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

Current status and challenges for cell-cultured milk technology: a systematic review

Cellular agriculture is an innovative technology for manufacturing sustainable agricultural products as an alternative to traditional agriculture. While most cellular agriculture is predominantly centered on the production of cultured meat, there is a growing demand for an understanding of the production techniques involved in dairy products within cellular agriculture. This review focuses on the current status of cellular agriculture in the dairy sector and technical challenges for cell-cultured milk production. Cellular agriculture technology in the dairy sector has been classified into fermentation-based and animal cell culture-based cellular agriculture. Currently, various companies synthesize milk components through precision fermentation technology. Nevertheless, several startup companies are pursuing animal cell-based technology, driven by public concerns regarding genetically modified organisms in precision fermentation technology. Hence, this review offers an up-to-date exploration of animal cell-based cellular agriculture to produce milk components, specifically emphasizing the structural, functional, and productive aspects of mammary epithelial cells, providing new information for industry and academia.

Spatial Transcriptomics Suggests That Alterations Occur in the Preneoplastic Breast Microenvironment of BRCA1/2 Mutation Carriers

Breast cancer is the most common cancer in females, affecting one in every eight women and accounting for the majority of cancer-related deaths in women worldwide. Germline mutations in the BRCA1 and BRCA2 genes are significant risk factors for specific subtypes of breast cancer. BRCA1 mutations are associated with basal-like breast cancers, whereas BRCA2 mutations are associated with luminal-like disease. Defects in mammary epithelial cell differentiation have been previously recognized in germline BRCA1/2 mutation carriers even before cancer incidence. However, the underlying mechanism is largely unknown. Here, we employ spatial transcriptomics to investigate defects in mammary epithelial cell differentiation accompanied by distinct microenvironmental alterations in preneoplastic breast tissues from BRCA1/2 mutation carriers and normal breast tissues from noncarrier controls. We uncovered spatially defined receptor-ligand interactions in these tissues for the investigation of autocrine and paracrine signaling. We discovered that β1-integrin-mediated autocrine signaling in BRCA2-deficient mammary epithelial cells may differ from BRCA1-deficient mammary epithelial cells. In addition, we found that the epithelial-to-stromal paracrine signaling in the breast tissues of BRCA1/2 mutation carriers is greater than in control tissues. More integrin-ligand pairs were differentially correlated in BRCA1/2-mutant breast tissues than noncarrier breast tissues with more integrin receptor-expressing stromal cells.

IMPLICATIONS

These results suggest alterations in the communication between mammary epithelial cells and the microenvironment in BRCA1 and BRCA2 mutation carriers, laying the foundation for designing innovative breast cancer chemo-prevention strategies for high-risk patients.

Pathogenesis of Common Ocular Diseases: Emerging Trends in Extracellular Matrix Remodeling

The prevalence of visual impairments in human societies is worrying due to retinopathy complications of several chronic diseases such as diabetes, cardiovascular diseases, and many more that are on the rise worldwide. Since the proper function of this organ plays a pivotal role in people's quality of life, identifying factors affecting the development/exacerbation of ocular diseases is of particular interest among ophthalmology researchers. The extracellular matrix (ECM) is a reticular, three-dimensional (3D) structure that determines the shape and dimensions of tissues in the body. The ECM remodeling/hemostasis is a critical process in both physiological and pathological conditions. It consists of ECM deposition, degradation, and decrease/increase in the ECM components. However, disregulation of this process and an imbalance between the synthesis and degradation of ECM components are associated with many pathological situations, including ocular disorders. Despite the impact of ECM alterations on the development of ocular diseases, there is not much research conducted in this regard. Therefore, a better understanding in this regard, can pave the way toward discovering plausible strategies to either prevent or treat eye disorders. In this review, we will discuss the importance of ECM changes as a sentimental factor in various ocular diseases based on the research done up to now.

Mutations F352A and Y528A in human HSP90α reduce fibronectin association and fibrillogenesis in cell-derived matrices

HSP90 is a ubiquitously expressed chaperone protein that regulates the maturation of numerous substrate proteins called 'clients'. The glycoprotein fibronectin (FN) is an important protein of the extracellular matrix (ECM) and a client protein of HSP90. FN and HSP90 interact directly, and the FN ECM is regulated by exogenous HSP90 or HSP90 inhibitors. Here, we extend the analysis of the HSP90 - FN interaction. The importance of the N-terminal 70-kDa fragment of fibronectin (FN70) and FN type I repeat was demonstrated by competition for FN binding between HSP90 and the functional upstream domain (FUD) of the Streptococcus pyogenes F1 adhesin protein. Furthermore, His-HSP90α mutations F352A and Y528A (alone and in combination) reduced the association with full-length FN (FN-FL) and FN70 in vitro. Unlike wild type His-HSP90α, these HSP90 mutants did not enhance FN matrix assembly in the Hs578T cell line model when added exogenously. Interestingly, the HSP90 E353A mutation, which did not significantly reduce the HSP90 - FN interaction in vitro, dramatically blocked FN matrix assembly in Hs578T cell-derived matrices. Taken together, these data extend our understanding of the role of HSP90 in FN fibrillogenesis and suggest that promotion of FN ECM assembly by HSP90 is not solely regulated by the affinity of the direct interaction between HSP90 and FN.

Generation of functionally distinct T-cell populations by altering the viscoelasticity of their extracellular matrix

The efficacy of adoptive T-cell therapies largely depends on the generation of T-cell populations that provide rapid effector function and long-term protective immunity. Yet it is becoming clearer that the phenotypes and functions of T cells are inherently linked to their localization in tissues. Here we show that functionally distinct T-cell populations can be generated from T cells that received the same stimulation by altering the viscoelasticity of their surrounding extracellular matrix (ECM). By using a model ECM based on a norbornene-modified collagen type I whose viscoelasticity can be adjusted independently from its bulk stiffness by varying the degree of covalent crosslinking via a bioorthogonal click reaction with tetrazine moieties, we show that ECM viscoelasticity regulates T-cell phenotype and function via the activator-protein-1 signalling pathway, a critical regulator of T-cell activation and fate. Our observations are consistent with the tissue-dependent gene-expression profiles of T cells isolated from mechanically distinct tissues from patients with cancer or fibrosis, and suggest that matrix viscoelasticity could be leveraged when generating T-cell products for therapeutic applications.

Adipocyte-Derived Paracrine Factors Regulate the In Vitro Development of Bovine Mammary Epithelial Cells

The mammary gland is composed of epithelial tissue forming ducts and lobules, and the stroma, composed of adipocytes, connective tissue, and other cell types. The stromal microenvironment regulates mammary gland development by paracrine and cell-cell interactions. In the present study, primary cultures of bovine mammary epithelial cells (bMEC) and bovine adipose-derived stem cells (bASC) subjected to adipogenic differentiation were used to investigate the influence of paracrine factors secreted by preadipocytes and adipocytes on bMEC development. Four types of conditioned media (CM) were collected from undifferentiated preadipocytes (preA) and adipocytes on days: 8, 12, 14 of differentiation. Next, bMEC were cultured for 24 h in CM and cell viability, apoptosis, migratory activity, ability to form spheroids on Matrigel, and secretory activity (alpha S1-casein concentration) were evaluated. CM derived from fully differentiated adipocytes (12 d and 14 d) significantly decreased the number of apoptotic cells in bMEC population and increased the size of spheroids formed by bMEC on Matrigel. CM collected from preadipocytes significantly enhanced bMEC's migration, and stimulated bMEC to produce alpha S1-casein, but only in the presence of prolactin. These results confirm that preadipocytes and adipocytes are important components of the stroma, providing paracrine factors that actively regulate the development of bovine mammary epithelium.

