@article {241, title = {Rapid disorganization of mechanically interacting systems of mammary acini.}, journal = {Proc Natl Acad Sci U S A}, volume = {111}, year = {2014}, month = {2014 Jan 14}, pages = {658-63}, abstract = {

Cells and multicellular structures can mechanically align and concentrate fibers in their ECM environment and can sense and respond to mechanical cues by differentiating, branching, or disorganizing. Here we show that mammary acini with compromised structural integrity can interconnect by forming long collagen lines. These collagen lines then coordinate and accelerate transition to an invasive phenotype. Interacting acini begin to disorganize within 12.5 \± 4.7 h in a spatially coordinated manner, whereas acini that do not interact mechanically with other acini disorganize more slowly (in 21.8 \± 4.1 h) and to a lesser extent (P \< 0.0001). When the directed mechanical connections between acini were cut with a laser, the acini reverted to a slowly disorganizing phenotype. When acini were fully mechanically isolated from other acini and also from the bulk gel by box-cuts with a side length \<900 μm, transition to an invasive phenotype was blocked in 20 of 20 experiments, regardless of waiting time. Thus, pairs or groups of mammary acini can interact mechanically over long distances through the collagen matrix, and these directed mechanical interactions facilitate transition to an invasive phenotype.

}, keywords = {Acinar Cells, Breast Neoplasms, Cell Communication, Cell Line, Tumor, Cell Separation, Collagen, Escherichia coli, Female, Humans, Kaplan-Meier Estimate, Mammary Glands, Human, Microscopy, Atomic Force, Microscopy, Electron, Scanning, Microscopy, Fluorescence}, issn = {1091-6490}, doi = {10.1073/pnas.1311312110}, author = {Shi, Quanming and Ghosh, Rajarshi P and Engelke, Hanna and Rycroft, Chris H and Cassereau, Luke and Sethian, James A and Weaver, Valerie M and Liphardt, Jan T} } @article {246, title = {Stromally derived lysyl oxidase promotes metastasis of transforming growth factor-β-deficient mouse mammary carcinomas.}, journal = {Cancer Res}, volume = {73}, year = {2013}, month = {2013 Sep 1}, pages = {5336-46}, abstract = {

The tumor stromal environment can dictate many aspects of tumor progression. A complete understanding of factors driving stromal activation and their role in tumor metastasis is critical to furthering research with the goal of therapeutic intervention. Polyoma middle T-induced mammary carcinomas lacking the type II TGF-β receptor (PyMT(mgko)) are highly metastatic compared with control PyMT-induced carcinomas (PyMT(fl/fl)). We hypothesized that the PyMT(mgko)-activated stroma interacts with carcinoma cells to promote invasion and metastasis. We show that the extracellular matrix associated with PyMT(mgko) tumors is stiffer and has more fibrillar collagen and increased expression of the collagen crosslinking enzyme lysyl oxidase (LOX) compared with PyMT(fl/fl) mammary carcinomas. Inhibition of LOX activity in PyMT(mgko) mice had no effect on tumor latency and size, but significantly decreased tumor metastasis through inhibition of tumor cell intravasation. This phenotype was associated with a decrease in keratin 14-positive myoepithelial cells in PyMT(mgko) tumors following LOX inhibition as well as a decrease in focal adhesion formation. Interestingly, the primary source of LOX was found to be activated fibroblasts. LOX expression in these fibroblasts can be driven by myeloid cell-derived TGF-β, which is significantly linked to human breast cancer. Overall, stromal expansion in PyMT(mgko) tumors is likely caused through the modulation of immune cell infiltrates to promote fibroblast activation. This feeds back to the epithelium to promote metastasis by modulating phenotypic characteristics of basal cells. Our data indicate that epithelial induction of microenvironmental changes can play a significant role in tumorigenesis and attenuating these changes can inhibit metastasis. Cancer Res; 73(17); 5336-46. \©2013 AACR.

}, keywords = {Animals, Carcinogenesis, Collagen, Enzyme Inhibitors, Female, Fibroblasts, Focal Adhesion Kinase 1, Humans, In Situ Hybridization, Keratin-14, Lung Neoplasms, Mammary Neoplasms, Experimental, Mice, Mice, Transgenic, Microscopy, Atomic Force, Myeloid Cells, Phosphorylation, Protein-Lysine 6-Oxidase, Protein-Serine-Threonine Kinases, Receptors, Transforming Growth Factor beta, Signal Transduction, Stromal Cells, Transforming Growth Factor beta}, issn = {1538-7445}, doi = {10.1158/0008-5472.CAN-13-0012}, author = {Pickup, Michael W and Laklai, Hanane and Acerbi, Irene and Owens, Philip and Gorska, Agnieszka E and Chytil, Anna and Aakre, Mary and Weaver, Valerie M and Moses, Harold L} } @article {281, title = {Exploring the link between human embryonic stem cell organization and fate using tension-calibrated extracellular matrix functionalized polyacrylamide gels.}, journal = {Methods Mol Biol}, volume = {916}, year = {2012}, month = {2012}, pages = {317-50}, abstract = {

