Suppression of ICE and apoptosis in mammary epithelial cells by extracellular matrix

Of plasticity and specificity: dialectics of the microenvironment and macroenvironment and the organ phenotype

The study of biological form and how it arises is the domain of the developmental biologists; but once the form is achieved, the organ poses a fascinating conundrum for all the life scientists: how are form and function maintained in adult organs throughout most of the life of the organism? That they do appears to contradict the inherently plastic nature of organogenesis during development. How do cells with the same genetic information arrive at, and maintain such different architectures and functions, and how do they keep remembering that they are different from each other? It is now clear that narratives based solely on genes and an irreversible regulatory dynamics cannot answer these questions satisfactorily, and the concept of microenvironmental signaling needs to be added to the equation. During development, cells rearrange and differentiate in response to diffusive morphogens, juxtacrine signals, and the extracellular matrix (ECM). These components, which constitute the modular microenvironment, are sensitive to cues from other tissues and organs of the developing embryo as well as from the external macroenvironment. On the other hand, once the organ is formed, these modular constituents integrate and constrain the organ architecture, which ensures structural and functional homeostasis and therefore, organ specificity. We argue here that a corollary of the above is that once the organ architecture is compromised in adults by mutations or by changes in the microenvironment such as aging or inflammation, that organ becomes subjected to the developmental and embryonic circuits in search of a new identity. But since the microenvironment is no longer embryonic, the confusion leads to cancer: hence as we have argued, tumors become new evolutionary organs perhaps in search of an elusive homeostasis.

ROCK1 inhibition promotes the self-renewal of a novel mouse mammary cancer stem cell

The differentiation of stem-like tumor cells may contribute to the cellular heterogeneity of breast cancers. We report the propagation of highly enriched mouse mammary cancer stem cells that retain the potential to differentiate both in vivo and in culture and their use to identify chemical compounds that influence both self-renewal and differentiation. We identify epithelial tumor-initiating cells (ETICs) that express lineage markers of both basal and luminal mammary cell lineages and retain the potential, from even single cells, to generate heterogeneous tumors similar to the tumor of origin. ETICs can progress through a Rho-associated coiled-coil containing protein kinase 1 dependent, epithelial to mesenchymal transition to generate mesenchymal tumor-initiating cells capable of initiating tumors of limited heterogeneity. The propagation of ETICs may allow for the identification of new therapeutic compounds that may inhibit or prevent progression of some types of breast cancer.

The perivascular niche regulates breast tumour dormancy

In a significant fraction of breast cancer patients, distant metastases emerge after years or even decades of latency. How disseminated tumor cells (DTCs) are kept dormant, and what ‘wakes them up’, are fundamental problems in tumor biology. To address these questions, we utilized metastasis assays in mice to show that dormant DTCs reside upon microvasculature of lung, bone marrow and brain. We then engineered organotypic microvascular niches to determine whether endothelial cells directly influence breast cancer cell (BCC) growth. These models demonstrated that endothelial-derived thrombospondin-1 induces sustained BCC quiescence. This suppressive cue was lost in sprouting neovasculature; time-lapse analysis showed that sprouting vessels not only permit, but accelerate BCC outgrowth. We confirmed this surprising result in dormancy models and in zebrafish, and identified active TGF-β1 and periostin as tumor-promoting, endothelial tip cell-derived factors. Our work reveals that stable microvasculature constitutes a ‘dormant niche,’ whereas sprouting neovasculature sparks micrometastatic outgrowth.

Mammary epithelial cell interactions with fibronectin stimulate epithelial-mesenchymal transition

In the mammary gland, the stromal extracellular matrix (ECM) undergoes dramatic changes during development and in tumorigenesis. For example, normal adult breast tissue is largely devoid of the ECM protein fibronectin (FN) whereas high FN levels have been detected in the stroma of breast tumors. FN is an established marker for epithelial-mesenchymal transition (EMT), which occurs during development and has been linked to cancer. During EMT, epithelial cell adhesion switches from cell-cell contacts to mainly cell-ECM interactions raising the possibility that FN may have a role in promoting this transition. Using MCF-10A mammary epithelial cells, we show that exposure to exogenous FN induces an EMT response including up-regulation of the EMT markers FN, Snail, N-cadherin, vimentin, the matrix metalloprotease MMP2, α-smooth muscle actin, and phospho-Smad2 as well as acquisition of cell migratory behavior. FN-induced EMT depends on Src kinase and ERK/MAP kinase signaling but not on the immediate early gene EGR-1. FN initiates EMT under serum-free conditions; this response is partially reversed by a TGFβ neutralizing antibody suggesting that FN enhances the effect of endogenous TGFβ. EMT marker expression is up-regulated in cells on a fragment of FN containing the integrin-binding domain but not other domains. Differences in gene expression between FN and MG are maintained with addition of a sub-threshold level of TGFβ1. Together, these results show that cells interacting with FN are primed to respond to TGFβ. The ability of FN to induce EMT shows an active role for the stromal ECM in this process and supports the notion that the increased levels of FN observed in breast tumors facilitate tumorigenesis.

The inflammasome as a target of modulation by DNA viruses

The cellular innate immune response represents the initial reaction of a host against infecting pathogens. Host cells detect incoming microbes by way of a large and expanding array of receptors that react with evolutionarily conserved molecular patterns exhibited by microbial intruders. These receptors are responsible for initiating signaling that leads to both transcriptional activation of immunologically important genes as well as protease-dependent processing of cellular proteins. The inflammasome refers to a protein complex that functions as an activation platform for the cysteine protease caspase-1, which then processes inflammatory molecules such as IL-1β and IL-18 into functional forms. Assembly of this complex is triggered following receptor-mediated detection of pathogen-associated molecules. Receptors have been identified that are essential to inflammasome activation in response to numerous molecular patterns including virus-associated molecules such as DNA. In fact, the importance of cytoplasmic DNA as an immune stimulus is exemplified by the existence of at least nine distinct cellular receptors capable of initiating innate reactivity in response to this molecule. Viruses that employ DNA as genomic material include herpesviruses, poxviruses and adenoviruses. Each has been described as capable of inducing inflammasome-mediated activity. Interestingly, however, the cellular molecules responsible for these responses appear to vary according to host species, cell type and even viral strain. Secretion of IL-1β and IL-18 are important components of antimicrobial immunity and, as a result, pathogens have evolved factors to evade or counteract this response. This includes DNA-based viruses, many of which encode multiple redundant counteractive molecules. However, it is clear that such phenotypes are only beginning to be uncovered. The purpose of this review is to describe what is known regarding the activation of inflammasome-mediated processes in response to infection with well-examined families of DNA viruses and to discuss characterized mechanisms of manipulation and neutralization of inflammasome-dependent activity. This review aims to shed light on the biologically important phenomena regarding this virus-host interaction and to highlight key areas where important information is lacking.

