@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 {261, title = {YAP forces fibroblasts to feel the tension.}, journal = {Nat Cell Biol}, volume = {15}, year = {2013}, month = {2013 Jun}, pages = {570-2}, abstract = {

Cancer-associated fibroblasts (CAFs) may contribute to tissue tension and cancer progression by increasing extracellular matrix (ECM) deposition and remodelling. However, how CAFs become activated and their roles in tumour mechanics have remained unclear. YAP is now identified as a tension-stimulated CAF activator that promotes malignancy through a mechanically reinforced feed-forward loop.

}, keywords = {Adaptor Proteins, Signal Transducing, Animals, Breast Neoplasms, Female, Fibroblasts, Humans, Mechanotransduction, Cellular, Phosphoproteins}, issn = {1476-4679}, doi = {10.1038/ncb2777}, author = {Maller, Ori and DuFort, Christopher C and Weaver, Valerie M} } @article {321, title = {Tumor microenvironment and progression.}, journal = {J Surg Oncol}, volume = {103}, year = {2011}, month = {2011 May 1}, pages = {468-74}, abstract = {

Tumor blood vessels are heterogeneous, of at least six distinct types, are induced primarily by vascular endothelial growth factor-A (VEGF-A), and provide a potentially useful therapeutic target. Breast cancer is characterized by changes in the microenvironment that result in altered tensional homeostasis. Also, breast cancers arise as the result of epigenetic as well as genetic changes. Tumor blood vessel pericytes result, in part, from bone marrow precursor cells, and VEGF is a negative regulator of glioblastoma tumor cell invasion.

}, keywords = {Angiogenesis Inhibitors, Breast Neoplasms, Disease Progression, Female, Humans, Molecular Targeted Therapy, Neoplasm Invasiveness, Neoplasms, Neovascularization, Pathologic, Tumor Microenvironment, Vascular Endothelial Growth Factor A}, issn = {1096-9098}, doi = {10.1002/jso.21709}, author = {Dvorak, Harold F and Weaver, Valerie M and Tlsty, Thea D and Bergers, Gabriele} } @article {351, title = {HOXA9 regulates BRCA1 expression to modulate human breast tumor phenotype.}, journal = {J Clin Invest}, volume = {120}, year = {2010}, month = {2010 May}, pages = {1535-50}, abstract = {

Breast cancer 1, early onset (BRCA1) expression is often reduced in sporadic breast tumors, even in the absence of BRCA1 genetic modifications, but the molecular basis for this is unknown. In this study, we identified homeobox A9 (HOXA9) as a gene frequently downregulated in human breast cancers and tumor cell lines and noted that reduced HOXA9 transcript levels associated with tumor aggression, metastasis, and patient mortality. Experiments revealed that loss of HOXA9 promoted mammary epithelial cell growth and survival and perturbed tissue morphogenesis. Restoring HOXA9 expression repressed growth and survival and inhibited the malignant phenotype of breast cancer cells in culture and in a xenograft mouse model. Molecular studies showed that HOXA9 restricted breast tumor behavior by directly modulating the expression of BRCA1. Indeed, ectopic expression of wild-type BRCA1 phenocopied the tumor suppressor function of HOXA9, and reducing BRCA1 levels or function inhibited the antitumor activity of HOXA9. Consistently, HOXA9 expression correlated with BRCA1 in clinical specimens and with tumor aggression in patients lacking estrogen receptor/progesterone receptor expression in their breast tissue. These findings indicate that HOXA9 restricts breast tumor aggression by modulating expression of the tumor suppressor gene BRCA1, which we believe provides an explanation for the loss of BRCA1 expression in sporadic breast tumors in the absence of BRCA1 genetic modifications.