Epithelial multicellular clustering enabled by polarized macrophages on soft matrices

Formation of epithelial structures of variegated geometries and sizes is essential for organogenesis, tumor growth, and wound repair. Although epithelial cells are predisposed with potential for multicellular clustering, it remains unclear whether immune cells and mechanical cues from their microenvironment influence this process. To explore this possibility, we cocultured human mammary epithelial cells with prepolarized macrophages on soft or stiff hydrogels. In the presence of M1 (proinflammatory) macrophages on soft matrices, epithelial cells migrated faster and subsequently formed larger multicellular clusters compared to cocultures with M0 (unpolarized) or M2 (anti-inflammatory) macrophages. By contrast, stiff matrices disabled active clustering of epithelial cells due to their enhanced migration and cell-ECM adhesion, regardless of macrophage polarization. We found that the copresence of soft matrices and M1 macrophages reduced focal adhesions, but enhanced fibronectin deposition and nonmuscle myosin-IIA expression, which altogether optimize conditions for epithelial clustering. Upon ROCK inhibition, epithelial clustering was abrogated, indicating a requirement for optimized cellular forces. In these cocultures, TNF-α secretion was the highest with M1 macrophages and TGF-β secretion was exclusively detectable in case of M2 macrophages on soft gels, which indicated potential role of macrophage secreted factors in the observed epithelial clustering. Indeed, exogenous addition of TGF-β promoted epithelial clustering with M1 coculture on soft gels. According to our findings, optimization of both mechanical and immune factors can tune epithelial clustering responses, which could have implications in tumor growth, fibrosis, and would healing.

Weaving the nest: extracellular matrix roles in pre-metastatic niche formation

The discovery that primary tumors condition distant organ sites of future metastasis for seeding by disseminating tumor cells through a process described as the pre-metastatic niche (PMN) formation revolutionized our understanding of cancer progression and opened new avenues for therapeutic interventions. Given the inherent inefficiency of metastasis, PMN generation is crucial to ensure the survival of rare tumor cells in the otherwise hostile environments of metastatic organs. Early on, it was recognized that preparing the "soil" of the distal organ to support the outgrowth of metastatic cells is the initiating event in PMN development, achieved through the remodeling of the organ's extracellular matrix (ECM). Remote restructuring of ECM at future sites of metastasis under the influence of primary tumor-secreted factors is an iterative process orchestrated through the crosstalk between resident stromal cells, such as fibroblasts, epithelial and endothelial cells, and recruited innate immune cells. In this review, we will explore the ECM changes, cellular effectors, and the mechanisms of ECM remodeling throughout PMN progression, as well as its impact on shaping the PMN and ultimately promoting metastasis. Moreover, we highlight the clinical and translational implications of PMN ECM changes and opportunities for therapeutically targeting the ECM to hinder PMN formation.

Alterations in the preneoplastic breast microenvironment of BRCA1/2 mutation carriers revealed by spatial transcriptomics

Breast cancer is the most common cancer in females, affecting one in every eight women and accounting for the majority of cancer-related deaths in women worldwide. Germline mutations in the BRCA1 and BRCA2 genes are significant risk factors for specific subtypes of breast cancer. BRCA1 mutations are associated with basal-like breast cancers, whereas BRCA2 mutations are associated with luminal-like disease. There are currently few chemoprevention strategies available for BRCA1/2 mutation carriers, and irreversible prophylactic mastectomy is the primary option. Designing chemo-preventive strategies requires an in-depth understanding of the physiological processes underlying tumor initiation. Here, we employ spatial transcriptomics to investigate defects in mammary epithelial cell differentiation accompanied by distinct microenvironmental alterations in preneoplastic breast tissues from BRCA1/2 mutation carriers and normal breast tissues from non-carrier controls. We uncovered spatially defined receptor-ligand interactions in these tissues for the investigation of autocrine and paracrine signaling. We discovered that β1-integrin-mediated autocrine signaling in BRCA2-deficient mammary epithelial cells differs from BRCA1-deficient mammary epithelial cells. In addition, we found that the epithelial-to-stromal paracrine signaling in the breast tissues of BRCA1/2 mutation carriers is greater than in control tissues. More integrin-ligand pairs were differentially correlated in BRCA1/2-mutant breast tissues than non-carrier breast tissues with more integrin receptor-expressing stromal cells. These results reveal alterations in the communication between mammary epithelial cells and the microenvironment in BRCA1 and BRCA2 mutation carriers, laying the foundation for designing innovative breast cancer chemo-prevention strategies for high-risk patients.

FGFR2 Controls Growth, Adhesion and Migration of Nontumorigenic Human Mammary Epithelial Cells by Regulation of Integrin β1 Degradation

The role of fibroblast growth factor receptor 2 (FGFR2), an important mediator of stromal paracrine and autocrine signals, in mammary gland morphogenesis and breast cancer has been extensively studied over the last years. However, the function of FGFR2 signalling in the initiation of mammary epithelial oncogenic transformation remains elusive. Here, FGFR2-dependent behaviour of nontumorigenic model of mammary epithelial cells was studied. In vitro analyses demonstrated that FGFR2 regulates epithelial cell communication with extracellular matrix (ECM) proteins. Silencing of FGFR2 significantly changed the phenotype of cell colonies in three-dimensional cultures, decreased integrins α2, α5 and β1 protein levels and affected integrin-driven processes, such as cell adhesion and migration. More detailed analysis revealed the FGFR2 knock-down-induced proteasomal degradation of integrin β1. Analysis of RNA-seq databases showed significantly decreased FGFR2 and ITGB1 mRNA levels in breast tumour samples, when compared to non-transformed tissues. Additionally, high risk healthy individuals were found to have disrupted correlation profiles of genes associated with FGFR2 and integrin signalling, cell adhesion/migration and ECM remodelling. Taken together, our results strongly suggest that FGFR2 loss with concomitant integrin β1 degradation is responsible for deregulation of epithelial cell-ECM interactions and this process may play an important role in the initiation of mammary gland epithelial tumorigenesis.

Epithelial multicellular clustering enabled by polarized macrophages on soft matrices

Formation of epithelial structures of variegated geometries and sizes is essential for organogenesis, tumor growth, and wound repair. Although epithelial cells are predisposed with potential for multicellular clustering, it remains unclear whether immune cells and mechanical cues from their microenvironment influence this process. To explore this possibility, we co-cultured human mammary epithelial cells with pre-polarized macrophages on soft or stiff hydrogels. In the presence of M1 (proinflammatory) macrophages on soft matrices, epithelial cells migrated faster and subsequently formed larger multicellular clusters, compared to co-cultures with M0 (unpolarized) or M2 (anti-inflammatory) macrophages. By contrast, stiff extracellular matrix (ECM) disabled active clustering of epithelial cells due to their enhanced migration and cell-ECM adhesion, regardless of macrophage polarization. We found that the co-presence of soft matrices and M1 macrophages reduced focal adhesions, but enhanced fibronectin deposition and non-muscle myosin-IIA expression, which altogether optimize conditions for epithelial clustering. Upon Rho-associated kinase (ROCK) inhibition, epithelial clustering was abrogated, indicating a requirement for optimized cellular forces. In these co-cultures, Tumor Necrosis Factor (TNF)-α secretion was the highest with M1 macrophages and Transforming growth factor (TGF)-β secretion was exclusively detectable in case of M2 macrophages on soft gels, which indicated potential role of macrophage secreted factors in the observed epithelial clustering. Indeed, exogenous addition of TGB-β promoted epithelial clustering with M1 co-culture on soft gels. According to our findings, optimization of both mechanical and immune factors can tune epithelial clustering responses, which could have implications in tumor growth, fibrosis, and would healing.

Summary

Authors show proinflammatory macrophages on soft matrices enable epithelial cells to form multicellular clusters. This phenomenon is disabled on stiff matrices due to increased stability of focal adhesions. Inflammatory cytokine secretion is macrophage-dependent, and external addition of cytokines accentuates epithelial clustering on soft matrices.

Impact Statement

Formation of multicellular epithelial structures is critical to tissue homeostasis. However, it has not been shown how the immune system and mechanical environment affect these structures. The present work illustrates how macrophage type affects epithelial clustering in soft and stiff matrix environments.