Human embryonic stem cell (hESc) lines are likely the in vitro equivalent of the pluripotent epiblast. hESc express high levels of the extracellular matrix (ECM) laminin integrin receptor α6β1 and consequently can adhere robustly and be propagated in an undifferentiated state on tissue culture plastic coated with the laminin rich basement membrane preparation, Matrigel, even in the absence of supporting fibroblasts. Such cultures represent a critical step in the development of more defined feeder free cultures of hESc; a goal deemed necessary for regenerative medical applications and have been used as the starting point in some differentiation protocols. However, on standard non-deformable tissue culture plastic hESc either fail or inadequately develop the structural/morphological organization of the epiblast in vivo. By contrast, growth of hESc on appropriately defined mechanically deformable polyacrylamide substrates permits recapitulation of many of these in vivo features. These likely herald differences in the precise nature of the integration of signal transduction pathways from soluble morphogens and represent an unexplored variable in hESc (fate) state space. In this chapter we describe how to establish viable hESc colonies on these functionalized polyacrylamide gels. We suggest this strategy as a prospective in vitro model of the genetics, biochemistry, and cell biology of pre- and early-gastrulation stage human embryos and the permissive and instructive roles that cellular and substrate mechanics might play in early embryonic cell fate decisions. Such knowledge should inform regenerative medical applications aimed at enabling or improving the differentiation of specific cell types from embryonic or induced embryonic stem cells.

}, keywords = {Acrylamides, Acrylic Resins, Calibration, Cell Culture Techniques, Cell Differentiation, Cell Polarity, Collagen, Crystallization, Drug Combinations, Elastic Modulus, Embryonic Stem Cells, Extracellular Matrix, Glutaral, Humans, Laminin, Ligands, Proteoglycans, Stress, Mechanical, Trypsin}, issn = {1940-6029}, doi = {10.1007/978-1-61779-980-8_24}, author = {Lakins, Johnathon N and Chin, Andrew R and Weaver, Valerie M} } @article {286, title = {Morphogenesis: Laying down the tracks.}, journal = {Nat Mater}, volume = {11}, year = {2012}, month = {2012 Jun}, pages = {490-2}, keywords = {Cell Movement, Collagen, Epithelium, Extracellular Matrix, Feedback, Morphogenesis}, issn = {1476-1122}, doi = {10.1038/nmat3345}, author = {Cassereau, Luke and DuFort, Christopher C and Weaver, Valerie M} } @article {341, title = {Dynamic interplay between the collagen scaffold and tumor evolution.}, journal = {Curr Opin Cell Biol}, volume = {22}, year = {2010}, month = {2010 Oct}, pages = {697-706}, abstract = {

The extracellular matrix (ECM) is a key regulator of cell and tissue function. Traditionally, the ECM has been thought of primarily as a physical scaffold that binds cells and tissues together. However, the ECM also elicits biochemical and biophysical signaling. Controlled proteolysis and remodeling of the ECM network regulate tissue tension, generate pathways for migration, and release ECM protein fragments to direct normal developmental processes such as branching morphogenesis. Collagens are major components of the ECM of which basement membrane type IV and interstitial matrix type I are the most prevalent. Here we discuss how abnormal expression, proteolysis and structure of these collagens influence cellular functions to elicit multiple effects on tumors, including proliferation, initiation, invasion, metastasis, and therapy response.

}, keywords = {Cell Movement, Collagen, Humans, Neoplasms, Tissue Scaffolds}, issn = {1879-0410}, doi = {10.1016/j.ceb.2010.08.015}, author = {Egeblad, Mikala and Rasch, Morten G and Weaver, Valerie M} } @article {371, title = {Filamin A-beta1 integrin complex tunes epithelial cell response to matrix tension.}, journal = {Mol Biol Cell}, volume = {20}, year = {2009}, month = {2009 Jul}, pages = {3224-38}, abstract = {

The physical properties of the extracellular matrix (ECM) regulate the behavior of several cell types; yet, mechanisms by which cells recognize and respond to changes in these properties are not clear. For example, breast epithelial cells undergo ductal morphogenesis only when cultured in a compliant collagen matrix, but not when the tension of the matrix is increased by loading collagen gels or by increasing collagen density. We report that the actin-binding protein filamin A (FLNa) is necessary for cells to contract collagen gels, and pull on collagen fibrils, which leads to collagen remodeling and morphogenesis in compliant, low-density gels. In stiffer, high-density gels, cells are not able to contract and remodel the matrix, and morphogenesis does not occur. However, increased FLNa-beta1 integrin interactions rescue gel contraction and remodeling in high-density gels, resulting in branching morphogenesis. These results suggest morphogenesis can be \"tuned\" by the balance between cell-generated contractility and opposing matrix stiffness. Our findings support a role for FLNa-beta1 integrin as a mechanosensitive complex that bidirectionally senses the tension of the matrix and, in turn, regulates cellular contractility and response to this matrix tension.