Resilin-Like Polypeptide Hydrogels Engineered for Versatile Biological Functions

Natural resilin, the rubber-like protein that exists in specialized compartments of most arthropods, possesses excellent mechanical properties such as low stiffness, high resilience and effective energy storage. Recombinantly-engineered resilin-like polypeptides (RLPs) that possess the favorable attributes of native resilin would be attractive candidates for the modular design of biomaterials for engineering mechanically active tissues. Based on our previous success in creating a novel RLP-based hydrogel and demonstrating useful mechanical and cell-adhesive properties, we have produced a suite of new RLP-based constructs, each equipped with 12 repeats of the putative resilin consensus sequence and a single, distinct biologically active domain. This approach allows independent control over the concentrations of cell-binding, MMP-sensitive, and polysaccharide-sequestration domains in hydrogels comprising mixtures of the various RLPs. The high purity, molecular weight and correct compositions of each new polypeptide have been confirmed via high performance liquid chromatography (HPLC), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and amino acid analysis. These RLP-based polypeptides exhibit largely random-coil conformation, both in solution and in the cross-linked hydrogels, as indicated by circular dichroic and infrared spectroscopic analyses. Hydrogels of various compositions, with a range of elastic moduli (1kPa to 25kPa) can be produced from these polypeptides, and the activity of the cell-binding and matrix metalloproteinase (MMP) sensitive domains was confirmed. Tris(hydroxymethyl phosphine) cross-linked RLP hydrogels were able to maintain their mechanical integrity as well as the viability of encapsulated primary human mesenchymal stem cells (MSCs). These results validate the promising properties of these RLP-based elastomeric biomaterials.

Three-dimensional culture of human breast epithelial cells: the how and the why

Organs are made of the organized assembly of different cell types that contribute to the architecture necessary for functional differentiation. In those with exocrine function, such as the breast, cell-cell and cell-extracellular matrix (ECM) interactions establish mechanistic constraints and a complex biochemical signaling network essential for differentiation and homeostasis of the glandular epithelium. Such knowledge has been elegantly acquired for the mammary gland by placing epithelial cells under three-dimensional (3D) culture conditions.Three-dimensional cell culture aims at recapitulating normal and pathological tissue architectures, hence providing physiologically relevant models to study normal development and disease. The specific architecture of the breast epithelium consists of glandular structures (acini) connected to a branched ductal system. A single layer of basoapically polarized luminal cells delineates ductal or acinar lumena at the apical pole. Luminal cells make contact with myoepithelial cells and, in certain areas at the basal pole, also with basement membrane (BM) components. In this chapter, we describe how this exquisite organization as well as stages of disorganization pertaining to cancer progression can be reproduced in 3D cultures. Advantages and limitations of different culture settings are discussed. Technical designs for induction of phenotypic modulations, biochemical analyses, and state-of-the-art imaging are presented. We also explain how signaling is regulated differently in 3D cultures compared to traditional two-dimensional (2D) cultures. We believe that using 3D cultures is an indispensable method to unravel the intricacies of human mammary functions and would best serve the fight against breast cancer.

Amniotic membrane in oral and maxillofacial surgery

PURPOSE

Following its renaissance in ophthalmology during the 1990s, preserved human amniotic membrane (HAM) has become an attractive biomaterial for all surgical disciplines. This article reviews the current and potential use of HAM in oral and maxillofacial surgery, its postulated properties and common preservation techniques.

METHODS

Literature was identified by an electronic search of PubMed in July 2012; this was supplemented from the reference lists of the consulted papers.

RESULTS

HAM has been used in the field of oral and maxillofacial surgery from 1969 onwards because of its immunological preference and its pain-reducing, antimicrobial, mechanical and side-dependent adhesive or anti-adhesive properties. The effects of HAM on dermal and mucosal re-epithelialisation have been highlighted. Typically, HAM is applied after being banked in a glycerol-preserved, DMSO-preserved or freeze-dried and irradiated state. Whereas the use of HAM in flap surgery and in intra-oral and extra-oral lining is reported frequently, novel HAM applications in post-traumatic orbital surgery and temporomandibular joint surgery have been added since 2010. Tissue engineering with HAM is a fast-expanding field with a high variety of future options.

CONCLUSIONS

Preserved HAM is considered to be a safe and sufficient biomaterial in all fields of oral and maxillofacial wound healing. Recently published novel indications for HAM application lack a high level of evidence and need to be studied further.

The behavior of matrix metalloproteinases and their inhibitors in colorectal cancer

Matrix metalloproteinases (MMPs) play an important role in the degradation of extracellular matrix components crucial for tumor growth, invasion and metastasis. MMPs are controlled by natural inhibitors called tissue inhibitors of metalloproteinases (TIMPs). We and others have demonstrated that MMPs and TIMPs are especially important in the process of tumor invasion, progression and the metastasis of colorectal cancer (CRC). It has been proposed that MMPs and TIMPs might play a part not only in tumor invasion and initiation of metastasis but also in carcinogenesis from colorectal adenomas. Several recent studies demonstrated that high preoperative serum or plasma MMP-2, MMP-9 and TIMP-1 antigen levels are strong predictive factors for poor prognosis in patients with CRC and their determination might be useful for identification of patients with higher risk for cancer recurrence. MMP-9 and TIMP-1 have significant potential tumor marker impact in CRC. Their diagnostic sensitivity is consistently higher than those of conventional biomarkers. The pharmacological targeting of CRC by the development of a new generation of selective inhibitors of MMPs, that is highly specific for certain MMPs, is a promising and challenging area for the future.

Three-dimensional culture models of mammary gland

The mammary gland is a complex tissue comprised of a branching network of ducts embedded within an adipocyte-rich stroma. The ductal epithelium is a bi-layer of luminal and myoepithelial cells, the latter being in contact with a basement membrane. During pregnancy, tertiary branching occurs and lobuloalveolar structures, which produce milk during lactation, form in response to hormonal and cytokine signals. Postlactational regression is characterized by extensive cell death and tissue remodeling. These complex developmental events have been difficult to mimic in cell culture although many useful culture models exist. Recently, considerable advances in three-dimensional modelling of the mammary gland have been made with the use of collagen and other biomaterials for the study of branching morphogenesis and tumorigenesis, techniques which may enable rapid advances in our understanding of both basic biology and the study of cancer therapeutics.

Integrins, adhesion and apoptosis

Integrin-mediated adhesion to extracellular matrix proteins is required for survival of many cell types. This phenomenon appears to be a mechanism of tumour suppression and to participate in embryogenesis. Here, our current understanding of how integrin-dependent signals prevent apoptosis and implications of anchorage-dependent survival for development, physiology and pathology are discussed.

