Expression of ADAM12 is regulated by E2F1 in small cell lung cancer
Expression of ADAM12 is regulated by E2F1 in small cell lung cancer
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ADAM12 在小细胞肺癌中的表达受 E2F1 调节。
DOI：
10.3892/or.2015.4317
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发表时间：
2015-12-01
期刊：
影响因子：
4.2
通讯作者：
Chen, Xufang
中科院分区：
文献类型：
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作者：
Li, Zunling;Wang, Yaopeng;Chen, Xufang
我们之前的研究报道了ADAM12在小细胞肺癌（SCLC）中高表达，可以作为诊断和预后的有效标志物。然而，ADAM12在SCLC中高表达的原因还有待进一步阐明。转录因子E2F1因其在肿瘤中功能的复杂性和多样性而受到越来越多的关注。在本研究中，通过siRNA沉默E2F1表达后，ADAM12的表达显著降低，说明E2F1可能在转录水平上调控ADAM12的表达。染色质免疫沉淀-序列分析在ADAM12基因座上发现了E2F1的三个结合位点。分别是位于ADAM12内含子中的Chr10: 128010444-128011026，命名为seq0；Chr10: 128076927‑128078127，位于ADAM12的启动子中，命名为seq1；Chr10: 128086195‑128086876，位于ADAM12转录起始位点上游20kb处，命名为：seq2。双荧光素酶报告基因实验表明，seq1而不是seq0和seq2能够促进荧光素酶的表达。值得注意的是，共转染E2F1显著提高了seq1的活性，而不是seq0和seq2，但定量聚合酶链反应结果显示，seq0、seq1和seq2都可以招募E2F1，说明E2F1调节ADAM12表达的影响是复杂的。序列分析表明，seq1是ADAM12启动子的一部分，而seq0和seq2的功能未知。在荧光素酶构建体中分析含有seq0-seq1或seq2-seq1的融合片段。与单独的seq1相比，这些融合片段的活性没有明显降低。与E2F1共转染后，融合片段的活性显著降低。因此，本研究结果支持E2F1转录因子通过结合差异顺式作用元件调节ADAM12表达的结论。
Our previous study reported that ADAM12 was highly expressed in small cell lung cancer (SCLC) and could be an effective marker for diagnosis and prognosis. Yet, the reason for the high expression of ADAM12 in SCLC requires further elucidation. Transcription factor E2F1 has been receiving increasing attention due to the complexity and diversity of its function in cancer. In the present study, the expression of ADAM12 was significantly decreased following silencing of E2F1 expression by siRNA, thus indicating that E2F1 may regulate the expression of ADAM12 at the level of transcription. Chromatin immunoprecipitation-to-sequence analysis identified three binding sites for E2F1 in the locus for ADAM12. They were Chr10: 128010444-128011026, located in the intron of ADAM12, named seq0; Chr10: 128076927‑128078127, located in the promoter of ADAM12, named seq1; and Chr10: 128086195‑128086876, located in the upstream 20 kb from the transcription start site of ADAM12, named: seq2. Dual‑luciferase reporter experiments revealed that seq1 not seq0 and seq2 was able to promote the expression of luciferase. Notably, co-transfection of E2F1 significantly increased the activity of seq1 not seq0 and seq2, but quantitative polymerase chain reaction results showed that seq0, seq1 and seq2 could recruit E2F1, indicating that the influence of E2F1 in regulating the expression of ADAM12 was complex. Sequence analysis clarified that seq1 was a part of the ADAM12 promoter, yet the functions of seq0 and seq2 were unknown. Fusion fragments containing seq0-seq1 or seq2-seq1 were analyzed in luciferase constructs. Compared with seq1 alone, the activities of these fusion fragments were non-significantly reduced. The activities of fusion fragments were significantly decreased following co-transfection with E2F1. Thus, the present findings support the conclusion that the E2F1 transcription factor regulates the expression of ADAM12 by binding differential cis-acting elements.