Materials and extracellular matrix rigidity highlighted in tissue damages and diseases: Implication for biomaterials design and therapeutic targets

Rigidity (or stiffness) of materials and extracellular matrix has proven to be one of the most significant extracellular physicochemical cues that can control diverse cell behaviors, such as contractility, motility, and spreading, and the resultant pathophysiological phenomena. Many 2D materials engineered with tunable rigidity have enabled researchers to elucidate the roles of matrix biophysical cues in diverse cellular events, including migration, lineage specification, and mechanical memory. Moreover, the recent findings accumulated under 3D environments with viscoelastic and remodeling properties pointed to the importance of dynamically changing rigidity in cell fate control, tissue repair, and disease progression. Thus, here we aim to highlight the works related with material/matrix-rigidity-mediated cell and tissue behaviors, with a brief outlook into the studies on the effects of material/matrix rigidity on cell behaviors in 2D systems, further discussion of the events and considerations in tissue-mimicking 3D conditions, and then examination of the in vivo findings that concern material/matrix rigidity. The current discussion will help understand the material/matrix-rigidity-mediated biological phenomena and further leverage the concepts to find therapeutic targets and to design implantable materials for the treatment of damaged and diseased tissues.

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Discuss the cutting-edge findings on the role of matrix rigidity in dictating diverse cell behaviors.

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Underscore the dynamic matrix rigidity that interplays with cells, and the related pathophysiological phenomena.

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Illuminate the significance of matrix rigidity in clinically-relevant settings.

The Tumor Microenvironment in Tumorigenesis and Therapy Resistance Revisited

Tumorigenesis is a complex and dynamic process involving cell-cell and cell-extracellular matrix (ECM) interactions that allow tumor cell growth, drug resistance and metastasis. This review provides an updated summary of the role played by the tumor microenvironment (TME) components and hypoxia in tumorigenesis, and highlight various ways through which tumor cells reprogram normal cells into phenotypes that are pro-tumorigenic, including cancer associated- fibroblasts, -macrophages and -endothelial cells. Tumor cells secrete numerous factors leading to the transformation of a previously anti-tumorigenic environment into a pro-tumorigenic environment. Once formed, solid tumors continue to interact with various stromal cells, including local and infiltrating fibroblasts, macrophages, mesenchymal stem cells, endothelial cells, pericytes, and secreted factors and the ECM within the tumor microenvironment (TME). The TME is key to tumorigenesis, drug response and treatment outcome. Importantly, stromal cells and secreted factors can initially be anti-tumorigenic, but over time promote tumorigenesis and induce therapy resistance. To counter hypoxia, increased angiogenesis leads to the formation of new vascular networks in order to actively promote and sustain tumor growth via the supply of oxygen and nutrients, whilst removing metabolic waste. Angiogenic vascular network formation aid in tumor cell metastatic dissemination. Successful tumor treatment and novel drug development require the identification and therapeutic targeting of pro-tumorigenic components of the TME including cancer-associated- fibroblasts (CAFs) and -macrophages (CAMs), hypoxia, blocking ECM-receptor interactions, in addition to the targeting of tumor cells. The reprogramming of stromal cells and the immune response to be anti-tumorigenic is key to therapeutic success. Lastly, this review highlights potential TME- and hypoxia-centered therapies under investigation.

Predictive role of neostromal CD10 expression in breast cancer patients treated with neoadjuvant chemotherapy

Background: The therapeutic strategy of invasive breast cancer is based on routine histopathological markers (estrogen-, progesterone receptor, HER2, Ki67) routinely evaluated in tumor cells. However, the assessment of cancer stroma could influence therapeutic strategies. Studies have shown that stromal expression of CD10, a zinc-dependent metalloproteinase, is associated with biological aggressiveness of the tumor. In the present retrospective study, we aimed to evaluate stromal CD10 expression and association between CD10 expression and response to neoadjuvant chemotherapy in invasive breast cancer. Methods: CD10 immunohistochemistry was performed on core biopsies taken before the neoadjuvant therapy. Stromal CD10 expression was determined and compared with well-known predictive and prognostic tissue markers as well as with the following groups defined according to the degree of tumor response: no regression, partial regression, and complete regression. Results: A total of 60 locally advanced invasive breast carcinomas of "no special type" were included. The proportion of CD10 positive tumors was significantly higher in the "no regression" group compared to "complete regression" group (p = 0.000). Stromal CD10 expression was found to be significantly associated with decrease in response to neoadjuvant chemotherapy. According to CD10 expression we did not find any difference in hormone receptor status, Ki67, tumor grade or neostromal area. Conclusion: Our data suggest that CD10 expression can serve as a predictive marker of the effect of neoadjuvant chemotherapy in breast cancer patients. Therefore, its inclusion into the routine assessment of biopsies to tailor tumor-specific therapeutic strategies merits consideration.

ECM-transmitted shear stress induces apoptotic cell extrusion in early breast gland development

Epithelial cells of human breast glands are exposed to various mechanical ECM stresses that regulate tissue development and homeostasis. Mechanoadaptation of breast gland tissue to ECM-transmitted shear stress remained poorly investigated due to the lack of valid experimental approaches. Therefore, we created a magnetic shear strain device that enabled, for the first time, to analyze the instant shear strain response of human breast gland cells. MCF10A-derived breast acini with basement membranes (BM) of defined maturation state and basoapical polarization were used to resemble breast gland morphogenesis in vitro. The novel biophysical tool was used to apply cyclic shear strain with defined amplitudes (≤15%, 0.2 Hz) over 22 h on living spheroids embedded in an ultrasoft matrix (<60 Pa). We demonstrated that breast spheroids gain resistance to shear strain, which increased with BM maturation and basoapical polarization. Most intriguingly, poorly developed spheroids were prone to cyclic strain-induced extrusion of apoptotic cells from the spheroid body. In contrast, matured spheroids were insensitive to this mechanoresponse—indicating changing mechanosensing or mechanotransduction mechanisms during breast tissue morphogenesis. Together, we introduced a versatile tool to study cyclic shear stress responses of 3D cell culture models. It can be used to strain, in principle, all kinds of cell clusters, even those that grow only in ultrasoft hydrogels. We believe that this approach opens new doors to gain new insights into dynamic shear strain-induced mechanobiological regulation circuits between cells and their ECM.

The Extracellular Matrix Stiffening: A Trigger of Prostate Cancer Progression and Castration Resistance?

Despite advancements made in diagnosis and treatment, prostate cancer remains the second most diagnosed cancer among men worldwide in 2020, and the first in North America and Europe. Patients with localized disease usually respond well to first-line treatments, however, up to 30% develop castration-resistant prostate cancer (CRPC), which is often metastatic, making this stage of the disease incurable and ultimately fatal. Over the last years, interest has grown into the extracellular matrix (ECM) stiffening as an important mediator of diseases, including cancers. While this process is increasingly well-characterized in breast cancer, a similar in-depth look at ECM stiffening remains lacking for prostate cancer. In this review, we scrutinize the current state of literature regarding ECM stiffening in prostate cancer and its potential association with disease progression and castration resistance.

Matrix stiffening and acquired resistance to chemotherapy: concepts and clinical significance

Extracellular matrix (ECM) refers to the non-cellular components of the tumour microenvironment, fundamentally providing a supportive scaffold for cellular anchorage and transducing signaling cues that orchestrate cellular behaviour and function. The ECM integrity is abrogated in several cases of cancer, ending in aberrant activation of a number of mechanotransduction pathways and induction of multiple tumorigenic events such as extended proliferation, cell death resistance, epithelial-mesenchymal transition and most importantly the development of chemoresistance. In this regard, the present study mainly aims to elucidate how the ECM-stiffening process may contribute to the development of chemoresistance during cancer progression and what pharmacological approaches are required for tackling this issue. Hence, the first section of this review explains the process of ECM stiffening and the ways it may affect biochemical pathways to induce chemoresistance in a clinic. In addition, the second part focuses on describing some of the most important pharmacological agents capable of targeting ECM components and underlying pathways for overcoming ECM-induced chemoresistance. Finally, the third part discusses the obtained results from the application of these agents in the clinic for overcoming chemoresistance.

