Tissue architecture: the ultimate regulator of epithelial function?

Topological packing statistics of living and nonliving matter

Complex disordered matter is of central importance to a wide range of disciplines, from bacterial colonies and embryonic tissues in biology to foams and granular media in materials science to stellar configurations in astrophysics. Because of the vast differences in composition and scale, comparing structural features across such disparate systems remains challenging. Here, by using the statistical properties of Delaunay tessellations, we introduce a mathematical framework for measuring topological distances between general three-dimensional point clouds. The resulting system-agnostic metric reveals subtle structural differences between bacterial biofilms as well as between zebrafish brain regions, and it recovers temporal ordering of embryonic development. We apply the metric to construct a universal topological atlas encompassing bacterial biofilms, snowflake yeast, plant shoots, zebrafish brain matter, organoids, and embryonic tissues as well as foams, colloidal packings, glassy materials, and stellar configurations. Living systems localize within a bounded island-like region of the atlas, reflecting that biological growth mechanisms result in characteristic topological properties.

Meibomian gland development: Where, when and how?

The Meibomian gland (MG) is an indispensable adnexal structure of eye that produces meibum, an important defensive component for maintaining ocular homeostasis. Normal development and maintenance of the MGs is required for ocular health since atrophic MGs and disturbances in composition and/or secretion of meibum result in major ocular pathologies, collectively termed as Meibomian gland dysfunction (MGD). Currently available therapies for MGD merely provide symptomatic relief and do not treat the underlying deficiency of the MGs. Hence, a thorough understanding of the timeline of MG development, maturation and aging is required for regenerative purposes along with signaling molecules & pathways controlling proper differentiation of MG lineage in mammalian eye. Understanding the factors that contribute to the development of MGs, developmental abnormalities of MGs, and changes in the quality & quantity of meibum with developing phases of MGs are essential for developing potential treatments for MGD. In this review, we compiled a timeline of events and the factors involved in the structural and functional development of MGs and the associated developmental defects of MGs during development, maturation and aging.

Evaluation of breast stiffness pathology based on breast compression during mammography: Proposal for novel breast stiffness scale classification

Breast cancer is diagnosed through a patient's Breast Self-Examination (BSE), Clinical Breast Examination (CBE), or para-clinical methods. False negativity of PCM in breast cancer diagnostics leads to a persisting problem associated with breast tumors diagnosed only in advanced stages. As the tumor volume/size at which it becomes invasive is not clear, BSE and CBE play an exceedingly important role in the early diagnosis of breast cancer. The quality and effectiveness of BSE and CBE depend on several factors, among which breast stiffness is the most important one. In this study, the authors present four methods for evaluating breast stiffness pathology during mammography examination based on the outputs obtained during the breast compression process, id est, without exposing the patient to X-Ray radiation. Based on the subjective assessment of breast stiffness by experienced medical examiners, a novel breast stiffness classification was designed, and the best method of its objective measurement was calibrated to fit the scale. Hence, this study provides an objective tool for the identification of patients who, being unable to perform valid BSE, could benefit from an increased frequency of mammography screening. Dum vivimus servimus.

A Bioprinted Tubular Intestine Model Using a Colon-Specific Extracellular Matrix Bioink

Tremendous advances have been made toward accurate recapitulation of the human intestinal system in vitro to understand its developmental process, and disease progression. However, current in vitro models are often confined to 2D or 2.5D microarchitectures, which is difficult to mimic the systemic level of complexity of the native tissue. To overcome this problem, physiologically relevant intestinal models are developed with a 3D hollow tubular structure using 3D bioprinting strategy. A tissue-specific biomaterial, colon-derived decellularized extracellular matrix (Colon dECM) is developed and it provides significant maturation-guiding potential to human intestinal cells. To fabricate a perfusable tubular model, a simultaneous printing process of multiple materials through concentrically assembled nozzles is developed and a light-activated Colon dECM bioink is employed by supplementing with ruthenium/sodium persulfate as a photoinitiator. The bioprinted intestinal tissue models show spontaneous 3D morphogenesis of the human intestinal epithelium without any external stimuli. In consequence, the printed cells form multicellular aggregates and cysts and then differentiate into several types of enterocytes, building junctional networks. This system can serve as a platform to evaluate the effects of potential drug-induced toxicity on the human intestinal tissue and create a coculture model with commensal microbes and immune cells for future therapeutics.

p73 as a Tissue Architect

The TP73 gene belongs to the p53 family comprised by p53, p63, and p73. In response to physiological and pathological signals these transcription factors regulate multiple molecular pathways which merge in an ensemble of interconnected networks, in which the control of cell proliferation and cell death occupies a prominent position. However, the complex phenotype of the Trp73 deficient mice has revealed that the biological relevance of this gene does not exclusively rely on its growth suppression effects, but it is also intertwined with other fundamental roles governing different aspects of tissue physiology. p73 function is essential for the organization and homeostasis of different complex microenvironments, like the neurogenic niche, which supports the neural progenitor cells and the ependyma, the male and female reproductive organs, the respiratory epithelium or the vascular network. We propose that all these, apparently unrelated, developmental roles, have a common denominator: p73 function as a tissue architect. Tissue architecture is defined by the nature and the integrity of its cellular and extracellular compartments, and it is based on proper adhesive cell-cell and cell-extracellular matrix interactions as well as the establishment of cellular polarity. In this work, we will review the current understanding of p73 role as a neurogenic niche architect through the regulation of cell adhesion, cytoskeleton dynamics and Planar Cell Polarity, and give a general overview of TAp73 as a hub modulator of these functions, whose alteration could impinge in many of the Trp73 ^-/- phenotypes.

Interactions and Feedbacks in E-Cadherin Transcriptional Regulation

Epithelial tissues rely on the adhesion between participating cells to retain their integrity. The transmembrane protein E-cadherin is the major protein that mediates homophilic adhesion between neighbouring cells and is, therefore, one of the critical components for epithelial integrity. E-cadherin downregulation has been described extensively as a prerequisite for epithelial-to-mesenchymal transition and is a hallmark in many types of cancer. Due to this clinical importance, research has been mostly focused on understanding the mechanisms leading to transcriptional repression of this adhesion molecule. However, in recent years it has become apparent that re-expression of E-cadherin is a major step in the progression of many cancers during metastasis. Here, we review the currently known molecular mechanisms of E-cadherin transcriptional activation and inhibition and highlight complex interactions between individual mechanisms. We then propose an additional mechanism, whereby the competition between adhesion complexes and heterochromatin protein-1 for binding to STAT92E fine-tunes the levels of E-cadherin expression in Drosophila but also regulates other genes promoting epithelial robustness. We base our hypothesis on both existing literature and our experimental evidence and suggest that such feedback between the cell surface and the nucleus presents a powerful paradigm for epithelial resilience.

Upregulation of Versican Associated with Tumor Progression, Metastasis, and Poor Prognosis in Bladder Carcinoma

Objective

This work analyzes the role of versican (VCAN) on bladder cancer (BLCA). Versican (VCAN) is a chondroitin sulfate proteoglycan which is important for tumorigenesis and the development of cancer. However, the expression of VCAN on human bladder cancer (BLCA) has been rarely reported.

Methods

The clinical significance of VCAN in BLCA has been determined by our bioinformatics tools. Then, we performed immunohistochemical staining (IHC) and analyzed the correlation between VCAN expression and clinicopathological features.

