@article {696, title = {A 3D tension bioreactor platform to study the interplay between ECM stiffness and tumor phenotype.}, journal = {J Biotechnol}, volume = {193}, year = {2015}, month = {2015 Jan 10}, pages = {66-9}, abstract = {

Extracellular matrix (ECM) structure, composition, and stiffness have profound effects on tissue development and pathologies such as cardiovascular disease and cancer. Accordingly, a variety of synthetic hydrogel systems have been designed to study the impact of ECM composition, density, mechanics, and topography on cell and tissue phenotype. However, these synthetic systems fail to accurately recapitulate the biological properties and structure of the native tissue ECM. Natural three dimensional (3D) ECM hydrogels, such as collagen or hyaluronic acid, feature many of the chemical and physical properties of tissue, yet, these systems have limitations including the inability to independently control biophysical properties such as stiffness and pore size. Here, we present a 3D tension bioreactor system that permits precise mechanical tuning of collagen hydrogel stiffness, while maintaining consistent composition and pore size. We achieve this by mechanically loading collagen hydrogels covalently-conjugated to a polydimethylsiloxane (PDMS) membrane to induce hydrogel stiffening. We validated the biological application of this system with oncogenically transformed mammary epithelial cell organoids embedded in a 3D collagen I hydrogel, either uniformly stiffened or calibrated to create a gradient of ECM stiffening, to visually demonstrate the impact of ECM stiffening on transformation and tumor cell invasion. As such, this bioreactor presents the first tunable 3D natural hydrogel system that is capable of independently assessing the role of ECM stiffness on tissue phenotype.

}, issn = {1873-4863}, doi = {10.1016/j.jbiotec.2014.11.008}, author = {Cassereau, Luke and Miroshnikova, Yekaterina A and Ou, Guanqing and Lakins, Johnathon and Weaver, Valerie M} } @article {766, title = {Tumor-induced solid stress activates β-catenin signaling to drive malignant behavior in normal, tumor-adjacent cells.}, journal = {Bioessays}, volume = {37}, year = {2015}, month = {2015 Dec}, pages = {1293-7}, abstract = {

Recent work by Fern{\'a}ndez-S{\'a}nchez and coworkers examining the impact of applied pressure on the malignant phenotype of murine colon tissue in vivo revealed that mechanical perturbations can drive malignant behavior in genetically normal cells. Their findings build upon an existing understanding of how the mechanical cues experienced by cells within a tissue become progressively modified as the tissue transforms. Using magnetically stimulated ultra-magnetic liposomes to mimic tumor growth -induced solid stress, Fern{\'a}ndez-S{\'a}nchez and coworkers were able to stimulate β-catenin to promote the cancerous behavior of both a normal and genetically modified colon epithelium. In this perspective, we discuss their findings in the context of what is currently known regarding the role of the mechanical landscape in cancer progression and β-catenin as a mechanotransducer. We review data that suggest that mechanically regulated activation of β-catenin fosters development of a malignant phenotype in tissue and predict that mechanical cues may contribute to tumor heterogeneity.

}, issn = {1521-1878}, doi = {10.1002/bies.201500090}, author = {Ou, Guanqing and Weaver, Valerie Marie} } @article {236, title = {Deconstructing Signaling in 3 Dimensions.}, journal = {Biochemistry}, year = {2014}, month = {2014 Mar 20}, abstract = {

Cells in vivo exist within the context of a multicellular tissue, where their behavior is governed by homo- and heterotypic cell-cell interactions, the material properties of the extracellular matrix, and the distribution and accessibility of various soluble and physical factors. Yet, most of the methods currently used to study and manipulate cellular behavior in vitro sacrifice physiological relevance for experimental expediency. The fallacy of such approaches to biological investigation has been highlighted by the recent development and application of three dimensional culture models to cell biology, which have revealed striking phenotypic differences in cell survival, migration, and differentiation in otherwise seemingly identical cells simply by varying culture conditions. These perplexing findings beg the question: what constitutes a three dimensional culture and why do cells behave so differently in a two versus a three dimensional culture format? In the following review, we dissect the fundamental differences between two and three dimensional culture conditions. We begin by establishing a basic definition of what \"three dimensions\" means at different biological scales and discuss how dimensionality influences cell signaling across different length scales. We identify which three dimensional features most potently influence intracellular signaling and distinguish between conserved biological principles that are maintained across culture conditions and cellular behaviors that are sensitive to microenvironmental context. Finally, we highlight state of the art molecular tools amenable to the study of signaling in three dimensions under conditions that facilitate deconstructing cell signaling in a more physiologically relevant manner.

