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In JoVE (1)
Other Publications (16)
- The Journal of Biological Chemistry
- Cancer Metastasis Reviews
- Molecular Imaging
- Seminars in Cancer Biology
- Annual Review of Pharmacology and Toxicology
- Cancer Research
- Protein Expression and Purification
- Molecular Cancer Research : MCR
- Current Protocols in Cell Biology / Editorial Board, Juan S. Bonifacino ... [et Al.]
- Clinical & Experimental Metastasis
- Methods in Molecular Biology (Clifton, N.J.)
- Proceedings of the National Academy of Sciences of the United States of America
- Cellular Physiology and Biochemistry : International Journal of Experimental Cellular Physiology, Biochemistry, and Pharmacology
- Biochimica Et Biophysica Acta
- The Journal of Biological Chemistry
- Cancer Research
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Articles by Kamiar Moin in JoVE
JoVE Clinical and Translational Medicine
MAME 4D ट्यूमर लाइव सेल इमेजिंग के लिए मॉडल: Microenvironment सहभागिता कि प्रभाव घातक प्रगति
1Department of Pharmacology, Wayne State University, 2Barbara Ann Karmanos Cancer Institute, Wayne State University
हम उनके microenvironment में स्तन ट्यूमर कोशिकाओं और अन्य कोशिकाओं के बीच बातचीत के वास्तविक समय में रहते सेल इमेजिंग के लिए 3 डी coculture मॉडल विकसित किया है कि प्रभाव एक आक्रामक phenotype के लिए प्रगति. इन मॉडलों paracrine - प्रेरित, proteolytic, / chemokine साइटोकाइन और kinase invasiveness में फंसा रास्ते को लक्षित करने के लिए दवाओं के लिए preclinical स्क्रीन के रूप में सेवा कर सकते हैं.
Other articles by Kamiar Moin on PubMed
Interaction of Human Breast Fibroblasts with Collagen I Increases Secretion of Procathepsin B
Interactions of stromal and tumor cells with the extracellular matrix may regulate expression of proteases including the lysosomal proteases cathepsins B and D. In the present study, we determined whether the expression of these two proteases in human breast fibroblasts was modulated by interactions with the extracellular matrix component, collagen I. Breast fibroblasts were isolated from non-malignant breast tissue as well as from tissue surrounding malignant human breast tumors. Growth of these fibroblasts on collagen I gels affected cell morphology, but not the intracellular localization of vesicles staining for cathepsin B or D. Cathepsins B and D levels (mRNA or intracellular protein) were not affected in fibroblasts growing on collagen I gels or plastic, nor was cathepsin D secreted from these cells. In contrast, protein expression and secretion of cathepsin B, primarily procathepsin B, was induced by growth on collagen I gels. The induced secretion appeared to be mediated by integrins binding to collagen I, as inhibitory antibodies against alpha(1), alpha(2), and beta(1) integrin subunits prevented procathepsin B secretion from fibroblasts grown on collagen. In addition, procathepsin B secretion was induced when cells were plated on beta(1) integrin antibodies. To our knowledge, this is the first examination of cathepsin B and D expression and localization in human breast fibroblasts and their regulation by a matrix protein. Secretion of the cysteine protease procathepsin B from breast fibroblasts may have physiological and pathological consequences, as proteases are required for normal development and for lactation of the mammary gland, yet can also initiate and accelerate the progression of breast cancer.
Pericellular Cathepsin B and Malignant Progression
Cathepsin B is a lysosomal cysteine protease in normal cells and tissues. In malignant tumors and premalignant lesions, the expression of cathepsin B is highly upregulated and the enzyme is secreted and becomes associated with the cell surface. Increases in expression are mediated at many levels ranging from gene amplification to increased stability of mRNA and protein. Cathepsin B is synthesized as a preproenzyme and the primary pathways for its normal trafficking to the lysosome utilize mannose 6-phosphate receptors (MPRs). Inactive procathepsin B is processed to active single and double chain forms of cathepsin B in the late endosomes and lysosomes, respectively. Tumor cells secrete procathepsin B and both active forms of cathepsin B. Secretion of procathepsin B occurs principally as a result of increased expression, whereas secretion of active cathepsin B seems to involve active processes that can be induced by a variety of mechanisms. Once secreted procathepsin B binds to the tumor cell surface via p11, the light chain of the annexin II heterotetramer. This binding seems to facilitate conversion of procathepsin B to its active forms. Cathepsin B and the annexin II heterotetramer colocalize in caveolae (lipid raft) fractions isolated from tumor cells. Serine proteases and matrix metalloproteinases also have been found to associate with caveolae and some with the annexin II heterotetramer. Our working hypothesis is that pericellular cathepsin B through its proximity to other proteases in caveolae participates in, perhaps even initiates, a proteolytic cascade on the tumor cell surface.