Results

The bioinformatics results reveal that a high VCAN mRNA level was significantly associated with stage, histological subtype, molecular subtype, and metastasis in BLCA. Furthermore, IHC reveals that expression of VCAN was significantly correlated with the number of tumors, invasion depth, lymph node metastasis, distant metastasis, and histological grade. Kaplan-Meier survival analysis reveals that patients with a high expression of VCAN have poor prognosis than those patients with a low expression of VCAN. According to our result from the bioinformatics database, the mechanism of VCAN in BLCA revealed that VCAN was related to FBN1 and genes of the ECM remodeling pathway (MMP1, MMP2).

Conclusion

VCAN expression might be included in the process of carcinogenesis and prognosis. Hence, VCAN could be a reliable biomarker of the clinical prognosis on BLCA.

The Usefulness of 4 Immunoperoxidase Stains Applied to Urinary Cytology Samples in the Pathologic Stage of Urothelial Carcinoma: A Study With Histologic Correlation

BACKGROUND

Currently, the golden rule for the diagnosis of urothelial carcinoma is biopsy and cystoscopy, unfortionally both are costly, invasive, and uncomfortable. While most urothelial cancers are noninvasive at presentation, it is necessary to find a highly sensitive, noninvasive way to diagnose in its earlier stages, Cytology with immunostaining is a noninvasive, reliable method that might play a role in detecting the earlier stages before its progression and accurate correlation with different stages of these tumors.

AIM

This study aimed to reach an accurate level in the staging of urothelial carcinoma using CD44, ProExC, Laminin, and Fascin on urinary cytology.

DESIGN

We include a total of 180 urinary cytology specimens with their surgical biopsies' counterparts, the staging of the surgical specimens were done according to AJCC2017TNM classification, while their counterpart urinary samples were centrifuged and the sediment was used for H&E and immunocytochemical staining with CD44, ProExC, Laminin, and Fascin.

RESULTS

The diagnosis of Ta-stage tumors was done according to the following immunohistochemical (IHC) profile [positive (+ve) CD44, negative (-ve) proExC, -ve Laminin, and -ve Fascin] with 100% sensitivity, 100% specificity. The diagnosis of Tis stage tumors was done according to IHC profile [-ve CD44, +ve proExC, -ve Laminin, and -ve Fascin] with 100% sensitivity, 93% specificity. The diagnosis of T1 stage tumors according to IHC profile [-ve CD44, +ve proExC, +ve Laminin, and -ve Fascin] with 100% sensitivity, 97% specificity, The diagnosis of T2 and T3 stage tumors was done according to IHC profile [-ve CD44, +ve proExC, +ve Laminin and weak to moderate +ve Fascin] with 100% sensitivity, 92% specificity, while the diagnosis of T4 stage tumors according to the IHC profile [-ve CD44, +ve proExC, +ve Laminin, and intense +ve Fascin] with 100% sensitivity, 100% specificity.

CONCLUSION

Using (CD44, ProExC, Laminin, and Fascin) on urinary cytology is a simple, reliable, and noninvasive method for the staging of urothelial carcinoma with 99% total accuracy.

Expression of laminin-5 gamma 2 chain predicts invasion of extramammary Paget's disease cell

Extramammary Paget's disease (EMPD) is a rare malignant skin neoplasm characterized by intraepidermal proliferation of tumor cells. The tumor cells of EMPD may sometimes invade into the dermis or metastasize into the regional lymph nodes. Several studies have proposed mechanisms underlying the increased invasiveness of EMPD; however, molecular markers indicating invasiveness have yet to be well characterized. Laminin-5 (Lam-5), a heterotrimer composed of three chains (α3, β3, and γ2), is a major component of the basement membrane in many tissues. One of the chains, Lam-5 γ2, is a marker of invasion, because it often develops as a monomer in malignant neoplasms. We investigated the expression of Lam-5 γ2 and its role for the invasiveness in EMPD. Paraffin-embedded specimens of EMPD obtained from 36 patients were examined immunohistochemically for Lam-5 γ2. The cases adopted into this study comprised 16 cases of intraepidermal lesions and 20 cases with dermal invasion. The basement membrane seen in normal skin disappeared in one-third of non-invasive cases and in most invasive cases. The disappearance of Lam-5 γ2 in the basement membrane and its cytoplasmic expression was more observed in the invasive cases than non-invasive cases. Expression of Lam-5 γ2 may be a biological marker to predict invasiveness of EMPD.

Tissue rheology in embryonic organization

Tissue morphogenesis in multicellular organisms is brought about by spatiotemporal coordination of mechanical and chemical signals. Extensive work on how mechanical forces together with the well-established morphogen signalling pathways can actively shape living tissues has revealed evolutionary conserved mechanochemical features of embryonic development. More recently, attention has been drawn to the description of tissue material properties and how they can influence certain morphogenetic processes. Interestingly, besides the role of tissue material properties in determining how much tissues deform in response to force application, there is increasing theoretical and experimental evidence, suggesting that tissue material properties can abruptly and drastically change in development. These changes resemble phase transitions, pointing at the intriguing possibility that important morphogenetic processes in development, such as symmetry breaking and self-organization, might be mediated by tissue phase transitions. In this review, we summarize recent findings on the regulation and role of tissue material properties in the context of the developing embryo. We posit that abrupt changes of tissue rheological properties may have important implications in maintaining the balance between robustness and adaptability during embryonic development.

Effect of Spheroidal Age on Sorafenib Diffusivity and Toxicity in a 3D HepG2 Spheroid Model

The enhanced predictive power of 3D multi-cellular spheroids in comparison to conventional monolayer cultures makes them a promising drug screening tool. However, clinical translation for pharmacology and toxicology is lagging its technological progression. Even though spheroids show a biological complexity resembling native tissue, standardization and validation of drug screening protocols are influenced by continuously changing physiological parameters during spheroid formation. Such cellular heterogeneities impede the comparability of drug efficacy studies and toxicological screenings. In this paper, we demonstrated that aside from already well-established physiological parameters, spheroidal age is an additional critical parameter that impacts drug diffusivity and toxicity in 3D cell culture models. HepG2 spheroids were generated and maintained on a self-assembled ultra-low attachment nanobiointerface and characterized regarding time-dependent changes in morphology, functionality as well as anti-cancer drug resistance. We demonstrated that spheroidal aging directly influences drug response due to the evolution of spheroid micro-structure and organo-typic functions, that alter inward diffusion, thus drug uptake.

Structures of collagen IV globular domains: insight into associated pathologies, folding and network assembly

Basement membranes are extracellular structures of epithelia and endothelia that have collagen IV scaffolds of triple α-chain helical protomers that associate end-to-end, forming networks. The molecular mechanisms by which the noncollagenous C-terminal domains of α-chains direct the selection and assembly of the α1α2α1 and α3α4α5 hetero-oligomers found in vivo remain obscure. Autoantibodies against the noncollagenous domains of the α3α4α5 hexamer or mutations therein cause Goodpasture's or Alport's syndromes, respectively. To gain further insight into oligomer-assembly mechanisms as well as into Goodpasture's and Alport's syndromes, crystal structures of non-collagenous domains produced by recombinant methods were determined. The spontaneous formation of canonical homohexamers (dimers of trimers) of these domains of the α1, α3 and α5 chains was shown and the components of the Goodpasture's disease epitopes were viewed. Crystal structures of the α2 and α4 non-collagenous domains generated by recombinant methods were also determined. These domains spontaneously form homo-oligomers that deviate from the canonical architectures since they have a higher number of subunits (dimers of tetramers and of hexamers, respectively). Six flexible structural motifs largely explain the architectural variations. These findings provide insight into noncollagenous domain folding, while supporting the in vivo operation of extrinsic mechanisms for restricting the self-assembly of noncollagenous domains. Intriguingly, Alport's syndrome missense mutations concentrate within the core that nucleates the folding of the noncollagenous domain, suggesting that this syndrome, when owing to missense changes, is a folding disorder that is potentially amenable to pharmacochaperone therapy.

