The T Box Transcription Factor TBX2 Promotes Epithelial-Mesenchymal Transition and Invasion of Normal and Malignant Breast Epithelial Cells

PLOS ONE, Dec 2019

The T box transcription factor TBX2, a master regulator of organogenesis, is aberrantly amplified in aggressive human epithelial cancers. While it has been shown that overexpression of TBX2 can bypass senescence, a failsafe mechanism against cancer, its potential role in tumor invasion has remained obscure. Here we demonstrate that TBX2 is a strong cell-autonomous inducer of the epithelial-mesenchymal transition (EMT), a latent morphogenetic program that is key to tumor progression from noninvasive to invasive malignant states. Ectopic expression of TBX2 in normal HC11 and MCF10A mammary epithelial cells was sufficient to induce morphological, molecular, and behavioral changes characteristic of EMT. These changes included loss of epithelial adhesion and polarity gene (E-cadherin, ß-catenin, ZO1) expression, and abnormal gain of mesenchymal markers (N-cadherin, Vimentin), as well as increased cell motility and invasion. Conversely, abrogation of endogenous TBX2 overexpression in the malignant human breast carcinoma cell lines MDA-MB-435 and MDA-MB-157 led to a restitution of epithelial characteristics with reciprocal loss of mesenchymal markers. Importantly, TBX2 inhibition abolished tumor cell invasion and the capacity to form lung metastases in a Xenograft mouse model. Meta-analysis of gene expression in over one thousand primary human breast tumors further showed that high TBX2 expression was significantly associated with reduced metastasis-free survival in patients, and with tumor subtypes enriched in EMT gene signatures, consistent with a role of TBX2 in oncogenic EMT. ChIP analysis and cell-based reporter assays further revealed that TBX2 directly represses transcription of E-cadherin, a tumor suppressor gene, whose loss is crucial for malignant tumor progression. Collectively, our results uncover an unanticipated link between TBX2 deregulation in cancer and the acquisition of EMT and invasive features of epithelial tumor cells.

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The T Box Transcription Factor TBX2 Promotes Epithelial-Mesenchymal Transition and Invasion of Normal and Malignant Breast Epithelial Cells

et al. (2012) The T Box Transcription Factor TBX2 Promotes Epithelial-Mesenchymal Transition and Invasion of Normal and Malignant Breast Epithelial Cells. PLoS ONE 7(7): e41355. doi:10.1371/journal.pone.0041355 The T Box Transcription Factor TBX2 Promotes Epithelial- Mesenchymal Transition and Invasion of Normal and Malignant Breast Epithelial Cells Bin Wang 0 Linsey E. Lindley 0 Virneliz Fernandez-Vega 0 Megan E. Rieger 0 Andrew H. Sims 0 Karoline J. Briegel 0 Patrick Derksen, University Medical Center Utrecht, Netherlands 0 1 Department of Biochemistry and Molecular Biology, Braman Family Breast Cancer Institute, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, United States of America, 2 Applied Bioinformatics of Cancer Research Group, Breakthrough Research Unit, Edinburgh Cancer Research Centre , Edinburgh , United Kingdom The T box transcription factor TBX2, a master regulator of organogenesis, is aberrantly amplified in aggressive human epithelial cancers. While it has been shown that overexpression of TBX2 can bypass senescence, a failsafe mechanism against cancer, its potential role in tumor invasion has remained obscure. Here we demonstrate that TBX2 is a strong cellautonomous inducer of the epithelial-mesenchymal transition (EMT), a latent morphogenetic program that is key to tumor progression from noninvasive to invasive malignant states. Ectopic expression of TBX2 in normal HC11 and MCF10A mammary epithelial cells was sufficient to induce morphological, molecular, and behavioral changes characteristic of EMT. These changes included loss of epithelial adhesion and polarity gene (E-cadherin, -catenin, ZO1) expression, and abnormal gain of mesenchymal markers (N-cadherin, Vimentin), as well as increased cell motility and invasion. Conversely, abrogation of endogenous TBX2 overexpression in the malignant human breast carcinoma cell lines MDA-MB-435 and MDA-MB-157 led to a restitution of epithelial characteristics with reciprocal loss of mesenchymal markers. Importantly, TBX2 inhibition abolished tumor cell invasion and the capacity to form lung metastases in a Xenograft mouse model. Meta-analysis of gene expression in over one thousand primary human breast tumors further showed that high TBX2 expression was significantly associated with reduced metastasis-free survival in patients, and with tumor subtypes enriched in EMT gene signatures, consistent with a role of TBX2 in oncogenic EMT. ChIP analysis and cell-based reporter assays further revealed that TBX2 directly represses transcription of E-cadherin, a tumor suppressor gene, whose loss is crucial for malignant tumor progression. Collectively, our results uncover an unanticipated link between TBX2 deregulation in cancer and the acquisition of EMT and invasive features of epithelial tumor cells. - Funding: This work was supported by grants from the Flight Attendant Medical Research Institute/FAMRI (CIA_072080), the Bankhead Coley Cancer Research Program - Florida State Department of Health (08-BB-03), and the Braman Family Breast Cancer Institute, UM Sylvester Cancer Center to KJB; a DOD predoctoral fellowship (W81XWH-08-1-0253) to MER; and from Breakthrough Breast Cancer to AHS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. The developmentally important transcription factor T box 2 (TBX2) is abnormally amplified with high prevalence in aggressive human epidermal cancers. TBX2 maps to chromosome 17q23.2, a region that is aberrantly amplified in over 40% of breast cancers [1], 40% of melanomas [2], 40% of ovarian [3], 56% of endometrial [4], and 60% of pancreatic cancers [5], correlating with poor clinical outcome. In breast cancer, TBX2 gene amplification is associated with invasive hereditary BRCA1- and BRCA2-related cancers, highgrade-sporadic breast tumors, and distant metastases [6,7,8]. TBX2 is also amplified and overexpressed in several human breast carcinoma cell lines [6,9,10]. However, the potential role of TBX2 in malignant tumor progression has remained unclear. TBX2 is a member of the evolutionary conserved T box transcription factor family [11,12], a class of master regulators of embryogenesis that share a T box DNA binding domain and comprise many disease genes [13]. TBX2 acts mainly as a transcriptional repressor [14,15,16] that has been shown to recruit Histone Deacetylase 1 (HDAC1) to target gene promoters [2]. During embryogenesis, TBX2 is fundamental to the regulation of cell fate decisions, cell migration, and morphogenesis in a variety of organs including the limbs, heart, kidney, nervous system, and eyes [17,18,19,20,21,22] albeit through mechanisms that remain poorly understood. TBX2 is also prominently expressed in the embryonic mammary glands with a restricted expression in breast mesenchymal cells, whic (...truncated)


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Bin Wang, Linsey E. Lindley, Virneliz Fernandez-Vega, Megan E. Rieger, Andrew H. Sims, Karoline J. Briegel. The T Box Transcription Factor TBX2 Promotes Epithelial-Mesenchymal Transition and Invasion of Normal and Malignant Breast Epithelial Cells, PLOS ONE, 2012, 7, DOI: 10.1371/journal.pone.0041355