Functional Imaging of Proteolysis: Stromal and Inflammatory Cells Increase Tumor Proteolysis
The underlying basement membrane is degraded during progression of breast and colon carcinoma. Thus, we imaged degradation of a quenched fluorescent derivative of basement membrane type IV collagen (DQ-collagen IV) by living human breast and colon tumor spheroids. Proteolysis of DQ-collagen IV by HCT 116 and HKh-2 human colon tumor spheroids was both intracellular and pericellular. In contrast, proteolysis of DQ-collagen IV by BT20 human breast tumor spheroids was pericellular. As stromal elements can contribute to proteolytic activities associated with tumors, we also examined degradation of DQ-collagen IV by human monocytes/macrophages and colon and breast fibroblasts. Fibroblasts themselves exhibited a modest amount of pericellular degradation. Degradation was increased 4-17-fold in cocultures of fibroblasts and tumor cells as compared to either cell type alone. Inhibitors of matrix metalloproteinases, plasmin, and the cysteine protease, cathepsin B, all reduced degradation in the cocultures. Monocytes did not degrade DQ-collagen IV; however, macrophages degraded DQ-collagen IV intracellularly. In coculture of tumor cells, fibroblasts, and macrophages, degradation of DQ-collagen IV was further increased. Imaging of living tumor and stromal cells has, thus, allowed us to establish that tumor proteolysis occurs pericellularly and intracellularly and that tumor, stromal, and inflammatory cells all contribute to degradative processes.
Cathepsin B and Tumor Proteolysis: Contribution of the Tumor Microenvironment
Tumor-stromal interactions induce expression of matrix metalloproteinases and serine proteases and, as shown recently, the cysteine protease cathepsin B. We speculate that such interactions upregulate the transcription factor Ets1, resulting in increased cathepsin B expression. This would be consistent with the observed concomitant upregulation of matrix metalloproteinases and serine proteases as well as with the ability of extracellular matrices and their binding partners to alter cathepsin B expression and secretion. Using a confocal assay to analyze the contribution of tumor-stromal interactions to proteolysis, we have been able to confirm enhanced degradation of extracellular matrices by all three classes of proteases.
Functional Imaging of Tumor Proteolysis
The roles of proteases in cancer are now known to be much broader than simply degradation of extracellular matrix during tumor invasion and metastasis. Furthermore, proteases from tumor-associated cells (e.g., fibroblasts, inflammatory cells, endothelial cells) as well as tumor cells are recognized to contribute to pathways critical to neoplastic progression. Although elevated expression (transcripts and proteins) of proteases, and in some cases protease inhibitors, has been documented in many tumors, techniques to assess functional roles for proteases require that we measure protease activity and inhibition of that activity rather than levels of proteases, activators, and inhibitors. Novel techniques for functional imaging of protease activity, both in vitro and in vivo, are being developed as are imaging probes that will allow us to determine protease activity and in some cases to discriminate among protease activities. These should be useful clinically as surrogate endpoints for therapies that alter protease activities.
Analysis of Host- and Tumor-derived Proteinases Using a Custom Dual Species Microarray Reveals a Protective Role for Stromal Matrix Metalloproteinase-12 in Non-small Cell Lung Cancer
We used a customized Affymetrix protease microarray (Hu/Mu ProtIn chip) designed to distinguish human and mouse genes to analyze the expression of proteases and protease inhibitors in lung cancer. Using an orthotopic lung cancer model, we showed that murine matrix metalloproteinase (MMP)-12, MMP-13, and cathepsin K were up-regulated in tumor tissue compared with normal mouse lung. To determine the relevance of stromal proteases detected using this model system, we compared the results to an analysis of human lung adenocarcinoma specimens using the U133 Plus 2.0 Affymetrix microarray. MMP-12, MMP-13, and cathepsin K showed an increase in expression in human tumors compared with normal lung similar to that seen in the orthotopic model. Immunohistochemical analysis confirmed MMP-12 expression in the stroma of human lung tumor samples. To determine the biological relevance of stromal MMP-12, murine Lewis lung carcinoma cells were injected into the tail vein of syngeneic wild-type (WT) and MMP-12-null mice. MMP-12-null and WT mice developed equivalent numbers of lung tumors; however, there was a 2-fold increase in the number of tumors that reached >2 mm in diameter in MMP-12-null mice compared with WT controls. The increase in tumor size correlated with an increase in CD31-positive blood vessels and a decrease in circulating levels of the K1-K4 species of angiostatin. These results show a protective role for stromal MMP-12 in lung tumor growth. The use of the Hu/Mu ProtIn chip allows us to distinguish tumor- and host-derived proteases and guides the further analysis of the significance of these genes in tumor progression.
