Hu Xueting, Lin Jiatong, Jiang Ming, He Xiaotian, Wang Kefeng, Wang Wenjian, Hu Chuwen, Shen Zhiwen, He Zhanghai, Lin Huayue, Wu Duoguang, Wang Minghui
Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.
Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.
J Cancer. 2020 Jan 1;11(1):229-240. doi: 10.7150/jca.35537. eCollection 2020.
In microenvironment of malignant tumors, Hypoxia-Inducible Factors (HIF), most importantly HIF-1α, play an important role in regulation of adaptive biological response to hypoxia, promoting angiogenesis and metastasis. However, the underlying mechanism that HIF-1α regulates metastasis needs to be further clarified. The expressions of HIF-1α and SP1 were detected in 182 samples of esophageal squamous cell carcinoma (ESCC) and adjacent normal tissues by immunohistochemistry (IHC), and the correlation between the expression levels of HIF-1α and SP1 was analyzed. The expression of HIF-1α in ESCC cell lines TE1 and KYSE30 was then detected using qRT-PCR and western blot. The potential binding sites of HIF-1α on the promoter were analyzed using UCSC and JASPAR databases, verified by chromosomal immunoprecipitation (ChIP) assay and qRT-PCR. The effects of HIF-1α and SP1 on ESCC cell migration and invasion were then tested with Transwell and Matrigel experiments. The expression of HIF-1α in cancer tissues is higher than adjacent normal tissues, and is correlated with metastasis, recurrence and poor prognosis. Upon silencing HIF-1α by siRNA, the invasion and migration ability of ESCC cells were significantly inhibited, which could be restored by the overexpression of SP1. Hypoxic conditions significantly increased the expression of HIF-1α and SP1 at both protein and mRNA levels in ESCC cells. HIF-1α enhanced transcription through binding to the promoter region. The expression of protein and mRNA levels of SP1 was decreased by silencing HIF-1α in cells. In contrast, overexpression of HIF-1α significantly increased the mRNA and protein levels of SP1. The expression of SP1 in ESCC was positively correlated with the protein expression of HIF-1α and poor prognosis. The results of our study indicate that HIF-1α promotes metastasis of ESCC by targeting SP1 in a hypoxic microenvironment. Further study on this mechanism may elucidate the possibility of HIF-1α and SP1 as new targets for the treatment of ESCC.
在恶性肿瘤的微环境中，缺氧诱导因子（HIF），尤其是HIF-1α，在调节对缺氧的适应性生物学反应、促进血管生成和转移方面发挥着重要作用。然而，HIF-1α调节转移的潜在机制仍需进一步阐明。通过免疫组织化学（IHC）检测了182例食管鳞状细胞癌（ESCC）样本及癌旁正常组织中HIF-1α和SP1的表达，并分析了HIF-1α与SP1表达水平之间的相关性。随后，使用qRT-PCR和蛋白质印迹法检测了ESCC细胞系TE1和KYSE30中HIF-1α的表达。利用UCSC和JASPAR数据库分析了HIF-1α在启动子上的潜在结合位点，并通过染色体免疫沉淀（ChIP）试验和qRT-PCR进行验证。然后，通过Transwell和基质胶实验检测了HIF-1α和SP1对ESCC细胞迁移和侵袭的影响。癌组织中HIF-1α的表达高于癌旁正常组织，且与转移、复发及不良预后相关。通过siRNA沉默HIF-1α后，ESCC细胞的侵袭和迁移能力显著受到抑制，而SP1的过表达可使其恢复。缺氧条件显著增加了ESCC细胞中HIF-1α和SP1在蛋白质和mRNA水平上的表达。HIF-1α通过与启动子区域结合增强转录。在细胞中沉默HIF-1α可使SP1的蛋白质和mRNA水平表达降低。相反，HIF-1α的过表达显著增加了SP1的mRNA和蛋白质水平。ESCC中SP1的表达与HIF-1α的蛋白质表达及不良预后呈正相关。我们的研究结果表明，在缺氧微环境中，HIF-1α通过靶向SP1促进ESCC的转移。对这一机制的进一步研究可能阐明HIF-1α和SP1作为ESCC治疗新靶点的可能性。
