Bone morphogenetic protein 4 is induced in hepatocellular carcinoma by hypoxia and promotes tumour progression
Bone morphogenetic protein 4 is induced in hepatocellular carcinoma by hypoxia and promotes tumour progression
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DOI：
10.1002/path.2563
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发表时间：
2009-08-01
影响因子：
7.3
通讯作者：
Bosserhoff, Anja-Katrin
中科院分区：
文献类型：
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作者：
Maegdefrau, Ulrike;Amann, Thomas;Bosserhoff, Anja-Katrin
胚胎肝发育和肝细胞癌（HCC）发生发展的分子机制有着惊人的相似性。骨形态发生蛋白（BMPs），特别是BMP 4，已被提出来调节胚胎肝脏发育。在肿瘤形成中观察到BMP表达，但BMP 4在人HCC中的表达和生物学作用尚不清楚。我们发现与原代人肝细胞和相应的非肿瘤组织相比，HCC细胞系和组织样本中BMP 4 mRNA和蛋白质增加。缺氧进一步诱导HCC细胞中BMP 4的表达，其通过转染显性负性形式的HIF-1 α（dnHIF-1 α）而被消除。然而，凝胶迁移分析显示，只有轻微的结合活性，在核提取物（缺氧）肝癌细胞的BMP 4启动子中的一个假定的缺氧反应元件。BMP 4启动子的序列分析揭示了两个Ets-1结合位点，并且Ets-1活性在低氧条件下在HCC细胞中增加。dnHIF-1 α的转染完全消除了缺氧诱导的Ets-1活性以及BMP 4表达。Ets-1的过表达显著增强了BMP 4启动子的活性，而反义Ets-1几乎完全消除了基础以及缺氧诱导的BMP 4表达。这些数据表明，Ets-1活性有助于BMP 4基因的基线表达，并且是低氧条件下HIF依赖性BMP 4诱导的主要介质。为了确定BMP 4表达的功能相关性，用针对BMP 4的反义BMP 4构建体或siRNA处理HCC细胞系。BMP 4抑制导致迁移和侵袭潜力以及锚定非依赖性生长的强烈降低。此外，管形成试验表明，由HCC细胞表达的BMP 4促进血管生成。我们的研究结果表明，BMP 4在HCC中增加，并促进HCC进展。因此，BMP 4表达可能具有临床相关性，并且干扰BMP 4信号传导似乎是这种高度侵袭性肿瘤的有吸引力的治疗靶点。版权所有（C）2009大不列颠和爱尔兰病理学会。由John Wiley & Sons有限公司出版
Striking similarities exist between molecular mechanisms driving embryonic liver development and progression of hepatocellular carcinoma (HCC). Bone morphogenetic proteins (BMPs), particularly BMP4, have been proposed to regulate embryonic hepatic development. BMP expression has been observed in neoplasia but the expression and biological role of BMP4 in human HCC are unknown. We found increased BMP4 mRNA and protein in HCC cell lines and tissue samples compared to primary human hepatocytes and corresponding non-tumourous tissue. Hypoxia further induced BMP4 expression in HCC cells, which was abolished by transfection of a dominant negative form of HIF-1alpha (dnHIF-1alpha). However, gel shift assays revealed only minor binding activity in nuclear extracts from (hypoxic) HCC cells to a putative hypoxia-response element in the BMP4 promoter. Sequence analysis of the BMP4 promoter revealed two Ets-1 binding sites, and Ets-1 activity was increased in HCC cells under hypoxic conditions. Transfection of dnHIF-1alpha completely abrogated hypoxia-induced Ets-1 activity as well as BMP4 expression. Overexpression of Ets-1 markedly enhanced BMP4 promoter activity, while antisense Ets-1 almost completely abolished basal as well as hypoxia-induced BMP4 expression. These data demonstrate that Ets-1 activity contributes to baseline expression of the BMP4 gene and is the predominant mediator of the HIF-dependent BMP4 induction under hypoxic conditions. To determine the functional relevance of BMP4 expression, HCC cell lines were treated with antisense BMP4 constructs or siRNA against BMP4. BMP4 suppression resulted in a strong reduction of the migratory and invasive potential and anchorage-independent growth. Furthermore, tube formation assays indicated that BMP4 expressed by HCC cells promotes vasculogenesis. Our findings demonstrate that BMP4 is increased in HCC and promotes HCC progression. Therefore, BMP4 expression may have clinical relevance, and interfering with BMP4 signalling appears as an attractive therapeutic target for this highly aggressive tumour. Copyright (C) 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.