The hemopexin domain of MMP3 is responsible for mammary epithelial invasion and morphogenesis through extracellular interaction with HSP90β

YWHAB is regulated by IRX5 and inhibits the migration and invasion of breast cancer cells

Highly metastatic and heterogeneous breast cancer affects the health of women worldwide. Abnormal expression of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein β (YWHAB), also known as 14-3-3β, is associated with the tumorigenesis and progression of bladder cancer, lung cancer and hepatocellular carcinoma; however, to the best of our knowledge, the role of YWHAB in breast cancer remains unknown. In the present study, a dual luciferase assay demonstrated that the transcription factor iroquois homeobox 5 may regulate YWHAB expression by affecting the promoter sequence upstream of its transcription start site. Subsequently, it was demonstrated that overexpression of YWHAB did not affect proliferation, but did reduce the migration and invasion of MDA-MB-231 cells. Furthermore, knockdown of YWHAB promoted the migration and invasion of MCF7 cells. Transcriptomics analysis demonstrated that when YWHAB was overexpressed, 61 genes were differentially expressed, of which 43 genes were upregulated and 18 genes were downregulated. These differentially expressed genes (DEGs) were enriched in cancer-related pathways, such as 'TNF signaling pathway' [Kyoto Encyclopedia of Genes and Genomes (KEGG): map04688]. The pathway with the largest number of DEGs was 'Rheumatoid arthritis' (KEGG: map05323). Notably, YWHAB downregulated vimentin, which is a mesenchymal marker, thus suggesting that it may weaken the mesenchymal properties of cells. These findings indicate that YWHAB may be a potential therapeutic target in breast cancer and further work should be performed to assess its actions as a potential tumor suppressor.

Tumor Dormancy and Reactivation: The Role of Heat Shock Proteins

Tumors are a heterogeneous group of cell masses originating in various organs or tissues. The cellular composition of the tumor cell mass interacts in an intricate manner, influenced by humoral, genetic, molecular, and tumor microenvironment cues that dictate tumor growth or suppression. As a result, tumors undergo a period of a dormant state before their clinically discernible stage, which surpasses the clinical dormancy threshold. Moreover, as a genetically imprinted strategy, early-seeder cells, a distinct population of tumor cells, break off to dock nearby or extravasate into blood vessels to secondary tissues, where they form disseminated solitary dormant tumor cells with reversible capacity. Among the various mechanisms underlying the dormant tumor mass and dormant tumor cell formation, heat shock proteins (HSPs) might play one of the most important roles in how the dormancy program plays out. It is known that numerous aberrant cellular processes, such as malignant transformation, cancer cell stemness, tumor invasion, metastasis, angiogenesis, and signaling pathway maintenance, are influenced by the HSPs. An accumulating body of knowledge suggests that HSPs may be involved in the angiogenic switch, immune editing, and extracellular matrix (ECM) remodeling cascades, crucial genetically imprinted strategies important to the tumor dormancy initiation and dormancy maintenance program. In this review, we highlight the biological events that orchestrate the dormancy state and the body of work that has been conducted on the dynamics of HSPs in a tumor mass, as well as tumor cell dormancy and reactivation. Additionally, we propose a conceptual framework that could possibly underlie dormant tumor reactivation in metastatic relapse.

Maggot Extract Inhibits Cell Migration and Tumor Growth by Targeting HSP90AB1 in Ovarian Cancer

Ovarian cancer is one of the most lethal gynecological malignancies, because of metastatic dissemination with poor late clinical therapy. Maggots have been used in traditional Chinese medicine, where they are also known as 'Wu Gu Chong'. Previous studies have indicated that maggot extract (ME) was beneficial for the treatment of gastric cancer when combined with other drugs, but the effect on anti-ovarian cancer and the underlying mechanism remains unclear. The aim of this study was to investigate the effects of ME on suppressing the proliferation and migration of ovarian cancer cells, and to clarify the underlying mechanism. In this research, Cell Counting Kit-8 (CCK-8), colony formation assay, and luciferase-positive cell quantification assay were employed to identify the inhibitory effects of ME on cell proliferation. Then, the pro-apoptosis and anti-metastasis effects of ME were explored by Western blot, dual annexin V-fluorescein isothiocyanate/propidium iodide (FITC/PI) assay, immunofluorescent staining, and wound-healing assay. We further established a xenograft model by subcutaneously or intraperitoneally injecting BALB/c nude mice with SKOV3 cells stably expressing luciferase, and the mice were treated with ME. The results showed that ME therapy effectively restrained the growth and metastasis of ovarian tumors in vivo. Furthermore, the mRNA levels of cancer factors including heat shock protein 90 alpha family class B member 1 (HSP90AB1), MYC, and insulin like growth factor 1 receptor (IGF1R) were analyzed by quantitative real-time PCR assay to explore the possible antitumor mechanisms of ME. Next, HSP90 ATPase activity was inhibited by geldanamycin in A2780, and the cell viability was shown to be dramatically reduced, decreasing further with the combination of ME and cisplatin. In turn, HSP90AB1 overexpression effectively inhibited the effect of ME in suppressing capability for cell viability and migration. In addition, HSP90AB1 overexpression limited the ability of ME to inhibit expression of MYC and IGF1R, while the opposite effect was observed for expression of pro-apoptosis protein caspase3 and BAX. Therefore, this study confirmed the potential roles and mechanisms of ME in inhibiting the growth and metastasis of ovarian tumors and promoting apoptosis of ovarian cancer cells by inhibiting overexpression of HSP90AB1.

Cytosolic Hsp90 Isoform-Specific Functions and Clinical Significance

The heat shock protein 90 (Hsp90) is a molecular chaperone and a key regulator of proteostasis under both physiological and stress conditions. In mammals, there are two cytosolic Hsp90 isoforms: Hsp90α and Hsp90β. These two isoforms are 85% identical and encoded by two different genes. Hsp90β is constitutively expressed and essential for early mouse development, while Hsp90α is stress-inducible and not necessary for survivability. These two isoforms are known to have largely overlapping functions and to interact with a large fraction of the proteome. To what extent there are isoform-specific functions at the protein level has only relatively recently begun to emerge. There are studies indicating that one isoform is more involved in the functionality of a specific tissue or cell type. Moreover, in many diseases, functionally altered cells appear to be more dependent on one particular isoform. This leaves space for designing therapeutic strategies in an isoform-specific way, which may overcome the unfavorable outcome of pan-Hsp90 inhibition encountered in previous clinical trials. For this to succeed, isoform-specific functions must be understood in more detail. In this review, we summarize the available information on isoform-specific functions of mammalian Hsp90 and connect it to possible clinical applications.