Ultrasound-Induced Mechanical Compaction in Acoustically Responsive Scaffolds Promotes Spatiotemporally Modulated Signaling in Triple Negative Breast Cancer

Cancer cells continually sense and respond to mechanical cues from the extracellular matrix (ECM). Interaction with the ECM can alter intracellular signaling cascades, leading to changes in processes that promote cancer cell growth, migration, and survival. The present study used a recently developed composite hydrogel composed of a fibrin matrix and phase-shift emulsion, termed an acoustically responsive scaffold (ARS), to investigate effects of local mechanical properties on breast cancer cell signaling. Treatment of ARSs with focused ultrasound drives acoustic droplet vaporization (ADV) in a spatiotemporally controlled manner, inducing local compaction and stiffening of the fibrin matrix adjacent to the matrix-bubble interface. Combining ARSs and live single cell imaging of triple-negative breast cancer cells, it is discovered that both basal and growth-factor stimulated activities of protein kinase B (also known as Akt) and extracellular signal-regulated kinase (ERK), two major kinases driving cancer progression, negatively correlate with increasing distance from the ADV-induced bubble both in vitro and in a mouse model. Together, these data demonstrate that local changes in ECM compaction regulate Akt and ERK signaling in breast cancer and support further applications of the novel ARS technology to analyze spatial and temporal effects of ECM mechanics on cell signaling and cancer biology.

Extracellular matrix in cancer progression and therapy

The tumor ecosystem with heterogeneous cellular compositions and the tumor microenvironment has increasingly become the focus of cancer research in recent years. The extracellular matrix (ECM), the major component of the tumor microenvironment, and its interactions with the tumor cells and stromal cells have also enjoyed tremendously increased attention. Like the other components of the tumor microenvironment, the ECM in solid tumors differs significantly from that in normal organs and tissues. We review recent studies of the complex roles the tumor ECM plays in cancer progression, from tumor initiation, growth to angiogenesis and invasion. We highlight that the biomolecular, biophysical, and mechanochemical interactions between the ECM and cells not only regulate the steps of cancer progression, but also affect the efficacy of systemic cancer treatment. We further discuss the strategies to target and modify the tumor ECM to improve cancer therapy.

Cell-cell adhesion impacts epithelia response to substrate stiffness: Morphology and gene expression

Monolayer epithelial cells interact constantly with the substrate they reside on and their surrounding neighbors. As such, the properties of epithelial cells are profoundly governed by the mechanical and molecular cues that arise from both the substrate and contiguous cell neighbors. Although both cell-substrate and cell-cell interactions have been studied individually, these results are difficult to apply to native confluent epithelia, in which both jointly regulate the cell phenotype. Specifically, it remains poorly understood about the intertwined contributions from intercellular adhesion and substrate stiffness on cell morphology and gene expression, two essential microenvironment properties. Here, by adjusting the substrate modulus and altering the intercellular adhesion within confluent kidney epithelia, we found that cell-substrate and cell-cell interactions can mask each other's influence. For example, we found that epithelial cells exhibit an elongated morphological phenotype only when the substrate modulus and intercellular adhesions are both reduced, whereas their motility can be upregulated by either reduction. These results illustrate that combinatorial changes of the physical microenvironment are required to alter cell morphology and gene expression.

Non-muscle myosin II isoforms orchestrate substrate stiffness sensing to promote cancer cell contractility and migration

The stiffening of the extracellular matrix (ECM) during tumor progression results in an increase in cancer cell motility. In cell migration, two major isoforms of non-muscle myosin II (NMII), NMIIA and NMIIB, are expressed and assembled into the cytoskeleton. However, the isoform-specific regulatory roles of NMIIA and NMIIB as well as the underlying mechanisms in response to mechanical cues of the ECM are still elusive. Here, based on polyacrylamide (PAA) gels with tunable elastic modulus, we mimicked the mechanical properties of tumor tissue at different stages of breast cancer in vitro and investigated the distinct roles of NMII isoforms in the regulation of substrate stiffness. We demonstrate that NMIIA is engaged in establishing cell polarity by facilitating lamellipodia formation, focal adhesion turnover, and actin polymerization at the cell leading edge, while NMIIB is recruited to the cell perinuclear region and contributes to traction force generation and polarized distribution, both in a substrate stiffness-dependent manner. We further validated that substrate stiffness modulates the distribution and activation of NMII isoforms via the Rac1/p-PAK1/pS1916-NMIIA and PKCζ/pS1935-NMIIB signaling pathways in a site- and kinase-specific phosphoregulation manner. Our study is helpful for understanding the mechanotransduction of cancer cells and provides inspiration for molecular targets in antimetastatic therapy.

HSP90 as a regulator of extracellular matrix dynamics

The extracellular matrix (ECM) is a dynamic and organised extracellular network assembled from proteins and carbohydrates exported from the cell. The ECM is critical for multicellular life, providing spatial and temporal cellular cues to maintain tissue homeostasis. Consequently, ECM production must be carefully balanced with turnover to ensure homeostasis; ECM dysfunction culminates in disease. Hsp90 is a molecular chaperone central to protein homeostasis, including in the ECM. Intracellular and extracellular Hsp90 isoforms collaborate to regulate the levels and status of proteins in the ECM via multiple mechanisms. In so doing, Hsp90 regulates ECM dynamics, and changes in Hsp90 levels or activity support the development of ECM-related diseases, like cancer and fibrosis. Consequently, Hsp90 levels may have prognostic value, while inhibition of Hsp90 may have therapeutic potential in conditions characterised by ECM dysfunction.

External cues to drive B cell function towards immunotherapy

Immunotherapy stands out as a powerful and promising therapeutic strategy in the treatment of cancer, infections, and autoimmune diseases. Adoptive immune therapies are usually centered on modified T cells and their specific expansion towards antigen-specific T cells against cancer and other diseases. However, despite their unmatched features, the potential of B cells in immunotherapy is just beginning to be explored. The main role of B cells in the immune response is to secrete antigen-specific antibodies and provide long-term protection against foreign pathogens. They further function as antigen-presenting cells (APCs) and secrete pro- and anti-inflammatory cytokines and thus exert positive and negative regulatory stimuli on other cells involved in the immune response such as T cells. Therefore, while hyperactivation of B cells can cause autoimmunity, their dysfunctions lead to severe immunodeficiencies. Only suitably activated B cells can play an active role in the treatment of cancers, infections, and autoimmune diseases. As a result, studies have focused on B cell-targeted immunotherapies in recent years. For this, the development, functions, interactions with the microenvironment, and clinical importance of B cells should be well understood. In this review, we summarize the main events during B cell activation. From the viewpoint of mechanobiology we discuss the translation of external cues such as surface topology, substrate stiffness, and biochemical signaling into B cell functions. We further dive into current B cell-targeted therapy strategies and their clinical applications. STATEMENT OF SIGNIFICANCE: B cells are proving as a promising tool in the field of immunotherapy. B cells exhibit various functions such as antibody production, antigen presentation or secretion of immune-regulatory factors which can be utilized in the fight against oncological or immunological disorders. In this review we discuss the importance of external mechanobiological cues such as surface topology, substrate stiffness, and biochemical signaling on B cell function. We further summarize B cell-targeted therapy strategies and their clinical applications, as in the context of anti-tumor responses and autoimmune diseases.

Protective autophagy attenuates soft substrate-induced apoptosis through ROS/JNK signaling pathway in breast cancer cells

Tumor microenvironments are characterized not only in terms of chemical composition, but also by physical properties such as stiffness, which influences morphology, proliferation, and fate of tumor cells. However, the underlying mechanisms between matrix stiffness and the apoptosis-autophagy balance remain largely unexplored. In this study, we cultured human breast cancer MDA-MB-231 cells on rigid (57 kPa), stiff (38 kPa) or soft (10 kPa) substrates and demonstrated that increasing autophagy levels and autophagic flux in the cells cultured on soft substrates partly attenuated soft substrate-induced apoptosis. Mechanistically, this protective autophagy is regulated by intracellular reactive oxygen species (ROS) accumulation, which triggers the downstream signals of JNK, Bcl-2 and Beclin-1. More importantly, soft substrate-induced activation of ROS/JNK signaling promotes cell apoptosis through the mitochondrial pathway, whereas it increases protective autophagy by suppressing the interaction of Bcl-2 and Beclin-1. Taken together, our data suggest that JNK is the mediator of soft substrate-induced breast cancer cell apoptosis and autophagy which is likely to be the mechanism that partly attenuates mitochondrial apoptosis. This study provides new insights into the molecular mechanism by which autophagy plays a protective role against soft substrate-induced apoptosis in human breast cancer cells.

