Inaguma Shingo, Riku Miho, Ito Hideaki, Tsunoda Takumi, Ikeda Hiroshi, Kasai Kenji
Department of Pathology, Aichi Medical University School of Medicine, Nagakute, Aichi 480-1195, Japan.
Oncotarget. 2015 Oct 20;6(32):33648-57. doi: 10.18632/oncotarget.5203.
The up-regulation of chemokine receptors CXCR4 and CXCR7 impacts on the distant metastasis and prognosis of breast cancer, though knowledge about the regulatory mechanism of their expressions is limited. Meanwhile, the GLI transcription factors of Hedgehog signaling have been reported to play a pivotal role in the development and progression of many types of human cancer. In breast cancer, the increased expression of GLI1 correlated with metastasis and unfavorable overall prognosis, though its molecular mechanism is also not fully understood. Based on our findings that GLI1 enhanced the lung metastasis of breast cancer cells in a mouse model system, we comprehensively screened for genes up-regulated by GLI1 in breast cancer cells, and as such identified CXCR4, CXCR7/ACKR3, and actin-binding protein LCP1/L-PLASTIN, all of which have been reported to be involved in CXCL12-stimulating signaling. In breast cancer cells, we found that GLI1 and GLI2 up-regulated these expressions, while treatment with GLI-specific inhibitor GANT61 reduced the expressions. As for CXCR4, we confirmed it as a direct target of GLI1 through the reporter assay and the chromatin immunoprecipitation assay. We also found that GLI1 enhanced CXCL12-induced ERK phosphorylation and cell migration, both of which were blocked by either CXCR4-specific inhibitor or knockdown of CXCR7 or LCP1. These evidences suggest an indispensable role of GLI1 in the migration and metastasis of breast cancer cells through CXCL12/CXCR4 signaling enhancement.
趋化因子受体CXCR4和CXCR7的上调影响乳腺癌的远处转移和预后，尽管对其表达调控机制的了解有限。同时，据报道，Hedgehog信号通路的GLI转录因子在多种人类癌症的发生和发展中起关键作用。在乳腺癌中，GLI1表达增加与转移及不良的总体预后相关，但其分子机制也尚未完全阐明。基于我们在小鼠模型系统中发现GLI1增强乳腺癌细胞肺转移的结果，我们全面筛选了乳腺癌细胞中被GLI1上调的基因，从而鉴定出CXCR4、CXCR7/ACKR3和肌动蛋白结合蛋白LCP1/L - PLASTIN，所有这些都已报道参与CXCL12刺激信号传导。在乳腺癌细胞中，我们发现GLI1和GLI2上调这些表达，而用GLI特异性抑制剂GANT61处理可降低这些表达。对于CXCR4，我们通过报告基因检测和染色质免疫沉淀检测证实它是GLI1的直接靶点。我们还发现GLI1增强CXCL12诱导的ERK磷酸化和细胞迁移，这两者都被CXCR4特异性抑制剂或CXCR7或LCP1的敲低所阻断。这些证据表明GLI1通过增强CXCL12/CXCR4信号传导在乳腺癌细胞迁移和转移中起不可或缺的作用。