New insights into the kinetic resistance to anticancer agents

Kinetic resistance plays a major role in the failure of chemotherapy towards many solid tumors. Kinetic resistance to cytotoxic drugs can be reproduced in vitro by growing the cells as multicellular spheroids (Multicellular Resistance) or as hyperconfluent cultures (Confluence-Dependent Resistance). Recent findings on the cell cycle regulation have permitted a better understanding why cancer cells which arrest in long quiescent phases are poorly sensitive to cell-cycle specific anticancer drugs. Two cyclin-dependent kinase inhibitors (CDKI) seem particularly involved in the cell cycle arrest at the G1 to S transition checkpoint: the p53-dependent p21(cip1) protein which is activated by DNA damage and the p27(kip1) which is a mediator of the contact inhibition signal. Cell quiescence could alter drug-induced apoptosis which is partly dependent on an active progression in the cell cycle and which is facilitated by overexpression of oncogenes such as c-Myc or cyclins. Investigations are yet necessary to determine the influence of the cell cycle on the balance between antagonizing (bcl-2, bcl-X(L)...) or stimulating (Bax, Bcl-X(S), Fas...) factors in chemotherapy-induced apoptosis. Quiescent cells could also be protected from toxic agents by an enhanced expression of stress proteins, such as HSP27 which is induced by confluence. New strategies are required to circumvent kinetic resistance of solid tumors: adequate choice of anticancer agents whose activity is not altered by quiescence (radiation, cisplatin), recruitment from G1 to S/G2 phases by cell pretreatment with alkylating drugs or attenuation of CDKI activity by specific inhibitors.

Apoptosis resistance in tumor cells

Various antitumor agents induce apoptotic cell death in tumor cells. Since the apoptosis program in tumor cells plays a critical role in the chemotherapy-induced tumor cell killing, it is suggested that the defect in the signaling pathway of apoptosis could cause a new form of multidrug resistance in tumor cells. This article describes the recent findings concerning the mechanisms of chemotherapy-induced apoptosis and discusses the implication of apoptosis resistance in cancer chemotherapy.

Gene transfection of multicellular spheroid of hepatocytes on an artificial substrate

The handling of hepatocytes, a major cell population in the liver, is an important technique in both liver tissue engineering and hepatology. However, these cells are so fragile that it has been impossible to harvest hepatocytes with high viability from tissue culture dishes after a period of culture in vitro. In this study, we employed an artificial substrate for transfection of multilayer hepatocytes and harvested these cells with high viability after transfection. Hepatocytes cultured on an amphiphilic artificial substrate form multilayer aggregates (spheroids) in the presence of growth factors during gene transfection with cation liposomes. Compared to cells cultured on a collagen-coated plate, these spheroids are easily harvested with high viability by pipetting in EDTA solution. In addition, these spheroids rapidly spread on collagen after transfer from the artificial substrate, demonstrating that hepatocytes in the center of the spheroids were viable. Epidermal growth factor (EGF) increased the transfection efficiency into hepatocytes while hepatocyte growth factor (HGF) alone did not increase the efficiency. However, HGF synergestically increased the effect of EGF on transfection. Interestingly, this transfection required the process of spheroid formation because the gene was not transfected once the spheroid formation completed or under conditions where hepatocytes did not form spheroids. This method using spheroidal hepatocytes for in vitro transfection is promising for the development of ex vivo gene therapy.

Evaluation of predictive markers for patients with advanced colorectal cancer

BACKGROUND

To evaluate the predictive and prognostic value of serum and plasma tumor markers, in comparison with clinical and biomedical parameters for response rate (RR), progression-free survival (PFS) and overall survival (OS) among patients with metastatic colorectal cancer (mCRC) treated with combination chemotherapy.

MATERIAL AND METHODS

One-hundred and six patients with mCRC from three centers, part of a multicenter study, received irinotecan with the Nordic bolus 5-fluorouracil (5-FU) and folinic acid schedule (FLIRI) or the de Gramont schedule (Lv5FU2-IRI). Blood samples for CEA, CA19-9, TPA, TIMP-1, SAA, transthyretin and CRP were taken at baseline and after two, four and eight weeks of treatment. Tumor marker levels at baseline and longitudinally were compared with responses evaluated (CT/MRI) after two and four months of treatment. The correlations to RR, PFS and OS were evaluated with regression analyses.

RESULTS

A significant correlation to OS was seen for baseline levels of all markers. In multivariate analyses with clinical parameters, TPA, CRP, SAA and TIMP-1 provided independent information. The baseline values of CEA, TPA and TIMP-1 were also significantly correlated to PFS and TPA to RR. Changes during treatment, i.e. the slope gave with the exception of CA19-9 for OS less information about outcomes. The best correlation to response was seen for CEA, CA19-9 and TPA with AUC values of 0.78, 0.83 and 0.79, respectively, using a combined model based upon an interaction between the slope and the baseline value.

CONCLUSIONS

Baseline tumor markers together with clinical parameters provide prognostic information about survival in patients with mCRC. The ability of the individual tumor markers to predict treatment response and PFS is limited. Changes in marker levels during the first two months of treatment are less informative of outcome.

PAR6B is required for tight junction formation and activated PKCζ localization in breast cancer

Dysregulation of mechanisms that govern the control of epithelial cell polarity, morphology and plasticity are emerging as key processes in tumor progression. In this study we report amplification and overexpression of PAR6B, an essential component in epithelial cell tight junction (TJ) formation and maintenance of apico-basal polarity, in breast cancer cell lines. Analysis of chromosome 20q13.13 in 11 breast cancer cell lines by fluorescence in situ hybridization (FISH) identified a novel small amplicon centered at PARD6B in 5 cell lines, with copy number ranging from 7 to 27. The presence of the PARD6B amplicon correlated with PARD6B transcript and PAR6B protein abundance. Expression of related isoforms PARD6A and PARD6G were detectable at significantly lower levels. PARD6B overexpression correlated with TJ network formation in cultured cell monolayers. SiRNA-mediated inhibition of PAR6B in MCF7 resulted in loss of TJ assembly and membrane localization of atypical PKCζ (aPKC), but did not affect adherens junction formation. SiRNA-mediated inhibition of CDC42 in MCF7 also resulted in loss of TJ networks, confirming the requirement of a complete PAR6-aPKC-CDC42-PAR3 complex to activate and stabilize TJs. Immunohistochemical analysis of PAR6B expression on breast tumor microarrays indicated exquisite epithelial cell-specificity. Few quantitative differences in staining were observed between normal epithelium and adjacent tumor margins. However staining appeared reduced and cytoplasmic in more poorly differentiated tumors. We propose that quantitative imbalances in the components of pathways governing normal epithelial cell polarity arising from gain or loss of function may radically alter epithelial cell architecture and contribute to tumor progression.

Amniotic membrane: from structure and functions to clinical applications

Amniotic membrane (AM) or amnion is a thin membrane on the inner side of the fetal placenta; it completely surrounds the embryo and delimits the amniotic cavity, which is filled by amniotic liquid. In recent years, the structure and function of the amnion have been investigated, particularly the pluripotent properties of AM cells, which are an attractive source for tissue transplantation. AM has anti-inflammatory, anti-bacterial, anti-viral and immunological characteristics, as well as anti-angiogenic and pro-apoptotic features. AM is a promoter of epithelialization and is a non-tumorigenic tissue and its use has no ethical problems. Because of its attractive properties, AM has been applied in several surgical procedures related to ocular surface reconstruction and the genito-urinary tract, skin, head and neck, among others. So far, the best known and most auspicious applications of AM are ocular surface reconstruction, skin applications and tissue engineering. However, AM can also be applied in oncology. In this area, AM can prevent the delivery of nutrients and oxygen to cancer cells and consequently interfere with tumour angiogenesis, growth and metastasis.