Intrinsic and growth-mediated cell and matrix specialization during murine meniscus tissue assembly

The incredible mechanical strength and durability of mature fibrous tissues and their extremely limited turnover and regenerative capacity underscores the importance of proper matrix assembly during early postnatal growth. In tissues with composite extracellular matrix (ECM) structures, such as the adult knee meniscus, fibrous (Collagen-I rich), and cartilaginous (Collagen-II, proteoglycan-rich) matrix components are regionally segregated to the outer and inner portions of the tissue, respectively. While this spatial variation in composition is appreciated to be functionally important for resisting complex mechanical loads associated with gait, the establishment of these specialized zones is poorly understood. To address this issue, the following study tracked the growth of the murine meniscus from its embryonic formation through its first month of growth, encompassing the critical time-window during which animals begin to ambulate and weight bear. Using histological analysis, region specific high-throughput qPCR, and Col-1, and Col-2 fluorescent reporter mice, we found that matrix and cellular features defining specific tissue zones were already present at birth, before continuous weight-bearing had occurred. These differences in meniscus zones were further refined with postnatal growth and maturation, resulting in specialization of mature tissue regions. Taken together, this work establishes a detailed timeline of the concurrent spatiotemporal changes that occur at both the cellular and matrix level throughout meniscus maturation. The findings of this study provide a framework for investigating the reciprocal feedback between cells and their evolving microenvironments during assembly of a mechanically robust fibrocartilage tissue, thus providing insight into mechanisms of tissue degeneration and effective regenerative strategies.

Effects of sodium salicylate and time postpartum on mammary tissue proliferation, gene transcript profile, and DNA methylation

Previous studies have demonstrated nonsteroidal antiinflammatory drug treatment in early lactation had a positive impact on whole-lactation milk production in older cows. The objective of this study was to evaluate proliferative, transcriptional, and epigenetic changes in the mammary gland that could explain increased production responses due to nonsteroidal antiinflammatory drug treatment. Sodium salicylate (SAL; 125 g/d) or water (CON) were administered via oral drench to multiparous Holstein cows (n = 8/treatment) once daily for 3 d beginning approximately 24 h after parturition, and mammary tissue was collected on d 1, 4, and 45 postpartum. Day 1 tissue was collected immediately preceding the initial drench, and d 4 tissue was collected 24 h following the final drench. Blood was collected twice weekly and analyzed for plasma glucose, insulin, β-hydroxybutyrate, free fatty acids, and prolactin. Cows were milked twice daily until d 7 of lactation, and thrice daily for the remainder of the study. Total RNA extracted from tissue was deep-sequenced and analyzed for differential gene expression using DESeq2. We detected no treatment effect on milk yield or plasma metabolites through 45 d of lactation; additionally, no change in mammary epithelial cell proliferation was detected when assessed by Ki67 labeling. Comparison of SAL versus CON revealed that only 16 of 18,286 genes were differentially expressed (false discovery rate <0.1) in mammary tissue collected on d 45, whereas no differentially expressed genes due to treatment were detected on d 1 or 4. Analysis of transcriptional differences over time showed downregulation of pathways related to immune cell recruitment and differentiation, and extensive overlap with pathways related to cholesterol synthesis and liver X receptor signaling. Global DNA methylation of mammary tissue was decreased for CON compared with SAL. Transcriptome analysis emphasized extensive involvement of immune-related signaling pathways in the switch from lactogenesis to galactopoiesis, and changes in methylation with SAL treatment merit future investigation into epigenetic effects on milk production.

A Signaling View into the Inflammatory Tumor Microenvironment

The development of tumors requires an initiator event, usually exposure to DNA damaging agents that cause genetic alterations such as gene mutations or chromosomal abnormalities, leading to deregulated cell proliferation. Although the mere stochastic accumulation of further mutations may cause tumor progression, it is now clear that an inflammatory microenvironment has a major tumor-promoting influence on initiated cells, in particular when a chronic inflammatory reaction already existed before the initiated tumor cell was formed. Moreover, inflammatory cells become mobilized in response to signals emanating from tumor cells. In both cases, the microenvironment provides signals that initiated tumor cells perceive by membrane receptors and transduce via downstream kinase cascades to modulate multiple cellular processes and respond with changes in cell gene expression, metabolism, and morphology. Cytokines, chemokines, and growth factors are examples of major signals secreted by immune cells, fibroblast, and endothelial cells and mediate an intricate cell-cell crosstalk in an inflammatory microenvironment, which contributes to increased cancer cell survival, phenotypic plasticity and adaptation to surrounding tissue conditions. Eventually, consequent changes in extracellular matrix stiffness and architecture, coupled with additional genetic alterations, further fortify the malignant progression of tumor cells, priming them for invasion and metastasis. Here, we provide an overview of the current knowledge on the composition of the inflammatory tumor microenvironment, with an emphasis on the major signals and signal-transducing events mediating different aspects of stromal cell-tumor cell communication that ultimately lead to malignant progression.

Ferroptosis-Related Gene Signature Promotes Ovarian Cancer by Influencing Immune Infiltration and Invasion

Ovarian cancer is a kind of gynecological malignancy with high mortality. Ferroptosis is a new type of iron-dependent cell death characterized by the formation of lipid peroxides and excessive accumulation of reactive oxygen species. Studies have shown that ferroptosis modulates tumor genesis, progression, and invasion, including ovarian cancer. Based on the mRNA expression data from TCGA, we construct a scoring system using consensus clustering analysis, univariate Cox regression analysis, and least absolute selection operator. Then, we systematically evaluate the relationship between score and clinical characteristics of ovarian cancer. The result from the prediction of biofunction pathways shows that score serves as an independent prognostic marker for ovarian cancer and affects tumor progression by modulating tumor metastasis. Moreover, immunocytes such as activated CD4 T cell, activated CD8 T cell, regulatory T cells, macrophage, and stromal cells, including adipocytes, epithelial cells, and fibroblast infiltrate more in the tumor microenvironment in a high-score group, indicating ferroptosis can also affect tumor immune landscape. Critically, four potentially sensitive drugs, including staurosporine, epothilone B, DMOG, and HG6-64-1 based on the scores, are predicted, and DMOG is recognized as a novel targeted drug for ovarian cancer. In general, we construct the scoring system based on ferroptosis-related genes that can predict the prognosis of ovarian cancer patients and propose that ferroptosis may affect ovarian cancer progression by mediating tumor metastasis and immune landscape. Novel drugs to target ovarian cancer are also predicted.

Cell orientation under stretch: Stability of a linear viscoelastic model

The sensitivity of cells to alterations in the microenvironment and in particular to external mechanical stimuli is significant in many biological and physiological circumstances. In this regard, experimental assays demonstrated that, when a monolayer of cells cultured on an elastic substrate is subject to an external cyclic stretch with a sufficiently high frequency, a reorganization of actin stress fibres and focal adhesions happens in order to reach a stable equilibrium orientation, characterized by a precise angle between the cell major axis and the largest strain direction. To examine the frequency effect on the orientation dynamics, we propose a linear viscoelastic model that describes the coupled evolution of the cellular stress and the orientation angle. We find that cell orientation oscillates tending to an angle that is predicted by the minimization of a very general orthotropic elastic energy, as confirmed by a bifurcation analysis. Moreover, simulations show that the speed of convergence towards the predicted equilibrium orientation presents a changeover related to the viscous-elastic transition for viscoelastic materials. In particular, when the imposed oscillation period is lower than the characteristic turnover rate of the cytoskeleton and of adhesion molecules such as integrins, reorientation is significantly faster.

Mechanical plasticity of collagen directs branch elongation in human mammary gland organoids

Epithelial branch elongation is a central developmental process during branching morphogenesis in diverse organs. This fundamental growth process into large arborized epithelial networks is accompanied by structural reorganization of the surrounding extracellular matrix (ECM), well beyond its mechanical linear response regime. Here, we report that epithelial ductal elongation within human mammary organoid branches relies on the non-linear and plastic mechanical response of the surrounding collagen. Specifically, we demonstrate that collective back-and-forth motion of cells within the branches generates tension that is strong enough to induce a plastic reorganization of the surrounding collagen network which results in the formation of mechanically stable collagen cages. Such matrix encasing in turn directs further tension generation, branch outgrowth and plastic deformation of the matrix. The identified mechanical tension equilibrium sets a framework to understand how mechanical cues can direct ductal branch elongation.