Targeting extracellular Hsp90: A unique frontier against cancer

The molecular chaperone Heat Shock Protein-90 (Hsp90) is known to interact with over 300 client proteins as well as regulatory factors (eg. nucleotide and proteins) that facilitate execution of its role as a chaperone and, ultimately, client protein activation. Hsp90 associates transiently with these molecular modulators during an eventful chaperone cycle, resulting in acquisition of flexible structural conformations, perfectly customized to the needs of each one of its client proteins. Due to the plethora and diverse nature of proteins it supports, the Hsp90 chaperone machinery is critical for normal cellular function particularly in response to stress. In diseases such as cancer, the Hsp90 chaperone machinery is hijacked for processes which encompass many of the hallmarks of cancer, including cell growth, survival, immune response evasion, migration, invasion, and angiogenesis. Elevated levels of extracellular Hsp90 (eHsp90) enhance tumorigenesis and the potential for metastasis. eHsp90 has been considered one of the new targets in the development of anti-cancer drugs as there are various stages of cancer progression where eHsp90 function could be targeted. Our limited understanding of the regulation of the eHsp90 chaperone machinery is a major drawback for designing successful Hsp90-targeted therapies, and more research is still warranted.

Hsp90: From Cellular to Organismal Proteostasis

Assuring a healthy proteome is indispensable for survival and organismal health. Proteome disbalance and the loss of the proteostasis buffer are hallmarks of various diseases. The essential molecular chaperone Hsp90 is a regulator of the heat shock response via HSF1 and a stabilizer of a plethora of signaling proteins. In this review, we summarize the role of Hsp90 in the cellular and organismal regulation of proteome maintenance.

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 Role and Therapeutic Value of Syndecan-1 in Cancer Metastasis and Drug Resistance

Metastasis and relapse are major causes of cancer-related fatalities. The elucidation of relevant pathomechanisms and adoption of appropriate countermeasures are thus crucial for the development of clinical strategies that inhibit malignancy progression as well as metastasis. An integral component of the extracellular matrix, the type 1 transmembrane glycoprotein syndecan-1 (SDC-1) binds cytokines and growth factors involved in tumor microenvironment modulation. Alterations in its localization have been implicated in both cancer metastasis and drug resistance. In this review, available data regarding the structural characteristics, shedding process, and nuclear translocation of SDC-1 are detailed with the aim of highlighting strategies directly targeting SDC-1 as well as SDC-1-mediated carcinogenesis.

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.

Targeted search for scaling genes reveals matrixmetalloproteinase 3 as a scaler of the dorsal-ventral pattern in Xenopus laevis embryos

How embryos scale patterning according to size is still not fully understood. Through in silico screening and analysis of reaction-diffusion systems that could be responsible for scaling, we predicted the existence of genes whose expression is sensitive to embryo size and which regulate the scaling of embryonic patterning. To find these scalers, we identified genes with strongly altered expression in half-size Xenopus laevis embryos compared with full-size siblings at the gastrula stage. Among found genes, we investigated the role of matrix metalloproteinase-3 (mmp3), which was most strongly downregulated in half-size embryos. We show that Mmp3 scales dorsal-ventral patterning by degrading the slowly diffusing embryonic inducers Noggin1 and Noggin2 but preventing cleavage of the more rapidly diffusing inducer Chordin via degradation of a Tolloid-type proteinase. In addition to unraveling the mechanism underlying the scaling of dorsal-ventral patterning, this work provides proof of principal for scalers identification in embryos of other species.

MicroRNA-18a-5p Suppresses Tumor Growth via Targeting Matrix Metalloproteinase-3 in Cisplatin-Resistant Ovarian Cancer

Cumulating evidence indicates that dysregulation of microRNAs (miRNAs) plays a central role in the initiation, progression, and drug resistance of cancer cells. However, the specific miRNAs contributing to drug resistance in ovarian cancer cells have not been fully elucidated. Aimed to identify potential miRNAs involved in platinum resistance, we performed a miRNA expression profile in cisplatin-sensitive and cisplatin-resistant ovarian cancer cells, and we found several differentially abundant miRNAs in the pair of cell lines. Notably, miR-18a-5p (miR-18a), a member of the oncogenic associated miR-17-92 cluster, was decreased in cisplatin-resistant as compared with cisplatin-sensitive cells. Real-time PCR analysis confirmed these findings. We then studied the biological, molecular, and therapeutic consequences of increasing the miR-18a levels with oligonucleotide microRNA mimics (OMM). Compared with a negative control OMM, transient transfection of a miR-18a-OMM reduced cell growth, cell proliferation, and cell invasion. Intraperitoneal injections of miR-18a-OMM-loaded folate-conjugated liposomes significantly reduced the tumor weight and the number of nodules in ovarian cancer-bearing mice when compared with a control-OMM group. Survival analysis using the Kaplan-Meier plotter database showed that ovarian cancer patients with high miR-18a levels live longer in comparison to patients with lower miR-18a levels. Bioinformatic analyses, real-time-PCR, Western blots, and luciferase reporter assays revealed that Matrix Metalloproteinase-3 (MMP-3) is a direct target of miR-18a. Small-interfering RNA (siRNA)-mediated silencing of MMP-3 reduced cell viability, cell growth, and the invasiveness potential of cisplatin-resistant ovarian cancer cells. Our study suggests that targeting miR-18a is a plausible therapeutic strategy for cisplatin-resistant ovarian cancer.