Mouse stem cells seeded into decellularized rat kidney scaffolds endothelialize and remodel basement membranes

INTRODUCTION

To address transplant organ shortage, a promising strategy is to decellularize kidneys in a manner that the scaffold retains signals for seeded pluripotent precursor cells to differentiate and recapitulate native structures: matrix-to-cell signaling followed by cell-cell and cell-matrix interactions, thereby remodeling and replacing the original matrix. This would reduce scaffold antigenicity and enable xeno-allografts.

RESULTS

DAPI-labeled cells in arterial vessels and glomeruli were positive for both endothelial lineage markers, BsLB4 and VEGFR2. Rat scaffold's basement membrane demonstrated immunolabeling with anti-mouse laminin β1. Labeling intensified over time with 14 day incubations.

CONCLUSION

We provide new evidence for matrix-to-cell signaling in acellular whole organ scaffolds that induces differentiation of pluripotent precursor cells to endothelial lineage. Production of mouse basement membrane supports remodeling of host (rat)-derived scaffolds and thereby warrants further investigation as a promising approach for xenotransplantation.

METHODS

We previously showed that murine embryonic stem cells arterially seeded into acellular rat whole kidney scaffolds multiply and demonstrate morphologic, immunohistochemical and gene expression evidence for differentiation. Vascular cell endothelialization was now further tested by endothelial specific BsLB4 lectin and anti-VEGFR2 (Flk1) antibodies. Remodeling of the matrix basement membranes from rat to mouse ("murinization") was assessed by a monoclonal antibody specific for mouse laminin β1 chain.

Molecular alterations associated with osteosarcoma development

Osteosarcoma is the most frequent malignant primary bone tumor characterized by a high potency to form lung metastases which is the main cause of death. Unfortunately, the conventional chemotherapy is not fully effective on osteosarcoma metastases. The progression of a primary tumor to metastasis requires multiple processes, which are neovascularization, proliferation, invasion, survival in the bloodstream, apoptosis resistance, arrest at a distant organ, and outgrowth in secondary sites. Consequently, recent studies have revealed new insights into the molecular mechanisms of metastasis development. The understanding of the mechanism of molecular alterations can provide the identification of novel therapeutic targets and/or prognostic markers for osteosarcoma treatment to improve the clinical outcome.

The tumor microenvironment is a dominant force in multidrug resistance

The emergence of clinical drug resistance is still one of the most challenging factors in cancer treatment effectiveness. Until more recently, the assumption has been that random genetic lesions are sufficient to explain the progression of malignancy and escape from chemotherapy. Here we propose an additional perspective, one in which the tumor cells despite the malignant genome could find a microenvironment either within the tumor or as a dormant cell to remain polar and blend into an organized context. Targeting this dynamic interplay could be considered a new avenue to prevent therapeutic resistance, and may even provide a promising effective cancer treatment.

Interconnected contribution of tissue morphogenesis and the nuclear protein NuMA to the DNA damage response

Epithelial tissue morphogenesis is accompanied by the formation of a polarity axis--a feature of tissue architecture that is initiated by the binding of integrins to the basement membrane. Polarity plays a crucial role in tissue homeostasis, preserving differentiation, cell survival and resistance to chemotherapeutic drugs among others. An important aspect in the maintenance of tissue homeostasis is genome integrity. As normal tissues frequently experience DNA double-strand breaks (DSBs), we asked how tissue architecture might participate in the DNA damage response. Using 3D culture models that mimic mammary glandular morphogenesis and tumor formation, we show that DSB repair activity is higher in basally polarized tissues, regardless of the malignant status of cells, and is controlled by hemidesmosomal integrin signaling. In the absence of glandular morphogenesis, in 2D flat monolayer cultures, basal polarity does not affect DNA repair activity but enhances H2AX phosphorylation, an early chromatin response to DNA damage. The nuclear mitotic apparatus protein 1 (NuMA), which controls breast glandular morphogenesis by acting on the organization of chromatin, displays a polarity-dependent pattern and redistributes in the cell nucleus of basally polarized cells upon the induction of DSBs. This is shown using high-content analysis of nuclear morphometric descriptors. Furthermore, silencing NuMA impairs H2AX phosphorylation--thus, tissue polarity and NuMA cooperate to maintain genome integrity.

Matrix metalloproteinases

Remodeling of extracellular matrix is crucial for many physiological (cell migration, proliferation, growth, and development) and pathological (remodeling of heart, carcinogenesis, metastasis, etc.) events. Thus, the interaction between cells and extracellular matrix plays a key role in normal development and differentiation of organism and many pathological states as well. Changes in extracellular matrix are regulated by a system of proteolytic enzymes that are responsible for proteolysis of huge quantity of extracellular matrix components. Matrix metalloproteinases (MMPs) represent the main group of regulating proteases in ECM. Ability of matrix metalloproteinases to modify the structural integrity of tissues is essential for certain aspects of normal physiology and pathology. The ability to process molecules such as growth factors, receptors, adhesion molecules, other proteinases, and proteinase inhibitors makes MMPs potent controllers of physiological and pathological events in the cell microenvironment. Overactivation of MMPs has been implicated in numerous disease states.

Three-dimensional culture of human breast epithelial cells: the how and the why

Organs are made of the organized assembly of different cell types that contribute to the architecture necessary for functional differentiation. In those with exocrine function, such as the breast, cell-cell and cell-extracellular matrix (ECM) interactions establish mechanistic constraints and a complex biochemical signaling network essential for differentiation and homeostasis of the glandular epithelium. Such knowledge has been elegantly acquired for the mammary gland by placing epithelial cells under three-dimensional (3D) culture conditions.Three-dimensional cell culture aims at recapitulating normal and pathological tissue architectures, hence providing physiologically relevant models to study normal development and disease. The specific architecture of the breast epithelium consists of glandular structures (acini) connected to a branched ductal system. A single layer of basoapically polarized luminal cells delineates ductal or acinar lumena at the apical pole. Luminal cells make contact with myoepithelial cells and, in certain areas at the basal pole, also with basement membrane (BM) components. In this chapter, we describe how this exquisite organization as well as stages of disorganization pertaining to cancer progression can be reproduced in 3D cultures. Advantages and limitations of different culture settings are discussed. Technical designs for induction of phenotypic modulations, biochemical analyses, and state-of-the-art imaging are presented. We also explain how signaling is regulated differently in 3D cultures compared to traditional two-dimensional (2D) cultures. We believe that using 3D cultures is an indispensable method to unravel the intricacies of human mammary functions and would best serve the fight against breast cancer.

