Stromal matrix metalloproteinase-11 is involved in the mammary gland postnatal development

Mutation of SOCS2 induces structural and functional changes in mammary development

Lactation is an essential process for mammals. In sheep, the R96C mutation in suppressor of cytokine signaling 2 (SOCS2) protein is associated with greater milk production and increased mastitis sensitivity. To shed light on the involvement of R96C mutation in mammary gland development and lactation, we developed a mouse model carrying this mutation (SOCS2KI/KI). Mammary glands from virgin adult SOCS2KI/KI mice presented a branching defect and less epithelial tissue, which were not compensated for in later stages of mammary development. Mammary epithelial cell (MEC) subpopulations were modified, with mutated mice having three times as many basal cells, accompanied by a decrease in luminal cells. The SOCS2KI/KI mammary gland remained functional; however, MECs contained more lipid droplets versus fat globules, and milk lipid composition was modified. Moreover, the gene expression dynamic from virgin to pregnancy state resulted in the identification of about 3000 differentially expressed genes specific to SOCS2KI/KI or control mice. Our results show that SOCS2 is important for mammary gland development and milk production. In the long term, this finding raises the possibility of ensuring adequate milk production without compromising animal health and welfare.

Cancer invasion and metastasis: Insights from murine pubertal mammary gland morphogenesis

Cancer invasion and metastasis accounts for the majority of cancer related mortality. A better understanding of the players that drive the aberrant invasion and migration of tumors cells will provide critical targets to inhibit metastasis. Postnatal pubertal mammary gland morphogenesis is characterized by highly proliferative, invasive, and migratory normal epithelial cells. Identifying the molecular regulators of pubertal gland development is a promising strategy since tumorigenesis and metastasis is postulated to be a consequence of aberrant reactivation of developmental stages. In this review, we summarize the pubertal morphogenesis regulators that are involved in cancer metastasis and revisit pubertal mammary gland transcriptome profiling to uncover both known and unknown metastasis genes. Our updated list of pubertal morphogenesis regulators shows that most are implicated in invasion and metastasis. This review highlights molecular linkages between development and metastasis and provides a guide for exploring novel metastatic drivers.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

The paradoxical role of matrix metalloproteinase-11 in cancer

The microenvironment surrounding the tumor affects biological processes, such as cell proliferation, angiogenesis, apoptosis, and invasion. Therefore, the ability to change these environments is an important attribute for tumor cells to obtain specific functions necessary for growth and metastasis. Matrix metalloproteinases (MMPs) are zinc-dependent proteolytic metalloenzymes that facilitate protease-dependent tumor progression by degrading extracellular matrix (ECM) proteins, releasing cytokines, growth factors, and other cell surface molecules. As one of the most widely studied MMPs, MMP-11 is an important protease that is expressed in cancer cells, stromal cells, and the adjacent microenvironment. MMP-11 has a dual effect on tumors. On one hand, MMP-11 promotes tumor development by inhibiting apoptosis and promoting the migration and invasion of cancer cells in the early stage. On the other hand, in animal models, MMP-11 has a protective effect on tumor growth and metastasis at an advanced stage. Based on current findings regarding the importance of MMP-11 in altering the tumor microenvironment, there is a need to further understand how stromal cells and the ECM regulate tumor progression, which may result in the re-examination of MMPs as drug targets for cancer and other diseases. In this review, we summarize the dual role of MMP-11 in cancer and its potential clinical significance.

Repression of endogenous retroviruses prevents antiviral immune response and is required for mammary gland development

The role of heterochromatin in cell fate specification during development is unclear. We demonstrate that loss of the lysine 9 of histone H3 (H3K9) methyltransferase G9a in the mammary epithelium results in de novo chromatin opening, aberrant formation of the mammary ductal tree, impaired stem cell potential, disrupted intraductal polarity, and loss of tissue function. G9a loss derepresses long terminal repeat (LTR) retroviral sequences (predominantly the ERVK family). Transcriptionally activated endogenous retroviruses generate double-stranded DNA (dsDNA) that triggers an antiviral innate immune response, and knockdown of the cytosolic dsDNA sensor Aim2 in G9a knockout (G9acKO) mammary epithelium rescues mammary ductal invasion. Mammary stem cell transplantation into immunocompromised or G9acKO-conditioned hosts shows partial dependence of the G9acKO mammary morphological defects on the inflammatory milieu of the host mammary fat pad. Thus, altering the chromatin accessibility of retroviral elements disrupts mammary gland development and stem cell activity through both cell-autonomous and non-autonomous mechanisms.