}, keywords = {Adult, Animals, BRCA1 Protein, Breast Neoplasms, Female, Gene Expression Regulation, Neoplastic, Homeodomain Proteins, Humans, Mice, Middle Aged, Models, Genetic, Neoplasm Transplantation, Phenotype, Receptors, Estrogen, Receptors, Progesterone, Treatment Outcome}, issn = {1558-8238}, doi = {10.1172/JCI39534}, author = {Gilbert, Penney M and Mouw, Janna K and Unger, Meredith A and Lakins, Johnathon N and Gbegnon, Mawuse K and Clemmer, Virginia B and Benezra, Miriam and Licht, Jonathan D and Boudreau, Nancy J and Tsai, Kelvin K C and Welm, Alana L and Feldman, Michael D and Weber, Barbara L and Weaver, Valerie M} } @article {381, title = {CpG island tumor suppressor promoter methylation in non-BRCA-associated early mammary carcinogenesis.}, journal = {Cancer Epidemiol Biomarkers Prev}, volume = {18}, year = {2009}, month = {2009 Mar}, pages = {901-14}, abstract = {

BACKGROUND: Only 5\% of all breast cancers are the result of BRCA1/2 mutations. Methylation silencing of tumor suppressor genes is well described in sporadic breast cancer; however, its role in familial breast cancer is not known.

METHODS: CpG island promoter methylation was tested in the initial random periareolar fine-needle aspiration sample from 109 asymptomatic women at high risk for breast cancer. Promoter methylation targets included RARB (M3 and M4), ESR1, INK4a/ARF, BRCA1, PRA, PRB, RASSF1A, HIN-1, and CRBP1.

RESULTS: Although the overall frequency of CpG island promoter methylation events increased with age (P\<0.0001), no specific methylation event was associated with age. In contrast, CpG island methylation of RARB M4 (P=0.051), INK4a/ARF (P=0.042), HIN-1 (P=0.044), and PRA (P=0.032), as well as the overall frequency of methylation events (P=0.004), was associated with abnormal Masood cytology. The association between promoter methylation and familial breast cancer was tested in 40 unaffected premenopausal women in our cohort who underwent BRCA1/2 mutation testing. Women with BRCA1/2 mutations had a low frequency of CpG island promoter methylation (15 of 15 women had

CONCLUSIONS: This is the first evidence of CpG island methylation of tumor suppressor gene promoters in non-BRCA1/2 familial breast cancer.

}, keywords = {Biopsy, Fine-Needle, Breast Neoplasms, Chi-Square Distribution, CpG Islands, Cyclin-Dependent Kinase Inhibitor p16, Cytokines, DNA Methylation, Female, Genes, BRCA1, Genes, BRCA2, Genes, Tumor Suppressor, Humans, Mutation, Polymerase Chain Reaction, Premenopause, Promoter Regions, Genetic, Receptors, Progesterone, Receptors, Retinoic Acid, Risk, Risk Assessment, Statistics, Nonparametric, Tumor Suppressor Proteins}, issn = {1055-9965}, doi = {10.1158/1055-9965.EPI-08-0875}, author = {Vasilatos, Shauna N and Broadwater, Gloria and Barry, William T and Baker, Joseph C and Lem, Siya and Dietze, Eric C and Bean, Gregory R and Bryson, Andrew D and Pilie, Patrick G and Goldenberg, Vanessa and Skaar, David and Paisie, Carolyn and Torres-Hernandez, Alejandro and Grant, Tracey L and Wilke, Lee G and Ibarra-Drendall, Catherine and Ostrander, Julie H and D{\textquoteright}Amato, Nicholas C and Zalles, Carola and Jirtle, Randy and Weaver, Valerie M and Seewaldt, Victoria L} } @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 {516, title = {Autocrine laminin-5 ligates alpha6beta4 integrin and activates RAC and NFkappaB to mediate anchorage-independent survival of mammary tumors.}, journal = {J Cell Biol}, volume = {163}, year = {2003}, month = {2003 Dec 22}, pages = {1397-407}, abstract = {

