Mammary epithelial cell: influence of extracellular matrix composition and organization during development and tumorigenesis

CD98hc facilitates B cell proliferation and adaptive humoral immunity

The proliferation of antigen-specific lymphocytes and resulting clonal expansion are essential for adaptive immunity. We report here that B cell-specific deletion of the heavy chain of CD98 (CD98hc) resulted in lower antibody responses due to total suppression of B cell proliferation and subsequent plasma cell formation. Deletion of CD98hc did not impair early B cell activation but did inhibit later activation of the mitogen-activated protein kinase Erk1/2 and downregulation of the cell cycle inhibitor p27. Reconstitution of CD98hc-deficient B cells with CD98hc mutants showed that the integrin-binding domain of CD98hc was required for B cell proliferation but that the amino acid-transport function of CD98hc was dispensable for this. Thus, CD98hc supports integrin-dependent rapid proliferation of B cells. We propose that the advantage of adaptive immunity favored the appearance of CD98hc in vertebrates.

Signal co-operation between integrins and other receptor systems

The multicellular nature of metazoans means that all cellular processes need to be tuned by adhesive interactions between cells and their local microenvironment. The spatial organization of cells within tissues requires sophisticated networks of extracellular signals to control their survival and proliferation, movements and positioning, and differentiated function. These cellular characteristics are mediated by multiple inputs from adhesion systems in combination with soluble and developmental signals. In the present review we explore how one class of adhesion receptor, the integrins, co-operate with other types of receptor to control diverse aspects of cell fate. In particular we discuss: (i) how β3 and β1 integrins work together with growth factors to control angiogenesis; (ii) how α6β4 integrin co-operates with receptor tyrosine kinases in normal epithelial function and cancer; (iii) the interplay between β1 integrins and EGF (epidermal growth factor) receptor; (iv) signal integration connecting integrins and cytokine receptors for interleukins, prolactin and interferons; and (v) how integrins and syndecans co-operate in cell migration.

The carboxyl terminal trimer of procollagen I induces pro-metastatic changes and vascularization in breast cancer cells xenografts

BACKGROUND

The COOH terminal peptide of Pro-collagen type I (PICP, also called C3) is chemotactic for endothelial melanoma and breast cancer cells. PICP induces the expression of Metalloproteinases-2 and -9, of Vascular endothelial growth factor and of the chemokine CXCL-12 receptor CXCR4 in MDA MB231 breast carcinoma cells in vitro.

METHODS

We used a model of xenografts in BalbC/nude mice obtaining tumors by implanting in contro-lateral subcutaneous positions MDA MB231 cells added or not with purified PICP and studied the earlier phases of tumor development, up to 48 days from implant, by histology, immunostain and in situ hybridization.

RESULTS

Addition of PICP promotes rapid vascularization of the tumors while does not affect mitotic and apoptotic indexes and overall tumor growth. PICP-treated, relative to control tumors, show up-modulation of Vascular endothelial factor, Metalloproteinase-9 and CXCR4, all tumor prognostic genes; they also show down-modulation of the endogenous Metalloproteinase inhibitor, reversion-inducing-cysteine-rich protein with kazal motifs, and a different pattern of modulation of Tissue Inhibitor of Metalloproteinase-2. These changes occur in absence of detectable expression of CXCL-12, up to 38 days, in control and treated tumors.

CONCLUSION

PICP has an early promoting effect in the acquisition by the tumors of prometastatic phenotype. PICP may be play a relevant role in the productive interactions between stroma and tumor cells by predisposing the tumor cells to respond to the proliferation stimuli ensuing the activation of signaling by engagement of CXCR4 by cytokines and by fostering their extravasion, due to the induction of increased vascular development.

Biomechanical regulation of cell orientation and fate

Biomechanical regulation of tumor phenotypes have been noted for several decades, yet the function of mechanics in the co-evolution of the tumor epithelium and altered cancer extracellular matrix has not been appreciated until fairly recently. In this review, we examine the dynamic interaction between the developing epithelia and the extracellular matrix, and discuss how similar interactions are exploited by the genetically modified epithelium during tumor progression. We emphasize the process of mechanoreciprocity, which is a phenomenon observed during epithelial transformation, in which tension generated within the extracellular microenvironment induce and cooperate with opposing reactive forces within transformed epithelium to drive tumor progression and metastasis. We highlight the importance of matrix remodeling, and present a new, emerging paradigm that underscores the importance of tissue morphology as a key regulator of epithelial cell invasion and metastasis.