Matrilysins and Stromelysins in Pathogenesis and Diagnostics of Cancers

Matrix metalloproteinases (MMPs) are endopeptidases which are widely studied in terms of their role in the physiological and pathological processes in the organism. In this article, we consider usefulness of matrilysins and stromelysins in pathogenesis and diagnostic of the most common malignancies in the world, e.g., lung, breast, prostate, and colorectal cancers. In all of the mentioned cancers, matrilysins and stromelysins have a pivotal role in their development and also may have diagnostic utility. Influence to the cancerous process is connected with specific dependencies between these enzymes and components of the extracellular matrix (ECM), non-matrix components like cell surface components. All the information provided below allows to take a closer look at matrilysins and stromelysins and their functions in the cancer development.

Matrix Metalloproteinase-11 Promotes Early Mouse Mammary Gland Tumor Growth through Metabolic Reprogramming and Increased IGF1/AKT/FoxO1 Signaling Pathway, Enhanced ER Stress and Alteration in Mitochondrial UPR

Matrix metalloproteinase 11 (MMP11) is an extracellular proteolytic enzyme belonging to the matrix metalloproteinase (MMP11) family. These proteases are involved in extracellular matrix (ECM) remodeling and activation of latent factors. MMP11 is a negative regulator of adipose tissue development and controls energy metabolism in vivo. In cancer, MMP11 expression is associated with poorer survival, and preclinical studies in mice showed that MMP11 accelerates tumor growth. How the metabolic role of MMP11 contributes to cancer development is poorly understood. To address this issue, we developed a series of preclinical mouse mammary gland tumor models by genetic engineering. Tumor growth was studied in mice either deficient (Loss of Function-LOF) or overexpressing MMP11 (Gain of Function-GOF) crossed with a transgenic model of breast cancer induced by the polyoma middle T antigen (PyMT) driven by the murine mammary tumor virus promoter (MMTV) (MMTV-PyMT). Both GOF and LOF models support roles for MMP11, favoring early tumor growth by increasing proliferation and reducing apoptosis. Of interest, MMP11 promotes Insulin-like Growth Factor-1 (IGF1)/protein kinase B (AKT)/Forkhead box protein O1 (FoxO1) signaling and is associated with a metabolic switch in the tumor, activation of the endoplasmic reticulum stress response, and an alteration in the mitochondrial unfolded protein response with decreased proteasome activity. In addition, high resonance magic angle spinning (HRMAS) metabolomics analysis of tumors from both models established a metabolic signature that favors tumorigenesis when MMP11 is overexpressed. These data support the idea that MMP11 contributes to an adaptive metabolic response, named metabolic flexibility, promoting cancer growth.

Diagnostic value of Doppler ultrasound parameters combined with MMP-11 in early breast cancer and benign breast diseases

Diagnostic value of Doppler ultrasound parameters combined with matrix metalloproteinase-11 (MMP-11) in early breast cancer and benign breast diseases were investigated. A total of 72 patients who underwent color Doppler ultrasound examination in Liaocheng Third People's Hospital from March 2015 to August 2018 were collected as research subjects, and the blood of 60 healthy subjects who underwent physical examinations was collected. The expression level of MMP-11 in serum of breast cancer patients was evaluated, and the diagnostic value of color Doppler ultrasound combined with MMP-11 in breast cancer was assessed. The diagnostic results of color Doppler ultrasound and the imaging characteristics of breast cancer patients were recorded. The results of biopsy and ultrasound were compared. The expression level of MMP-11 in serum of breast cancer patients was significantly higher than that of healthy subjects (P<0.05). The AUC of MMP-11 was 0.735, the sensitivity was 66.67%, and the specificity was 86.11%. Among the 72 patients, there were 41 patients diagnosed with breast cancer by serum MMP-11 examination, 38 patients diagnosed by ultrasound examination, 33 patients diagnosed by combined diagnosis, and 30 patients diagnosed by pathology biopsy. The pathological biopsy was used as the gold standard. The diagnostic efficacy of ultrasound combined with mammography examination was significantly better than the other two single examinations (P<0.050). In conclusion, Doppler ultrasound parameters combined with MMP-11 has a high diagnostic accordance rate in the diagnosis of breast cancer. At the same time, different diagnostic methods combined with the clinical manifestations of patients can improve the diagnostic accuracy, which is worthy of providing reference and advice for future clinical practice.