Modeling Host-Pathogen Interactions in the Context of the Microenvironment: Three-Dimensional Cell Culture Comes of Age

Tissues and organs provide the structural and biochemical landscapes upon which microbial pathogens and commensals function to regulate health and disease. While flat two-dimensional (2-D) monolayers composed of a single cell type have provided important insight into understanding host-pathogen interactions and infectious disease mechanisms, these reductionist models lack many essential features present in the native host microenvironment that are known to regulate infection, including three-dimensional (3-D) architecture, multicellular complexity, commensal microbiota, gas exchange and nutrient gradients, and physiologically relevant biomechanical forces (e.g., fluid shear, stretch, compression). A major challenge in tissue engineering for infectious disease research is recreating this dynamic 3-D microenvironment (biological, chemical, and physical/mechanical) to more accurately model the initiation and progression of host-pathogen interactions in the laboratory. Here we review selected 3-D models of human intestinal mucosa, which represent a major portal of entry for infectious pathogens and an important niche for commensal microbiota. We highlight seminal studies that have used these models to interrogate host-pathogen interactions and infectious disease mechanisms, and we present this literature in the appropriate historical context. Models discussed include 3-D organotypic cultures engineered in the rotating wall vessel (RWV) bioreactor, extracellular matrix (ECM)-embedded/organoid models, and organ-on-a-chip (OAC) models. Collectively, these technologies provide a more physiologically relevant and predictive framework for investigating infectious disease mechanisms and antimicrobial therapies at the intersection of the host, microbe, and their local microenvironments.

A simple and cost-efficient adherent culture platform for human gastric primary cells, as an in vitro model for Helicobacter pylori infection

BACKGROUND

Most two- dimensional in vitro models for studying host- H. pylori interactions rely on tumor-derived cell lines, which harbor malignant alterations. The recent development of human gastric organoids has overcome this limitation and provides a highly sophisticated, yet costly, short-term model for H. pylori infection, with restricted use in low-budget centers.

METHOD

Tissue specimens from upper, middle, and lower stomachs of H. pylori-negative volunteers were collectively dispersed and cultured on mouse embryonic fibroblast (MEF) or collagen-coated plates. Gastric primary cells (GPCs) were evaluated by light microscopy, immunostaining, qRT-PCR and ELISA analysis of cellular secretions, before and after H. pylori infection.

RESULTS

The formation and long-term (up to 1 year) maintenance of GPCs was highly dependent on adherent inactivated MEF cells, cultured in enriched media. These cells were multipassageable and able to undergo stable freezer storage and subsequent revival. The cellular composition of GPCs included the combination of cytokeratin 18 (CK18) and E-cadherin (E-cad)-positive epithelial cells, MUC5AC-positive gastric cells, and leucine-rich repeat containing G protein-coupled receptor 5 (LGR5)-positive progenitor cells. These cells produced significant amounts of gastric pepsinogens I and II. GPCs also allowed for extended (up to 96 hours) H. pylori infection, during which they underwent morphological alterations (cellular vacuolation and elongation) and hyperproduction of gastric pepsinogens and inflammatory cytokines (IL-8 and TNF-α).

CONCLUSION

We, hereby, present a simple, consistent, and cost-efficient gastric cell culture system, which provides a suitable model for extended in vitro infection of H. pylori. This platform can be employed for a variety of gastric-related research.

Laminin signals initiate the reciprocal loop that informs breast-specific gene expression and homeostasis by activating NO, p53 and microRNAs

How mammalian tissues maintain their architecture and tissue-specificity is poorly understood. Previously, we documented both the indispensable role of the extracellular matrix (ECM) protein, laminin-111 (LN1), in the formation of normal breast acini, and the phenotypic reversion of cancer cells to acini-like structures in 3-dimensional (3D) gels with inhibitors of oncogenic pathways. Here, we asked how laminin (LN) proteins integrate the signaling pathways necessary for morphogenesis. We report a surprising reciprocal circuitry comprising positive players: laminin-5 (LN5), nitric oxide (NO), p53, HOXD10 and three microRNAs (miRNAs) — that are involved in the formation of mammary acini in 3D. Significantly, cancer cells on either 2-dimensional (2D) or 3D and non-malignant cells on 2D plastic do not produce NO and upregulate negative players: NFκB, EIF5A2, SCA1 and MMP-9 — that disrupt the network. Introducing exogenous NO, LN5 or individual miRNAs to cancer cells reintegrates these pathways and induces phenotypic reversion in 3D. These findings uncover the essential elements of breast epithelial architecture, where the balance between positive- and negative-players leads to homeostasis.

Most animal cells can secrete molecules into their surroundings to form a supportive meshwork of large proteins, called the extracellular matrix. This matrix is connected to the cell membrane through receptors that can transmit signals to the cell nucleus to change the levels of small RNA molecules called microRNAs. These, in turn, can switch genes on and off in the nucleus.

In the laboratory, cells that build breast tissue and glands can be grown in gels containing extracellular matrix proteins called laminins. Under these conditions, ‘normal’ cells form organized clusters that resemble breast glands. However, if the communication between healthy cells and the extracellular matrix is interrupted, the cells can become disorganized and start to form clumps that resemble tumors, and if injected into mice, can form tumors. Conversely, if the interaction between the extracellular matrix and the cells is restored, each single cancer cell can – despite mutations – be turned into a healthy-looking cell. These cells form a normal-looking tissue through a process called reversion. Until now, it was not known which signals help normal breast tissue to form, and how cancerous cells revert into a ‘normal’ shape.

To investigate this, Furuta et al. used a unique series of breast cells from a woman who underwent breast reduction. The cells taken from the discarded tissue had been previously grown by a different group of researchers in a specific way to ensure that both normal and eventual cancer cells were from the same individual. Furuta et al. then put these cells in the type of laminin found in extracellular matrix. The other set of cells used consisted of the same cancerous cells that had been reverted to normal-looking cells.

Analysis of the three cell sets identified 60 genes that were turned down in reverted cancer cells to a level found in healthy cells, as well as 10 microRNAs that potentially target these 60 genes. A database search suggested that three of these microRNAs, which are absent in cancer cells, are necessary for healthy breast cells to form organized structures. Using this as a starting point, Furuta et al. discovered a signaling loop that was previously unknown and that organizes breast cells into healthy looking tissue.

This showed that laminins help to produce nitric oxide, an important signaling molecule that activates several specific proteins inside the breast cells and restores the levels of the three microRNAs. These, in turn, switch off two genes that are responsible for activating an enzyme that can chop the laminins. Since the two genes are deactivated in the reverted cancer cells, the laminins remain intact and the cells can form organized structures. These findings suggest that if any of the components of the loop were missing, the cells would start to form cancerous clumps again. Reverting the cancer cells in the presence of laminins, however, could help cancer cells to form ‘normal’ structures again.

These findings shed new light on how the extracellular matrix communicates with proteins in the nucleus to influence how single cells form breast tissues. It also shows that laminins are crucial for generating signals that regulate both form and function of specific tissues. A better understanding of how healthy and cancerous tissues form and re-form may in the future help to develop new cancer treatments.

