IRX1 hypomethylation promotes osteosarcoma metastasis via induction of CXCL14/NF-κB signaling
Jinchang Lu, Guohui Song, Qinglian Tang, Changye Zou, Feng Han, Zhiqiang Zhao, Bicheng Yong, Junqiang Yin, Huaiyuan Xu, Xianbiao Xie, Tiebang Kang, YingLee Lam, Huiling Yang, Jingnan Shen, Jin Wang
Jinchang Lu, Guohui Song, Qinglian Tang, Changye Zou, Feng Han, Zhiqiang Zhao, Bicheng Yong, Junqiang Yin, Huaiyuan Xu, Xianbiao Xie, Tiebang Kang, YingLee Lam, Huiling Yang, Jingnan Shen, Jin Wang
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Research Article Oncology

IRX1 hypomethylation promotes osteosarcoma metastasis via induction of CXCL14/NF-κB signaling

Abstract

Osteosarcoma is a common malignant bone tumor with a propensity to metastasize to the lungs. Epigenetic abnormalities have been demonstrated to underlie osteosarcoma development; however, the epigenetic mechanisms that are involved in metastasis are not yet clear. Here, we analyzed 2 syngeneic primary human osteosarcoma cell lines that exhibit disparate metastatic potential for differences in epigenetic modifications and expression. Using methylated DNA immunoprecipitation (MeDIP) and microarray expression analysis to screen for metastasis-associated genes, we identified Iroquois homeobox 1 (IRX1). In both human osteosarcoma cell lines and clinical osteosarcoma tissues, IRX1 overexpression was strongly associated with hypomethylation of its own promoter. Furthermore, experimental modulation of IRX1 in osteosarcoma cell lines profoundly altered metastatic activity, including migration, invasion, and resistance to anoikis in vitro, and influenced lung metastasis in murine models. These prometastatic effects of IRX1 were mediated by upregulation of CXCL14/NF-κB signaling. In serum from osteosarcoma patients, the presence of IRX1 hypomethylation in circulating tumor DNA reduced lung metastasis–free survival. Together, these results identify IRX1 as a prometastatic gene, implicate IRX1 hypomethylation as a potential molecular marker for lung metastasis, and suggest that epigenetic reversion of IRX1 activation may be beneficial for controlling osteosarcoma metastasis.

Authors

Jinchang Lu, Guohui Song, Qinglian Tang, Changye Zou, Feng Han, Zhiqiang Zhao, Bicheng Yong, Junqiang Yin, Huaiyuan Xu, Xianbiao Xie, Tiebang Kang, YingLee Lam, Huiling Yang, Jingnan Shen, Jin Wang

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Figure 12

Prognostic relevance of IRX1 promoter methylation in serum DNA from osteosarcoma patients.

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Prognostic relevance of IRX1 promoter methylation in serum DNA from oste...
(A) Methylation-specific PCR analysis of the IRX1 promoter region in the serum DNA of osteosarcoma patients (n = 67). M, hypermethylated IRX1; U, unmethylated IRX1. Representative images of serum samples, including negative and positive controls. (B) Patients with hypomethylation of the IRX1 promoter in their serum DNA had a lower rate of lung metastasis–free survival (log-rank test, P = 0.014). (C) Potential mechanism by which IRX1 promotes osteosarcoma metastasis. IRX1 is activated by hypomethylation of its own promoter as osteosarcoma progresses. Overexpression of IRX1 leads to increased autocrine activity of CXCL14 and promotes metastatic behavior of osteosarcoma cells via NF-κB activation.