Folic Acid Induces Intake-Related Changes in the Mammary Tissue Transcriptome of C57BL/6 Mice

Folic acid (FA) intake has been associated with increased breast cancer risk in some studies. Although underlying mechanisms are unknown, epigenetic modifications that persistently alter transcription have been suggested. We tested the hypothesis that high FA (HFA) intake alters the adult mammary transcriptome in a manner consistent with increased potential for carcinogenesis, detectable beyond the period of intake. C57BL/6 mice were fed control FA (CFA) (1 mg/kg diet) or HFA (5 mg/kg diet) diets for 4 weeks, followed by AIN93M maintenance diet for 4 weeks. Plasma 5-methyltetrahydrofolate, p-aminobenzoylglutamate and unmetabolised FA concentrations were greater (1.62, 1.56, 5.80-fold, respectively) in HFA compared to CFA mice. RNA sequencing of the mammary transcriptome (~20 million reads) showed 222 transcripts (191 upregulated) differentially expressed between groups. Gene Set Enrichment showed upregulated genes significantly enriched in Epithelial Mesenchymal Transition, Myogenesis and Apical Junction and downregulated genes in E2F targets, MYC targets and G2M checkpoint. Cancer was the most altered Disease and Disorder pathway, with Metastasis, Mammary Tumour and Growth of Tumour the most upregulated pathways. ChIP-seq enrichment analysis showed that targets of histone methyltransferase EZH2 were enriched in HFA mice. This study demonstrates HFA intake during adulthood induces mammary transcriptome changes, consistent with greater tumorigenic potential.

Prostate cancer-derived MMP-3 controls intrinsic cell growth and extrinsic angiogenesis

Bone metastatic prostate cancer significantly impacts patient quality of life and overall survival, and despite available therapies, it is presently incurable with an unmet need for improved treatment options. As mediators of tumor progression, matrix metalloproteinases (MMPs) can degrade extracellular matrix components and regulate growth factor and cytokine bioactivity. Depending on tissue context, MMPs can either promote or inhibit tumorigenesis. Therefore, it is essential to study individual MMPs in specific cancer contexts and microenvironments to support the design and application of selective MMP inhibitors. Here we report that tumor-derived MMP-3 contributes to bone metastatic prostate cancer progression via intrinsic and extrinsic routes. MMP-3 ablation in prostate cancer cell lines significantly reduced in vitro growth combined with lowered AKT and ERK phosphorylation and total VEGFR1 and FGFR3 protein levels. In vivo, MMP-3 ablated tumors grew at a slower rate and were significantly less vascularized. Quantitative PCR analyses of wild type and MMP-3 silenced prostate cancer cells also demonstrate downregulation of a wide array of angiogenic factors. The extrinsic role for MMP-3 in angiogenesis was supported by in vitro endothelial tube formation assays where the lack of MMP-3 in prostate cancer conditioned media resulted in slower rates of tube formation. Taken together, our results suggest that tumor-derived MMP-3 contributes to prostate cancer growth in bone. These data indicate that selective inhibition of MMP-3 and/or targeting MMP generated products could be efficacious for the treatment of prostate to bone metastases.

Recent aspects of the effects of zinc on human health

Zinc (Zn) is one of the most important essential nutrients of great public health significance. It is involved in numerous biological functions and it is considered as a multipurpose trace element, due to its capacity to bind to more than 300 enzymes and more than 2000 transcriptional factors. Its role in biochemical pathways and cellular functions, such as the response to oxidative stress, homeostasis, immune responses, DNA replication, DNA damage repair, cell cycle progression, apoptosis and aging is significant. Zn is required for the synthesis of protein and collagen, thus contributing to wound healing and a healthy skin. Metallothioneins are metal-binding proteins and they are potent scavengers of heavy metals, including Zn, and protect the organism against stress. Zn deficiency is observed almost in 17% of the global population and affects many organ systems, leading to dysfunction of both humoral and cell-mediated immunity, thus increasing the susceptibility to infection. This review gives a thorough insight into the most recent evidence on the association between Zn biochemistry and human pathologies, epigenetic processes, gut microbial composition, drug targets and nanomedicine.

The Role of HSF1 and the Chaperone Network in the Tumor Microenvironment

Tumors are stressful environments. As tumors evolve from single mutated cancer cells into invasive malignancies they must overcome various constraints and barriers imposed by a hostile microenvironment. To achieve this, cancer cells recruit and rewire cells in their microenvironment to become pro-tumorigenic. We propose that chaperones are vital players in this process, and that activation of stress responses helps tumors adapt and evolve into aggressive malignancies, by enabling phenotypic plasticity in the tumor microenvironment (TME). In this chapter we will review evidence supporting non-cancer-cell-autonomous activity of chaperones in human patients and mouse models of cancer, discuss the mechanisms by which this non-cell-autonomous activity is mediated and provide an evolutionary perspective on the basis of this phenomenon.

Pyridine-Containing Macrocycles Display MMP-2/9 Inhibitory Activity and Distinct Effects on Migration and Invasion of 2D and 3D Breast Cancer Models

The role of metalloproteinases (MMPs) on the migration and invasion of cancer cells has been correlated with tumor aggressiveness, namely with the up-regulation of MMP-2 and 9. Herein, two pyridine-containing macrocyclic compounds, [15]pyN5 and [16]pyN5, were synthesized, chemically characterized and evaluated as potential MMP inhibitors for breast cancer therapy using 3D and 2D cellular models. [15]pyN5 and [16]pyN5 (5-20 µM) showed a marked inhibition of MMPs activity (100% at concentrations ≥ 7.5 μM) when compared to ARP-100, a known MMP inhibitor. The inhibitory activity of [15]pyN5 and [16]pyN5 was further supported through in silico docking studies using Goldscore and ChemPLP scoring functions. Moreover, although no significant differences were observed in the invasion studies in the presence of all MMPs inhibitors, cell migration was significantly inhibited by both pyridine-containing macrocycles at concentrations above 5 μM in 2D cells (p < 0.05). In spheroids, the same effect was observed, but only with [16]pyN5 at 20 μM and ARP-100 at 40 μM. Overall, [15]pyN5 and [16]pyN5 led to impaired breast cancer cell migration and revealed to be potential inhibitors of MMPs 2 and 9.

Normal mammary gland development after MMTV-Cre mediated conditional PAK4 gene depletion

p21-activated kinases (PAKs) are serine/threonine kinases functioning as downstream effectors of the small GTPases Rac1 and Cdc42. Members of the PAK family are overexpressed in human breast cancer, but their role in mammary gland development is not fully explored. Here we examined the functional role of PAK4 in mammary gland development by creating a mouse model of MMTV-Cre driven conditional PAK4 gene depletion in the mammary gland. The PAK4 conditional knock-out mice were born healthy, with no observed developmental deficits. Mammary gland whole-mounts revealed no defects in ductal formation or elongation of the mammary tree through the fat pad. PAK4 gene depletion also did not alter proliferation and invasion of the mammary epithelium in young virgin mice. Moreover, adult mice gave birth to healthy pups with normal body weight upon weaning. This implies that MMTV-Cre induced gene depletion of PAK4 in mice does not impair normal mammary gland development and thereby provides an in vivo model that can be explored for examination of the potential function of PAK4 in breast cancer.