Extracellular chloride signals collagen IV network assembly during basement membrane formation

Basement membranes are defining features of the cellular microenvironment; however, little is known regarding their assembly outside cells. We report that extracellular Cl(-) ions signal the assembly of collagen IV networks outside cells by triggering a conformational switch within collagen IV noncollagenous 1 (NC1) domains. Depletion of Cl(-) in cell culture perturbed collagen IV networks, disrupted matrix architecture, and repositioned basement membrane proteins. Phylogenetic evidence indicates this conformational switch is a fundamental mechanism of collagen IV network assembly throughout Metazoa. Using recombinant triple helical protomers, we prove that NC1 domains direct both protomer and network assembly and show in Drosophila that NC1 architecture is critical for incorporation into basement membranes. These discoveries provide an atomic-level understanding of the dynamic interactions between extracellular Cl(-) and collagen IV assembly outside cells, a critical step in the assembly and organization of basement membranes that enable tissue architecture and function. Moreover, this provides a mechanistic framework for understanding the molecular pathobiology of NC1 domains.

Deep nuclear invaginations are linked to cytoskeletal filaments - integrated bioimaging of epithelial cells in 3D culture

The importance of context in regulation of gene expression is now an accepted principle; yet the mechanism by which the microenvironment communicates with the nucleus and chromatin in healthy tissues is poorly understood. A functional role for nuclear and cytoskeletal architecture is suggested by the phenotypic differences observed between epithelial and mesenchymal cells. Capitalizing on recent advances in cryogenic techniques, volume electron microscopy and super-resolution light microscopy, we studied human mammary epithelial cells in three-dimensional (3D) cultures forming growth-arrested acini. Intriguingly, we found deep nuclear invaginations and tunnels traversing the nucleus, encasing cytoskeletal actin and/or intermediate filaments, which connect to the outer nuclear envelope. The cytoskeleton is also connected both to other cells through desmosome adhesion complexes and to the extracellular matrix through hemidesmosomes. This finding supports a physical and/or mechanical link from the desmosomes and hemidesmosomes to the nucleus, which had previously been hypothesized but now is visualized for the first time. These unique structures, including the nuclear invaginations and the cytoskeletal connectivity to the cell nucleus, are consistent with a dynamic reciprocity between the nucleus and the outside of epithelial cells and tissues.

Embryo implantation triggers dynamic spatiotemporal expression of the basement membrane toolkit during uterine reprogramming

Basement membranes (BMs) are specialized extracellular scaffolds that influence behaviors of cells in epithelial, endothelial, muscle, nervous, and fat tissues. Throughout development and in response to injury or disease, BMs are fine-tuned with specific protein compositions, ultrastructure, and localization. These features are modulated through implements of the BM toolkit that is comprised of collagen IV, laminin, perlecan, and nidogen. Two additional proteins, peroxidasin and Goodpasture antigen-binding protein (GPBP), have recently emerged as potential members of the toolkit. In the present study, we sought to determine whether peroxidasin and GPBP undergo dynamic regulation in the assembly of uterine tissue BMs in early pregnancy as a tractable model for dynamic adult BMs. We explored these proteins in the context of collagen IV and laminin that are known to extensively change for decidualization. Electron microscopic analyses revealed: 1) a smooth continuous layer of BM in between the epithelial and stromal layers of the preimplantation endometrium; and 2) interrupted, uneven, and progressively thickened BM within the pericellular space of the postimplantation decidua. Quantification of mRNA levels by qPCR showed changes in expression levels that were complemented by immunofluorescence localization of peroxidasin, GPBP, collagen IV, and laminin. Novel BM-associated and subcellular spatiotemporal localization patterns of the four components suggest both collective pericellular functions and distinct functions in the uterus during reprogramming for embryo implantation.

Mammographically dense human breast tissue stimulates MCF10DCIS.com progression to invasive lesions and metastasis

Background

High mammographic density (HMD) not only confers a significantly increased risk of breast cancer (BC) but also is associated with BCs of more advanced stages. However, it is unclear whether BC progression and metastasis are stimulated by HMD. We investigated whether patient-derived HMD breast tissue could stimulate the progression of MCF10DCIS.com cells compared with patient-matched low mammographic density (LMD) tissue.

Methods

Sterile breast specimens were obtained immediately after prophylactic mastectomy from high-risk women (n = 10). HMD and LMD regions of each specimen were resected under radiological guidance. Human MCF10DCIS.com cells, a model of ductal carcinoma in situ (DCIS), were implanted into silicone biochambers in the groins of severe combined immunodeficiency mice, either alone or with matched LMD or HMD tissue (1:1), and maintained for 6 weeks. We assessed biochamber weight as a measure of primary tumour growth, histological grade of the biochamber material, circulating tumour cells and metastatic burden by luciferase and histology. All statistical tests were two-sided.

Results

HMD breast tissue led to increased primary tumour take, increased biochamber weight and increased proportions of high-grade DCIS and grade 3 invasive BCs compared with LMD. This correlated with an increased metastatic burden in the mice co-implanted with HMD tissue.

Conclusions

Our study is the first to explore the direct effect of HMD and LMD human breast tissue on the progression and dissemination of BC cells in vivo. The results suggest that HMD status should be a consideration in decision-making for management of patients with DCIS lesions.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0767-4) contains supplementary material, which is available to authorized users.

Stromal dynamic reciprocity in cancer: intricacies of fibroblastic-ECM interactions

Stromal dynamic reciprocity (SDR) consists of the biophysical and biochemical interplay between connective tissue elements that regulate and maintain organ homeostasis. In epithelial cancers, chronic alterations of SDR result in the once tumor-restrictive stroma evolving into a 'new' tumor-permissive environment. This altered stroma, known as desmoplasia, is initiated and maintained by cancer associated fibroblasts (CAFs) that remodel the extracellular matrix (ECM). Desmoplasia fuels a vicious cycle of stromal dissemination enriching both CAFs and desmoplastic ECM. Targeting specific drivers of desmoplasia, such as CAFs, either enhances or halts tumor growth and progression. These conflicting effects suggest that stromal interactions are not fully understood. This review highlights known fibroblastic-ECM interactions in an effort to encourage therapies that will restore cancer-restrictive stromal cues.

Facile fabrication of a 3D electrospun fibrous mat by ice-templating for a tumor spheroid culture

A 3D polycaprolactone fibrous mat was fabricated by using spherical ice as a template during electrospinning for stabilizing droplets in a spheroid culture.

NFkB disrupts tissue polarity in 3D by preventing integration of microenvironmental signals

The microenvironment of cells controls their phenotype, and thereby the architecture of the emerging multicellular structure or tissue. We have reported more than a dozen microenvironmental factors whose signaling must be integrated in order to effect an organized, functional tissue morphology. However, the factors that prevent integration of signaling pathways that merge form and function are still largely unknown. We have identified nuclear factor kappa B (NFkB) as a transcriptional regulator that disrupts important microenvironmental cues necessary for tissue organization. We compared the gene expression of organized and disorganized epithelial cells of the HMT-3522 breast cancer progression series: the non-malignant S1 cells that form polarized spheres (‘acini’), the malignant T4-2 cells that form large tumor-like clusters, and the ‘phenotypically reverted’ T4-2 cells that polarize as a result of correction of the microenvironmental signaling. We identified 180 genes that display an increased expression in disorganized compared to polarized structures. Network, GSEA and transcription factor binding site analyses suggested that NFkB is a common activator for the 180 genes. NFkB was found to be activated in disorganized breast cancer cells, and inhibition of microenvironmental signaling via EGFR, beta1 integrin, MMPs, or their downstream signals suppressed its activation. The postulated role of NFkB was experimentally verified: Blocking the NFkB pathway with a specific chemical inhibitor or shRNA induced polarization and inhibited invasion of breast cancer cells in 3D cultures. These results may explain why NFkB holds promise as a target for therapeutic intervention: Its inhibition can reverse the oncogenic signaling involved in breast cancer progression and integrate the essential microenvironmental control of tissue architecture.

