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Oncogene. 2017 Mar;36(10):1404-1416. doi: 10.1038/onc.2016.307. Epub 2016 Sep 5.

DLX1 acts as a crucial target of FOXM1 to promote ovarian cancer aggressiveness by enhancing TGF-β/SMAD4 signaling.

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Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong SAR, China.
School of Biomedical Sciences, The University of Hong Kong, Hong Kong SAR, China.
Centre for Genomic Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
Department of Medical Laboratory Science, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Hudson Institute of Medical Research, Clayton, Victoria, Australia.
Macau Institute for Applied Research in Medicine and Health, State Key laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Macau SAR, China.
Departments of Obstetrics and Gynaecology, and Cellular and Molecular Medicine, Interdisciplinary School of Health Sciences, University of Ottawa, Ottawa, ON, Canada.
Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.


Recent evidence from a comprehensive genome analysis and functional studies have revealed that FOXM1 is a crucial metastatic regulator that drives cancer progression. However, the regulatory mechanism by which FOXM1 exerts its metastatic functions in cancer cells remains obscure. Here, we report that DLX1 acts as a FOXM1 downstream target, exerting pro-metastatic function in ovarian cancers. Both FOXM1 isoforms (FOXM1B or FOXM1C) could transcriptionally upregulate DLX1 through two conserved binding sites, located at +61 to +69bp downstream (TFBS1) and -675 to -667bp upstream (TFBS2) of the DLX1 promoter, respectively. This regulation was further accentuated by the significant correlation between the nuclear expression of FOXM1 and DLX1 in high-grade serous ovarian cancers. Functionally, the ectopic expression of DLX1 promoted ovarian cancer cell growth, cell migration/invasion and intraperitoneal dissemination of ovarian cancer in mice, whereas small interfering RNA-mediated DLX1 knockdown in FOXM1-overexpressing ovarian cancer cells abrogated these oncogenic capacities. In contrast, depletion of FOXM1 by shRNAi only partially attenuated tumor growth and exerted almost no effect on cell migration/invasion and the intraperitoneal dissemination of DLX1-overexpressing ovarian cancer cells. Furthermore, the mechanistic studies showed that DLX1 positively modulates transforming growth factor-β (TGF-β) signaling by upregulating PAI-1 and JUNB through direct interaction with SMAD4 in the nucleus upon TGF-β1 induction. Taken together, these data strongly suggest that DLX1 has a pivotal role in FOXM1 signaling to promote cancer aggressiveness through intensifying TGF-β/SMAD4 signaling in high-grade serous ovarian cancer cells.

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