Dr. Andrew Ewald, Ph.D.Dr. Andrew Ewald, Ph.D.
Department of Cell Biology
Johns Hopkins School of Medicine
Baltimore, MD, USA
Title: “Understanding breast cancer invasion and metastasis."
July 8th: Time: 9 am EST, 8 am CST, 7 am PST
Research Topic: Revealing the Cellular and Molecular Mechanisms Regulating Epithelial Morphogenesis in Development and Disease
Background and Summary
Epithelial cells in a tissue live a crowded life connected to, and interacting with, other cell types, the extracellular matrix, and diverse signaling molecules. A fundamental question in biology is: how do the constituent cells of an epithelium collaborate to build and remodel its structure? This seemingly simple question also has great relevance to human disease. Cancer is a disease of disregulated proliferation, but also of disregulated tissue growth and invasion. Tumors could grow through novel cellular mechanisms, or they could grow through normal cellular mechanisms occurring in abnormal contexts or to abnormal extents. Until we understand the cellular mechanisms of normal epithelial morphogenesis, it is not possible to distinguish these possibilities.
Experimental Approach: We combine advanced time-lapse microscopy techniques and 3D organotypic cultures to study the cell behavioral basis of normal and neoplastic epithelial growth and invasion. Organotypic culture allows us to contrast different epithelia under identical conditions or to contrast similar epithelia under different microenvironmental conditions. We use a common set of imaging, genetic, and molecular interference tools to study epithelial morphogenesis, whether from normal or cancerous epithelium.
Summary of Recent Work: We seek to answer a simple question: how does an epithelium grow and invade? To answer this question, we observed the cell behaviors that drive mammary branching morphogenesis. We found that ductal elongation was accomplished by a multilayered epithelium, within which cells rearranged vigorously. Surprisingly, cells at the elongation front lacked forward oriented actin protrusions. We have shown that during morphogenesis, mammary epithelium transitions from a bilayered to a multilayered organization, with dramatic, reversible changes in epithelial polarity and cell motility. We are collaborating with Manfred Auer's electron microscopy group at the Lawrence Berkeley Lab to study the intercellular junctional basis of this transition. We have now dissected the process of branching morphogenesis into discrete, observable subprocesses and have identified molecular regulators of each subprocess. (For further information see Ewald et al, Developmental Cell, April 2008).
Project 1. Quantitative analysis of the cell behavioral basis of epithelial morphogenesis
The foundation for a cell biological understanding of epithelial morphogenesis is to resolve the tissue level process of ductal initiation, elongation and bifurcation into discrete changes in the properties and behaviors of individual cells. We are currently using 4D confocal microscopy to dissect the relative contributions of cell movement, cell proliferation, cell shape change and extracellular matrix dynamics to mammary branching morphogenesis.
Project 2. Molecular and cellular regulation of epithelial morphogenesis
Building on a our understanding of the cell behavioral basis of epithelial morphogenesis, we are taking a combined candidate and systematic approach to identify molecules regulators of these behaviors. We are currently using microarrays to identify potential regulatory molecules and we will use pharmacologic inhibitors, function blocking antibodies, and virally mediated gene inactivation to validate targets. We also want to understand the role of microenvironmental factors such as extracellular matrix (ECM) and stromal cell populations. Preliminary data suggest that the cellular mechanisms of invasion depend on the protein composition of the ECM. We predict that the genetic regulation of epithelial morphogenesis will intimately depend on the ECM and stromal cell context in the epithelial microenvironment.
Project 3. Contrasting epithelial morphogenesis in mammary development and breast cancer
The varied morphologic appearance of invasive tumors could reflect differences in the fundamental mechanisms of cellular invasion. Alternately, similar underlying invasion mechanisms might generate different outcomes, and different morphologic appearances, in response to a changing tumor microenvironment. It is difficult to distinguish these possibilities in fixed sections, as the tumor and stroma are both changing dramatically as a function of stage of progression. We are addressing this question by comparing the cellular mechanisms of growth and invasion of normal and neoplastic epithelia, cultured in identical solution, matrix, and stromal cellular conditions. We have developed protocols to culture epithelium from normal ducts, hyperplasias, adenomas, and advanced tumors, either alone or in co-culture with corresponding stromal cells. We are committed to identifying molecular strategies for limiting the growth and spread of epithelial tumors, with a specific focus on identifying extracellular inhibitors of breast tumor invasion and metastasis.
Department of Cell Biology
Johns Hopkins University School of Medicine
855 N. Wolfe Street, 452 Rangos Bldg.
Baltimore, MD 21205
Research Interest: Cellular mechanisms and molecular regulation of epithelial morphogenesis in development and cancer.
Follow the Leader: Specialized Cancer Cells Lead Collective Invasion (Ewald Lab)
Research in the Ewald laboratory starts from a simple question: which cells in a breast tumor are the most dangerous to the patient and most responsible for metastatic disease? To answer this question, we developed novel 3D culture assays to allow real-time analysis of invasion. Briefly, we use enzymatic digestion to isolate thousands of “tumor organoids” from each primary tumor. Each organoid is composed of 200-500 epithelial cancer cells and reflects the cellular heterogeneity of the primary tumor.
Ewald AJ, "An arresting story about basement membrane invasion," Dev Cell. 2015 Oct 26;35(2):143-4
Teo WW, Merino V, Cho S, Korangath P, Liang X, Wu R, Neumann NM, Ewald AJ, Sukumar, S, “HOXA5, a regulator of cell fate transition, impedes tumor initiation and progression in breast cancer,” Oncogene. 2016 May 9.