Organogenesis in a dish: modeling development and disease using organoid technologies

Classical experiments performed half a century ago demonstrated the immense self-organizing capacity of vertebrate cells. Even after complete dissociation, cells can reaggregate and reconstruct the original architecture of an organ. More recently, this outstanding feature was used to rebuild organ parts or even complete organs from tissue or embryonic stem cells. Such stem cell-derived three-dimensional cultures are called organoids. Because organoids can be grown from human stem cells and from patient-derived induced pluripotent stem cells, they have the potential to model human development and disease. Furthermore, they have potential for drug testing and even future organ replacement strategies. Here, we summarize this rapidly evolving field and outline the potential of organoid technology for future biomedical research.

Evidence that breast tissue stiffness is associated with risk of breast cancer

Background

Evidence from animal models shows that tissue stiffness increases the invasion and progression of cancers, including mammary cancer. We here use measurements of the volume and the projected area of the compressed breast during mammography to derive estimates of breast tissue stiffness and examine the relationship of stiffness to risk of breast cancer.

Methods

Mammograms were used to measure the volume and projected areas of total and radiologically dense breast tissue in the unaffected breasts of 362 women with newly diagnosed breast cancer (cases) and 656 women of the same age who did not have breast cancer (controls). Measures of breast tissue volume and the projected area of the compressed breast during mammography were used to calculate the deformation of the breast during compression and, with the recorded compression force, to estimate the stiffness of breast tissue. Stiffness was compared in cases and controls, and associations with breast cancer risk examined after adjustment for other risk factors.

Results

After adjustment for percent mammographic density by area measurements, and other risk factors, our estimate of breast tissue stiffness was significantly associated with breast cancer (odds ratio = 1.21, 95% confidence interval = 1.03, 1.43, p = 0.02) and improved breast cancer risk prediction in models with percent mammographic density, by both area and volume measurements.

Conclusion

An estimate of breast tissue stiffness was associated with breast cancer risk and improved risk prediction based on mammographic measures and other risk factors. Stiffness may provide an additional mechanism by which breast tissue composition is associated with risk of breast cancer and merits examination using more direct methods of measurement.

The independent roles of mechanical, structural and adhesion characteristics of 3D hydrogels on the regulation of cancer invasion and dissemination

Metastasis begins with the escape, or dissemination, of cancer cells from the primary tumor. We recently demonstrated that tumors preferentially disseminate into collagen I and not into basement membrane protein gels (Matrigel). In this study, we used synthetic polymer systems to define material properties that could induce dissemination into Matrigel. We first specifically varied rigidity by varying the crosslinking density of poly(ethylene glycol) (PEG) networks within Matrigel scaffolds. Increased microenvironmental rigidity limited epithelial growth but did not promote dissemination. We next incorporated adhesive signals into the PEG network using peptide-conjugated cyclodextrin (α-CDYRGDS) rings. The α-CDYRGDS rings threaded along the PEG polymers, enabling independent control of matrix mechanics, adhesive peptide composition, and adhesive density. Adhesive PEG networks induced dissemination of normal and malignant mammary epithelial cells at intermediate values of adhesion and rigidity. Our data reveal that microenvironmental signals can induce dissemination of normal and malignant epithelial cells without requiring the fibrillar structure of collagen I or containing collagen I-specific adhesion sequences. Finally, the nanobiomaterials and assays developed in this study are generally useful both in 3D culture of primary mammalian tissues and in the systematic evaluation of the specific role of mechanical and adhesive inputs on 3D tumor growth, invasion, and dissemination.

Mammary ductal elongation and myoepithelial migration are regulated by the composition of the extracellular matrix

Mammary branching morphogenesis occurs over a period of weeks deep inside an adipocyte-rich stroma. The adipocytes contain light-scattering lipid droplets that limit the depth of penetration of visible light. Organotypic culture methods were developed to enable high-resolution optical monitoring of branching morphogenesis ex vivo. A challenge has been to identify the best culture conditions to model specific developmental events. We recently demonstrated that collagen I induces protrusive invasion in both normal and neoplastic mammary epithelium. In this study, we observed that the abundance of collagen I fibrils correlated strongly with invasive behaviour, even when the collagen I concentration was identical. We found that the extent of fibril assembly was experimentally manipulable by varying the incubation time at 4°C following pH neutralization. We next tested the capacity of collagen I fibrils to induce invasive behaviour when presented in combination with basement membrane proteins (Matrigel). We found that epithelial organoids in mixed gels of collagen I and basement membrane proteins exhibited more extensive branching morphogenesis but did not initiate protrusions into the matrix. Organoids in pure Matrigel produced many small epithelial buds that were bare of myoepithelial cells. Surprisingly, organoids in mixed gels of collagen I and Matrigel produced fewer epithelial buds, the buds elongated further, and the elongating buds remained covered by myoepithelial cells. Our mixed gels therefore provide a more physiologically accurate model of mammary branching morphogenesis. Our results also suggest that changes in the composition of the extracellular matrix could induce migration of epithelial cells past myoepithelial coverage.

Effect of laminin 332 on motility and invasion in bladder cancer

We examined the correlation between laminin 332 and malignancy in bladder cancer patients, and, using a strain of invasive bladder cancer cells, determined whether laminin 332 causes bladder cancer motility and invasion. To investigate the correlation between laminin 332 g2 distribution and patient outcome, we performed a semiquantitative immunohistochemical analysis of 35 paraffin-embedded samples using the antibody D4B5, which is specific for the laminin 5 γ2 chain. To evaluate the role of laminin 332 in NBT-II cell motility and invasion, we used a scratch assay and the Boyden chamber chemoinvasion system. Tumor stage and grade were significantly correlated with a loss of laminin 332 γ2 chain from the basement membrane (p = 0.001) and its retention in the cytoplasm (p = 0.001) (Kruskal-Wallis test). Kaplan-Meier survival curves revealed an association between the risk of progression and cytoplasmic retention of the laminin 332 γ2 chain. In addition, an in vitro scratch assay showed an increase in the migration of cells treated with laminin 332 from their cluster. The Boyden chamber assay showed that laminin 332 potentiated NBT-II cell invasion. Immunohistochemistry results showed that bladder cancer patients with a higher malignancy expressed more laminin 332. The in vitro scratch and invasion assay showed that laminin 332 stimulated the motility and invasion of bladder cancer cells. The invasion assay explains the correlation between laminin 332 expression and bladder cancer malignancy.

The modulation of MSC integrin expression by RGD presentation

Biomaterials designed to mimic the intricate native extracellular matrix (ECM) can use a variety of techniques to control the behavior of encapsulated cells. Common methods include controlling the mechanical properties of the material, incorporating bioactive signals, spatially patterning bioactive signals, and controlling the time-release of bioactive signals. Further design parameters like bioactive signal distribution can be used to manipulate cell behavior. Efforts on clustering adhesion peptides have focused on seeding cells on top of a biomaterial. Here we report the effect of clustering the adhesion peptide RGD on mouse mesenchymal stem cells encapsulated inside three-dimensional hyaluronic acid hydrogels. The clustered bioactive signals resulted in significant differences in both cell spreading and integrin expression. These results indicate that signal RGD peptide clustering is an additional hydrogel design parameter can be used to influence and guide the behavior of encapsulated cells.