Invasive carcinomas survive and evade apoptosis despite the absence of an exogenous basement membrane. How epithelial tumors acquire anchorage independence for survival remains poorly defined. Epithelial tumors often secrete abundant amounts of the extracellular matrix protein laminin 5 (LM-5) and frequently express alpha6beta4 integrin. Here, we show that autocrine LM-5 mediates anchorage-independent survival in breast tumors through ligation of a wild-type, but not a cytoplasmic tail-truncated alpha6beta4 integrin. alpha6beta4 integrin does not mediate tumor survival through activation of ERK or AKT. Instead, the cytoplasmic tail of beta4 integrin is necessary for basal and epidermal growth factor-induced RAC activity, and RAC mediates tumor survival. Indeed, a constitutively active RAC sustains the viability of mammary tumors lacking functional beta1 and beta4 integrin through activation of NFkappaB, and overexpression of NFkappaB p65 mediates anchorage-independent survival of nonmalignant mammary epithelial cells. Therefore, epithelial tumors could survive in the absence of exogenous basement membrane through autocrine LM-5-alpha6beta4 integrin-RAC-NFkappaB signaling.

}, keywords = {Autocrine Communication, Basement Membrane, Breast Neoplasms, Carcinoma, Cell Adhesion, Cell Adhesion Molecules, Cell Line, Tumor, Cell Survival, Epidermal Growth Factor, Humans, Integrin alpha6beta4, MAP Kinase Signaling System, Neoplasm Invasiveness, NF-kappa B, Protein Structure, Tertiary, rac GTP-Binding Proteins}, issn = {0021-9525}, doi = {10.1083/jcb.200302023}, author = {Zahir, Nastaran and Lakins, Johnathon N and Russell, Alan and Ming, WenYu and Chatterjee, Chandrima and Rozenberg, Gabriela I and Marinkovich, M Peter and Weaver, Valerie M} } @article {521, title = {The tissue microenvironment as an epigenetic tumor modifier.}, journal = {Methods Mol Biol}, volume = {223}, year = {2003}, month = {2003}, pages = {315-47}, keywords = {Animals, Breast Neoplasms, Cell Adhesion, Cell Nucleus, Dimerization, Epithelial Cells, Genes, Tumor Suppressor, Humans, Keratinocytes, Models, Biological, Neoplasm Metastasis, Neoplasms, Neovascularization, Pathologic, Phenotype, Promoter Regions, Genetic, Signal Transduction, Time Factors}, issn = {1064-3745}, doi = {10.1385/1-59259-329-1:315}, author = {Unger, Meredith and Weaver, Valerie M} } @article {531, title = {beta4 integrin-dependent formation of polarized three-dimensional architecture confers resistance to apoptosis in normal and malignant mammary epithelium.}, journal = {Cancer Cell}, volume = {2}, year = {2002}, month = {2002 Sep}, pages = {205-16}, abstract = {

Tumor cells can evade chemotherapy by acquiring resistance to apoptosis. We investigated the molecular mechanism whereby malignant and nonmalignant mammary epithelial cells become insensitive to apoptosis. We show that regardless of growth status, formation of polarized, three-dimensional structures driven by basement membrane confers protection to apoptosis in both nonmalignant and malignant mammary epithelial cells. By contrast, irrespective of their malignant status, nonpolarized structures are sensitive to induction of apoptosis. Resistance to apoptosis requires ligation of beta4 integrins, which regulates tissue polarity, hemidesmosome formation, and NFkappaB activation. Expression of beta4 integrin that lacks the hemidesmosome targeting domain interferes with tissue polarity and NFkappaB activation and permits apoptosis. These results indicate that integrin-induced polarity may drive tumor cell resistance to apoptosis-inducing agents via effects on NFkappaB.

}, keywords = {Apoptosis, Basement Membrane, Breast Neoplasms, Cell Polarity, Epithelial Cells, Extracellular Matrix, Female, Gene Expression Regulation, Neoplastic, Humans, Integrin beta4, NF-kappa B, Tumor Cells, Cultured}, issn = {1535-6108}, author = {Weaver, Valerie M and Leli{\`e}vre, Sophie and Lakins, Johnathon N and Chrenek, Micah A and Jones, Jonathan C R and Giancotti, Filippo and Werb, Zena and Bissell, Mina J} } @article {526, title = {The organizing principle: microenvironmental influences in the normal and malignant breast.}, journal = {Differentiation}, volume = {70}, year = {2002}, month = {2002 Dec}, pages = {537-46}, abstract = {