Cheung KJ, Ewald AJ, "A collective route to metastasis: Seeding by tumor cell clusters," Science. 2016 Apr 8;352(6282):167-9.
Huebner RJ, Neumann NM, Ewald AJ, "Mammary epithelial tubes elongate through MAPK-dependent coordination of cell migration," 2016, Feb 2, Development.
Ellison D, Mugler A, Brennan M, Lee SH, Huebner RJ, Shamir ER, Woo LA, Kim J, Amar P, Nemenman I, Ewald AJ, Levchenko A, “Cell-cell communication enhances the capacity of cell ensembles to sense shallow gradients during morphogenesis”, 2016, Jan 20, PNAS
Cheung KJ, Padmanaban VP, Silvestri V, Schipper K, Cohen JD, Fairchild AN, Gorin MA, Verdone JE, Pienta KJ, Ewald AJ, “Polyclonal breast cancer metastases arise from collective dissemination of keratin 14-expressing tumor cell clusters,” 2016, Feb 1, PNAS.
Kim M, Shewan A, Ewald AJ, Werb Z, Mostov KE, “P114RhoGEF governs cell motility and lumen formation during tubulogenesis via ROCK-myosin II pathway,” J Cell Sci. 2015 Oct 19.
Shamir ER and Ewald AJ, “Adhesion in mammary development: novel roles for E-cadherin in individual and collective cell migration,” Curr Top Dev Biol. 2015;112:353-82.
Chapiro J, Sur S, Savic LJ, Ganapathy-Kniappan S, Reyes J, Duran R, Chettiar-Thiruganasambandam S, Moats CR, Lin M, Luo W, Tran PT, Herman JM, Semenza GL, Ewald AJ, Vogelstein B, Geschwind JF, “Systemic delivery of microencapsulated 2-bromopyruvate for the therapy of pancreatic cancer, Clinical Cancer Research 2014 Dec 15;20(24):6406-17.
Cheung KJ and Ewald AJ, “Illuminating breast cancer invasion: diverse roles for cell-cell interactions”, Current Opinion in Cell Biology, 2014, Oct; 30:99-111.
Bryant DM, Roignot J, Datta A, Orvereem A, Kim M, Yu W, Peng X, Eastburn D, Ewald AJ, Werb Z, and Mostov K, “A molecular switch for the orientation of epithelial cell polarization,” Dev Cell, 2014 Oct 27;31(2):171-87.
Shamir ER and Ewald AJ, “3D Organotypic Culture: Experimental Models of Mammalian Biology and Disease,” Nature Reviews Molecular Cell Biology, 2014 Oct;15(10):647-64.
Huebner RJ, Lechler T, Ewald AJ, “Mammary epithelial stratification occurs through symmetry breaking vertical divisions of luminal cells,” Development. 2014 Mar;141(5):1085-94
Shamir ER, Papallardo E, Jorgens DM, Coutinho K, Tsai WT, Aziz K, Auer M, Tran PT, Bader JS, Ewald AJ, “Twist1-induced dissemination preserves epithelial identity and requires E-cadherin,” JCB 2014 Mar 3;204(5):839-56 (Selected for cover).
Chen Q, Zhang N, Gray RS, Li H, Ewald AJ, Zahnow CA, and Pan DJ, “A temporal requirement for Hippo signaling in mammary gland differentiation, growth and tumorigenesis”, Genes Dev. 2014 Mar 1;28(5):432-7.
Cheung KJ, Gabrielson, E, Werb Z, Ewald AJ, “Collective invasion in breast cancer requires a conserved basal epithelial program,” Cell, 2013 Dec;155(7):1639-51.
Beck JN, Singh A, Rothenberg AR, Elisseeff JH, Ewald AJ, The independent roles of mechanical, structural and adhesion characteristics of 3D hydrogels on the regulation of cancer invasion and dissemination, Biomaterials, 2013 Dec;34(37):9486-95.
Nguyen-Ngoc KV and Ewald AJ, “Mammary epithelial elongation and myoepithelial migration are regulated by the composition of the extracellular matrix,” J Microsc. 2013 Sep;251(3):212-23.
Nguyen-Ngoc KV, Cheung KJ, Brenot A, Shamir ER, Gray RS, Hines WC, Yaswen P, Werb Z, Ewald AJ, “The ECM microenvironment regulates collective migration and local dissemination in normal and malignant mammary epithelium” Proc Natl Acad Sci U S A. 2012 Sep 25;109(39):E2595-604. PMC3465416.
Ewald AJ, Huebner RJ, Palsdottir H, Lee JK, Perez MJ, Jorgens DM, Tauscher AN, Cheung KJ, Werb Z, Auer M, "Mammary collective cell migration involves transient loss of epithelial features and individual cell migration within the epithelium", J Cell Sci. 2012 Jun 1;125(Pt 11):2638-54. PMC3403234.
Egeblad* M, Ewald* AJ, Asketraud HA, Truitt M, Welm B, Bainbridge E, Peeters G, Krummel M, Werb Z, “Imaging stromal cells in different tumor microenvironments by spinning disk confocal microscopy”, Disease Models and Mechanisms. 2008 Sep/Oct; 1(2/3): 155-67. * = Co-First Authors. PMC2562195
Ewald, AJ, Brenot, A, Duong, M, Chan, BC, Werb, Z. Collective epithelial migration and cell rearrangements drive mammary branching morphogenesis. Developmental Cell, 2008 Apr; 14(4): 570-81.