The role of collagen in cancer: from bench to bedside

Collagen is the major component of the tumor microenvironment and participates in cancer fibrosis. Collagen biosynthesis can be regulated by cancer cells through mutated genes, transcription factors, signaling pathways and receptors; furthermore, collagen can influence tumor cell behavior through integrins, discoidin domain receptors, tyrosine kinase receptors, and some signaling pathways. Exosomes and microRNAs are closely associated with collagen in cancer. Hypoxia, which is common in collagen-rich conditions, intensifies cancer progression, and other substances in the extracellular matrix, such as fibronectin, hyaluronic acid, laminin, and matrix metalloproteinases, interact with collagen to influence cancer cell activity. Macrophages, lymphocytes, and fibroblasts play a role with collagen in cancer immunity and progression. Microscopic changes in collagen content within cancer cells and matrix cells and in other molecules ultimately contribute to the mutual feedback loop that influences prognosis, recurrence, and resistance in cancer. Nanoparticles, nanoplatforms, and nanoenzymes exhibit the expected gratifying properties. The pathophysiological functions of collagen in diverse cancers illustrate the dual roles of collagen and provide promising therapeutic options that can be readily translated from bench to bedside. The emerging understanding of the structural properties and functions of collagen in cancer will guide the development of new strategies for anticancer therapy.

Role of the Microenvironment in Regulating Normal and Cancer Stem Cell Activity: Implications for Breast Cancer Progression and Therapy Response

The epithelial cells in an adult woman’s breast tissue are continuously replaced throughout their reproductive life during pregnancy and estrus cycles. Such extensive epithelial cell turnover is governed by the primitive mammary stem cells (MaSCs) that proliferate and differentiate into bipotential and lineage-restricted progenitors that ultimately generate the mature breast epithelial cells. These cellular processes are orchestrated by tightly-regulated paracrine signals and crosstalk between breast epithelial cells and their tissue microenvironment. However, current evidence suggests that alterations to the communication between MaSCs, epithelial progenitors and their microenvironment plays an important role in breast carcinogenesis. In this article, we review the current knowledge regarding the role of the breast tissue microenvironment in regulating the special functions of normal and cancer stem cells. Understanding the crosstalk between MaSCs and their microenvironment will provide new insights into how an altered breast tissue microenvironment could contribute to breast cancer development, progression and therapy response and the implications of this for the development of novel therapeutic strategies to target cancer stem cells.

Expanding the Organismal Proteostasis Network: Linking Systemic Stress Signaling with the Innate Immune Response

Stress response pathways regulate proteostasis and mitigate macromolecular damage to promote long-term cellular health. Intercellular signaling is an essential layer of systemic proteostasis in an organism and is facilitated via transcellular signaling molecules that orchestrate the activation of stress responses across tissues and organs. Accumulating evidence indicates that components of the immune response act as signaling factors that regulate the cell-non-autonomous proteostasis network. Here, we review emergent advances in our understanding of cell-non-autonomous regulators of proteostasis networks in multicellular settings, from the model organism, Caenorhabditis elegans, to humans. We further discuss how innate immune responses can be players of the organismal proteostasis network and discuss how both are linked in cancer.

Cell surface heparan sulfate proteoglycans are involved in the extracellular Hsp90-stimulated migration and invasion of cancer cells

The extracellular heat shock protein 90 (Hsp90) is known to participate in cell migration and invasion. Recently, we have shown that cell surface heparan sulfate proteoglycans (HSPGs) are involved in the binding and anchoring of extracellular Hsp90 to the plasma membrane, but the biological relevance of this finding was unclear. Here, we demonstrated that the digestion of heparan sulfate (HS) moieties of HSPGs with a heparinase I/III blend and the metabolic inhibition of the sulfation of HS chains by sodium chlorate considerably impair the migration and invasion of human glioblastoma A-172 and fibrosarcoma HT1080 cells stimulated by extracellular native Hsp90. Heparin, a polysaccharide closely related to HS, also reduced the Hsp90-stimulated migration and invasion of cells. Phorbol 12-myristate 13-acetate, an intracellular inducer of cell motility bypassing the ligand activation of receptors, restored the basal migration of heparinase- and chlorate-treated cells almost to the control level, suggesting that the cell motility machinery was insignificantly affected in cells with degraded and undersulfated HS chains. On the other hand, the downstream phosphorylation of AKT in response to extracellular Hsp90 was substantially impaired in heparinase- and chlorate-treated cells as compared to untreated cells. Taken together, our results demonstrated for the first time that cell surface HSPGs play an important role in the migration and invasion of cancer cells stimulated by extracellular Hsp90 and that plasma membrane-associated HSPGs are required for the efficient transmission of signal from extracellular Hsp90 into the cell.

Matrix metalloproteinase-9 deficiency protects mice from severe influenza A viral infection

Matrix metalloproteinase-9 (MMP-9) cleaves various proteins to regulate inflammatory and injury responses. However, MMP-9's activities during influenza A viral (IAV) infections are incompletely understood. Herein, plasma MMP-9 levels were increased in patients with pandemic H1N1 and seasonal IAV infections. MMP-9 lung levels were increased and localized to airway epithelial cells and leukocytes in H1N1-infected WT murine lungs. H1N1-infected Mmp-9-/- mice had lower mortality rates, reduced weight loss, lower lung viral titers, and reduced lung injury, along with lower E-cadherin shedding in bronchoalveolar lavage fluid (BALF) samples than WT mice. H1N1-infected Mmp-9-/- mice had an altered immune response to IAV with lower BALF PMN and macrophage counts, higher Th1-like CD4+ and CD8+ T cell subsets, lower T regulatory cell counts, reduced lung type I interferon levels, and higher lung interferon-γ levels. Mmp-9 bone marrow-chimera studies revealed that Mmp-9 deficiency in lung parenchymal cells protected mice from IAV-induced mortality. H1N1-infected Mmp-9-/- lung epithelial cells had lower viral titers than H1N1-infected WT cells in vitro. Thus, H1N1-infected Mmp-9-/- mice are protected from IAV-induced lung disease due to a more effective adaptive immune response to IAV and reduced epithelial barrier injury due partly to reduced E-cadherin shedding. Thus, we believe that MMP-9 is a novel therapeutic target for IAV infections.

