Abstract POSTER-TECH-1112: Quantitate epithelial-mesenchymal transition in ovarian cancer
Authors: Tan Tuan Zea , Huang Ruby Yun-Ju , Miow Qing Hao , Ye Jieru , Wong Meng Kang , Lau Jieying Amelia , Mori Seiichi , Thiery Jean Paul 
Published: August 2015

Purpose: Metastases account for more than 90% of cancer deaths and hence, inhibiting metastasis is an attractive therapeutic option. Accumulating evidences show that invasion and metastasis of ovarian carcinoma could be driven by Epithelial-Mesenchymal Transition (EMT), a developmental program being employed during carcinoma progression. As EMT is a reversible process, inhibiting or reversing EMT thus emerges as a potential anti-metastasis strategy. EMT is a spectrum consisting of the binary epithelial and mesenchymal states as well as transitional intermediate states. Therefore, reversing EMT from the mesenchymal state would result in the sliding along an EMT Spectrum. Currently, there is no quantitative tool available to assess the EMT spectrum. In this study, we describe a bioinformatics method for quantitating EMT.

Experimental procedure: By using immunofluorescence staining of E-cadherin and N-cadherin, we defined the most epithelial and most mesenchymal cells in a panel of ovarian carcinoma cell lines. We derived an EMT signature from Affymetrix gene expression microarrays of these cell lines. Subsequently, with a Kolmogorov-Smirnov-based method, we computed EMT score that assesses the similarity of an ovarian carcinoma cell transcriptome with the derived EMT signature. This method scores ovarian carcinoma cell lines in the range of [-1.0,+1.0] which corresponded to the extreme epithelial and mesenchymal states respectively along the EMT spectrum. We thus applied the EMT scoring to estimate EMT status in ovarian carcinoma tissues.

Results: The EMT signature derived included known EMT inducers and markers such as ZEB1, ZEB2, SNAI2 and VIM. Expressions of selected markers such as ZEB1, VIM and FN1 were confirmed by immunofluorescence staining. Ovarian carcinoma cell lines displaying a mesenchymal morphology were accurately reflected as having high EMT scores. Cell lines with high EMT scores were anoikis resistant. In addition, ovarian carcinoma tissues displaying high EMT scores had poorer overall survival than those of low EMT scores. Correlation analysis of EMT scores and pathways revealed that ovarian carcinoma with high EMT scores are associated with increased TGFβ, WNT, NOTCH, and SRC signaling pathways. This suggested that inhibitors targeting these pathways could potentially reverse EMT. We thus treated mesenchymal ovarian carcinoma cell lines SKOV3, HEY, DOV13 with a SRC inhibitor, AZD0530. We observed a partial reversal of EMT evident by decreased EMT scores (-0.11 to -0.17) in these cells.

Conclusions: EMT scoring could reflect both the EMT status of a sample and the transitional changes along the EMT spectrum upon intervening with inhibitors. Thus, EMT scoring presents a promising tool to assess the effectiveness of anti-EMT or EMT reversing compounds.

Citation Format: Tuan Zea Tan, Ruby Yun-Ju Huang, Qing Hao Miow, Jieru Ye, Meng Kang Wong, Jieying Amelia Lau, Seiichi Mori, Jean Paul Thiery. Quantitate epithelial-mesenchymal transition in ovarian cancer [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-TECH-1112.