PI3K/Akt-dependent transcriptional regulation and activation of BMP-2-Smad signaling by NF-kappaB in metastatic prostate cancer cells.
PI3K/Akt-dependent transcriptional regulation and activation of BMP-2-Smad signaling by NF-kappaB in metastatic prostate cancer cells.
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DOI：
10.1002/pros.20870
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发表时间：
2009-02-01
期刊：
影响因子：
2.8
通讯作者：
Abdel-Mageed, Asim B.
中科院分区：
文献类型：
--
作者：
Graham, Tisheeka R.;Odero-Marah, Valerie A.;Chung, Leland W.;Agrawal, Krishna C.;Davis, Rodney;Abdel-Mageed, Asim B.
骨形态发生蛋白（BMPs）通过未表征的机制在前列腺癌（PC）中发挥骨诱导作用。在这项研究中，我们调查了核转录因子NF-κB，牵连在PC转移，是否参与转录调控和激活的BMP-2或BMP-4/Smad信号在PC细胞。IκBα超阻遏腺病毒载体可抑制NF-κB α的表达，EMSA和报告基因分析检测NF-κB的激活。通过PCR和报告基因测定来测量BMP表达和活化。通过染色质免疫沉淀（ChIP）测定进行启动子结合测定。通过Western印迹分析测量Smad 1/5/8磷酸化。PCR和嵌合BMP-2和BMP-4荧光素酶测定证明NF-κB在p65过表达或rhTNF-α刺激的PC细胞中赋予BMP-2稳健和选择性活化。抑制NF-κB可显著降低rhTNF-α刺激的C4- 2 B细胞的BMP-2转录水平和自分泌量，而亲本LNCaP细胞的水平较低。选择性抑制PI 3 K/Akt可抑制NF-κ B诱导的BMP-2启动子活性。此外，抑制NF-κB活化降低了PC细胞中BMP-2信号传导的关键下游靶点Smad 1/5/8的转录水平和BMP-2诱导的Smad 1/5/8磷酸化。值得注意的是，BMP-2激活BMPRII是PC细胞中NF-κB调节Smad激活所必需的。ChIP分析表明，NF-κB对BMP-2基因的转录调控可能部分是通过与BMP-2启动子上的B位点结合实现的。提示PI 3 K/Akt-NF-κB轴可能通过调节BMP-2-Smad信号级联的转录和激活，促进PC骨转移。
Bone morphogenetic proteins (BMPs) exert osteoinductive effects in prostate cancer (PC) via uncharacterized mechanisms. In this study, we investigated whether the nuclear transcription factor NF-κB, implicated in PC metastasis, is involved in transcriptional regulation and activation of BMP-2 or BMP-4/Smad signaling in PC cells. NF-κB inhibition was achieved by IκBα super-repressor adenoviral vector and activation was monitored by EMSA and reporter assays. BMP expression and activation was measured by PCR and reporter assays. Promoter binding assay was performed by chromatin immunoprecipitation (ChIP) assay. Smad1/5/8 phosphorylation was measured by Western blot analysis. PCR and chimeric BMP-2 and BMP-4 luciferase assays demonstrate that NF-κB confers robust and selective activation of BMP-2 in p65 overexpressing or rhTNF-α-stimulated PC cells. Inhibition of NF-κB significantly reduced transcript levels and autocrine production of BMP-2 by rhTNF-α stimulated C4-2B cells and to a lesser extent by the parental LNCaP cells. Selective inhibition of PI3K/Akt suppressed the NF-κB-induced BMP-2 promoter activity. Furthermore, suppression of NF-κB activation decreased the transcript levels and BMP-2-induced phosphorylation of Smad1/5/8, critical downstream targets of BMP-2 signaling in PC cells. Notably, the activation of BMPRII by BMP-2 is required for modulation of Smad activation by NF-κB in PC cells. Based on ChIP analysis, the transcriptional regulation of BMP-2 gene by NF-κB may be partially attributed to binding to b site on the BMP-2 promoter. The data suggest that PI3K/Akt-NF-κB axis may promote PC bone metastasis in part by regulating transcription and activation of the BMP-2-Smad signaling cascade in osteotropic PC cells.
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