Divergent Matrix-Remodeling Strategies Distinguish Developmental from Neoplastic Mammary Epithelial Cell Invasion Programs

Metastasizing breast carcinoma cells have been hypothesized to mobilize tissue-invasive activity by co-opting the proteolytic systems employed by normal mammary epithelial cells undergoing branching morphogenesis. However, the critical effectors underlying morphogenesis remain unidentified, and their relationship to breast cancer invasion programs is yet to be established. Here, we identify the membrane-anchored matrix metalloproteinase, Mmp14/MT1-MMP, but not the closely related proteinase Mmp15/MT2-MMP, as the dominant proteolytic effector of both branching morphogenesis and carcinoma cell invasion in vivo. Unexpectedly, however, epithelial cell-specific targeting of Mmp14/MT1-MMP in the normal mammary gland fails to impair branching, whereas deleting the proteinase in carcinoma cells abrogates invasion, preserves matrix architecture, and completely blocks metastasis. By contrast, in the normal mammary gland, extracellular matrix remodeling and morphogenesis are ablated only when Mmp14/MT1-MMP expression is specifically deleted from the periductal stroma. Together, these findings uncover the overlapping but divergent strategies that underlie developmental versus neoplastic matrix remodeling programs.

Hsp90ab1 stabilizes LRP5 to promote epithelial-mesenchymal transition via activating of AKT and Wnt/β-catenin signaling pathways in gastric cancer progression

Hsp90ab1 is upregulated in numerous solid tumors, which is thought to induce the angiogenesis and promote cancer metastasis. However, it’s actions in gastric cancer (GC) has not been exhibited. In this study, Hsp90ab1 was demonstrated to be overexpressed and correlated with the poor prognosis, proliferation and invasion of GC. Ectopic expression of Hsp90ab1 promoted the proliferation and metastasis of GC cells both in vitro in cell line models of GC and in vivo using two different xenograft mouse models, while opposite effects were observed in Hsp90ab1 silenced cells. Moreover, the underlining molecular mechanism was explored by the co-immunoprecipitation, immunofluorescence, GST pull-down and in vitro ubiquitination assay. Namely, Hsp90ab1 exerted these functions via the interaction of LRP5 and inhibited ubiquitin-mediated degradation of LRP5, an indispensable coreceptor of the Wnt/β-catenin signaling pathway. In addition, the crosstalk between Hsp90ab1 and LRP5 contributed to the upregulation of multiple mesenchymal markers, which are also targets of Wnt/β-catenin. Collectively, this study uncovers the details of the Hsp90ab1-LRP5 axis, providing novel insights into the role and mechanism of invasion and metastasis in GC.

MiR-519d suppresses breast cancer tumorigenesis and metastasis via targeting MMP3

Breast cancer (BC) is the most common cause of death in women throughout the world. Although microRNAs (miRNAs) have been identified as novel regulators in carcinogenesis, there are still abundant hidden treasure needed to be excavated. In the present study, we found that miR-519d expression was remarkably decreased in both human BC tissues and MCF-7 cells. CCK8 and 5-Ethynyl-2'-deoxyuridine (EdU) assays were used to evaluate cell proliferation. Wound-healing and transwell assays were performed for detection of cell migration and invasion. The results demonstrated miR-519d overexpression dramatically suppressed MCF-7 cells proliferation, migration and invasion. While downregulation of miR-519d by miR-519d inhibitor substantially increased MCF-7 cell carcinogenesis. Further analysis identified Matrix Metalloproteinase-3 (MMP3) as a direct target of miR-519d. QRT-PCR and western blot results indicated the correlative expression of miR-519d and MMP3 in BC tissues and MCF-7 cells. In summary, our data uncovered the novel molecular interaction between miR-519d and MMP3, indicating a therapeutic strategy of miR-519d for BC.

Optical imaging of ovarian cancer using a matrix metalloproteinase-3-sensitive near-infrared fluorescent probe

Epithelial ovarian cancer (EOC) is the seventh most common cancer among women worldwide. The 5-year survival rate for women with EOC is only 30%-50%, which is largely due to the typically late diagnosis of this condition. EOC is difficult to detect in its early stage because of its asymptomatic nature. Recently, near-infrared fluorescent (NIRF) imaging has been developed as a potential tool for detecting EOC at the molecular level. In this study, a NIRF-sensitive probe was designed to detect matrix metalloproteinase (MMP) activity in ovarian cancer cells. A cyanine fluorochrome was conjugated to the amino terminus of a peptide substrate with enzymatic specificity for MMP-3. To analyze the novel MMP-3 probe, an in vivo EOC model was established by subcutaneously implanting SKOV3 cells, a serous-type EOC cell line, in mice. This novel MMP-3-sensitive probe specifically reacted with only the active MMP-3 enzyme, resulting in a significantly enhanced NIRF emission intensity. Histological analysis demonstrated that MMP-3 expression and activity were enhanced in the stromal cells surrounding the ovarian cancer cells. These studies establish a molecular imaging reporter for diagnosing early-stage EOC. Additional studies are required to confirm the early-stage activity of MMP-3 in EOC and its diagnostic and prognostic significance.

Metalloproteinases: a Functional Pathway for Myeloid Cells

Myeloid cells have diverse roles in regulating immunity, inflammation, and extracellular matrix turnover. To accomplish these tasks, myeloid cells carry an arsenal of metalloproteinases, which include the matrix metalloproteinases and the adamalysins. These enzymes have diverse substrate repertoires, and are thus involved in mediating proteolytic cascades, cell migration, and cell signaling. Dysregulation of metalloproteinases contributes to pathogenic processes, including inflammation, fibrosis, and cancer. Metalloproteinases also have important nonproteolytic functions in controlling cytoskeletal dynamics during macrophage fusion and enhancing transcription to promote antiviral immunity. This review highlights the diverse contributions of metalloproteinases to myeloid cell functions.