Cooling rate dependent biophysical and viability response shift with attachment state in human dermal fibroblast cells

While studies on the freezing of cells in suspension have been carried out extensively, corresponding studies with cells in the attached state and in tissue or tissue-equivalents are less developed. As attachment is a hallmark of the tissue state it is important to understand its impact on biophysics and viability to better apply freezing towards tissue preservation. The current study reports on observed biophysical response changes observed during freezing human dermal fibroblasts in suspension, attached cell, and fibrin tissue-equivalent models. Specifically, intracellular ice formation is shown to increase and dehydration is inferred to increase from suspension to attached systems. Biophysical model parameters fit to these experimental observations reflect the higher kinetics in the attached state. Post-thaw viability values from fast cooling rates were higher for suspension systems, and correlated well with the amount of IIF observed. On the other hand, viability values from slow cooling rates were higher for attached systems, although the degree of dehydration was predicted to be comparable to suspension cells. This disconnect between biophysics and viability predictions at slow rates clearly requires further investigation as it runs counter to our current understanding of dehydration injury in cells. This may suggest a possible protective effect of the attachment state on cell systems.

Mechanisms by which the extracellular matrix and integrin signaling act to regulate the switch between tumor suppression and tumor promotion

Cell adhesion to the extracellular matrix (ECM) is necessary for development of the mammary gland, and to maintain the normal architecture and function of the gland. Cells adhere to the ECM via the integrin family of trans-membrane receptors, which signal to control mammary-specific gene expression and regulate cell proliferation and survival. During tumor formation, the ECM is extensively remodeled and signaling through integrins is altered such that cells become proliferative and invasive. A key regulator of whether integrin-mediated adhesion will promote tumor suppression or tumor formation is the stiffness of the stromal ECM. The normal mammary gland is typically surrounded by a loose collagenous stroma. An increase in the deposition of collagen and other stromal components is associated with mammographic density, which is one of the greatest risk factors for developing breast carcinoma. Several groups have demonstrated that increased stromal ECM density results in a matrix that is stiffer. Cells sense the stiffness of their surrounding ECM by Rho-mediated contraction of the actin-myosin cytoskeleton. If the surrounding ECM is stiffer than the cell's ability to contract it, then the tensile forces that result are able to drive the clustering of integrins and assemble adhesion signaling complexes. The result is subsequent activation of signaling pathways including FAK, ERK, and PI3K that drive cell proliferation and survival. In contrast, focal complexes are not formed in a compliant matrix, and activation of FAK and pERK is diminished, resulting in control of proliferation. Signaling from FAK moreover regulates p53 and miR-200 members, which control apoptosis and epithelial phenotype, such that a compliant matrix is predicted to promote normal mammary gland architecture and suppress tumor formation.

Differential expression of FAK and Pyk2 in metastatic and non-metastatic EL4 lymphoma cell lines

The murine EL4 lymphoma cell line exists in variants that are either sensitive or resistant to phorbol 12-myristate 13-acetate (PMA). In sensitive cells, PMA causes Erk MAPK activation and Erk-mediated growth arrest. In resistant cells, PMA induces a low level of Erk activation, without growth arrest. A relatively unexplored aspect of the phenotypes is that resistant cells are more adherent to culture substrate than are sensitive cells. In this study, the roles of the protein tyrosine kinases FAK and Pyk2 in EL4 phenotype were examined, with a particular emphasis on the role of these proteins in metastasis. FAK is expressed only in PMA-resistant (or intermediate phenotype) EL4 cells, correlating with enhanced cell-substrate adherence, while Pyk2 is more highly expressed in non-adherent PMA-sensitive cells. PMA treatment causes modulation of mRNA for FAK (up-regulation) and Pyk2 (down-regulation) in PMA-sensitive but not PMA-resistant EL4 cells. The increase in Pyk2 mRNA is correlated with an increase in Pyk2 protein expression. The roles of FAK in cell phenotype were further explored using transfection and knockdown experiments. The results showed that FAK does not play a major role in modulating PMA-induced Erk activation in EL4 cells. However, the knockdown studies demonstrated that FAK expression is required for proliferation and migration of PMA-resistant cells. In an experimental metastasis model using syngeneic mice, only FAK-expressing (PMA-resistant) EL4 cells form liver tumors. Taken together, these studies suggest that FAK expression promotes metastasis of EL4 lymphoma cells.

Plasma gelsolin facilitates interaction between β2 glycoprotein I and α5β1 integrin

Antiphospholipid syndrome (APS) is characterized by thrombosis and the presence of antiphospholipid antibodies (aPL) that directly recognizes plasma β₂-glycoprotein I (β₂GPI). Tissue factor (TF), the major initiator of the extrinsic coagulation system, is induced on monocytes by aPL in vitro, explaining in part the pathophysiology in APS. We previously reported that the mitogen-activated protein kinase (MAPK) pathway plays an important role in aPL-induced TF expression on monocytes. In this study, we identified plasma gelsolin as a protein associated with β₂GPI by using immunoaffinity chromatography and mass spectrometric analysis. An in vivo binding assay showed that endogenous β₂GPI interacts with plasma gelsolin, which binds to integrin a₅β₁ through fibronectin. The tethering of β₂GPI to monoclonal anti-β₂GPI autoantibody on the cell surface was enhanced in the presence of plasma gelsolin. Immunoblot analysis demonstrated that p38 MAPK protein was phosphorylated by monoclonal anti-β₂GPI antibody treatment, and its phosphorylation was attenuated in the presence of anti-integrin a₅β₁ antibody. Furthermore, focal adhesion kinase, a downstream molecule of the fibronectin-integrin signalling pathway, was phosphorylated by anti-β₂GPI antibody treatment. These results indicate that molecules including gelsolin and integrin are involved in the anti-β₂GPI antibody-induced MAPK pathway on monocytes and that integrin is a possible therapeutic target to modify a prothrombotic state in patients with APS.

Role of DDR1 in the gelatinases secretion induced by native type IV collagen in MDA-MB-231 breast cancer cells

Discoidin domain receptors (DDRs) are receptor tyrosine kinases that get activated by collagens in its native triple-helical form. In mammalian cells, DDR family consists of two members, namely DDR1 and DDR2, which mediates migration and proliferation of several cell types. DDR1 is activated by native type IV collagen and overexpressed in human breast cancer. Type IV collagen is the main component of basement membrane (BM), and the ability to degrade and penetrate BM is related with an increased potential for invasion and metastasis. Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that collectively are capable of degrading all components of the extracellular matrix, including the BM. In breast cancer cells, denatured type IV collagen induces MMP-9 secretion and invasion. However, the role of DDR1 in the regulation of gelatinases (MMP-2 and -9) secretion and invasion in breast cancer cells remains to be studied. We demonstrate here that native type IV collagen induces MMP-2 and -9 secretions and invasion through a DDR1 and Src-dependent pathway, together with an increase of MMP-2 and -9-cell surface levels. MMP-2 and -9 secretions require PKC kinase activity, epidermal growth factor receptor (EGFR) activation, arachidonic acid (AA) production and AA metabolites in MDA-MB-231 breast cancer cells. In summary, our data demonstrate, for the first time, that DDR1 mediates MMP-2 and -9 secretions and invasion induced by native type IV collagen in MDA-MB-231 breast cancer cells.

