Misregulated E-Cadherin Expression Associated with an Aggressive Brain Tumor Phenotype Laura J. Lewis-Tuffin1., Fausto Rodriguez2., Caterina Giannini2, Bernd Scheithauer2, Brian M. Necela1, Jann N. Sarkaria3, Panos Z. Anastasiadis1* 1 Department of Cancer Cell Biology, Mayo Clinic, Jacksonville, Florida, United States of America, 2 Department of Pathology, Mayo Clinic, Rochester, Minnesota, United States of America, 3 Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, United States of America Abstract Background: Cadherins are essential components of the adherens junction complexes that mediate cell-cell adhesion and regulate cell motility. During tissue morphogenesis, changes in cadherin expression (known as cadherin switching) are a common mechanism for altering cell fate. Cadherin switching is also common during epithelial tumor progression, where it is thought to promote tumor invasion and metastasis. E-cadherin is the predominant cadherin expressed in epithelial tissues, but its expression is very limited in normal brain. Methodology/Principal Findings: We identified E-cadherin expression in a retrospective series of glioblastomas exhibiting epithelial or pseudoepithelial differentiation. Unlike in epithelial tissues, E-cadherin expression in gliomas correlated with an unfavorable clinical outcome. Western blotting of two panels of human GBM cell lines propagated either as xenografts in nude mice or grown under conventional cell culture conditions confirmed that E-cadherin expression is rare. However, a small number of xenograft lines did express E-cadherin, its expression correlating with increased invasiveness when the cells were implanted orthotopically in mouse brain. In the conventionally cultured SF767 glioma cell line, E-cadherin expression was localized throughout the plasma membrane rather than being restricted to areas of cell-cell contact. ShRNA knockdown of E-cadherin in these cells resulted in decreased proliferation and migration in vitro. Conclusions/Significance: Our data shows an unexpected correlation between the abnormal expression of E-cadherin in a subset of GBM tumor cells and the growth and migration of this aggressive brain tumor subtype. Citation: Lewis-Tuffin LJ, Rodriguez F, Giannini C, Scheithauer B, Necela BM, et al. (2010) Misregulated E-Cadherin Expression Associated with an Aggressive Brain Tumor Phenotype. PLoS ONE 5(10): e13665. doi:10.1371/journal.pone.0013665 Editor: Kurt Anderson, The Beatson Institute for Cancer Research, United Kingdom Received June 9, 2010; Accepted October 7, 2010; Published October 27, 2010 Copyright: 2010 Lewis-Tuffin et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The work was supported by National Institutes of Health R01 CA100467, R01 NS069753, and R21 NS070117 (PZ Anastasiadis), P50 CA108961 Mayo Clinic SPORE in Brain Cancer (C Giannini and JN Sarkaria), and T32NS07494 ‘‘Research Training in Neuro-Oncology’’ (PI/PD: BP O’Neill). 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. * E-mail: panos@mayo.edu . These authors contributed equally to this work. Introduction Glioblastoma multiforme or glioblastoma (GBM) continues to be the most frequently diagnosed and lethal of primary brain tumors. This WHO grade IV brain tumor is remarkable in both its morphological diversity and biologic aggressiveness, the latter being partly due to its diffusely infiltrative nature [1,2]. Extensive, diffuse parenchymal invasion is an important reason for failure of the most accepted treatment modalities, including surgical resection combined with radiation and chemotherapy. These methods effectively target the main tumor and any remaining tumor cells that are proliferating. However, non-proliferating tumor cells are more resistant to cytotoxic therapies, and migration away from the grossly detectable tumor mass can lead to localized treatment failure beyond the surgical resection bed and high-dose radiation zone [3]. Migrating cells undergo changes in cell-cell and cell-extracel- lular matrix (ECM) adhesion that facilitate detachment from their surroundings and promote motility. The transmembrane protein family of cadherins regulates cell-cell adhesion during a variety of biological processes, including tissue morphogenesis as well as tumor invasion/metastasis [4–7]. Classical cadherins mediate cell- cell adhesion and induce adhesion-related signaling via their interaction with p120 catenin (p120) and b-catenin [8–10]. These catenins, in turn, regulate a variety of processes, including cadherin clustering and stabilization, modulation of Rho GTPase signaling, actin cytoskeleton rearrangement, and gene transcrip- tion [11,12]. Ultimately, such regulation governs the balance between cell-cell adhesion on the one hand and cell motility on the other, placing the cadherin-catenin complex in a significant position to regulate both tumor cell proliferation and invasion. Cadherins are critical players in an important mechanism that underlies both developmental processes and epithelial tumorigen- esis: the form of metaplasia known as epithelial-to-mesenchymal transition (EMT). During EMT, the expression of the epithelial E- cadherin is reduced in exchange for increased expression of mesenchymal cadherins such as N-cadherin or cadherin-11 [13]. One result of this transition is cells that are more motile. A PLoS ONE | www.plosone.org 1 October 2010 | Volume 5 | Issue 10 | e13665