Abstract 1034: ZEB2 promotes cell motility and metastasis in ER+ breast cancer cells
Authors: Burks Hope E. , Rhodes Lyndsay , Martin Elizabeth , Phamduy Theresa , Elliot Steven , Hoang Van , Segar Henry , Buechlein Aaron , Rusch Douglas , Miller Dave , Baddoo Melody , Flemington Erik , Nephew Kenneth , Chrisey Douglas , Collins-Burow Bridgette , Burow Matthew 
Published: May 2015

While the precise molecular mechanisms underlying metastasis remain unclear, epithelial-to-mesenchymal transition (EMT), the loss of an epithelial cell phenotype and acquisition of a mesenchymal cell phenotype, has been implicated in cancer cell invasion and dissemination. The ZEB family of transcription factors, which includes ZEB1 and ZEB2, has been demonstrated to mediate this transition by downregulating the expression of genes associated with an epithelial phenotype. We sought to investigate the effects of direct ZEB family overexpression on EMT in estrogen receptor-positive (ER+) breast cancer cell systems. We overexpressed ZEB1 or ZEB2 in the epithelial, ER+, luminal A breast cancer cell lines MCF-7 and ZR75. Overexpression of individual ZEB1 and ZEB2 levels were confirmed and localization of the ZEB factors to the nucleus was confirmed by confocal microscopy in both cell lines. ZEB2 overexpressing cells, but not ZEB1 overexpressing cells, showed increased migration and invasion in vitro compared to the vector control in both MCF-7 and ZR75 cell lines, suggesting differential function of the two ZEB family members. Additionally, MCF-7-ZEB2 xenografts exhibited increased lung metastasis compared to MCF-7-vector cells. To elucidate the effects of ZEB on our ER+ cell line we performed next generation deep sequencing on MCF-7 -vector, ZEB1 and ZEB2 overexpressing cells. Analysis of total gene regulation using the NCI Pathway Interaction Database demonstrated an increase in genes associated with RhoA activity, an important mediator of cell motility, in ZEB2 overexpressing cells. However, the ZEB overexpressing cells show no change in morphology and canonical EMT markers remained unchanged between cell lines, suggesting a potential post-translational modification affecting ZEB1 and ZEB2 function. Together these results indicate that ZEB factors drive motility in breast cancer cells but are incapable of promoting a complete EMT in ER+ cells, warranting further investigation into the mechanisms involved in ZEB action. Elucidating the pathways involved in ZEB family function is an important step in understanding the mechanisms underlying metastasis and has the potential to yield new therapeutic targets.

Citation Format: Hope E. Burks, Lyndsay Rhodes, Elizabeth Martin, Theresa Phamduy, Steven Elliot, Van Hoang, Henry Segar, Aaron Buechlein, Douglas Rusch, Dave Miller, Melody Baddoo, Erik Flemington, Kenneth Nephew, Douglas Chrisey, Bridgette Collins-Burow, Matthew Burow. ZEB2 promotes cell motility and metastasis in ER+ breast cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1034. doi:10.1158/1538-7445.AM2014-1034