Gain in cellular organization of inflammatory breast cancer: A 3D in vitro model that mimics the in vivo metastasis.
BACKGROUND
The initial step of metastasis in carcinomas, often referred to as the epithelial-mesenchymal transition (EMT), occurs via the loss of adherens junctions (e.g. cadherins) by the tumor embolus. This leads to a subsequent loss of cell polarity and cellular differentiation and organization, enabling cells of the embolus to become motile and invasive. However highly malignant inflammatory breast cancer (IBC) over-expresses E-cadherin. The human xenograft model of IBC (MARY-X), like IBC, displays the signature phenotype of an exaggerated degree of lymphovascular invasion (LVI) in situ by tumor emboli. An intact E-cadherin/alpha, beta-catenin axis mediates the tight, compact clump of cells found both in vitro and in vivo as spheroids and tumor emboli, respectively.


METHODS
Using electron microscopy and focused ion beam milling to acquire in situ sections, we performed ultrastructural analysis of both an IBC and non-IBC, E-cadherin positive cell line to determine if retention of this adhesion molecule contributed to cellular organization.


RESULTS
Here we report through ultrastructural analysis that IBC exhibits a high degree of cellular organization with polar elements such as apical/lateral positioning of E-cadherin, apical surface microvilli, and tortuous lumen-like (canalis) structures. In contrast, agarose-induced spheroids of MCF-7, a weakly invasive E-cadherin positive breast carcinoma cell line, do not exhibit ultrastructural polar features.


CONCLUSIONS
This study has determined that the highly metastatic IBC with an exaggerated malignant phenotype challenges conventional wisdom in that instead of displaying a loss of cellular organization, IBC acquires a highly structured architecture.These findings suggest that the metastatic efficiency might be linked to the formation and maintenance of these architectural features. The comparative architectural features of both the spheroid and embolus of MARY-X provide an in vitro model with tractable in vivo applications.
Morales
Jorge
J
Department of Biology, City University of New York, The City College of New York 138th and Convent Avenue, New York, NY 10031, USA. morales@sci.ccny.cuny.edu
Alpaugh
Mary L
ML
D000818:Animals; D001943:Breast Neoplasms / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D015820:Cadherins / Q000378:metabolism; D002277:Carcinoma / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D018929:Cell Culture Techniques; D005260:Female; D006801:Humans; D007249:Inflammation / Q000150:complications / Q000378:metabolism / Q000473:pathology; D008413:Mastitis / Q000150:complications / Q000378:metabolism / Q000473:pathology; D051379:Mice; D016513:Mice, SCID; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D009362:Neoplasm Metastasis; D009389:Neovascularization, Pathologic / Q000473:pathology; D018874:Spheroids, Cellular / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
D015820:Cadherins