A photo-modulatable material for probing cellular responses to substrate rigidity

Recent studies indicate that extracellular mechanical properties, including rigidity, profoundly affect cellular morphology, growth, migration, and differentiation [R. J. Pelham, Jr. and Y. Wang, Proc. Natl. Acad. Sci. U. S. A., 1997, 94(25), 13661-13665; H. B. Wang, M. Dembo and Y. L. Wang, Am. J. Physiol. Cell Physiol., 2000, 279(5), C1345-C1350; P. C. Georges, and P. A. Janmey, J. Appl. Physiol., 2005, 98(4), 1547-1553; C. M. Lo, H. B. Wang, M. Dembo and Y. L. Wang, Biophys. J., 2000. 79(1), 144-152; D. E. Discher, P. Janmey and Y. L. Wang, Science, 2005, 310(5751), 1139-1143; A. J. Engler, M. A. Griffin, S. Sen, C. G. Bonnemann, H. L. Sweeney and D. E. Discher, J. Cell Biol., 2004, 166(6), 877-887]. However, most studies involving rigidity sensing have been performed by comparing cells on separate substrata of fixed stiffness. To allow spatial and/or temporal manipulation of mechanical properties, we have developed a modulatable hydrogel by reacting linear polyacrylamide (PA) with a photosensitive crosslinker. This material allows UV-mediated control of rigidity, softening by 20-30% upon irradiation at a dose tolerated by live cells. Global UV irradiation induces an immediate recoiling of 3T3 fibroblasts and a reduced spread area at steady state. Furthermore, localized softening of the posterior substratum of polarized cells causes no apparent effect, while softening of the anterior substratum elicits pronounced retraction, indicating that rigidity sensing is localized to the frontal region. This type of material allows precise spatial and temporal control of mechanical signals for both basic research and regenerative medicine.

Cell response to matrix mechanics: focus on collagen

Many model systems and measurement tools have been engineered for observing and quantifying the effect of mechanics on cellular response. These have contributed greatly to our current knowledge of the molecular events by which mechanical cues affect cell biology. Cell responses to the mechanical properties of type 1 collagen gels are discussed, followed by a description of a model system of very thin, mechanically tunable collagen films that evoke similar responses from cells as do gel systems, but have additional advantages. Cell responses to thin films of collagen suggest that at least some of the mechanical cues that cells can respond to in their environment occur at the sub-micron scale. Mechanical properties of thin films of collagen can be tuned without altering integrin engagement, and in some cases without altering topology, making them useful in addressing questions regarding the roles of specific integrins in transducing or mitigating responses to mechanical cues. The temporal response of cells to differences in ECM may provide insight into mechanisms of signal transduction.

From cells to organs: building polarized tissue

How do animal cells assemble into tissues and organs? A diverse array of tissue structures and shapes can be formed by organizing groups of cells into different polarized arrangements and by coordinating their polarity in space and time. Conserved design principles underlying this diversity are emerging from studies of model organisms and tissues. We discuss how conserved polarity complexes, signalling networks, transcription factors, membrane-trafficking pathways, mechanisms for forming lumens in tubes and other hollow structures, and transitions between different types of polarity, such as between epithelial and mesenchymal cells, are used in similar and iterative manners to build all tissues.

The prognostic impact of NF-kappaB p105, vimentin, E-cadherin and Par6 expression in epithelial and stromal compartment in non-small-cell lung cancer

Vimentin, nuclear factor-κB (NF-κB) p105, fascin, E-cadherin, TGF-β, Par6 and atypical PKC are molecular markers that play an important role in cell differentiation. Herein, we investigate their prognostic impact in primary non-small-cell carcinoma (NSCLC). Tumour tissue samples from 335 resected patients with stage I–IIIA were used. Tissue microarrays were constructed from duplicate cores of both neoplastic cells and stromal cells and were immunohistochemically evaluated. In univariate analyses, high tumour epithelial cell expressions of NF-κB p105 (P=0.02) and E-cadherin (P=0.03) were positive prognostic indicators for disease-specific survival (DSS), whereas high tumour epithelial cell expression of vimentin (P=0.001) was a negative prognostic indicator. High expression of NF-κB p105 (P=0.001) and Par6 (P=0.0001) in the stromal compartment correlated with a good prognosis. In multivariate analyses, the tumour epithelial cell expression of NF-κB p105 (P=0.0001) and vimentin (P=0.005) and the stromal cell expression of NF-κB p105 (P=0.007) and Par6 (P=0.0001) were independent prognostic factors for DSS. High expression of NF-κB p105 and low expression of vimentin in tumour epithelial cells are independent predictors of better survival in primary NSCLC. In stromal cells, high expressions of NF-κB p105 and Par6 are both favourable independent prognostic indicators.