Heat shock protein 90β in the Vero cell membrane binds Japanese encephalitis virus

The pathogenesis of Japanese encephalitis virus (JEV) is complex and unclearly defined, and in particular, the effects of the JEV receptor (JEVR) on diverse susceptible cells are elusive. In contrast to previous studies investigating JEVR in rodent or mosquito cells, in this study, we used primate Vero cells instead. We noted that few novel proteins co‑immunoprecipitated with JEV, and discovered that one of these was heat shock protein 90β (HSP90β), which was probed by mass spectrometry with the highest score of 60.3 after questing the monkey and human protein databases. The specific HSP90β‑JEV binding was confirmed by western blot analysis under non‑reducing conditions, and this was significantly inhibited by an anti‑human HSP90β monoclonal antibody in a dose‑dependent manner, as shown by immunofluorescence assay and flow cytometry. In addition, the results of confocal laser scanning microscopic examination demonstrated that the HSP90β‑JEV binding occurred on the Vero cell surface. Finally, JEV progeny yields determined by plaque assay were also markedly decreased in siRNA‑treated Vero cells, particularly at 24 and 36 h post‑infection. Thus, our data indicate that HSP90β is a binding receptor for JEV in Vero cells.

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.

Both Drosophila matrix metalloproteinases have released and membrane-tethered forms but have different substrates

Matrix metalloproteinases (MMPs) are extracellular proteases that can cleave extracellular matrix and alter signaling pathways. They have been implicated in many disease states, but it has been difficult to understand the contribution of individual MMPs, as there are over 20 MMPs in vertebrates. The vertebrate MMPs have overlapping substrates, they exhibit genetic redundancy and compensation, and pharmacological inhibitors are non-specific. In contrast, there are only two MMP genes in Drosophila, DmMmp1 and DmMmp2, which makes Drosophila an attractive system to analyze the basis of MMP specificity. Previously, Drosophila MMPs have been categorized by their pericellular localization, as Mmp1 appeared to be secreted and Mmp2 appeared to be membrane-anchored, suggesting that protein localization was the critical distinction in this small MMP family. We report here that products of both genes are found at the cell surface and released into media. Additionally, we show that products of both genes contain GPI-anchors, and unexpectedly, that GPI-anchored MMPs promote cell adhesion when they are rendered inactive. Finally, by using new reagents and assays, we show that the two MMPs cleave different substrates, suggesting that this is the important distinction within this smallest MMP family.

Lack of matrix metalloproteinase 3 in mouse models of lung injury ameliorates the pulmonary inflammatory response in female but not in male mice

BACKGROUND

The acute respiratory distress syndrome (ARDS) is a complex pulmonary disorder in which the local release of cytokines and chemokines appears central to the pathophysiology.

OBJECTIVE

Based on the known role of matrix metalloproteinase-3 (MMP3) in inflammatory processes, the objective was to examine the role of MMP3 in the pathogenesis of ARDS through the modulation of pulmonary inflammation.

MATERIALS AND METHODS

Female and male, wild type (MMP3^+/+) and knock out (MMP3^-/-) mice were exposed to two, clinically relevant models of ARDS including (i) lipopolysaccharide (LPS)-induced lung injury, and (ii) hydrochloric acid-induced lung injury. Parameters of lung injury and inflammation were assessed through measurements in lung lavage including total protein content, inflammatory cell influx, and concentrations of mediators such as TNF-α, IL-6, G-CSF, CXCL1, CXCL2, and CCL2. Lung histology and compliance were also evaluated in the LPS model of injury.

RESULTS

Following intra-tracheal LPS instillation, all mice developed lung injury, as measured by an increase in lavage neutrophils, and decrease in lung compliance, with no overall effect of genotype observed. Increased concentrations of lavage inflammatory cytokines and chemokines were also observed following LPS injury, however, LPS-instilled female MMP3^-/- mice had lower levels of inflammatory mediators compared to LPS-instilled female MMP3^+/+ mice. This effect of the genotype was not observed in male mice. Similar findings, including the MMP3-related sex differences, were also observed after acid-induced lung injury.

CONCLUSION

MMP3 contributes to the pathogenesis of ARDS, by affecting the pulmonary inflammatory response in female mice in relevant models of lung injury.

Cell surface heparan sulfate proteoglycans are involved in the binding of Hsp90α and Hsp90β to the cell plasma membrane

Extracellular membrane-bound and secreted heat shock protein 90 (Hsp90) is known to be involved in cell motility and invasion. The mechanism of Hsp90 anchoring to the plasma membrane remains obscure. We showed that treatment of human glioblastoma A-172 and fibrosarcoma HT1080 cells with sodium chlorate, heparinase, and heparin causes a prominent loss of 2 Hsp90 cytosolic isoforms, Hsp90α and Hsp90β, from the cell surface and strongly inhibits the binding of exogenous Hsp90 to cells. We revealed that Hsp90α and Hsp90β are partly colocalized with heparan sulfate proteoglycans (HSPGs) on the cell surface and that this colocalization was sensitive to heparin. The results demonstrate that cell surface HSPGs are involved in the binding/anchoring of Hsp90α and Hsp90β to the plasma membrane.

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.

Anticancer effect of 20(S)-ginsenoside Rh2 on HepG2 liver carcinoma cells: Activating GSK-3β and degrading β-catenin

20(S)-ginsenoside Rh2 [(S)Rh2] possesses potential to prevent cancer in vitro as well as in vivo, but the underlying mechanism is still unknown. First, we infected HepG2 cells with lentivirus which carries β‑catenin. We detected the pharmacological effects of (S)Rh2 on HepG2 and HepG2‑β‑catenin cells and found that the IC50 of (S)Rh2 exposure on HepG2-β-catenin cells was higher than HepG2 cells. Flow cytometry (FCM) indicated that (S)Rh2 could be arrested in G0/G1 phase and induce early apoptosis in HepG2 and HepG2‑β‑catenin cells. Second, ELISA kit was used to check the activity of glycogen synthase kinase‑3β (GSK‑3β), which was upregulated by (S)Rh2. GSK‑3β inhibitor BIO, was used to verify that (S)Rh2 activated GSK‑3β. PCR and western blotting results indicated that (S)Rh2 could degrade the expression of β‑catenin, which combined with TCF in the nucleus and activate transcription of Wnt target genes, such as Bax, Bcl‑2, cyclin D1, MMP3, which were checked by chromatin immunoprecipitation (ChIP), PCR and western blotting. The results showed that the expression of Bax mRNA and proteins increased, while the cyclin D1, Bcl‑2, MMP3 mRNA and proteins were downregulated in HepG2 and HepG2‑β‑catenin cells which was induced by (S)Rh2. By contrast, with the HepG2-β-catenin + (S)Rh2 group, the expression of other mRNA and proteins in HepG2 + (S)Rh2 group changed significantly. In vivo, experiments were performed using a nude mouse xenograft model to investigate the (S)Rh2 effect. So these results suggested that (S)Rh2 could suppress proliferation, promote apoptosis and inhibit metastasis of HepG2, decrease weight of tumor by downregulating β‑catenin through activating GSK‑3β and the pharmacological effect of (S)Rh2 on HepG2 cells might be weakened by overexpression of β‑catenin.