Phenotypic transition maps of 3D breast acini obtained by imaging-guided agent-based modeling

We introduce an agent-based model of epithelial cell morphogenesis to explore the complex interplay between apoptosis, proliferation, and polarization. By varying the activity levels of these mechanisms we derived phenotypic transition maps of normal and aberrant morphogenesis. These maps identify homeostatic ranges and morphologic stability conditions. The agent-based model was parameterized and validated using novel high-content image analysis of mammary acini morphogenesis in vitro with focus on time-dependent cell densities, proliferation and death rates, as well as acini morphologies. Model simulations reveal apoptosis being necessary and sufficient for initiating lumen formation, but cell polarization being the pivotal mechanism for maintaining physiological epithelium morphology and acini sphericity. Furthermore, simulations highlight that acinus growth arrest in normal acini can be achieved by controlling the fraction of proliferating cells. Interestingly, our simulations reveal a synergism between polarization and apoptosis in enhancing growth arrest. After validating the model with experimental data from a normal human breast line (MCF10A), the system was challenged to predict the growth of MCF10A where AKT-1 was overexpressed, leading to reduced apoptosis. As previously reported, this led to non growth-arrested acini, with very large sizes and partially filled lumen. However, surprisingly, image analysis revealed a much lower nuclear density than observed for normal acini. The growth kinetics indicates that these acini grew faster than the cells comprising it. The in silico model could not replicate this behavior, contradicting the classic paradigm that ductal carcinoma in situ is only the result of high proliferation and low apoptosis. Our simulations suggest that overexpression of AKT-1 must also perturb cell-cell and cell-ECM communication, reminding us that extracellular context can dictate cellular behavior.

Cellular microenvironment influences the ability of mammary epithelia to undergo cell cycle

The use of cell culture models is a principal and fundamental technology used in understanding how mammalian cells work. However, for some cell types such as mammary epithelia, the lines selected for extended culture are often transformed or have chromosomal abnormalities, while primary cultures have such a curtailed lifespan that their use is restricted. For example, mammary luminal epithelial cells (MECs) are used to study mechanisms of breast cancer, but the proliferation of primary cell cultures is highly limited. Here we describe the establishment of a new culture system to allow extended analysis of cultures of primary mouse MECs. In 2D monolayer culture, primary MECs showed a burst of proliferation 2-3 days post isolation, after which cell cycle decreased substantially. Addition of mammary epithelial growth factors, such as Epidermal Growth Factor, Fibroblast Growth Factor-2, Hepatocyte Growth Factor, and Receptor Activator for Nuclear Factor κB Ligand, or extracellular matrix proteins did not maintain their proliferation potential, neither did replating the cells to increase the mitogenic response. However, culturing MECs directly after tissue extraction in a 3D microenvironment consisting of basement membrane proteins, extended the time in culture in which the cells could proliferate. Our data reveal that the cellular microenvironment has profound effects on the proliferative properties of the mammary epithelia and is dominant over growth factors. Moreover, manipulating the cellular environment using this novel method can maintain the proliferative potential of primary MECs, thus enabling cell cycle to be studied as an endpoint after gene transfer or gene deletion experiments.

Use of human amniotic membrane as an interpositional material in treatment of temporomandibular joint ankylosis

PURPOSE

The aim of the study was to demonstrate whether the human amniotic membrane (HAM) as an interpositional material could prevent temporomandibular joint (TMJ) reankylosis in the randomized rabbit model.

MATERIALS AND METHODS

In our experimental study, 24 New Zealand white rabbits were used and all right joints were operated. The rabbits were divided into 2 groups. The first group was specified as the demonstration group (n = 8). In this group, fibrous ankylosis formation was shown experimentally. The rabbits in the second group, the treatment group (n = 16), were divided into 2 subgroups: gap arthroplasty, performed in group A (n = 8); and HAM, used as an interpositional arthroplasty material in group B (n = 8).

RESULTS

In all rabbits, the range of jaw movements and weight decreased after induction of ankylosis. After surgical treatment of fibrous ankylosis, the vertical, right, and left movements of the jaw and weights of rabbits increased immediately. The results were evaluated clinically, macroscopically, histologically, and radiologically. There was a statistically significant difference in the jaw movements between groups A and B (P < .05). All operated joints in group A showed fibrous adhesions across the gap, and the articular surface was irregular with osteophytes and bony islands on the joint surface. In group B, no fibrous adhesions were observed.

CONCLUSION

It was concluded that interpositional arthroplasty with HAM was superior to gap arthroplasty in the rabbit model in preventing ankylosis.

Zinc in specialized secretory tissues: roles in the pancreas, prostate, and mammary gland

Zinc (Zn) is an essential micronutrient required for over 300 different cellular processes, including DNA and protein synthesis, enzyme activity, and intracellular signaling. Cellular Zn homeostasis necessitates the compartmentalization of Zn into intracellular organelles, which is tightly regulated through the integration of Zn transporting mechanisms. The pancreas, prostate, and mammary gland are secretory tissues that have unusual Zn requirements and thus must tightly regulate Zn metabolism through integrating Zn import, sequestration, and export mechanisms. Recent findings indicate that these tissues utilize Zn for basic cellular processes but also require Zn for unique cellular needs. In addition, abundant Zn is transported into the secretory pathway and a large amount is subsequently secreted in a tightly regulated manner for unique biological processes. Expression of numerous members of the SLC30A (ZnT) and SLC39A (Zip) gene families has been documented in these tissues, yet there is limited understanding of their precise functional role in Zn metabolism or their regulation. Impairments in Zn secretion from the pancreas, prostate, and mammary gland are associated with disorders such as diabetes, infertility, and cancer, respectively. In this review, we will provide a brief summary of the specific role of Zn in each tissue and describe our current knowledge regarding how Zn metabolism is regulated. Finally, in each instance, we will reflect upon how this information shapes our current understanding of the role of Zn in these secretory tissues with respect to human health and disease.

Dissecting regional variations in stress fiber mechanics in living cells with laser nanosurgery

The ability of a cell to distribute contractile stresses across the extracellular matrix in a spatially heterogeneous fashion underlies many cellular behaviors, including motility and tissue assembly. Here we investigate the biophysical basis of this phenomenon by using femtosecond laser nanosurgery to measure the viscoelastic recoil and cell-shape contributions of contractile stress fibers (SFs) located in specific compartments of living cells. Upon photodisruption and recoil, myosin light chain kinase-dependent SFs located along the cell periphery display much lower effective elasticities and higher plateau retraction distances than Rho-associated kinase-dependent SFs located in the cell center, with severing of peripheral fibers uniquely triggering a dramatic contraction of the entire cell within minutes of fiber irradiation. Image correlation spectroscopy reveals that when one population of SFs is pharmacologically dissipated, actin density flows toward the other population. Furthermore, dissipation of peripheral fibers reduces the elasticity and increases the plateau retraction distance of central fibers, and severing central fibers under these conditions triggers cellular contraction. Together, these findings show that SFs regulated by different myosin activators exhibit different mechanical properties and cell shape contributions. They also suggest that some fibers can absorb components and assume mechanical roles of other fibers to stabilize cell shape.