Extracellular matrix dynamics in tubulogenesis

Biological tubes form in a variety of shapes and sizes. Tubular topology of cells and tissues is a widely recognizable histological feature of multicellular life. Fluid secretion, storage, transport, absorption, exchange, and elimination-processes central to metazoans-hinge on the exquisite tubular architectures of cells, tissues, and organs. In general, the apparent structural and functional complexity of tubular tissues and organs parallels the architectural and biophysical properties of their constitution, i.e., cells and the extracellular matrix (ECM). Together, cellular and ECM dynamics determine the developmental trajectory, topological characteristics, and functional efficacy of biological tubes. In this review of tubulogenesis, we highlight the multifarious roles of ECM dynamics-the less recognized and poorly understood morphogenetic counterpart of cellular dynamics. The ECM is a dynamic, tripartite composite spanning the luminal, abluminal, and interstitial space within the tubulogenic realm. The critical role of ECM dynamics in the determination of shape, size, and function of tubes is evinced by developmental studies across multiple levels-from morphological through molecular-in model tubular organs.

Adipocyte and lipid metabolism in cancer drug resistance

Development of novel and effective therapeutics for treating various cancers is probably the most congested and challenging enterprise of pharmaceutical companies. Diverse drugs targeting malignant and nonmalignant cells receive clinical approval each year from the FDA. Targeting cancer cells and nonmalignant cells unavoidably changes the tumor microenvironment, and cellular and molecular components relentlessly alter in response to drugs. Cancer cells often reprogram their metabolic pathways to adapt to environmental challenges and facilitate survival, proliferation, and metastasis. While cancer cells' dependence on glycolysis for energy production is well studied, the roles of adipocytes and lipid metabolic reprogramming in supporting cancer growth, metastasis, and drug responses are less understood. This Review focuses on emerging mechanisms involving adipocytes and lipid metabolism in altering the response to cancer treatment. In particular, we discuss mechanisms underlying cancer-associated adipocytes and lipid metabolic reprogramming in cancer drug resistance.

Fibroblast-derived CXCL12 promotes breast cancer metastasis by facilitating tumor cell intravasation

The chemokine CXCL12 has been shown to regulate breast tumor growth, however, its mechanism in initiating distant metastasis is not well understood. Here, we generated a novel conditional allele of Cxcl12 in mice and used a fibroblast-specific Cre transgene along with various mammary tumor models to evaluate CXCL12 function in the breast cancer metastasis. Ablation of CXCL12 in stromal fibroblasts of mice significantly delayed the time to tumor onset and inhibited distant metastasis in different mouse models. Elucidation of mechanisms using in vitro and in vivo model systems revealed that CXCL12 enhances tumor cell intravasation by increasing vascular permeability and expansion of a leaky tumor vasculature. Furthermore, our studies revealed CXCL12 enhances permeability by recruiting endothelial precursor cells and decreasing endothelial tight junction and adherence junction proteins. High expression of stromal CXCL12 in large cohort of breast cancer patients was directly correlated to blood vessel density and inversely correlated to recurrence and overall patient survival. In addition, our analysis revealed that stromal CXCL12 levels in combination with number of CD31+ blood vessels confers poorer patient survival compared to individual protein level. However, no correlation was observed between epithelial CXCL12 and patient survival or blood vessel density. Our findings describe the novel interactions between fibroblasts-derived CXCL12 and endothelial cells in facilitating tumor cell intrvasation, leading to distant metastasis. Overall, our studies indicate that cross-talk between fibroblast-derived CXCL12 and endothelial cells could be used as novel biomarker and strategy for developing tumor microenvironment based therapies against aggressive and metastatic breast cancer.

Functional Optical Imaging of Primary Human Tumor Organoids: Development of a Personalized Drug Screen

Primary tumor organoids are a robust model of individual human cancers and present a unique platform for patient-specific drug testing. Optical imaging is uniquely suited to assess organoid function and behavior because of its subcellular resolution, penetration depth through the entire organoid, and functional endpoints. Specifically, optical metabolic imaging (OMI) is highly sensitive to drug response in organoids, and OMI in tumor organoids correlates with primary tumor drug response. Therefore, an OMI organoid drug screen could enable accurate testing of drug response for individualized cancer treatment. The objective of this perspective is to introduce OMI and tumor organoids to a general audience in order to foster the adoption of these techniques in diverse clinical and laboratory settings.