Mammary organoid growth from single primary human cells rely on distinct morphogenetic processes. Here, the authors observe by live cell imaging the importance of the plastic mechanical response of the extracellular matrix and cell migration for the underlying arborized structure formation process.

Extracellular Vesicles: An Emerging Mechanism Governing the Secretion and Biological Roles of Tenascin-C

ECM composition and architecture are tightly regulated for tissue homeostasis. Different disorders have been associated to alterations in the levels of proteins such as collagens, fibronectin (FN) or tenascin-C (TnC). TnC emerges as a key regulator of multiple inflammatory processes, both during physiological tissue repair as well as pathological conditions ranging from tumor progression to cardiovascular disease. Importantly, our current understanding as to how TnC and other non-collagen ECM components are secreted has remained elusive. Extracellular vesicles (EVs) are small membrane-bound particles released to the extracellular space by most cell types, playing a key role in cell-cell communication. A broad range of cellular components can be transported by EVs (e.g. nucleic acids, lipids, signalling molecules and proteins). These cargoes can be transferred to target cells, potentially modulating their function. Recently, several extracellular matrix (ECM) proteins have been characterized as bona fide EV cargoes, exosomal secretion being particularly critical for TnC. EV-dependent ECM secretion might underpin diseases where ECM integrity is altered, establishing novel concepts in the field such as ECM nucleation over long distances, and highlighting novel opportunities for diagnostics and therapeutic intervention. Here, we review recent findings and standing questions on the molecular mechanisms governing EV–dependent ECM secretion and its potential relevance for disease, with a focus on TnC.

Cell Force-Driven Basement Membrane Disruption Fuels EGF- and Stiffness-Induced Invasive Cell Dissemination from Benign Breast Gland Acini

Local basement membrane (BM) disruption marks the initial step of breast cancer invasion. The activation mechanisms of force-driven BM-weakening remain elusive. We studied the mechanical response of MCF10A-derived human breast cell acini with BMs of tuneable maturation to physical and soluble tumour-like extracellular matrix (ECM) cues. Traction force microscopy (TFM) and elastic resonator interference stress microscopy (ERISM) were used to quantify pro-invasive BM stress and protrusive forces. Substrate stiffening and mechanically impaired BM scaffolds induced the invasive transition of benign acini synergistically. Robust BM scaffolds attenuated this invasive response. Additional oncogenic EGFR activation compromised the BMs’ barrier function, fuelling invasion speed and incidence. Mechanistically, EGFR-PI3-Kinase downstream signalling modulated both MMP- and force-driven BM-weakening processes. We show that breast acini form non-proteolytic and BM-piercing filopodia for continuous matrix mechanosensation, which significantly push and pull on the BM and ECM under pro-invasive conditions. Invasion-triggered acini further shear and compress their BM by contractility-based stresses that were significantly increased (3.7-fold) compared to non-invasive conditions. Overall, the highest amplitudes of protrusive and contractile forces accompanied the highest invasiveness. This work provides a mechanistic concept for tumour ECM-induced mechanically misbalanced breast glands fuelling force-driven BM disruption. Finally, this could facilitate early cell dissemination from pre-invasive lesions to metastasize eventually.

MiR-485 targets the DTX4 gene to regulate milk fat synthesis in bovine mammary epithelial cells

MicroRNAs (miRNAs) are mRNA suppressors that regulate a variety of cellular and physiological processes, including cell proliferation, apoptosis, triglyceride synthesis, fat formation, and lipolysis, by post-transcriptional processing. In previous studies, we isolated and sequenced miRNAs from mammary epithelial cells from Chinese Holstein cows with high and low milk fat percentages. MiR-485 was one of the significantly differentially expressed miRNAs that were identified. In the present study, the relationship between the candidate target gene DTX4 and miR-485 was validated by bioinformatics and real-time fluorescent quantitative PCR (qRT-PCR) and Western blot (WB) analyses in bovine mammary epithelial cells (bMECs). The results indicated that miR-485 negatively regulated the mRNA expression of the target gene DTX4. Furthermore, an shRNA interference vector for the target gene DTX4 was constructed successfully, and it increased the triglyceride content and reduced the cholesterol content of transfected cells. These results suggest that miR-485 may affect the contents of triglycerides (TGs) and cholesterol (CHOL) by targeting the DTX4 gene. This study indicates that miR-485 has a role in regulating milk fat synthesis and that miR-485 targets the DTX4 gene to regulate lipid metabolism in bMECs. These findings contribute to the understanding of the functional significance of miR-485 in milk fat synthesis.

Molecular Actions Underlying Wolffian Duct Regression in Sexual Differentiation of Murine Reproductive Tracts

Sexually dimorphic establishment of the reproductive tract system requires sex-specific regression of the Wolffian duct and Müllerian duct in the mesonephros. In an XX embryo, the Wolffian duct regresses under the control of the mesenchymal transcription factor COUP-TFII. To understand cellular and molecular actions underlying Wolffian duct regression, we performed transcriptomic analyses of XX mesonephroi with or without Coup-tfII and genome-wide analysis of COUP-TFII chromatin occupancy in XX mesonephroi. The integrative analysis of COUP-TFII genome-wide binding and transcriptomic analysis revealed the suppression of muscle differentiation and extracellular matrix genes by COUP-TFII and identified a group of potential transcriptional partners of COUP-TFII in the mesenchyme that potentially facilitate Wolffian duct regression. These findings provide insights into the molecular action of COUP-TFII in the Wolffian duct mesenchyme and identify a list of biologically relevant candidate genes and pathways for future functional analyses in sexual differentiation of reproductive tracts.

A nonlinear elastic description of cell preferential orientations over a stretched substrate

The active response of cells to mechanical cues due to their interaction with the environment has been of increasing interest, since it is involved in many physiological phenomena, pathologies, and in tissue engineering. In particular, several experiments have shown that, if a substrate with overlying cells is cyclically stretched, they will reorient to reach a well-defined angle between their major axis and the main stretching direction. Recent experimental findings, also supported by a linear elastic model, indicated that the minimization of an elastic energy might drive this reorientation process. Motivated by the fact that a similar behaviour is observed even for high strains, in this paper we address the problem in the framework of finite elasticity, in order to study the presence of nonlinear effects. We find that, for a very large class of constitutive orthotropic models and with very general assumptions, there is a single linear relationship between a parameter describing the biaxial deformation and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\cos ^2\theta _{\mathrm{eq}}$$\end{document}cos2θeq, where \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\theta _{\mathrm{eq}}$$\end{document}θeq is the orientation angle of the cell, with the slope of the line depending on a specific combination of four parameters that characterize the nonlinear constitutive equation. We also study the effect of introducing a further dependence of the energy on the anisotropic invariants related to the square of the Cauchy–Green strain tensor. This leads to departures from the linear relationship mentioned above, that are again critically compared with experimental data.

Posterior capsule opacification: What's in the bag?

Cataract, a clouding of the lens, is the most common cause of blindness in the world. It has a marked impact on the wellbeing and productivity of individuals and has a major economic impact on healthcare providers. The only means of treating cataract is by surgical intervention. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior capsule and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens (IOL). The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. Lens epithelial cells, however, remain attached to the anterior capsule, and in response to surgical trauma initiate a wound-healing response that ultimately leads to light scatter and a reduction in visual quality known as posterior capsule opacification (PCO). There are two commonly-described forms of PCO: fibrotic and regenerative. Fibrotic PCO follows classically defined fibrotic processes, namely hyperproliferation, matrix contraction, matrix deposition and epithelial cell trans-differentiation to a myofibroblast phenotype. Regenerative PCO is defined by lens fibre cell differentiation events that give rise to Soemmerring's ring and Elschnig's pearls and becomes evident at a later stage than the fibrotic form. Both fibrotic and regenerative forms of PCO contribute to a reduction in visual quality in patients. This review will highlight the wealth of tools available for PCO research, provide insight into our current knowledge of PCO and discuss putative management of PCO from IOL design to pharmacological interventions.

