Abstract
Abstract Breast cancer prognosis is tightly correlated with the degree of spread beyond the primary tumor. A prerequisite for breast cancer cell dissemination is activation of a process called “epithelial - mesenchymal transition” (EMT). During EMT, epithelial cells lose epithelial characteristics, such as E-cadherin expression and gain mesenchymal properties, such as vimentin expression. The reversal process to EMT is mesenchymal-epithelial transition (MET), which occurs during colonization of the disseminated cancer cells to distant sites. Thus, EMT should be considered as a transient and reversible process in cancer progression. Despite the clinical importance, EMT and MET have been largely studied from a focused signalling standpoint, which may provide a biased view of the biological processes involved. In this study, RNAi technology followed up by lysate microarray analysis (LMA) using E-cadherin and vimentin as endpoint markers was performed to identify novel EMT and MET regulatory genes in cultured breast cancer cells. The screening conditions were optimized for the estrogen receptor (ER) positive E-cadherin expressing luminal MCF-7 breast cancer cells and for ER negative vimentin expressing mesenchymal bone metastatic MDA-MB 231 cells. The results from the replicate screens with >1012 siRNAs targeting 599 genes (1-3 siRNAs / gene) amplified and /or over-expressed in breast cancer cells were found to correlate (r > 0.9), and the validated siRNAs targeting E-cadherin and vimentin were among the top repressing hits for the corresponding endpoints, indicating reliability of the protocol. Interestingly, several novel putative E-cadherin (E-cadherin reducing siRNAs, genes inducing loss of metastatic potential) and vimentin (vimentin reducing siRNAs, metastasis-promoting candidate genes) regulators were identified and validated using secondary assays, indicating that our knowledge on EMT and MET is still far from comprehensive. Functional characterization of the identified candidate regulators in cultured breast cancer cells is on-going. Since modulation of the differentiation state of breast cancer cells is a promising therapeutic strategy, better understanding of EMT and MET may provide novel therapeutic opportunities to block breast cancer cell dissemination. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 334. doi:1538-7445.AM2012-334
Published Version
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