Song Li-Jie, Zhang Wei-Jie, Chang Zhi-Wei, Pan Yan-Feng, Zong Hong, Fan Qing-Xia, Wang Liu-Xing
Department of Oncology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China E-mail :
Asian Pac J Cancer Prev. 2015;16(9):3667-71. doi: 10.7314/apjcp.2015.16.9.3667.
Invasion and metastasis is the major cause of tumor recurrence, difficulty for cure and low survival rate. Excavating key transcription factors, which can regulate tumor invasion and metastasis, are crucial to the development of therapeutic strategies for cancers. PU.1 is a master hematopoietic transcription factor and a vital regulator in life. Here, we report that, compared to adjacent non-cancerous tissues, expression of PU.1 mRNA in metastatic hepatocellular carcinoma (HCC), but not primary HCC, was significantly down-regulated. In addition, levels of PU.1 mRNA in metastatic hepatoma cell lines MHCC97L and MHCC97H were much lower than in non-metastatic Hep3B cells. Transwell invasion assays after PU.1 siRNA transfection showed that the invasion of hepatoma cell lines was increased markedly by PU.1 knockdown. Oppositely, overexpression of PU.1 suppressed the invasion of these cells. However, knockdown and overexpression of PU.1 did not influence proliferation. Finally, we tried to explore the potential mechanism of PU.1 suppressing hepatoma cell invasion. ChIP-qPCR analysis showed that PU.1 exhibited a high binding capacity with miR-615-5p promoter sequence. Overexpression of PU.1 caused a dramatic increase of pri-, pre- and mature miR-615-5p, as well as a marked decrease of miR-615-5p target gene IGF2. These data indicate that PU.1 inhibits invasion of human HCC through promoting miR-615-5p and suppressing IGF2. These findings improve our understanding of PU.1 regulatory roles and provided a potential target for metastatic HCC diagnosis and therapy.
侵袭和转移是肿瘤复发、难以治愈及生存率低的主要原因。挖掘能够调控肿瘤侵袭和转移的关键转录因子对于癌症治疗策略的发展至关重要。PU.1是一种主要的造血转录因子，也是生命活动中的重要调节因子。在此，我们报告，与相邻的非癌组织相比，转移性肝细胞癌（HCC）而非原发性HCC中PU.1 mRNA的表达显著下调。此外，转移性肝癌细胞系MHCC97L和MHCC97H中PU.1 mRNA的水平远低于非转移性Hep3B细胞。PU.1 siRNA转染后的Transwell侵袭试验表明，敲低PU.1可显著增加肝癌细胞系的侵袭能力。相反，PU.1的过表达抑制了这些细胞的侵袭。然而，敲低和过表达PU.1均不影响细胞增殖。最后，我们试图探究PU.1抑制肝癌细胞侵袭的潜在机制。ChIP-qPCR分析表明，PU.1与miR-615-5p启动子序列具有高结合能力。PU.1的过表达导致pri-、pre-和成熟miR-615-5p显著增加，以及miR-615-5p靶基因IGF2显著减少。这些数据表明，PU.1通过促进miR-615-5p和抑制IGF2来抑制人肝癌的侵袭。这些发现增进了我们对PU.1调控作用的理解，并为转移性HCC的诊断和治疗提供了一个潜在靶点。
