA), we were able to restore MUC4 expression in a cell-specific manner. We showed by bisulfite-treated genomic DNA sequencing and chromatin immunoprecipitation that methylation of five CpG sites and establishment of a repressive histone code at the 5'-untranslated region were associated with MUC4 silencing and impaired its activation by Sp1. Direct involvement of DNMT3A, DNMT3B, HDAC1, and HDAC3 was demonstrated by RNA interference and chromatin immunoprecipitation. Moreover, inhibition of histone deacetylation by TSA was associated with strong MUC4 repression in high-expressing cells. In conclusion, this work shows for the first time the importance of epigenetics in regulating MUC4 expression and may represent a new strategy to inhibit its expression in epithelial tumors.