Functional Expression of Recombinant Human Stefin A in Mammalian and Bacterial Cells
Recombinant human cysteine protease inhibitor, stefin A, was expressed in both Escherichia coli and BS-C-1 monkey kidney cells utilizing pET and recombinant vaccinia virus systems, respectively. The expressed protein was purified and analyzed by SDS-PAGE and Western blot analysis utilizing a polyclonal antibody against rat cystatin alpha. In both cases the purified protein appeared as a single band corresponding to the molecular weight of stefin A ( approximately 10kDa). Viability of the expressed stefin A was determined by the inhibition of the plant cysteine protease, papain. Recombinant human stefin A expressed in both E. coli and BS-C-1 cells, was shown to almost completely inhibit papain. The expression of a fully functional recombinant human stefin A in the bacterial system provides a highly efficient tool for the production of large quantities of the protein. This can be an important tool in kinetic studies as well as in production of antibodies for other analytical studies (immunoblot, immunohistochemical studies, etc.). Expression in the mammalian cells, on the other hand, can provide a significant research tool to study the functional roles of stefin A in mammalian systems such as regulation of cysteine proteases.
Hu/Mu ProtIn Oligonucleotide Microarray: Dual-species Array for Profiling Protease and Protease Inhibitor Gene Expression in Tumors and Their Microenvironment
Proteolysis is a critical regulatory mechanism for a wide variety of physiologic and pathologic processes. To assist in the identification of proteases, their endogenous inhibitors, and proteins that interact with proteases or proteolytic pathways in biological tissues, a dual-species oligonucleotide microarray has been developed in conjunction with Affymetrix. The Hu/Mu ProtIn microarray contains 516 and 456 probe sets that survey human and mouse genes of interest (proteases, protease inhibitors, or interactors), respectively. To investigate the performance of the array, gene expression profiles were analyzed in pure mouse and human samples (reference RNA; normal and tumor cell lines/tissues) and orthotopically implanted xenografts of human A549 lung and MDA-MB-231 breast carcinomas. Relative gene expression and "present-call" P values were determined for each probe set using dChip and MAS5 software, respectively. Despite the high level of sequence identity of mouse and human protease/inhibitor orthologues and the theoretical potential for cross-hybridization of some of the probes, >95% of the "present calls" (P<0.01) resulted from same-species hybridizations (e.g., human transcripts to human probe sets). To further assess the performance of the microarray, differential gene expression and false discovery rate analyses were carried out on human or mouse sample groups, and data processing methods to optimize performance of the mouse and human probe sets were identified. The Hu/Mu ProtIn microarray is a valuable discovery tool for the identification of components of human and murine proteolytic pathways in health and disease and has particular utility in the determination of cellular origins of proteases and protease inhibitors in xenograft models of human cancer.
Visualizing Protease Activity in Living Cells: from Two Dimensions to Four Dimensions
Proteolytic degradation of extracellular matrix (ECM) components by cells is an important metabolic activity as cells grow, remodel, and migrate through the ECM. The ability to analyze ECM degradation can be valuable in the study of developmental processes as well as pathologies, such as cancer. In this unit we describe an in vitro live cell-based method to image and quantitatively measure the degradation of ECM components by live cells. Cells are grown in the presence of fluorescent dye-quenched protein substrates (DQ-gelatin, DQ-collagen I, and DQ-collagen IV) that are mixed with protein matrices. Upon proteolytic cleavage, fluorescence is released that directly reflects the level of proteolysis by the cells. Using confocal microscopy and advanced imaging software, the fluorescence is detected and accurate measurements of proteolytic degradation in three and four dimensions can be assessed.