A review of recent advances and current hypotheses on the pathogenesis of acute laminitis

With the increasing number of studies being published on the different experimental models used to induce and study acute laminitis, the pathophysiological events associated with these various models (i.e. starch overload, oligofructose overload, black walnut extract and hyperinsulinaemia) can be compared more realistically. Within this review, the mechanisms for metabolic vs. inflammatory laminitis are discussed, and the question of how pasture laminitis may fit into any of the proposed mechanisms is addressed.

Practical considerations for long-term time-lapse imaging of epithelial morphogenesis in three-dimensional organotypic cultures

Epithelia are one of the fundamental tissues in the animal body, and there is broad interest in understanding the cellular and molecular basis of their formation, growth, remodeling, and pathologic degeneration. Unfortunately, from an imaging perspective, many epithelial tissues develop deep within the animal and are inaccessible to high-resolution optical imaging with visible wavelengths. To circumvent this problem, researchers have long sought to model epithelial morphogenesis in culture systems. Protocols for culturing whole epithelial organs have existed since the 1950s, but the use of three-dimensional (3D) organotypic cultures of epithelial fragments has advanced dramatically in recent years. There has been a considerable increase in interest in imaging cell behaviors and molecular activities within these cultures. This article discusses the common technical challenges associated with imaging epithelial morphogenesis in 3D cultures and presents a range of specific strategies to address these challenges. Solutions are presented, first conceptually and then at several levels of sophistication and expense. The goal is to help you adapt those specific methods most useful to your own research, in a manner compatible with your needs and budget.

From Reductionism to Holism: Systems-oriented Approaches in Cancer Research

Somatic mutation theory of cancer has directed cancer research during the last century. A deluge of information on cellular, molecular, and genetic behavior was uncovered, but so was a mind-numbing complexity that still challenges research and concepts, and expectations in the war on cancer have by and large not been fulfilled. A change of paradigm beyond reductionism has been called for, especially as research ubiquitously points at the importance of tissue, microenvironment, extracellular matrix, embryonic and morphogenetic fields, and fields of tissue maintenance and organization in the processes of carcinogenesis, cancer control, and cancer progression, as well as in the control of cellular and genetic behavior. Holistic, organismic systems concepts open new perspectives for cancer research and treatment, as well as general biological understanding.

ECM microenvironment regulates collective migration and local dissemination in normal and malignant mammary epithelium

Breast cancer progression involves genetic changes and changes in the extracellular matrix (ECM). To test the importance of the ECM in tumor cell dissemination, we cultured epithelium from primary human breast carcinomas in different ECM gels. We used basement membrane gels to model the normal microenvironment and collagen I to model the stromal ECM. In basement membrane gels, malignant epithelium either was indolent or grew collectively, without protrusions. In collagen I, epithelium from the same tumor invaded with protrusions and disseminated cells. Importantly, collagen I induced a similar initial response of protrusions and dissemination in both normal and malignant mammary epithelium. However, dissemination of normal cells into collagen I was transient and ceased as laminin 111 localized to the basal surface, whereas dissemination of carcinoma cells was sustained throughout culture, and laminin 111 was not detected. Despite the large impact of ECM on migration strategy, transcriptome analysis of our 3D cultures revealed few ECM-dependent changes in RNA expression. However, we observed many differences between normal and malignant epithelium, including reduced expression of cell-adhesion genes in tumors. Therefore, we tested whether deletion of an adhesion gene could induce sustained dissemination of nontransformed cells into collagen I. We found that deletion of P-cadherin was sufficient for sustained dissemination, but exclusively into collagen I. Our data reveal that metastatic tumors preferentially disseminate in specific ECM microenvironments. Furthermore, these data suggest that breaks in the basement membrane could induce invasion and dissemination via the resulting direct contact between cancer cells and collagen I.

Soft-tissue alterations following exposure to tooth-whitening agents

BACKGROUND

Tooth-whitening agents are widely used, either as self-application products or under the supervision of a dentist. These products may be associated with transient gross morphologic changes in oral soft tissues. However, their potential effects on human keratinocytes and fibroblasts in a stratified squamous epithelium have yet to be elucidated.

METHODS

In this study, three-dimensional human tissue equivalents are exposed to varying concentrations of tooth-whitening agents for increasing time periods. Tissue alterations are investigated in terms of morphology, proliferation, apoptosis, and protein expression.

RESULTS

All whitening agents tested altered tissue morphology, induced proliferation of basal keratinocytes, and caused apoptosis of cells in all epithelial strata. In addition, whitening agents induced alterations in the expression of cytokines that are linked to inflammation.

CONCLUSIONS

These results suggest that whitening agents may induce similar changes in vivo and that these products should be used for limited periods of time or under the supervision of a dental professional.

Downregulation of Cockayne syndrome B protein reduces human 8-oxoguanine DNA glycosylase-1 expression and repair of UV radiation-induced 8-oxo-7,8-dihydro-2'-deoxyguanine

Human 8-oxoguanine DNA glycosylase-1 (hOGG1) is the key DNA repair enzyme responsible for initiating repair of UV radiation-induced 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG). Previously we have shown that basal cells in human epidermis are particularly sensitive to UVA-mediated DNA damage probably due to low expression of hOGG1. Here we investigate some aspects of the regulatory role of Cockayne syndrome B (CSB) on hOGG1 expression and function. Cockayne syndrome B and hOGG1 genes were knocked down by miRNA technology in the HaCaT human keratinocyte cell line. Loss of the CSB gene decreased hOGG1 mRNA, and loss of hOGG1 increased CSB, indicating that they influence each other's expression. Protein levels were assessed in cells grown into engineered human skin using immunohistochemistry. This confirmed that CSB knockdown with miRNA reduced hOGG1 protein levels, but hOGG1 knockdown did not influence expression of CSB protein. Using comet assay we found that both hOGG1 and CSB knockdown reduced repair of both UVA- and UVB-induced 8-oxo-dG, consistent with CSB downregulation of hOGG1 mRNA and protein. In contrast, CSB but not hOGG1 knockdown reduced repair of UVB- and UVA-induced cyclobutane pyrimidine dimer photolesions. In engineered human skin, repair of UVA-induced 8-oxo-dG was inhibited by both hOGG1 and CSB knockdown, confirming the functional role of both proteins in cells with 3-D cellular contacts. These findings directly indicate that hOGG1 and CSB influence each other's expression. CSB is required for maintaining hOGG1 enzyme levels and function. Cockayne syndrome B could therefore be required for 8-oxo-dG repair due to its regulatory effect on hOGG1 expression. Cockayne syndrome B but not hOGG1 is also required for efficient repair of cyclobutane pyrimidine dimers. Cockayne syndrome B regulation of DNA repair could contribute to the effect of UVA in causing mutations that lead to skin cancer in humans.

Tuba and N-WASP function cooperatively to position the central lumen during epithelial cyst morphogenesis

The process of epithelial lumenogenesis requires coordination of a network of signaling machinery communicated to each cell through subsequent cell divisions. Formation of a single hollow lumen has previously been shown to require Tuba, a Cdc42 GEF, for Cdc42 activation and correct spindle orientation. Using a Caco-2 model of lumenogenesis, we show that knockdown (KD) of the actin regulator N-WASP, causes a multilumen phenotype similar to Tuba KD. Defects in lumenogenesis in Tuba KD and N-WASP KD cells are observed at the two cell stage with inappropriate marking of the pre-apical patch (PAP) - the precursor to lumen formation. Strikingly, both Tuba and N-WASP depend on each other for localization to the PAP. We conclude that N-WASP functions cooperatively with Tuba to facilitate lumenogenesis and this requires the polyproline region of N-WASP.