Muscle-derived matrix metalloproteinase regulates stem cell proliferation in planarians

BACKGROUND

Matrix metalloproteinases (MMPs) are a large family of regulatory enzymes that function in extracellular matrix degradation and facilitate a diverse range of cellular processes. Despite the significant focus on the activities of MMPs in human disease, there is a lack of substantial knowledge regarding their normal physiological roles and their role in regulating aspects of stem cell biology. The freshwater planarian Schmidtea mediterranea (S. mediterranea) is an excellent system in which to study robust and nearly unlimited regeneration, guided by a population of mitotically active stem cells, termed neoblasts.

RESULTS

We characterized MMPs in the context of planarian stem cells, specifically exploring the role of S. mediterranea MT-MMPB. Using in situ hybridization and available functional genomic tools, we observed that mt-mmpB is expressed in the dorsoventral muscle cells, and its loss results in a reduction in animal size accompanied by a decrease in mitotic cells, suggesting that it plays a unique role in regulating stem cell proliferation.

CONCLUSIONS

The novel findings of this study bring to light the unique and critical roles that muscles play in regulating neoblast function, and more broadly, highlight the importance of MMPs in stem cell biology. Developmental Dynamics 245:963-970, 2016. © 2016 Wiley Periodicals, Inc.

New insight into the role of MMP14 in metabolic balance

Membrane-anchored matrix metalloproteinase 14 (MMP14) is involved broadly in organ development through both its proteolytic and signal-transducing functions. Knockout of Mmp14 (KO) in mice results in a dramatic reduction of body size and wasting followed by premature death, the mechanism of which is poorly understood. Since the mammary gland develops after birth and is thus dependent for its functional progression on systemic and local cues, we chose it as an organ model for understanding why KO mice fail to thrive. A global analysis of the mammary glands' proteome in the wild type (WT) and KO mice provided insight into an unexpected role of MMP14 in maintaining metabolism and homeostasis. We performed mass spectrometry and quantitative proteomics to determine the protein signatures of mammary glands from 7 to 11 days old WT and KO mice and found that KO rudiments had a significantly higher level of rate-limiting enzymes involved in catabolic pathways. Glycogen and lipid levels in KO rudiments were reduced, and the circulating levels of triglycerides and glucose were lower. Analysis of the ultrastructure of mammary glands imaged by electron microscopy revealed a significant increase in autophagy signatures in KO mice. Finally, Mmp14 silenced mammary epithelial cells displayed enhanced autophagy. Applied to a systemic level, these findings indicate that MMP14 is a crucial regulator of tissue homeostasis. If operative on a systemic level, these findings could explain how Mmp14KO litter fail to thrive due to disorder in metabolism.

Novel effects of sphingosylphosphorylcholine on invasion of breast cancer: Involvement of matrix metalloproteinase-3 secretion leading to WNT activation

Sphingosylphosphorylcholine (SPC) participates in several cellular processes including metastasis. SPC induces keratin reorganization and regulates the viscoelasticity of metastatic cancer cells including PANC-1 cancer cells leading to enhanced migration and invasion. The role of SPC and the relevant mechanism in invasion of breast cell are as yet unknown. SPC dose-dependently induces invasion of breast cancer cells or breast immortalized cells. Reverse transcription polymerase chain reaction and Western blot analyses of MCF10A and ZR-75-1 cells indicated that SPC induces expression and secretion of matrix metalloproteinase-3 (MMP3). From online KMPLOT, relapse free survival is high in patients having low MMP3 expressed basal breast cancer (n=581, p=0.032). UK370106 (MMP3 inhibitor) or gene silencing of MMP3 markedly inhibited the SPC-induced invasion of MCF10A cells. An extracellular signal-regulated kinase (ERK) inhibitor, PD98059, significantly suppressed the secretion and the gelatinolytic activity of MMP3, and invasion in MCF10A cells. Over-expression of ERK1 and ERK2 promoted both the expression and secretion of MMP3. In contrast, gene silencing of ERK1 and ERK2 attenuated the secretion of MMP3 in MCF10A cells. The effects of SPC-induced MMP3 secretion on β-catenin and TCF/lymphoid enhancer factor (LEF) promoter activity were examined since MMP3 indirectly activates canonical Wnt signaling. SPC induced translocation of β-catenin to nucleus and increased TCF/LEF promoter activity. These events were suppressed by UK370106 or PD98059. Wnt inhibitor, FH535 inhibited SPC-induced MMP3 secretion and invasion. Taken together, these results suggest that SPC induces MMP3 expression and secretion via ERK leading to Wnt activation.

MMP3-mediated tumor progression is controlled transcriptionally by a novel IRF8-MMP3 interaction

Interferon regulatory factor-8 (IRF8), originally identified as a leukemic tumor suppressor, can also exert anti-neoplastic activities in solid tumors. We previously showed that IRF8-loss enhanced tumor growth, which was accompanied by reduced tumor-cell susceptibility to apoptosis. However, the impact of IRF8 expression on tumor growth could not be explained solely by its effects on regulating apoptotic response. Exploratory gene expression profiling further revealed an inverse relationship between IRF8 and MMP3 expression, implying additional intrinsic mechanisms by which IRF8 modulated neoplastic behavior. Although MMP3 expression was originally linked to tumor initiation, the role of MMP3 beyond this stage has remained unclear. Therefore, we hypothesized that MMP3 governed later stages of disease, including progression to metastasis, and did so through a novel IRF8-MMP3 axis. Altogether, we showed an inverse mechanistic relationship between IRF8 and MMP3 expression in tumor progression. Importantly, the growth advantage due to IRF8-loss was significantly compromised after silencing MMP3 expression. Moreover, MMP3-loss reduced spontaneous lung metastasis in an orthotopic mouse model of mammary carcinoma. MMP3 acted, in part, in a cell-intrinsic manner and served as a direct transcriptional target of IRF8. Thus, we identified a novel role of an IRF8-MMP3 axis in tumor progression, which unveils new therapeutic opportunities.