The current paradigm for cancer initiation and progression rests on the groundbreaking discoveries of oncogenes and tumor suppressor genes. This framework has revealed much about the role of genetic alterations in the underlying signaling pathways central to normal cellular function and to tumor progression. However, it is clear that single gene theories or even sequential acquisition of mutations underestimate the nature of the genetic and epigenetic changes in tumors, and do not account for the observation that many cancer susceptibility genes (e.g. BRCA1, APC) show a high degree of tissue specificity in their association with neoplastic transformation. Therefore, the cellular and tissue context itself must confer additional and crucial information necessary for mutated genes to exert their influence. A considerable body of evidence now shows that cell-cell and cell-extracellular matrix (ECM) interactions are essential organizing principles that help define the nature of the tissue context, and play a crucial role in regulating homeostasis and tissue specificity. How this context determines functional integrity, and how its loss can lead to malignancy, appears to have much to do with tissue structure and polarity.

}, keywords = {Apoptosis, Breast, Breast Neoplasms, Coculture Techniques, Female, Humans, Signal Transduction}, issn = {0301-4681}, doi = {10.1046/j.1432-0436.2002.700907.x}, author = {Bissell, Mina J and Radisky, Derek C and Rizki, Aylin and Weaver, Valerie M and Petersen, Ole W} } @article {541, title = {Tumour-stromal interactions. Integrins and cell adhesions as modulators of mammary cell survival and transformation.}, journal = {Breast Cancer Res}, volume = {3}, year = {2001}, month = {2001}, pages = {224-9}, abstract = {

Stromal-epithelial interactions modulate mammary epithelial cell (MEC) growth and apoptosis by influencing cell adhesion and tissue organization. Perturbations in the mammary stroma and cell adhesion characterize breast tumors and underlie the altered tissue organization, disrupted tissue homeostasis and enhanced survival phenotype of the disease. Apoptosis resistance likely arises during malignant transformation via genetic and epigenetic modification of cell adhesion pathways induced by a changing tissue microenvironment. Acquisition of adhesion-linked survival networks that enhance MEC viability in the absence of basement membrane interactions probably promote malignant transformation, and may render breast tumors sufficiently resistant to exogenous apoptotic stimuli to generate multidrug resistance.

}, keywords = {Apoptosis, Basement Membrane, Breast Neoplasms, Cell Adhesion Molecules, Cell Communication, Cell Differentiation, Cell Survival, Cell Transformation, Neoplastic, Drug Resistance, Multiple, Epithelial Cells, Female, Gene Expression Regulation, Neoplastic, Humans, Integrins, Stromal Cells}, issn = {1465-5411}, author = {Chrenek, M A and Wong, P and Weaver, V M} } @article {546, title = {Structural cues from the tissue microenvironment are essential determinants of the human mammary epithelial cell phenotype.}, journal = {J Mammary Gland Biol Neoplasia}, volume = {3}, year = {1998}, month = {1998 Apr}, pages = {201-13}, abstract = {

Historically, the study of normal human breast function and breast disorders has been significantly impaired by limitations inherent to available model systems. Recent improvements in human breast epithelial cell lines and three-dimensional (3-D)3 culture systems have contributed to the development of in vitro model systems that recapitulate differentiated epithelial cell phenotypes with remarkable fidelity. Molecular characterization of these human breast cell models has demonstrated that normal breast epithelial cell behavior is determined in part by the precise interplay that exists between a cell and its surrounding microenvironment. Recent functional studies of integrins in a human model system provide evidence to support the idea that the structural stability afforded by integrin-mediated cell-extracellular matrix interactions is an important determinant of normal cellular behavior, and that alterations in tissue structure can give rise to tumorigenic progression.