Computational modeling of epithelial tissues

There is an extensive literature on the computational modeling of epithelial tissues at all levels from subcellular to whole tissue. This review concentrates on behavior at the individual cell to whole tissue level, and particularly on organizational aspects, and provides an indication of where information from other areas, such as the modeling of angiogenesis, is relevant. The skin, and the lining of all of the body cavities (lung, gut, cervix, bladder etc) are epithelial tissues, which in a topological sense are the boundary between inside and outside the body. They are thin sheets of cells (usually of the order of 0.5 mm thick) without extracellular matrix, have a relatively simple structure, and contain few types of cells. They have important barrier, secretory and transport functions, which are essential for the maintenance of life, so homeostasis and wound healing are important aspects of the behavior of epithelial tissues. Carcinomas originate in epithelial tissues.There are essentially two approaches to modeling tissues--to start at the level of the tissue (i.e., a length scale of the order of 1 mm) and develop generalized equations for behavior (a continuum approach); or to start at the level of the cell (i.e., a length scale of the order of 10 µm) and develop tissue behavior as an emergent property of cellular behavior (an individual-based approach). As will be seen, these are not mutually exclusive approaches, and they come in a variety of flavors.

Cellular mechanisms regulating epithelial morphogenesis and cancer invasion

The cellular mechanisms driving mammalian epithelial morphogenesis are of significant fundamental and practical interest. Historically, these processes have been difficult to study directly, owing to the opacity and relative inaccessibility of mammalian tissues. Recent experimental advances in timelapse imaging and in 3D organotypic culture have enabled direct observation of epithelial morphogenesis. In the mammary gland, branching morphogenesis is observed to proceed through a novel form of collective epithelial migration. The active unit of morphogenesis is a multilayered epithelium with reduced apico-basal polarity, within which cells rearranged vigorously. From within this multilayered state, new ducts initiate and elongate into the matrix without leading cellular extensions or dedicated leaders. We discuss the implications of these findings on our understanding of epithelial morphogenesis in other organs and in cancer progression.

A sub-cellular viscoelastic model for cell population mechanics

Understanding the biomechanical properties and the effect of biomechanical force on epithelial cells is key to understanding how epithelial cells form uniquely shaped structures in two or three-dimensional space. Nevertheless, with the limitations and challenges posed by biological experiments at this scale, it becomes advantageous to use mathematical and 'in silico' (computational) models as an alternate solution. This paper introduces a single-cell-based model representing the cross section of a typical tissue. Each cell in this model is an individual unit containing several sub-cellular elements, such as the elastic plasma membrane, enclosed viscoelastic elements that play the role of cytoskeleton, and the viscoelastic elements of the cell nucleus. The cell membrane is divided into segments where each segment (or point) incorporates the cell's interaction and communication with other cells and its environment. The model is capable of simulating how cells cooperate and contribute to the overall structure and function of a particular tissue; it mimics many aspects of cellular behavior such as cell growth, division, apoptosis and polarization. The model allows for investigation of the biomechanical properties of cells, cell-cell interactions, effect of environment on cellular clusters, and how individual cells work together and contribute to the structure and function of a particular tissue. To evaluate the current approach in modeling different topologies of growing tissues in distinct biochemical conditions of the surrounding media, we model several key cellular phenomena, namely monolayer cell culture, effects of adhesion intensity, growth of epithelial cell through interaction with extra-cellular matrix (ECM), effects of a gap in the ECM, tensegrity and tissue morphogenesis and formation of hollow epithelial acini. The proposed computational model enables one to isolate the effects of biomechanical properties of individual cells and the communication between cells and their microenvironment while simultaneously allowing for the formation of clusters or sheets of cells that act together as one complex tissue.

Up-regulation of stromal versican expression in advanced stage serous ovarian cancer

OBJECTIVE

The purpose of this study is to examine the role of versican (VCAN) in advanced stage serous ovarian cancer by investigating its expression, its function, and its correlation with clinical outcomes.

METHODS

Microarray analysis was performed on RNA isolated from tumor and stromal components of advanced stage serous ovarian cancer and normal ovarian epithelial tissue to identify genes up-regulated in ovarian tumor stroma. Validation studies using immunohistochemistry and quantitative real-time PCR (Q-RT-PCR) was performed on one of the up-regulated genes, VCAN. Immunolocalization of VCAN (n=111) and CD31 (n=56) was done on serous ovarian tumors. CD31 staining was performed to examine microvessel density (MVD). Q-RT-PCR was performed on 65 samples to evaluate the differential expression of VCAN isoforms. Cell proliferation and invasion assays were performed to examine how V1-treated ovarian cancer cell lines and an endothelial cell line would differ from controls. Univariate survival analyses were done with VCAN expression. Correlation analysis was done with CD31, platinum resistance, and clinical data.

RESULTS

Validation studies using Q-RT-PCR and immunohistochemistry showed significantly higher VCAN V1 isoform expression in ovarian cancer stroma compared with normal ovarian stroma and ovarian cancer cells. Correlation studies showed stromal VCAN expression was associated with poorer overall and progression-free survival, platinum resistance, and increased MVD. VCAN-treated ovarian cancer and endothelial cells showed increased invasion potential.

CONCLUSIONS

VCAN overexpression is associated with increased MVD and invasion potential, which may lead to poorer overall and progression-free survival and platinum resistance.

Breast tissue composition and susceptibility to breast cancer

Breast density, as assessed by mammography, reflects breast tissue composition. Breast epithelium and stroma attenuate x-rays more than fat and thus appear light on mammograms while fat appears dark. In this review, we provide an overview of selected areas of current knowledge about the relationship between breast density and susceptibility to breast cancer. We review the evidence that breast density is a risk factor for breast cancer, the histological and other risk factors that are associated with variations in breast density, and the biological plausibility of the associations with risk of breast cancer. We also discuss the potential for improved risk prediction that might be achieved by using alternative breast imaging methods, such as magnetic resonance or ultrasound. After adjustment for other risk factors, breast density is consistently associated with breast cancer risk, more strongly than most other risk factors for this disease, and extensive breast density may account for a substantial fraction of breast cancer. Breast density is associated with risk of all of the proliferative lesions that are thought to be precursors of breast cancer. Studies of twins have shown that breast density is a highly heritable quantitative trait. Associations between breast density and variations in breast histology, risk of proliferative breast lesions, and risk of breast cancer may be the result of exposures of breast tissue to both mitogens and mutagens. Characterization of breast density by mammography has several limitations, and the uses of breast density in risk prediction and breast cancer prevention may be improved by other methods of imaging, such as magnetic resonance or ultrasound tomography.

Induction and progression of cholangiofibrosis in rat liver injured by oral administration of furan

Cholangiofibrosis is a structural anomaly that precedes the development of cholangiocarcinoma in some rodent models. In this article, the authors examine the contribution of the epithelial and mesenchymal cells in the pathogenesis of this complex lesion. Furan was administered to rats by gavage in corn oil at 30 mg/kg b.w. (five daily doses per week) and livers were sampled between eight hr to three months. Characteristically the administration of furan caused centrilobular injury, and restoration was accomplished by proliferation of hepatocytes. Some areas of the liver were, however, more severely affected, and here, injury extended into portal and capsular areas, which resulted in a rapid proliferation of ductular cells that extended into the parenchyma accompanied by a subtype of liver fibroblasts. These ductules either differentiated into hepatocytes, with loss of the associated fibroblasts, or progressed to form tortuous ductular structures that replaced much of the parenchyma, leading to cholangiofibrosis. Although it is unclear what determines the difference in the hepatic response, a loss of micro-environmental cues that instigate hepatocyte differentiation and termination of the hepatocyte stem cell repair response may be perturbed by continual furan administration that results in an irreversible expansile lesion that may mimic the features of cholangiocarcinoma.