Breast cancer carcinoma-associated fibroblasts differ from breast fibroblasts in immunological and extracellular matrix regulating pathways

Tumor stroma has been recently shown to play a crucial role in the development of breast cancer. Since the origin of the stromal cells in the tumor is unknown, we have examined differences and similarities between three stromal cell types of mesenchymal origin, namely carcinoma associated fibroblasts from breast tumor (CAFs), fibroblasts from normal breast area (NFs) and bone marrow derived mesenchymal stromal cells (MSCs). In a microarray analysis, immunological, developmental and extracellular matrix -related pathways were over-represented in CAFs when compared to NFs (p<0.001). Under hypoxic conditions, the expression levels of pyruvate dehydrogenase kinase-1 (PDK1) and pyruvate dehydrogenase kinase-4 (PDK4) were lower in CAFs when compared to NFs (fold changes 0.6 and 0.4, respectively). In normoxia, when compared to NFs, CAFs displayed increased expression of glucose transporter 1 (GLUT-1) and PDK1 (fold changes 1.5 and 1.3, respectively). With respect to the assessed surface markers, only CD105 was expressed differently in MSCs when compared to fibroblasts, being more often expressed on MSCs. Cells with myofibroblast features were present in both NF and CAF samples. We conclude, that CAFs differ distinctly from NFs at the gene expression level, this hypothesis was also tested in silico for other available gene expression data.

Multiple myeloma-derived MMP-13 mediates osteoclast fusogenesis and osteolytic disease

Multiple myeloma (MM) cells secrete osteoclastogenic factors that promote osteolytic lesions; however, the identity of these factors is largely unknown. Here, we performed a screen of human myeloma cells to identify pro-osteoclastogenic agents that could potentially serve as therapeutic targets for ameliorating MM-associated bone disease. We found that myeloma cells express high levels of the matrix metalloproteinase MMP-13 and determined that MMP-13 directly enhances osteoclast multinucleation and bone-resorptive activity by triggering upregulation of the cell fusogen DC-STAMP. Moreover, this effect was independent of the proteolytic activity of the enzyme. Further, in mouse xenograft models, silencing MMP-13 expression in myeloma cells inhibited the development of osteolytic lesions. In patient cohorts, MMP-13 expression was localized to BM-associated myeloma cells, while elevated MMP-13 serum levels were able to correctly predict the presence of active bone disease. Together, these data demonstrate that MMP-13 is critical for the development of osteolytic lesions in MM and that targeting the MMP-13 protein - rather than its catalytic activity - constitutes a potential approach to mitigating bone disease in affected patients.

Maximizing the Therapeutic Potential of HSP90 Inhibitors

HSP90 is required for maintaining the stability and activity of a diverse group of client proteins, including protein kinases, transcription factors, and steroid hormone receptors involved in cell signaling, proliferation, survival, oncogenesis, and cancer progression. Inhibition of HSP90 alters the HSP90-client protein complex, leading to reduced activity, misfolding, ubiquitination, and, ultimately, proteasomal degradation of client proteins. HSP90 inhibitors have demonstrated significant antitumor activity in a wide variety of preclinical models, with evidence of selectivity for cancer versus normal cells. In the clinic, however, the efficacy of this class of therapeutic agents has been relatively limited to date, with promising responses mainly observed in breast and lung cancer, but no major activity seen in other tumor types. In addition, adverse events and some significant toxicities have been documented. Key to improving these clinical outcomes is a better understanding of the cellular consequences of inhibiting HSP90 that may underlie treatment response or resistance. This review considers the recent progress that has been made in the study of HSP90 and its inhibitors and highlights new opportunities to maximize their therapeutic potential.

New approaches to selectively target cancer-associated matrix metalloproteinase activity

Heightened matrix metalloproteinase (MMP) activity has been noted in the context of the tumor microenvironment for many years, and causal roles for MMPs have been defined across the spectrum of cancer progression. This is primarily due to the ability of the MMPs to process extracellular matrix (ECM) components and to regulate the bioavailability/activity of a large repertoire of cytokines and growth factors. These characteristics made MMPs an attractive target for therapeutic intervention but notably clinical trials performed in the 1990s did not fulfill the promise of preclinical studies. The reason for the failure of early MMP inhibitor (MMPI) clinical trials that are multifold but arguably principal among them was the inability of early MMP-based inhibitors to selectively target individual MMPs and to distinguish between MMPs and other members of the metzincin family. In the decades that have followed the MMP inhibitor trials, innovations in chemical design, antibody-based strategies, and nanotechnologies have greatly enhanced our ability to specifically target and measure the activity of MMPs. These advances provide us with the opportunity to generate new lines of highly selective MMPIs that will not only extend the overall survival of cancer patients, but will also afford us the ability to utilize heightened MMP activity in the tumor microenvironment as a means by which to deliver MMPIs or MMP activatable prodrugs.

Reversible Aptamer-Au Plasmon Rulers for Secreted Single Molecules

Plasmon rulers, consisting of pairs of gold nanoparticles, allow single-molecule analysis without photobleaching or blinking; however, current plasmon rulers are irreversible, restricting detection to only single events. Here, we present a reversible plasmon ruler, comprised of coupled gold nanoparticles linked by a single aptamer, capable of binding individual secreted molecules with high specificity. We show that the binding of target secreted molecules to the reversible plasmon ruler is characterized by single-molecule sensitivity, high specificity, and reversibility. Such reversible plasmon rulers should enable dynamic and adaptive live-cell measurement of secreted single molecules in their local microenvironment.

Matrix metalloproteinases as breast cancer drivers and therapeutic targets

Members of the matrix metalloproteinase (MMP) family have been identified as poor prognosis markers for breast cancer patients and as drivers of many facets of the tumor phenotype in experimental models. Early enthusiasm for MMPs as therapeutic targets was tempered following disappointing clinical trials that utilized broad spectrum, small molecule catalytic site inhibitors. However, subsequent research has continued to define key roles for MMPs as breast cancer promoters, to elucidate the complex roles that that these proteins play in breast cancer development and progression, and to identify how these roles are linked to specific and unique biochemical features of individual members of the MMP family. Here, we provide an overview of the structural features of the MMPs, then discuss clinical studies identifying which MMP family members are linked with breast cancer development and new experimental studies that reveal how these specific MMPs may play unique roles in the breast cancer microenvironment. We conclude with a discussion of the most promising avenues for development of therapeutic agents capable of targeting the tumor-promoting properties of MMPs.