}, keywords = {Breast, Breast Neoplasms, Cell Line, Epithelial Cells, Extracellular Matrix, Female, Humans, Integrins, Models, Biological}, issn = {1083-3021}, author = {Schmeichel, K L and Weaver, V M and Bissell, M J} } @article {561, title = {Reversion of the malignant phenotype of human breast cells in three-dimensional culture and in vivo by integrin blocking antibodies.}, journal = {J Cell Biol}, volume = {137}, year = {1997}, month = {1997 Apr 7}, pages = {231-45}, abstract = {

In a recently developed human breast cancer model, treatment of tumor cells in a 3-dimensional culture with inhibitory beta1-integrin antibody or its Fab fragments led to a striking morphological and functional reversion to a normal phenotype. A stimulatory beta1-integrin antibody proved to be ineffective. The newly formed reverted acini re-assembled a basement membrane and re-established E-cadherin-catenin complexes, and re-organized their cytoskeletons. At the same time they downregulated cyclin D1, upregulated p21(cip,wat-1), and stopped growing. Tumor cells treated with the same antibody and injected into nude mice had significantly reduced number and size of tumors in nude mice. The tissue distribution of other integrins was also normalized, suggesting the existence of intimate interactions between the different integrin pathways as well as adherens junctions. On the other hand, nonmalignant cells when treated with either alpha6 or beta4 function altering antibodies continued to grow, and had disorganized colony morphologies resembling the untreated tumor colonies. This shows a significant role of the alpha6/beta4 heterodimer in directing polarity and tissue structure. The observed phenotypes were reversible when the cells were disassociated and the antibodies removed. Our results illustrate that the extracellular matrix and its receptors dictate the phenotype of mammary epithelial cells, and thus in this model system the tissue phenotype is dominant over the cellular genotype.

}, keywords = {Animals, Antibodies, Monoclonal, Antigens, CD, Antigens, CD29, Basement Membrane, Binding, Competitive, Breast Neoplasms, Cell Division, Extracellular Matrix, Female, Fluorescent Antibody Technique, Genotype, Humans, Immunoglobulin Fab Fragments, Integrin beta4, Mice, Phenotype, Rats, Signal Transduction, Transformation, Genetic, Tumor Cells, Cultured}, issn = {0021-9525}, author = {Weaver, V M and Petersen, O W and Wang, F and Larabell, C A and Briand, P and Damsky, C and Bissell, M J} } @article {566, title = {The importance of the microenvironment in breast cancer progression: recapitulation of mammary tumorigenesis using a unique human mammary epithelial cell model and a three-dimensional culture assay.}, journal = {Biochem Cell Biol}, volume = {74}, year = {1996}, month = {1996}, pages = {833-51}, abstract = {

The extracellular matrix (ECM) is a dominant regulator of tissue development and homeostasis. \"Designer microenvironments\" in culture and in vivo model systems have shown that the ECM regulates growth, differentiation, and apoptosis in murine and human mammary epithelial cells (MEC) through a hierarchy of transcriptional events involving the intricate interplay between soluble and physical signaling pathways. Furthermore, these studies have shown that these pathways direct and in turn are influenced by the tissue structure. Tissue structure is directed by the cooperative interactions of the cell-cell and cell-ECM pathways and can be modified by stromal factors. Not surprisingly then, loss of tissue structure and alterations in ECM components are associated with the appearance and dissemination of breast tumors, and malignancy is associated with perturbations in cell adhesion, changes in adhesion molecules, and a stromal reaction. Several lines of evidence now support the contention that the pathogenesis of breast cancer is determined (at least in part) by the dynamic interplay between the ductal epithelial cells, the microenvironment, and the tissue structure (acini). Thus, to understand the mechanisms involved in carcinogenesis, the role of the microenvironment (ECM as well as the stromal cells) with respect to tissue structure should be considered and studied. Towards this goal, we have established a unique human MEC model of tumorigenesis, which in concert with a three-dimensional assay, recapitulates many of the genetic and morphological changes observed in breast in cancer in vivo. We are currently using this system to understand the role of the microenvironment and tissue structure in breast cancer progression.

}, keywords = {Animals, Breast Neoplasms, Cell Adhesion, Epithelium, Extracellular Matrix, Humans, Models, Biological, Tumor Cells, Cultured}, issn = {0829-8211}, author = {Weaver, V M and Fischer, A H and Peterson, O W and Bissell, M J} }