}, issn = {1520-4995}, doi = {10.1021/bi401710d}, author = {Rubashkin, Matthew G and Ou, Guanqing and Weaver, Valerie M} } @article {651, title = {Extracellular matrix assembly: a multiscale deconstruction.}, journal = {Nat Rev Mol Cell Biol}, year = {2014}, month = {2014 Nov 5}, abstract = {

The biochemical and biophysical properties of the extracellular matrix (ECM) dictate tissue-specific cell behaviour. The molecules that are associated with the ECM of each tissue, including collagens, proteoglycans, laminins and fibronectin, and the manner in which they are assembled determine the structure and the organization of the resultant ECM. The product is a specific ECM signature that is comprised of unique compositional and topographical features that both reflect and facilitate the functional requirements of the tissue.

}, issn = {1471-0080}, doi = {10.1038/nrm3902}, author = {Mouw, Janna K and Ou, Guanqing and Weaver, Valerie M} } @article {641, title = {Force engages vinculin and promotes tumor progression by enhancing PI3K activation of phosphatidylinositol (3,4,5)-triphosphate.}, journal = {Cancer Res}, volume = {74}, year = {2014}, month = {2014 Sep 1}, pages = {4597-611}, abstract = {

Extracellular matrix (ECM) stiffness induces focal adhesion assembly to drive malignant transformation and tumor metastasis. Nevertheless, how force alters focal adhesions to promote tumor progression remains unclear. Here, we explored the role of the focal adhesion protein vinculin, a force-activated mechanotransducer, in mammary epithelial tissue transformation and invasion. We found that ECM stiffness stabilizes the assembly of a vinculin-talin-actin scaffolding complex that facilitates PI3K-mediated phosphatidylinositol (3,4,5)-triphosphate phosphorylation. Using defined two- and three-dimensional matrices, a mouse model of mammary tumorigenesis with vinculin mutants, and a novel super resolution imaging approach, we established that ECM stiffness, per se, promotes the malignant progression of a mammary epithelium by activating and stabilizing vinculin and enhancing Akt signaling at focal adhesions. Our studies also revealed that vinculin strongly colocalizes with activated Akt at the invasive border of human breast tumors, where the ECM is stiffest, and we detected elevated mechanosignaling. Thus, ECM stiffness could induce tumor progression by promoting the assembly of signaling scaffolds, a conclusion underscored by the significant association we observed between highly expressed focal adhesion plaque proteins and malignant transformation across multiple types of solid cancer. See all articles in this Cancer Research section, "Physics in Cancer Research."

}, issn = {1538-7445}, doi = {10.1158/0008-5472.CAN-13-3698}, author = {Rubashkin, Matthew G and Cassereau, Luke and Bainer, Russell and DuFort, Christopher C and Yui, Yoshihiro and Ou, Guanqing and Paszek, Matthew J and Davidson, Michael W and Chen, Yunn-Yi and Weaver, Valerie M} } @article {226, title = {Tissue mechanics modulate microRNA-dependent PTEN expression to regulate malignant progression.}, journal = {Nat Med}, year = {2014}, month = {2014 Mar 16}, abstract = {

Tissue mechanics regulate development and homeostasis and are consistently modified in tumor progression. Nevertheless, the fundamental molecular mechanisms through which altered mechanics regulate tissue behavior and the clinical relevance of these changes remain unclear. We demonstrate that increased matrix stiffness modulates microRNA expression to drive tumor progression through integrin activation of β-catenin and MYC. Specifically, in human and mouse tissue, increased matrix stiffness induced miR-18a to reduce levels of the tumor suppressor phosphatase and tensin homolog (PTEN), both directly and indirectly by decreasing levels of homeobox A9 (HOXA9). Clinically, extracellular matrix stiffness correlated directly and significantly with miR-18a expression in human breast tumor biopsies. miR-18a expression was highest in basal-like breast cancers in which PTEN and HOXA9 levels were lowest, and high miR-18a expression predicted poor prognosis in patients with luminal breast cancers. Our findings identify a mechanically regulated microRNA circuit that can promote malignancy and suggest potential prognostic roles for HOXA9 and miR-18a levels in stratifying patients with luminal breast cancers.

}, issn = {1546-170X}, doi = {10.1038/nm.3497}, author = {Mouw, Janna K and Yui, Yoshihiro and Damiano, Laura and Bainer, Russell O and Lakins, Johnathon N and Acerbi, Irene and Ou, Guanqing and Wijekoon, Amanda C and Levental, Kandice R and Gilbert, Penney M and Hwang, E Shelley and Chen, Yunn-Yi and Weaver, Valerie M} }