BACKGROUND: The role of ZEB1, a master epithelial-to-mesenchymal transition gene, in malignant pleural mesothelioma (MPM) is unclear. METHODS: The expression of ZEB1, E-cadherin, vimentin, and epithelial cell adhesion molecule (EpCAM) in 18 MPM cell lines and a normal pleural mesothelial cell line MeT-5A was determined by quantitative real-time polymerase chain reaction and Western blot testing. RNA interference-mediated transient and/or stable knockdown of ZEB1 and EpCAM was performed. Microarray expression analysis was performed with a TORAY-3D gene chip. Growth was evaluated by colorimetric proliferation and colony formation assays. Luciferase reporter assay was performed to access the effects of ZEB1 knockdown on EpCAM promoter activity. RESULTS: Most MPM cell lines exhibited mesenchymal phenotype and expressed ZEB1. Transient ZEB1 knockdown suppressed growth in all four cell lines studied (ACC-MESO-1, H2052, Y-MESO-8A, Y-MESO-29) while stable ZEB1 knockdown suppressed growth only in Y-MESO-29. Genome-wide gene expression analysis revealed that EpCAM was the most prominently up-regulated gene by both transient and stable ZEB1 knockdown in ACC-MESO-1, with more marked up-regulation in stable knockdown. We hypothesized that EpCAM up-regulation counteracts the stable ZEB1 knockdown-induced growth inhibition in ACC-MESO-1. Transient EpCAM knockdown suppressed growth dramatically in ACC-MESO-1 cells expressing shZEB1 but only modestly in those expressing shGFP, supporting our hypothesis. Luciferase reporter assay showed that ZEB1 knockdown resulted in increased EpCAM promoter activity. EpCAM was also up-regulated in Y-MESO-29 expressing shZEB1, but this EpCAM up-regulation did not counteract ZEB1knockdown-induced growth suppression, suggesting that the counteracting effects of EpCAM may be cellular context dependent. CONCLUSIONS: RNA interference-mediated ZEB1 knockdown may be a promising therapeutic strategy for MPM, but one has to consider the possibility of diminished growth inhibitory effects of long-term ZEB1 knockdown, possibly as a result of EpCAM up-regulation and/or other gene expression changes resulting from ZEB1 knockdown.
BACKGROUND: The role of ZEB1, a master epithelial-to-mesenchymal transition gene, in malignant pleural mesothelioma (MPM) is unclear. METHODS: The expression of ZEB1, E-cadherin, vimentin, and epithelial cell adhesion molecule (EpCAM) in 18 MPM cell lines and a normal pleural mesothelial cell line MeT-5A was determined by quantitative real-time polymerase chain reaction and Western blot testing. RNA interference-mediated transient and/or stable knockdown of ZEB1 and EpCAM was performed. Microarray expression analysis was performed with a TORAY-3D gene chip. Growth was evaluated by colorimetric proliferation and colony formation assays. Luciferase reporter assay was performed to access the effects of ZEB1 knockdown on EpCAM promoter activity. RESULTS: Most MPM cell lines exhibited mesenchymal phenotype and expressed ZEB1. Transient ZEB1 knockdown suppressed growth in all four cell lines studied (ACC-MESO-1, H2052, Y-MESO-8A, Y-MESO-29) while stable ZEB1 knockdown suppressed growth only in Y-MESO-29. Genome-wide gene expression analysis revealed that EpCAM was the most prominently up-regulated gene by both transient and stable ZEB1 knockdown in ACC-MESO-1, with more marked up-regulation in stable knockdown. We hypothesized that EpCAM up-regulation counteracts the stable ZEB1 knockdown-induced growth inhibition in ACC-MESO-1. Transient EpCAM knockdown suppressed growth dramatically in ACC-MESO-1 cells expressing shZEB1 but only modestly in those expressing shGFP, supporting our hypothesis. Luciferase reporter assay showed that ZEB1 knockdown resulted in increased EpCAM promoter activity. EpCAM was also up-regulated in Y-MESO-29 expressing shZEB1, but this EpCAM up-regulation did not counteract ZEB1knockdown-induced growth suppression, suggesting that the counteracting effects of EpCAM may be cellular context dependent. CONCLUSIONS: RNA interference-mediated ZEB1 knockdown may be a promising therapeutic strategy for MPM, but one has to consider the possibility of diminished growth inhibitory effects of long-term ZEB1 knockdown, possibly as a result of EpCAM up-regulation and/or other gene expression changes resulting from ZEB1 knockdown.
Authors: Robert M Gemmill; Joëlle Roche; Vincent A Potiron; Patrick Nasarre; Michael Mitas; Chris D Coldren; Barbara A Helfrich; Elizabeth Garrett-Mayer; Paul A Bunn; Harry A Drabkin Journal: Cancer Lett Date: 2010-10-25 Impact factor: 8.679
Authors: Tetsunari Hase; Mitsuo Sato; Kenya Yoshida; Luc Girard; Yoshihiro Takeyama; Mihoko Horio; Momen Elshazley; Tomoyo Oguri; Yoshitaka Sekido; David S Shames; Adi F Gazdar; John D Minna; Masashi Kondo; Yoshinori Hasegawa Journal: Cancer Sci Date: 2011-06-02 Impact factor: 6.716
Authors: Noriaki Sunaga; David S Shames; Luc Girard; Michael Peyton; Jill E Larsen; Hisao Imai; Junichi Soh; Mitsuo Sato; Noriko Yanagitani; Kyoichi Kaira; Yang Xie; Adi F Gazdar; Masatomo Mori; John D Minna Journal: Mol Cancer Ther Date: 2011-02 Impact factor: 6.261
Authors: Noriaki Sunaga; Kuniharu Miyajima; Makoto Suzuki; Mitsuo Sato; Michael A White; Ruben D Ramirez; Jerry W Shay; Adi F Gazdar; John D Minna Journal: Cancer Res Date: 2004-06-15 Impact factor: 12.701