Native type IV collagen induces cell migration through a CD9 and DDR1-dependent pathway in MDA-MB-231 breast cancer cells

CD9 is a member of the tetraspanin family and is widely expressed in the plasma membrane of several cell types as well as malignant cells. CD9 associates with a number of transmembrane proteins, which facilitates biological processes, including cell signaling, adhesion, migration and proliferation. DDR1 is activated by native type IV collagen and overexpressed in human breast cancer. Type IV collagen is the main component of basement membranes, and may interact with cell surface biomolecules, promoting adhesion and motility. However, the role of DDR1 and type IV collagen in the regulation of CD9-cell surface levels and migration in breast cancer cells has not been studied in detail. We demonstrate here that native type IV collagen induces a transient increase of CD9-cell surface levels through a DDR1-dependent pathway in MDA-MB-231 breast cancer cells, as revealed by flow cytometry and Western blotting using specific antibodies that recognize CD9. In contrast, type IV collagen does not induce any increase of CD9-cell surface levels in the mammary non-tumorigenic epithelial cells MCF10A and MCF12A. Transient increase of CD9-cell surface levels is coupled with clathrin-mediated endocytosis and it is dependent of DDR1 expression. In addition, type IV collagen induces cell migration through a DDR1 and CD9-dependent pathway. In summary, our data demonstrate, for the first time, that native type IV collagen induces a transient increase of CD9-cell surface levels and cell migration through a DDR1 and CD9-dependent pathway in MDA-MB-231 breast cancer cells.

Rac1 is essential for basement membrane-dependent epiblast survival

During murine peri-implantation development, the egg cylinder forms from a solid cell mass by the apoptotic removal of inner cells that do not contact the basement membrane (BM) and the selective survival of the epiblast epithelium, which does. The signaling pathways that mediate this fundamental biological process are largely unknown. Here we demonstrate that Rac1 ablation in embryonic stem cell-derived embryoid bodies (EBs) leads to massive apoptosis of epiblast cells in contact with the BM. Expression of wild-type Rac1 in the mutant EBs rescues the BM-contacting epiblast, while expression of a constitutively active Rac1 additionally blocks the apoptosis of inner cells and cavitation, indicating that the spatially regulated activation of Rac1 is required for epithelial cyst formation. We further show that Rac1 is activated through integrin-mediated recruitment of the Crk-DOCK180 complex and mediates BM-dependent epiblast survival through activating the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway. Our results reveal a signaling cascade triggered by cell-BM interactions essential for epithelial morphogenesis.

Connective Tissue Growth Factor (CTGF/CCN2) enhances lactogenic differentiation of mammary epithelial cells via integrin-mediated cell adhesion

Background

Connective Tissue Growth Factor (CTGF/CCN2), a known matrix-associated protein, is required for the lactogenic differentiation of mouse mammary epithelial cells. An HC11 mammary epithelial cell line expressing CTGF/CCN2 was constructed to dissect the cellular responses to CTGF/CCN2 that contribute to this differentiation program.

Results

Tetracycline-regulated expression of CTGF/CCN2 in HC11 cells enhanced multiple markers of lactogenic differentiation including β-casein transcription and mammosphere formation. In a separate measure of mammary differentiation the addition of CTGF/CCN2 to cultures of MCF10A cells increased the development of acini in vitro. In HC11 cells the elevated levels of CTGF/CCN2 diminished the requirement for extracellular matrix proteins in the activation of β-casein transcription, indicating that CTGF/CCN2 contributed to lactogenic differentiation through the regulation of matrix dependent cell adhesion. CTGF/CCN2 expression in HC11 cells increased expression of extracellular matrix proteins and integrins, enhanced the formation of focal adhesion complexes, and increased survival signaling. In addition, HC11 cells adhered to immobilized CTGF/CCN2 and this was inhibited by function-blocking antibodies to the integrins α6 and β1, and to a lesser degree by antibody to β3 integrin.

Conclusions

CTGF/CCN2 expression in HC11 cells led to an increase in multiple markers of lactogenic differentiation. The mechanisms by which CTGF/CCN2 contributed to lactogenic differentiation include direct binding of CTGF/CCN2 to integrin complexes and CTGF/CCN2-induced matrix protein expression resulting in elevated integrin functionality.

Understanding micrometastatic disease and Anoikis resistance in ewing family of tumors and osteosarcoma

Detection of micrometastatic tumor cells in the bone marrow or peripheral blood of patients with Ewing family of tumors (EFTs) and osteosarcoma has been shown to correlate with poor outcome. Although one of the aims of chemotherapy is eradication of micrometastatic disease, these cells vary phenotypically from primary tumor cells and appear to be more resistant to chemotherapy. As a barrier to metastasis, cells normally undergo a form of cell death termed anoikis after they lose contact with the extracellular matrix or neighboring cells. Tumor cells that acquire malignant potential have developed mechanisms to resist anoikis and thereby survive after detachment from their primary site and while traveling through the circulation. Investigating mechanisms of resistance to anoikis, therefore, provides a valuable model to investigate regulation of micrometastatic disease. This review focuses on the current understanding of the mechanisms involved in mediating cell survival and resistance to anoikis in EFTs and osteosarcoma and discusses future studies that may help to identify novel therapeutics targeted at micrometastatic disease.

Jaagsiekte sheep retrovirus transformation in Madin-Darby canine kidney epithelial cell three-dimensional culture

Jaagsiekte sheep retrovirus (JSRV) is the causative agent of a contagious lung cancer in sheep that shares similarities with human bronchioloalveolar carcinoma (BAC). JSRV is unique because the envelope gene (env) is the oncogene, as it can transform cells in culture and induce tumors in animals. The phosphatidylinositol 3-kinase (PI3K)-Akt-mTOR and H/N-Ras-MEK-mitogen-activated protein kinase (MAPK) pathways have been shown to be critical for Env transformation. However, the question still remains of how disruption of these pathways relates to tumor formation. To address this, JSRV Env transformation was studied in the context of epithelial structure, using the polarized Madin-Darby canine kidney (MDCK) epithelial cell three-dimensional (3-D) culture system. The results indicated that JSRV Env-transformed MDCK cells were larger and had full or multiple lumens, in contrast to the single lumens observed in controls. The altered phenotype was largely mediated by an increase in proliferation, in addition to overcoming the proliferative suppression signal. JSRV Env was not found to disrupt polarity or tight junctions or to inhibit lumen apoptosis. The PI3K-Akt-mTOR pathway was important for Env transformation in MDCK cells, although the mechanisms of action differed in 3-D and monolayer cultures. PI3K-dependent signaling to mTOR occurred in monolayers, while PI3K-independent signaling to mTOR occurred in 3-D culture. In contrast, the H/N-Ras-MEK-MAPK pathway was found to be inhibitory to transformation in both normal and transformed MDCK cells in 3-D culture. However, in monolayer culture, inhibition of MEK reverted the transformed phenotype, suggesting a different mechanism(s) of action in monolayer versus 3-D culture.