Probing variations of fibrous structures during the development of breast ductal carcinoma tissues via Mueller matrix imaging

Recently, we developed a label-free method to probe the microstructural information and optical properties of unstained thin tissue slices based on microscopic Mueller matrix imaging technique. In this paper, we take the microscopic Mueller matrix images of human breast ductal carcinoma tissue samples at different pathological stages, and then calculate and analyze their retardance-related Mueller matrix-derived parameters. To reveal the microstructural features more quantitatively and precisely, we propose a new method based on first-order statistical properties of image to transform the 2D images of Mueller matrix parameters into several statistical feature vectors. We evaluate each statistical feature vector by corresponding classification characteristic value extracted from the statistical features of Mueller matrix parameters images of healthy breast duct tissue samples. The experimental results indicate that these statistical feature vectors of Mueller matrix derived parameters may become powerful tools to quantitatively characterize breast ductal carcinoma tissue samples at different pathological stages. It has the potential to facilitate automating the staging process of breast ductal carcinoma tissue, resulting in the improvement of diagnostic efficiency.

MR Elastography of the Breast: Evolution of Technique, Case Examples, and Future Directions

Recognizing that breast cancers present as firm, stiff lesions, the foundation of breast magnetic resonance elastography (MRE) is to combine tissue stiffness parameters with sensitive breast MR contrast-enhanced imaging. Breast MRE is a non-ionizing, cross-sectional MR imaging technique that provides for quantitative viscoelastic properties, including tissue stiffness, elasticity, and viscosity, of breast tissues. Currently, the technique continues to evolve as research surrounding the use of MRE in breast tissue is still developing. In the setting of a newly diagnosed cancer, associated desmoplasia, stiffening of the surrounding stroma, and necrosis are known to be prognostic factors that can add diagnostic information to patient treatment algorithms. In fact, mechanical properties of the tissue might also influence breast cancer risk. For these reasons, exploration of breast MRE has great clinical value. In this review, we will: (1) address the evolution of the various MRE techniques; (2) provide a brief overview of the current clinical studies in breast MRE with interspersed case examples; and (3) suggest directions for future research.

Matrix stiffness-sensitive long noncoding RNA NEAT1 seeded paraspeckles in cancer cells

Cancer progression is influenced by changes in the tumor microenvironment, such as the stiffening of the extracellular matrix. Yet our understanding of how cancer cells sense and convert mechanical stimuli into biochemical signals and physiological responses is still limited. The long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1), which forms the backbone of subnuclear "paraspeckle" bodies, has been identified as a key genetic regulator in numerous cancers. Here, we investigated whether paraspeckles, as defined by NEAT1 localization, are mechanosensitive. Using tunable polyacrylamide hydrogels of extreme stiffnesses, we measured paraspeckle parameters in several cancer cell lines and observed an increase in paraspeckles in cells cultured on soft (3 kPa) hydrogels compared with stiffer (40 kPa) hydrogels. This response to soft substrate is erased when cells are first conditioned on stiff substrate, and then transferred onto soft hydrogels, suggestive of mechanomemory upstream of paraspeckle regulation. We also examined some well-characterized mechanosensitive markers, but found that lamin A expression, as well as YAP and MRTF-A nuclear translocation did not show consistent trends between stiffnesses, despite all cell types having increased migration, nuclear, and cell area on stiffer hydrogels. We thus propose that paraspeckles may prove of use as mechanosensors in cancer mechanobiology.

Corneal Stiffness and Collagen Cross-Linking Proteins in Glaucoma: Potential for Novel Therapeutic Strategy

Biomechanical properties of the cornea have recently emerged as clinically useful in risk assessment of diagnosing glaucoma and predicting disease progression. Corneal hysteresis (CH) is a dynamic tool, which measures viscoelasticity of the cornea. It represents the overall deformability of the cornea, and reduces significantly with age. Low CH has also been associated with optic nerve damage and progression of visual field loss in glaucoma. The extracellular matrix (ECM) constituents of the cornea, trabecular meshwork (TM), sclera, and lamina cribrosa (LC) are similar, as they are predominantly made of fibrillar collagen. This suggests that biomechanical changes in the cornea may also reflect optic nerve compliance in glaucomatous optic neuropathy, and in the known increase of TM tissue stiffness in glaucoma. Increased collagen cross-linking contributes to tissue stiffening throughout the body, which is observed in normal aging and occurs at an accelerated rate in systemic conditions such as fibrotic and cardiovascular diseases, cancer, and glaucoma. We reviewed 3 ECM cross-linking proteins that may have a potential role in the disease process of increased tissue stiffness in glaucoma, including lysyl oxidase (LOX)/lysyl oxidase-like 1 (LOXL1), tissue transglutaminase (TG2), and advanced glycation end products. We also report elevated messenger RNA (mRNA) levels of LOX and TG2 in glaucoma LC cells to support our proposed theory that increased levels of cross-linking proteins in glaucoma play a role in LC tissue stiffness. We highlight areas of research that are needed to better understand the role of cross-linking in glaucoma pathogenesis, leading potentially to a novel therapeutic strategy.

The Physical Microenvironment of Tumors: Characterization and Clinical Impact

The tumor microenvironment plays a critical role in tumorigenesis and metastasis. As tightly controlled extracellular matrix homeostasis is lost during tumor progression, a dysregulated extracellular matrix can significantly alter cellular phenotype and drive malignancy. Altered physical properties of the tumor microenvironment alter cancer cell behavior, limit delivery and efficacy of therapies, and correlate with tumorigenesis and patient prognosis. The physical features of the extracellular matrix during tumor progression have been characterized; however, a wide range of methods have been used between studies and cancer types resulting in a large range of reported values. Here, we discuss the significant mechanical and structural properties of the tumor microenvironment, summarizing their reported values and clinical impact across cancer type and grade. We attempt to integrate the values in the literature to identify sources of reported differences and commonalities to better understand how aberrant extracellular matrix dynamics contribute to cancer progression. An intimate understanding of altered matrix properties during malignant transformation will be crucial in effectively detecting, monitoring, and treating cancer.

Silver nanoparticles compromise the development of mouse pubertal mammary glands through disrupting internal estrogen signaling

Despite numerous studies on the environmental health and safety (EHS) of silver nanoparticles (AgNPs), most studies looked into their gross toxicities with rather limited understanding on their labyrinthine implicit effects on the target sites, such as the endocrine system. Burgeoning evidence documents the disrupting effects of AgNPs on endocrine functions; however, little research has been invested to recognize the potential impacts on the mammary gland, a susceptible estrogen-responsive organ. Under this setting, we here aimed to scrutinize AgNP-induced effects on the development of pubertal mammary glands at various concentrations that bear significant EHS relevance. We unearthed that AgNPs could accumulate in mouse mammary glands and result in a decrease in the percentage of ducts and terminal ducts in the adult mice after chronic exposure. Strikingly, smaller sized AgNPs showed greater capability to alter the pubertal mammary development than larger sized particles. Intriguingly, mechanistic investigation revealed that the reduction of epithelial proliferation in response to AgNPs was ascribed to reduced ERα expression, which, at least partially, accounted for diseased epithelial morphology in mammary glands. Meanwhile, the decline in fibrous collagen deposition around the epithelium was found to contribute to the compromised development of mammary glands under the exposure of AgNPs. Moreover, as an extension of the mechanism, AgNPs diminished serum levels of estradiol in exposed animals. Together, these results uncovered a novel toxicity feature of AgNPs: compromised development of mouse pubertal mammary glands through the endocrine-disrupting actions. This study would open a new avenue to unveil the EHS impacts of AgNPs.

3D Extracellular Matrix Mimics: Fundamental Concepts and Role of Materials Chemistry to Influence Stem Cell Fate

Synthetic 3D extracellular matrices (ECMs) find application in cell studies, regenerative medicine, and drug discovery. While cells cultured in a monolayer may exhibit unnatural behavior and develop very different phenotypes and genotypes than in vivo, great efforts in materials chemistry have been devoted to reproducing in vitro behavior in in vivo cell microenvironments. This requires fine-tuning the biochemical and structural actors in synthetic ECMs. This review will present the fundamentals of the ECM, cover the chemical and structural features of the scaffolds used to generate ECM mimics, discuss the nature of the signaling biomolecules required and exploited to generate bioresponsive cell microenvironments able to induce a specific cell fate, and highlight the synthetic strategies involved in creating functional 3D ECM mimics.