The tumor microenvironment in colorectal carcinogenesis

Colorectal cancer is the second leading cause of cancer-related mortality in the United States. Therapeutic developments in the past decade have extended life expectancy in patients with metastatic disease. However, metastatic colorectal cancers remain incurable. Numerous agents that were demonstrated to have significant antitumor activity in experimental models translated into disappointing results in extending patient survival. This has resulted in more attention being focused on the contribution of tumor microenvironment to the progression of a number of solid tumors including colorectal cancer. A more complete understanding of interactions between tumor epithelial cells and their stromal elements will enhance therapeutic options and improve clinical outcome. Here we will review the role of various stromal components in colorectal carcinogenesis and discuss the potential of targeting these components for the development of future therapeutic agents.

Apical polarity in three-dimensional culture systems: where to now?

Delineation of the mechanisms that establish and maintain the polarity of epithelial tissues is essential to understanding morphogenesis, tissue specificity and cancer. Three-dimensional culture assays provide a useful platform for dissecting these processes but, as discussed in a recent study in BMC Biology on the culture of mammary gland epithelial cells, multiple parameters that influence the model must be taken into account.

See research article http://www.biomedcentral.com/1741-7007/7/77.

The role of focal adhesion kinase in tumor initiation and progression

Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase that acts as a primary regulator of focal adhesion signaling to regulate cell proliferation, survival and migration. While FAK is known to directly influence many fundamental adhesion and growth factor signaling pathways important in cancer and FAK is overexpressed in multiple human cancers studies addressing a causal role for FAK in tumor initiation and progression using transgenic models of human cancer had not been performed. Recently, using tissue-specific FAK-knockout in mouse models of human cancer, the consequences of FAK ablation in carcinoma were demonstrated by multiple independent research groups. Strong consensus evidence indicates that epithelial cells are able to transform in the absence of FAK, but do not undergo a malignant conversion to invasive carcinoma, and as such, metastasis is impaired. This is likely the consequence of decreased Src and p130Cas activation in concert with misregulated actin cytoskeleton dynamics and Rho GTPase signaling. Hence, FAK, as well as the FAK-regulating/regulated signaling network, are viable candidates for cancer metastasis therapies.

Tissue architecture and function: dynamic reciprocity via extra- and intra-cellular matrices

Mammary gland development, functional differentiation, and homeostasis are orchestrated and sustained by a balance of biochemical and biophysical cues from the organ's microenvironment. The three-dimensional microenvironment of the mammary gland, predominantly 'encoded' by a collaboration between the extracellular matrix (ECM), hormones, and growth factors, sends signals from ECM receptors through the cytoskeletal intracellular matrix to nuclear and chromatin structures resulting in gene expression; the ECM in turn is regulated and remodeled by signals from the nucleus. In this chapter, we discuss how coordinated ECM deposition and remodeling is necessary for mammary gland development, how the ECM provides structural and biochemical cues necessary for tissue-specific function, and the role of the cytoskeleton in mediating the extra--to intracellular dialogue occurring between the nucleus and the microenvironment. When operating normally, the cytoskeletal-mediated dynamic and reciprocal integration of tissue architecture and function directs mammary gland development, tissue polarity, and ultimately, tissue-specific gene expression. Cancer occurs when these dynamic interactions go awry for an extended time.

Anti-Ro/SSA autoantibody-mediated regulation of extracellular matrix fibulins in human epithelial cells of the salivary gland

OBJECTIVES

The fibulins are a family of extracellular matrix (ECM) molecules that regulate the organ shape along with other growth factors and stromal cells and have recently been shown to be involved in a variety of cellular functions including proliferation, migration, differentiation, and survival. Important changes in acinar and ductal morphology and function, together with pronounced ECM remodelling, are detectable in the labial salivary glands (LSGs) of patients with Sjögren's syndrome (SS). Here we report the in vitro expression of the recently identified ECM proteins fibulin-6 and fibulin-7 by human salivary gland epithelial cells (SGECs). The ability of anti-Ro/SSA autoantibodies (Abs) to modulate fibulin-6 and fibulin-7 expression was investigated.

METHODS

Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and real-time PCR were used to analyse fibulin-6 and fibulin-7 mRNA expression. Confocal microscopy and fluorescence-activated cell sorting (FACS) were used to study expression of the proteins in primary human SGEC cultures, established from biopsies of minor LSGs, in both untreated control cells and anti-Ro/SSA Abs-treated cells.

RESULTS

The methods used show the expression of fibulin-6 and fibulin-7 in SGECs. Treatment of cells with anti-Ro/SSA Abs results in a down-regulation of fibulin-6 mRNA expression whereas no significant differences were observed in fibulin-7 expression between untreated and treated cells.

CONCLUSION

Dysregulation of fibulin expression in SGECs by anti-Ro/SSA Abs may contribute to disorganization of the ECM environment and thus cause injury to the salivary gland architecture and functionality observed in SS.

Fibulin-6 expression and anoikis in human salivary gland epithelial cells: implications in Sjogren's syndrome

Important changes in acinar and ductal morphology and function, together with pronounced extracellular matrix (ECM) remodelling, are detectable in the labial salivary glands of Sjögren's syndrome (SS) patients. The objective of this work was to determine the effect of treatment with the anti-Ro/SSA auto-antibodies, characterizing SS, on the expression of fibulin-6, a member of the fibulins family of the ECM, in primary human salivary gland epithelial cell (SGEC) cultures established from biopsies of labial minor salivary glands obtained from healthy donors. The induction of cell detachment and anoikis in SGECs treated with anti-Ro/SSA auto-antibodies were also investigated. Changes in fibulin-6 mRNA expression were measured by semi-quantitative reverse transcriptase-PCR and real-time PCR. Fibulin-6 expression in cells treated with anti-Ro/SSA auto-antibodies was evaluated by flow cytometric analysis and confocal laser scanning microscopy. SGECs undergoing death by anoikis were identified and quantified using Calcein blue/YOPRO-1 dyes. Herein, we present the first evidence of fibulin-6 expression in SGEC that results distributed in the cytoplasm surrounding the inner side of the plasma membrane. Fibulin-6 was down-regulated in SGECs treated with anti-Ro/SSA auto-antibodies in which a marked cell detachment and a reduction of cell viability were observed. Notably, a reduction of fibulin-6 expression in SGECs treated with anti-Ro/SSA auto-antibodies corresponds to an increase of anoikis cell death. Our observations demonstrate a dysregulation of fibulin-6 in the pathological processes observed in SS and provide new evidence that disorganization of the ECM environment could damage the architecture and function of the salivary glands.

Three-dimensional tissue models of normal and diseased skin

Over the last decade, the development of in vitro, human, three-dimensional (3D) tissue models, known as human skin equivalents (HSEs), has furthered understanding of epidermal cell biology and provided novel experimental systems. Signaling pathways that mediate the linkage between growth and differentiation function optimally when cells are spatially organized to display the architectural features seen in vivo, but are uncoupled and lost in two-dimensional culture systems. HSEs consist of a stratified squamous epithelium grown at an air-liquid interface on a collagen matrix populated with dermal fibroblasts. These 3D tissues demonstrate in vivo-like epithelial differentiation and morphology, and rates of cell division, similar to those found in human skin. This unit describes fabrication of HSEs, allowing the generation of human tissues that mimic the morphology, differentiation, and growth of human skin, as well as disease processes of cancer and wound re-epithelialization, providing powerful new tools for the study of diseases in humans.