SHARPIN regulates collagen architecture and ductal outgrowth in the developing mouse mammary gland

SHARPIN is a widely expressed multifunctional protein implicated in cancer, inflammation, linear ubiquitination and integrin activity inhibition; however, its contribution to epithelial homeostasis remains poorly understood. Here, we examined the role of SHARPIN in mammary gland development, a process strongly regulated by epithelial-stromal interactions. Mice lacking SHARPIN expression in all cells (Sharpin^cpdm), and mice with a stromal (S100a4-Cre) deletion of Sharpin, have reduced mammary ductal outgrowth during puberty. In contrast, Sharpin^cpdm mammary epithelial cells transplanted in vivo into wild-type stroma, fully repopulate the mammary gland fat pad, undergo unperturbed ductal outgrowth and terminal differentiation. Thus, SHARPIN is required in mammary gland stroma during development. Accordingly, stroma adjacent to invading mammary ducts of Sharpin^cpdm mice displayed reduced collagen arrangement and extracellular matrix (ECM) stiffness. Moreover, Sharpin^cpdm mammary gland stromal fibroblasts demonstrated defects in collagen fibre assembly, collagen contraction and degradation in vitro Together, these data imply that SHARPIN regulates the normal invasive mammary gland branching morphogenesis in an epithelial cell extrinsic manner by controlling the organisation of the stromal ECM.

Functional roles of MMP14 and MMP15 in early postnatal mammary gland development

During late embryogenesis, mammary epithelial cells initiate migration programs that drive ductal invasion into the surrounding adipose-rich mesenchyme. Currently, branching morphogenesis is thought to depend on the mobilization of the membrane-anchored matrix metalloproteinases MMP14 (MT1-MMP) and MMP15 (MT2-MMP), which drive epithelial cell invasion by remodeling the extracellular matrix and triggering associated signaling cascades. However, the roles that these proteinases play during mammary gland development in vivo remain undefined. Here, we characterize the impact of global Mmp14 and Mmp15 targeting on early postnatal mammary gland development in mice. Unexpectedly, both Mmp14^-/- and Mmp15^-/- mammary glands retain the ability to generate intact ductal networks. Although neither proteinase is required for branching morphogenesis, transcriptome profiling reveals a key role for MMP14 and MMP15 in regulating mammary gland adipocyte differentiation. Whereas MMP14 promotes the generation of white fat depots crucial for energy storage, MMP15 differentially controls the formation of thermogenic brown fat. Taken together, these data not only indicate that current paradigms relevant to proteinase-dependent morphogenesis need be revisited, but also identify new roles for the enzymes in regulating adipocyte fate determination in the developing mammary gland.

Matrix metalloproteinase 11 protects from diabesity and promotes metabolic switch

MMP11 overexpression is a bad prognostic factor in various human carcinomas. Interestingly, this proteinase is not expressed in malignant cells themselves but is secreted by adjacent non-malignant mesenchymal/stromal cells, such as cancer associated fibroblasts (CAFs) and adipocytes (CAAs), which favors cancer cell survival and progression. As MMP11 negatively regulates adipogenesis in vitro, we hypothesized that it may play a role in whole body metabolism and energy homeostasis. We used an in vivo gain- (Mmp11-Tg mice) and loss- (Mmp11−/− mice) of-function approach to address the systemic function of MMP11. Strikingly, MMP11 overexpression protects against type 2 diabetes while Mmp11−/− mice exhibit hallmarks of metabolic syndrome. Moreover, Mmp11-Tg mice were protected from diet-induced obesity and display mitochondrial dysfunction, due to oxidative stress, and metabolic switch from oxidative phosphorylation to aerobic glycolysis. This Warburg-like effect observed in adipose tissues might provide a rationale for the deleterious impact of CAA-secreted MMP11, favouring tumor progression. MMP11 overexpression also leads to increased circulating IGF1 levels and the activation of the IGF1/AKT/FOXO1 cascade, an important metabolic signalling pathway. Our data reveal a major role for MMP11 in controlling energy metabolism, and provide new clues for understanding the relationship between metabolism, cancer progression and patient outcome.