}, keywords = {Animals, Antigens, CD29, Biomechanical Phenomena, Cell Line, Tumor, Collagen, Contractile Proteins, Epithelial Cells, Extracellular Matrix, Filamins, Gels, Humans, Mice, Microfilament Proteins, Morphogenesis, Myosin Light Chains, Phosphorylation, Protein Binding}, issn = {1939-4586}, doi = {10.1091/mbc.E08-12-1186}, author = {Gehler, Scott and Baldassarre, Massimiliano and Lad, Yatish and Leight, Jennifer L and Wozniak, Michele A and Riching, Kristin M and Eliceiri, Kevin W and Weaver, Valerie M and Calderwood, David A and Keely, Patricia J} } @article {366, title = {Matrix crosslinking forces tumor progression by enhancing integrin signaling.}, journal = {Cell}, volume = {139}, year = {2009}, month = {2009 Nov 25}, pages = {891-906}, abstract = {

Tumors are characterized by extracellular matrix (ECM) remodeling and stiffening. The importance of ECM remodeling to cancer is appreciated; the relevance of stiffening is less clear. We found that breast tumorigenesis is accompanied by collagen crosslinking, ECM stiffening, and increased focal adhesions. Induction of collagen crosslinking stiffened the ECM, promoted focal adhesions, enhanced PI3 kinase (PI3K) activity, and induced the invasion of an oncogene-initiated epithelium. Inhibition of integrin signaling repressed the invasion of a premalignant epithelium into a stiffened, crosslinked ECM and forced integrin clustering promoted focal adhesions, enhanced PI3K signaling, and induced the invasion of a premalignant epithelium. Consistently, reduction of lysyl oxidase-mediated collagen crosslinking prevented MMTV-Neu-induced fibrosis, decreased focal adhesions and PI3K activity, impeded malignancy, and lowered tumor incidence. These data show how collagen crosslinking can modulate tissue fibrosis and stiffness to force focal adhesions, growth factor signaling and breast malignancy.

}, keywords = {Aging, Animals, Breast Neoplasms, Collagen, Epidermal Growth Factor, Extracellular Matrix, Female, Fibrosis, Genes, ras, Humans, Integrins, Mammary Glands, Human, Mice, Mice, Inbred BALB C, Protein-Lysine 6-Oxidase, Signal Transduction}, issn = {1097-4172}, doi = {10.1016/j.cell.2009.10.027}, author = {Levental, Kandice R and Yu, Hongmei and Kass, Laura and Lakins, Johnathon N and Egeblad, Mikala and Erler, Janine T and Fong, Sheri F T and Csiszar, Katalin and Giaccia, Amato and Weninger, Wolfgang and Yamauchi, Mitsuo and Gasser, David L and Weaver, Valerie M} } @article {401, title = {Three-dimensional context regulation of metastasis.}, journal = {Clin Exp Metastasis}, volume = {26}, year = {2009}, month = {2009}, pages = {35-49}, abstract = {

Tumor progression ensues within a three-dimensional microenvironment that consists of cellular and non-cellular components. The extracellular matrix (ECM) and hypoxia are two non-cellular components that potently influence metastasis. ECM remodeling and collagen cross-linking stiffen the tissue stroma to promote transformation, tumor growth, motility and invasion, enhance cancer cell survival, enable metastatic dissemination, and facilitate the establishment of tumor cells at distant sites. Matrix degradation can additionally promote malignant progression and metastasis. Tumor hypoxia is functionally linked to altered stromal-epithelial interactions. Hypoxia additionally induces the expression of pro-migratory, survival and invasion genes, and up-regulates expression of ECM components and modifying enzymes, to enhance tumor progression and metastasis. Synergistic interactions between matrix remodeling and tumor hypoxia influence common mechanisms that maximize tumor progression and cooperate to drive metastasis. Thus, clarifying the molecular pathways by which ECM remodeling and tumor hypoxia intersect to promote tumor progression should identify novel therapeutic targets.

}, keywords = {Cell Division, Collagen, Disease Progression, Homeostasis, Humans, Neoplasm Invasiveness, Neoplasm Metastasis, Neoplasms}, issn = {1573-7276}, doi = {10.1007/s10585-008-9209-8}, author = {Erler, Janine T and Weaver, Valerie M} }