A computational approach to resolve cell level contributions to early glandular epithelial cancer progression

Background

Three-dimensional (3D) embedded cell cultures provide an appropriate physiological environment to reconstruct features of early glandular epithelial cancer. Although these are orders of magnitude simpler than tissues, they too are complex systems that have proven challenging to understand. We used agent-based, discrete event simulation modeling methods to build working hypotheses of mechanisms of epithelial 3D culture phenotype and early cancer progression. Starting with an earlier software analogue, we validated an improved in silico epithelial analogue (ISEA) for cardinal features of a normally developed MDCK cyst. A set of axiomatic operating principles defined simulated cell actions. We explored selective disruption of individual simulated cell actions. New framework features enabled recording detailed measures of ISEA cell activities and morphology.

Results

Enabled by a small set of cell operating principles, ISEA cells multiplied and self-organized into cyst-like structures that mimicked those of MDCK cells in a 3D embedded cell culture. Selective disruption of "anoikis" or directional cell division caused the ISEA to develop phenotypic features resembling those of in vitro tumor reconstruction models and cancerous tissues in vivo. Disrupting either process, or both, altered cell activity patterns that resulted in morphologically similar outcomes. Increased disruption led to a prolonged presence of intraluminal cells.

Conclusions

ISEA mechanisms, behaviors, and morphological properties may have biological counterparts. To the extent that in silico-to-in vitro mappings are valid, the results suggest plausible, additional mechanisms of in vitro cancer reconstruction or reversion, and raise potentially significant implications for early cancer diagnosis based on histology. Further ISEA development and use are expected to provide a viable platform to complement in vitro methods for unraveling the mechanistic basis of epithelial morphogenesis and cancer progression.

Upregulation of Hic-5 in glomerulosclerosis and its regulation of mesangial cell apoptosis

Glomerulosclerosis is characterized by the loss of glomerular cells by apoptosis and deposition of collagen type I into the normal collagen IV-containing mesangial matrix. We sought to determine the alterations that might contribute to these changes by performing proteomic analysis of rat mesangial cell lysates comparing cells cultured on normal collagen type IV to those grown on abnormal collagen type I surfaces. Subculture on collagen type I was associated with changed expression of several proteins, including a significant upregulation of the paxillin-like LIM protein, hydrogen-peroxide-induced clone 5 (Hic-5), and increased the susceptibility of the cells to apoptosis in response to physiological triggers. When we knocked down Hic-5 (using siRNA), we found mesangial cells grown on collagen type I were protected from apoptosis to the same degree as untreated cells grown on collagen type IV. Further we found that the level of Hic-5 in vivo was almost undetectable in control rats but increased dramatically in the glomerular mesangium of remnant kidneys 90 and 120 days after subtotal nephrectomy. This induction of Hic-5 paralleled the upregulation of mesangial collagen type I expression and glomerular cell apoptosis. Our results suggest that Hic-5 is pivotal in mediating the response of mesangial cells to attachment on abnormal extracellular matrix during glomerular scarring.

Calreticulin: non-endoplasmic reticulum functions in physiology and disease

Calreticulin (CRT), when localized to the endoplasmic reticulum (ER), has important functions in directing proper conformation of proteins and glycoproteins, as well as in homeostatic control of cytosolic and ER calcium levels. There is also steadily accumulating evidence for diverse roles for CRT localized outside the ER, including data suggesting important roles for CRT localized to the outer cell surface of a variety of cell types, in the cytosol, and in the extracellular matrix (ECM). Furthermore, the addition of exogenous CRT rescues numerous CRT-driven functions, such as adhesion, migration, phagocytosis, and immunoregulatory functions of CRT-null cells. Recent studies show that topically applied CRT has diverse and profound biological effects that enhance cutaneous wound healing in animal models. This evidence for extracellular bioactivities of CRT has provided new insights into this classically ER-resident protein, despite a lack of knowledge of how CRT exits from the ER to the cell surface or how it is released into the extracellular milieu. Nonetheless, it has become clear that CRT is a multicompartmental protein that regulates a wide array of cellular responses important in physiological and pathological processes, such as wound healing, the immune response, fibrosis, and cancer.-Gold, L. I., Eggleton, P., Sweetwyne, M. T., Van Duyn, L. B., Greives, M. R., Naylor, S.-M., Michalak, M., Murphy-Ullrich, J. E. Calreticulin: non-endoplamic reticulum functions in physiology and disease.

Monocyte derived microvesicles deliver a cell death message via encapsulated caspase-1

Apoptosis depends upon the activation of intracellular caspases which are classically induced by either an intrinsic (mitochondrial based) or extrinsic (cytokine) pathway. However, in the process of explaining how endotoxin activated monocytes are able to induce apoptosis of vascular smooth muscle cells when co-cultured, we uncovered a transcellular apoptosis inducing pathway that utilizes caspase-1 containing microvesicles. Endotoxin stimulated monocytes induce the cell death of VSMCs but this activity is found in 100,000 g pellets of cell free supernatants of these monocytes. This activity is not a direct effect of endotoxin, and is inhibited by the caspase-1 inhibitor YVADcmk but not by inhibitors of Fas-L, IL-1beta and IL-18. Importantly, the apoptosis inducing activity co-purifies with 100 nm sized microvesicles as determined by TEM of the pellets. These microvesicles contain caspase-1 and caspase-1 encapsulation is required since disruption of microvesicular integrity destroys the apoptotic activity but not the caspase-1 enzymatic activity. Thus, monocytes are capable of delivering a cell death message which depends upon the release of microvesicles containing functional caspase-1. This transcellular apoptosis induction pathway describes a novel pathway for inflammation induced programmed cell death.

Embryonic stem cells proliferate and differentiate when seeded into kidney scaffolds

The scarcity of transplant allografts for diseased organs has prompted efforts at tissue regeneration using seeded scaffolds, an approach hampered by the enormity of cell types and complex architectures. Our goal was to decellularize intact organs in a manner that retained the matrix signal for differentiating pluripotent cells. We decellularized intact rat kidneys in a manner that preserved the intricate architecture and seeded them with pluripotent murine embryonic stem cells antegrade through the artery or retrograde through the ureter. Primitive precursor cells populated and proliferated within the glomerular, vascular, and tubular structures. Cells lost their embryonic appearance and expressed immunohistochemical markers for differentiation. Cells not in contact with the basement membrane matrix became apoptotic, thereby forming lumens. These observations suggest that the extracellular matrix can direct regeneration of the kidney, and studies using seeded scaffolds may help define differentiation pathways.