Regulation and involvement of matrix metalloproteinases in vascular diseases

Matrix metalloproteinases (MMPs) are a family of zinc dependent endopeptidases whose main function is to degrade and deposit structural proteins within the extracellular matrix (ECM). A dysregulation of MMPs is linked to vascular diseases. MMPs are classified into collagenases, gelatinases, membrane-type, metalloelastase, stromelysins, matrilysins, enamelysins, and unclassified subgroups. The production of MMPs is stimulated by factors such as oxidative stress, growth factors and inflammation which lead to its up- or down-regulation with subsequent ECM remodeling. Normally, excess activation of MMPs is controlled by their endogenous inhibitors, tissue inhibitors of metalloproteinases (TIMPs). An imbalance of MMPs and TIMPs has been implicated in hypertension, atherosclerotic plaque formation and instability, aortic aneurysms and varicose vein wall remodeling. Also, recent evidence suggests epigenetic regulation of some MMPs in angiogenesis and atherosclerosis. Over the years, pharmacological inhibitors of MMPs have been used to modify or prevent the development of the disease with some success. In this review, we discuss recent advances in MMP biology, and their involvement in the manifestation of vascular disease.

Local adipocyte cancer cell paracrine loop: can "sick fat" be more detrimental?

This review article focuses on the emerging role of tumor resident adipocytes. It provides in vitro and in vivo evidence that they are essential for cancer development/progression. In addition to systemic effects, their tumor-promoting impact is dependent on local functions, notably via a complex adipocyte cancer cell paracrine loop (ACCPL). Indeed, this event leads to dramatic phenotypic and/or functional modifications of both cell types as well as of the extracellular matrix. Adipocytes undergo delipidation leading to adipocytes/cancer-associated adipocytes/cancer-associated fibroblasts de-differentiation processes. In turn, cancer cell aggressiveness is exacerbated through increased proliferation, migration, and invasion properties. This is accompanied by intense tissue remodeling, conducting to the occurrence of the tumor stroma. The molecular pathways involved in ACCPL remain largely unknown. Nevertheless, several clues are starting to emerge. Moreover, obesity is currently a sign of increased risk and poor prognosis in human carcinomas. How adiposopathy might impact tumors and specifically the ACCPL is still under investigation. However, available experimental, epidemiological, and clinical data allow to draw some directions. Interestingly, there are numerous similarities between the ACCPL-induced and obesity-related molecular alterations. It might, therefore, be hypothesized that obesity provides a "constitutively active" local permissive environment for cancer cells. Improving our knowledge about ACCPL in both lean and obese patients remains a challenging task. Indeed, deciphering the cellular and molecular mechanisms behind ACCPL might provide new targets for improving diagnosis/prognosis and the design of innovative therapeutic strategies, and even, in case of obesity, for preventing cancer.

Progenitor Epithelium: Sorting Out Pancreatic Lineages

Insulin-producing β cells within the vertebrate fetal pancreas acquire their fate in a step-wise manner. Whereas the intrinsic factors dictating the transcriptional or epigenetic status of pancreatic lineages have been intensely examined, less is known about cell-cell interactions that might constitute a niche for the developing β cell lineage. It is becoming increasingly clear that understanding and recapitulating these steps may instruct in vitro differentiation of embryonic stem cells and/or therapeutic regeneration. Indeed, directed differentiation techniques have improved since transitioning from 2D to 3D cultures, suggesting that the 3D microenvironment in which β cells are born is critical. However, to date, it remains unknown whether the changing architecture of the pancreatic epithelium impacts the fate of cells therein. An emerging challenge in the field is to elucidate how progenitors are allocated during key events, such as the stratification and subsequent resolution of the pre-pancreatic epithelium, as well as the formation of lumens and branches. Here, we assess the progenitor epithelium and examine how it might influence the emergence of pancreatic multipotent progenitors (MPCs), which give rise to β cells and other pancreatic lineages.

Spatiotemporal proliferation of human stromal cells adjusts to nutrient availability and leads to stanniocalcin-1 expression in vitro and in vivo

Cells and tissues are intrinsically adapted to molecular gradients and use them to maintain or change their activity. The effect of such gradients is particularly important for cell populations that have an intrinsic capacity to differentiate into multiple cell lineages, such as bone marrow derived mesenchymal stromal cells (MSCs). Our results showed that nutrient gradients prompt the spatiotemporal organization of MSCs in 3D culture. Cells adapted to their 3D environment without significant cell death or cell differentiation. Kinetics data and whole-genome gene expression analysis suggest that a low proliferation activity phenotype predominates in stromal cells cultured in 3D, likely due to increasing nutrient limitation. These differences implied that despite similar surface areas available for cell attachment, higher cell concentrations in 3D reduced MSCs proliferation, while activating hypoxia related-pathways. To further understand the in vivo effects of both proliferation and cell concentrations, we increased cell concentrations in small (1.8 μl) implantable wells. We found that MSCs accumulation and conditioning by nutrient competition in small volumes leads to an ideal threshold of cell-concentration for the induction of blood vessel formation, possibly signaled by the hypoxia-related stanniocalcin-1 gene.