Bioprinting 101: Design, Fabrication, and Evaluation of Cell-Laden 3D Bioprinted Scaffolds

3D bioprinting is an additive manufacturing technique that recapitulates the native architecture of tissues. This is accomplished through the precise deposition of cell-containing bioinks. The spatiotemporal control over bioink deposition permits for improved communication between cells and the extracellular matrix, facilitates fabrication of anatomically and physiologically relevant structures. The physiochemical properties of bioinks, before and after crosslinking, are crucial for bioprinting complex tissue structures. Specifically, the rheological properties of bioinks determines printability, structural fidelity, and cell viability during the printing process, whereas postcrosslinking of bioinks are critical for their mechanical integrity, physiological stability, cell survival, and cell functions. In this review, we critically evaluate bioink design criteria, specifically for extrusion-based 3D bioprinting techniques, to fabricate complex constructs. The effects of various processing parameters on the biophysical and biochemical characteristics of bioinks are discussed. Furthermore, emerging trends and future directions in the area of bioinks and bioprinting are also highlighted. Graphical abstract [Figure: see text] Impact statement Extrusion-based 3D bioprinting is an emerging additive manufacturing approach for fabricating cell-laden tissue engineered constructs. This review critically evaluates bioink design criteria to fabricate complex tissue constructs. Specifically, pre- and post-printing evaluation approaches are described, as well as new research directions in the field of bioink development and functional bioprinting are highlighted.

Inter-Individual Variation in Response to Estrogen in Human Breast Explants

Exposure to estrogen is strongly associated with increased breast cancer risk. While all women are exposed to estrogen, only 12% are expected to develop breast cancer during their lifetime. These women may be more sensitive to estrogen, as rodent models have demonstrated variability in estrogen sensitivity. Our objective was to determine individual variation in expression of estrogen receptor (ER) and estrogen-induced responses in the normal human breast. Human breast tissue from female donors undergoing reduction mammoplasty surgery were collected for microarray analysis of ER expression. To examine estrogen-induced responses, breast tissue from 23 female donors were cultured ex- vivo in basal or 10 nM 17β-estradiol (E2) media for 4 days. Expression of ER genes (ESR1 and ESR2) increased significantly with age. E2 induced consistent increases in global gene transcription, but expression of target genes AREG, PGR, and TGFβ2 increased significantly only in explants from nulliparous women. E2-treatment did not induce consistent changes in proliferation or radiation induced apoptosis. Responses to estrogen are highly variable among women and not associated with levels of ER expression, suggesting differences in intracellular signaling among individuals. The differences in sensitivity to E2-stimulated responses may contribute to variation in risk of breast cancer.

Glyphosate-based herbicide induces hyperplastic ducts in the mammary gland of aging Wistar rats

Glyphosate-based herbicide (GBH) exposure is known to have adverse effects on endocrine-related tissues. Here, we aimed to determine whether early postnatal exposure to a GBH induces long-term effects on the rat mammary gland. Thus, female Wistar pups were injected with saline solution (Control) or GBH (2 mg glyphosate/kg/day) on postnatal days (PND) 1, 3, 5 and 7. At 20 months of age, mammary gland samples were collected to determine histomorphological features, proliferation index and the expression of steroid hormone receptors expression, by immunohistochemistry, and serum samples were collected to assess 17β-estradiol (E2) and progesterone (P4) levels. GBH exposure induced morphological changes evidenced by a higher percentage of hyperplastic ducts and a fibroblastic-like stroma in the mammary gland. GBH-treated rats also showed a high expression of steroid hormone receptors in hyperplastic ducts. The results indicate that early postnatal exposure to GBH induces long-term alterations in the mammary gland morphology of aging female rats.

Extra domain A-containing fibronectin expression in Spin90-deficient fibroblasts mediates cancer-stroma interaction and promotes breast cancer progression

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment play major roles in supporting cancer progression. A previous report showed that SPIN90 downregulation is correlated with CAF activation and that SPIN90-deficient CAFs promote breast cancer progression. However, the mechanisms that mediate cancer-stroma interaction and how such interactions regulate cancer progression are not well understood. Here, we show that extra domain A (EDA)-containing fibronectin (FN), FN(+)EDA, produced by mouse embryonic fibroblasts (MEFs) derived from Spin90-knockout (KO) mice increases their own myofibroblast differentiation, which facilitates breast cancer progression. Increased FN(+)EDA in Spin90-KO MEFs promoted fibril formation in the extracellular matrix (ECM) and specifically interacted with integrin α4β1 as the mediating receptor. Moreover, FN(+)EDA expression by Spin90-KO MEFs increased proliferation, migration, and invasion of breast cancer cells. Irigenin, a specific inhibitor of the interaction between integrin α4β1 and FN(+)EDA, significantly blocked the effects of FN(+)EDA, such as fibril formation by Spin90-KO MEFs and proliferation, migration, and invasion of breast cancer cells. In orthotopic breast cancer mouse models, irigenin injection remarkably reduced tumor growth and lung metastases. It was supported by that FN(+)EDA in assembled fibrils was accumulated in cancer stroma of human breast cancer patients in which SPIN90 expression was downregulated. Our data suggest that SPIN90 downregulation increases FN(+)EDA and promotes ECM stiffening in breast cancer stroma through an assembly of long FN(+)EDA-rich fibrils; moreover, engagement of the Integrin α4β1 receptor facilitates breast cancer progression. Inhibitory effects of irigenin on tumor growth and metastasis suggest the potential of this agent as an anticancer therapeutic.

Potential of breastmilk in stem cell research

Breastmilk is a dynamic, multi-faceted, and complex fluid containing a plethora of biochemical and cellular components that execute developmental effects or differentiation program, providing nourishment and immunity to newborns. Recently, it was reported that breastmilk contains a heterogeneous population of naïve cells, including pluripotent stem cells, multipotent stem cells, immune cells, and non-immune cells. The stem cells derived from breastmilk possess immune privilege and non-tumorigenic properties. Thus, breastmilk may represent an ideal source of stem cells collected by non-perceive procedure than other available sources. Thus, this "maternally originating natural regenerative medicine" may have innumerable applications in clinical biology, cosmetics, and pharmacokinetics. This review describes the efficient integrated cellular system of mammary glands, the impressive stem cell hierarchy of breastmilk, and their possible implications in translational research and therapeutics.

Evaluation of breast stiffness measured by ultrasound and breast density measured by MRI using a prone-supine deformation model

Background

This study evaluated breast tissue stiffness measured by ultrasound elastography and the percent breast density measured by magnetic resonance imaging to understand their relationship.

Methods

Magnetic resonance imaging and whole breast ultrasound were performed in 20 patients with suspicious lesions. Only the contralateral normal breasts were analyzed. Breast tissue stiffness was measured from the echogenic homogeneous fibroglandular tissues in the central breast area underneath the nipple. An automatic, computer algorithm-based, segmentation method was used to segment the whole breast and fibroglandular tissues on three dimensional magnetic resonanceimaging. A finite element model was applied to deform the prone magnetic resonance imaging to match the supine ultrasound images, by using the inversed gravity loaded transformation. After deformation, the tissue level used in ultrasound elastography measurement could be estimated on the deformed supine magnetic resonance imaging to measure the breast density in the corresponding tissue region.

Results

The mean breast tissue stiffness was 2.3 ± 0.8 m/s. The stiffness was not correlated with age (r = 0.29). Overall, there was no positive correlation between breast stiffness and breast volume (r = - 0.14), or the whole breast percent density (r = - 0.09). There was also no correlation between breast stiffness and the local percent density measured from the corresponding region (r = - 0.12).

Conclusions

The lack of correlation between breast stiffness measured by ultrasound and the whole breast or local percent density measured by magnetic resonance imaging suggests that breast stiffness is not solely related to the amount of fibroglandular tissue. Further studies are needed to investigate whether they are dependent or independent cancer risk factors.