Three-dimensional context regulation of metastasis

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.

Integrins in lens development and disease

Integrins are the major cell surface receptors for proteins in the extracellular matrix. These receptors form major cell signaling centers that are bidirectional, communicating messages between the cell and its environment. They are a large receptor family, with members well-known to regulate cellular processes essential to both development and disease. In this review we examine the literature regarding integrins in the lens. Here we cover integrin function in lens cell differentiation, in the development of the lens and in protection of the lens epithelial cell phenotype. In addition, we analyze the role of integrins in the progression of lens fibrotic diseases, focusing particularly on integrin regulation of TGFbeta signaling pathways in posterior capsule opacification (PCO) and anterior subcapsular cataract (ASC).

Focal adhesion kinase: targeting adhesion signaling pathways for therapeutic intervention

The tumor microenvironment plays a central role in cancer progression and metastasis. Within this environment, cancer cells respond to a host of signals including growth factors and chemotactic factors, as well as signals from adjacent cells, cells in the surrounding stroma, and signals from the extracellular matrix. Targeting the pathways that mediate many of these signals has been a major goal in the effort to develop therapeutics.

Gene regulatory networks in lactation: identification of global principles using bioinformatics

Background

The molecular events underlying mammary development during pregnancy, lactation, and involution are incompletely understood.

Results

Mammary gland microarray data, cellular localization data, protein-protein interactions, and literature-mined genes were integrated and analyzed using statistics, principal component analysis, gene ontology analysis, pathway analysis, and network analysis to identify global biological principles that govern molecular events during pregnancy, lactation, and involution.

Conclusion

Several key principles were derived: (1) nearly a third of the transcriptome fluctuates to build, run, and disassemble the lactation apparatus; (2) genes encoding the secretory machinery are transcribed prior to lactation; (3) the diversity of the endogenous portion of the milk proteome is derived from fewer than 100 transcripts; (4) while some genes are differentially transcribed near the onset of lactation, the lactation switch is primarily post-transcriptionally mediated; (5) the secretion of materials during lactation occurs not by up-regulation of novel genomic functions, but by widespread transcriptional suppression of functions such as protein degradation and cell-environment communication; (6) the involution switch is primarily transcriptionally mediated; and (7) during early involution, the transcriptional state is partially reverted to the pre-lactation state. A new hypothesis for secretory diminution is suggested – milk production gradually declines because the secretory machinery is not transcriptionally replenished. A comprehensive network of protein interactions during lactation is assembled and new regulatory gene targets are identified. Less than one fifth of the transcriptionally regulated nodes in this lactation network have been previously explored in the context of lactation. Implications for future research in mammary and cancer biology are discussed.

Parvin-beta inhibits breast cancer tumorigenicity and promotes CDK9-mediated peroxisome proliferator-activated receptor gamma 1 phosphorylation

Parvin-beta is a focal adhesion protein downregulated in human breast cancer cells. Loss of Parvin-beta contributes to increased integrin-linked kinase activity, cell-matrix adhesion, and invasion through the extracellular matrix in vitro. The effect of ectopic Parvin-beta expression on the transcriptional profile of MDA-MB-231 breast cancer cells, which normally do not express Parvin-beta, was evaluated. Particular emphasis was placed upon propagating MDA-MB-231 breast cancer cells in three-dimensional culture matrices. Interestingly, Parvin-beta reexpression in MDA-MB-231 cells increased the mRNA expression, serine 82 phosphorylation (mediated by CDK9), and activity of the nuclear hormone receptor peroxisome proliferator-activated receptor gamma (PPARgamma), and there was a concomitant increase in lipogenic gene expression as a downstream effector of PPARgamma. Importantly, Parvin-beta suppressed breast cancer growth in vivo, with associated decreased proliferation. These data suggest that Parvin-beta might influence breast cancer progression.