Heterotypic control of basement membrane dynamics during branching morphogenesis

Many mammalian organs undergo branching morphogenesis to create highly arborized structures with maximized surface area for specialized organ function. Cooperative cell-cell and cell-matrix adhesions that sculpt the emerging tissue architecture are guided by dynamic basement membranes. Properties of the basement membrane are reciprocally controlled by the interacting epithelial and mesenchymal cell populations. Here we discuss how basement membrane remodeling is required for branching morphogenesis to regulate cell-matrix and cell-cell adhesions that are required for cell patterning during morphogenesis and how basement membrane impacts morphogenesis by stimulation of cell patterning, force generation, and mechanotransduction. We suggest that in addition to creating mature epithelial architecture, remodeling of the epithelial basement membrane during branching morphogenesis is also essential to promote maturation of the stromal mesenchyme to create mature organ structure. Recapitulation of developmental cell-matrix and cell-cell interactions are of critical importance in tissue engineering and regeneration strategies that seek to restore organ function.

Remodelling the extracellular matrix in development and disease

The extracellular matrix (ECM) is a highly dynamic structure that is present in all tissues and continuously undergoes controlled remodelling. This process involves quantitative and qualitative changes in the ECM, mediated by specific enzymes that are responsible for ECM degradation, such as metalloproteinases. The ECM interacts with cells to regulate diverse functions, including proliferation, migration and differentiation. ECM remodelling is crucial for regulating the morphogenesis of the intestine and lungs, as well as of the mammary and submandibular glands. Dysregulation of ECM composition, structure, stiffness and abundance contributes to several pathological conditions, such as fibrosis and invasive cancer. A better understanding of how the ECM regulates organ structure and function and of how ECM remodelling affects disease progression will contribute to the development of new therapeutics.

Application of Sholl analysis to quantify changes in growth and development in rat mammary gland whole mounts

Studies that utilize the rodent mammary gland (MG) as an endpoint for assessing the developmental toxicity of chemical exposures typically employ either basic dimensional measurements or developmental scoring of morphological characteristics as a means to quantify MG development. There are numerous means by which to report these developmental changes, leading to inconsistent translation across laboratories. The Sholl analysis is a method historically used for quantifying neuronal dendritic patterns. The present study describes the use of the Sholl analysis to quantify MG branching characteristics. Using this method, we were able to detect significant differences in branching density in MG of peripubertal female Sprague Dawley rats that had been exposed to vehicle or a potent estrogen. These data suggest the Sholl analysis can be an effective tool for quantitatively measuring an important characteristic of MG development and for examining associations between MG growth and density and adverse effects in the breast.

Cellular and physical mechanisms of branching morphogenesis

Branching morphogenesis is the developmental program that builds the ramified epithelial trees of various organs, including the airways of the lung, the collecting ducts of the kidney, and the ducts of the mammary and salivary glands. Even though the final geometries of epithelial trees are distinct, the molecular signaling pathways that control branching morphogenesis appear to be conserved across organs and species. However, despite this molecular homology, recent advances in cell lineage analysis and real-time imaging have uncovered surprising differences in the mechanisms that build these diverse tissues. Here, we review these studies and discuss the cellular and physical mechanisms that can contribute to branching morphogenesis.

Functional relationship between matrix metalloproteinase-11 and matrix metalloproteinase-14

MMP-11 is a key factor in physiopathological tissue remodeling. As an active form is secreted, its activity must be tightly regulated to avoid detrimental effects. Although TIMP-1 and TIMP-2 reversibly inhibit MMP-11, another more drastic scenario, presumably via hydrolysis, could be hypothesized. In this context, we have investigated the possible implication of MMP-14, since it exhibits a spatiotemporal localization similar to MMP-11. Using native HFL1-produced MMP-11 and HT-1080-produced MMP-14 as well as recombinant proteins, we show that MMP-11 is a MMP-14 substrate. MMP-14 cleaves MMP-11 catalytic domain at the PGG(P1)-I(P1′)LA and V/IQH(P1)-L(P1′)YG scissile bonds, two new cleavage sites. Interestingly, a functional test showed a dramatical reduction in MMP-11 enzymatic activity when incubated with active MMP-14, whereas inactive point-mutated MMP-14 had no effect. This function is conserved between human and mouse. Thus, in addition to the canonical reversible TIMP-dependent inhibitory system, irreversible MMP proteolytic inactivation might occur by cleavage of the catalytic domain in a MMP-dependent manner. Since MMP-14 is produced by HT-1080 cancer cells, whereas MMP-11 is secreted by HFL1 stromal cells, our findings support the emerging importance of tumor-stroma interaction/cross-talk. Moreover, they highlight a Janus-faced MMP-14 function in the MMP cascade, favoring activation of several pro-MMPs, but limiting MMP-11 activity. Finally, both MMPs are active at the cell periphery. Since MMP-14 is present at the cell membrane, whereas MMP-11 is soluble into the cellular microenvironment, this MMP-14 function might represent one critical regulatory mechanism to control the extent of pericellular MMP-11 bioavailability and protect cells from excessive/inappropriate MMP-11 function.

The tumor suppressive role of NUMB isoform 1 in esophageal squamous cell carcinoma

Esophageal quamous cell carcinoma (ESCC) is the predominant histological type of esophageal carcinoma in Asian populations. To date, few biomarkers have been identified for ESCC. In present study, we found a tumor suppressor, NUMB isoform 1 (NUMB-1), as a promising prognostic biomarker for patients with ESCC. NUMB-1 mRNA was downregulated in 66.7% of primary ESCC tissues when compared with matched adjacent non-tumor tissues. The low expression of NUMB-1 was significantly associated with high tumor recurrence (p=0.029) and poor post-operative overall survival (p=0.016). To further explore the underlying mechanisms by which NUMB-1 regulates ESCC, we demonstrated that ectopic expression of NUMB-1 inhibited cell proliferation through inducing G2/M phase arrest, which was accompanied by an increase in p21 and cyclin B1-cdc2 levels. However, it had no impact on apoptosis of ESCC cells. In addition, overexpression of NUMB-1 prevented epithelial-mesenchymal transition, inhibited invasion of ESCC cells and NOTCH pathway, suppressed Aurora-A activity by preventing phosphorylation of Aurora-A at T288 which resulted in cell cycle arrest. Taken together, our findings suggested NUMB-1 functions as a tumor-suppressor and serves as a prognositc biomarker for ESCC patients; thus, NUMB-1 may be a potential novel therapeutic target for treatment of ESCC.

Candidate prognostic markers in breast cancer: focus on extracellular proteases and their inhibitors

The extracellular matrix (ECM) is the complex network of proteins that surrounds cells in multicellular organisms. Due to its diverse nature and composition, the ECM has a multifaceted role in both normal tissue homeostasis and pathophysiology. It provides structural support, segregates tissues from one another, and regulates intercellular communication. Furthermore, the ECM sequesters a wide range of growth factors and cytokines that may be released upon specific and well-coordinated cues. Regulation of the ECM is performed by the extracellular proteases, which are tasked with cleaving and remodeling this intricate and diverse protein matrix. Accordingly, extracellular proteases are differentially expressed in various tissue types and in many diseases such as cancer. In fact, metastatic dissemination of tumor cells requires degradation of extracellular matrices by several families of proteases, including metalloproteinases and serine proteases, among others. Extracellular proteases are emerging as strong candidate cancer biomarkers for aiding and predicting patient outcome. Not surprisingly, inhibition of these protumorigenic enzymes in animal models of metastasis has shown impressive therapeutic effects. As such, many of these proteolytic inhibitors are currently in various phases of clinical investigation. In addition to direct approaches, aberrant expression of extracellular proteases in disease states may also facilitate the selective delivery of other therapeutic or imaging agents. Herein, we outline extracellular proteases that are either bona fide or probable prognostic markers in breast cancer. Furthermore, using existing patient data and multiple robust statistical analyses, we highlight several extracellular proteases and associated inhibitors (eg, uPA, ADAMs, MMPs, TIMPs, RECK) that hold the greatest potential as clinical biomarkers. With the recent advances in high-throughput technology and targeted therapies, the incorporation of extracellular protease status in breast cancer patient management may have a profound effect on improving outcomes in this deadly disease.