Imaging and Quantifying the Dynamics of Tumor-associated Proteolysis
The roles of proteases in cancer are dynamic. Furthermore, the roles or functions of any one protease may differ from one stage of cancer to another. Proteases from tumor-associated cells (e.g., fibroblasts, inflammatory cells, endothelial cells) as well as from tumor cells make important contributions to 'tumor proteolysis'. Many tumors exhibit increases in expression of proteases at the level of transcripts and protein; however, whether those proteases play causal roles in malignant progression is known for only a handful of proteases. What the critical substrate or substrates that are cleaved in vivo by any given protease is also known for only a few proteases. Therefore, the recent development of techniques and reagents for live cell imaging of protease activity, in conjunction with informed knowledge of critical natural substrates, should help to define protease functions. Here we describe live cell assays for imaging proteolysis, protocols for quantifying proteolysis and the use of such assays to follow the dynamics of proteolysis by tumor cells alone and tumor cells interacting with other cells found in the tumor microenvironment. In addition, we describe an in vitro model that recapitulates the architecture of the mammary gland, a model designed to determine the effects of dynamic interactions with the surrounding microenvironment on 'tumor proteolysis' and the respective contributions of various cell types to 'tumor proteolysis'. The assays and models described here could serve as screening platforms for the identification of proteolytic pathways that are potential therapeutic targets and for further development of technologies and imaging probes for in vivo use.
Microarrays for Protease Detection in Tissues and Cells
Expression of a given protease and of the endogenous inhibitors that regulate protease activity can be readily determined at the transcript level by using whole genome microarray chips. In the case of proteases and protease inhibitors, however, determining which cells are expressing them is often critical to understanding the functional roles of the proteases. For example, in cancer many of the proteases are derived from cells that are found in the microenvironment surrounding the tumor, e.g., fibroblasts and inflammatory cells. Proteases from both fibroblasts and inflammatory cells have been implicated in malignant progression. Therefore, it is important to recognize the origin of these molecules if one is to develop effective therapies. In this regard, mouse transgenic models and xenograft models in which human tumor cells are implanted in mice are useful tools. To profile human and mouse proteases, protease inhibitors, and protease interactors, we have developed in partnership with Affymetrix a custom, single platform, dual species chip: the Hu/Mu ProtIn chip. The Hu/Mu ProtIn chip has been validated for its ability to identify human and mouse transcripts in single species specimens and to identify and distinguish between human and mouse transcripts in dual species specimens such as xenografts. In the latter specimens, the Hu/Mu ProtIn chip has enabled us to identify host (mouse) proteases that play a protective role in development of lung tumors. Here we outline a protocol for using the Hu/Mu ProtIn chip to profile proteases, protease inhibitors, and protease interactors in tissues and cells.
Chiral Porphyrazine Near-IR Optical Imaging Agent Exhibiting Preferential Tumor Accumulation
A chiral porphyrazine (pz), H(2)[pz(trans-A(2)B(2))] (247), has been prepared that exhibits preferential in vivo accumulation in the cells of tumors. Pz 247 exhibits near-infrared (NIR) emission with lambda > 700 nm in the required wavelength range for maximum tissue penetration. When MDA-MB-231 breast tumor cells are treated with 247, the agent shows strong intracellular fluorescence with an emission maximum, 704 nm, which indicates that it localizes within a hydrophobic microenvironment. Pz 247 is shown to associate with the lipophilic core of LDL and undergo cellular entry primarily through receptor-mediated endocytosis accumulating in lysosomes. Preliminary in vivo studies show that 247 exhibits preferential accumulation and retention in the cells of MDA-MB-231 tumors subcutaneously implanted in mice, thereby enabling NIR optical imaging with excellent contrast between tumor and surrounding tissue. The intensity of fluorescence from 247 within the tumor increases over time up to 48 h after injection presumably due to the sequestration of circulating 247/LDL complex by the tumor tissue. As the need for cholesterol, and thus LDL, is elevated in highly proliferative tumor cells over nontumorigenic cells, 247 has potential application for all such tumors.
Interleukin-6 Increases Expression and Secretion of Cathepsin B by Breast Tumor-associated Monocytes
In the tumor microenvironment, monocytes respond to paracrine stimuli from breast cancer cells by secreting molecules that participate in breast cancer growth, invasion, intravasation and metastasis. Here we examined the effects of media conditioned by MDA-MB-231 human breast carcinoma cells (231-CM) on expression and secretion of proteases and secretion of cytokines by U937 human monocytes. We found that 231-CM increased U937: 1) proliferation; 2) expression, activity and secretion of the cysteine protease cathepsin B (CTSB); 3) secretion of matrix metalloproteinases (MMP)-2 and -9; and 4) secretion of interleukin-6 (IL-6) and insulin-like growth factor binding protein-1 (IGFBP-1). We further demonstrated by western blotting and enzymatic activity assays that the increases in CTSB secretion and activity induced by 231-CM could be reduced by neutralizing antibodies against IL-6. Our data suggest a role for IL-6 in increased monocyte expression and secretion of CTSB in response to soluble factors secreted by breast cancer cells.
Live-cell Imaging of Tumor Proteolysis: Impact of Cellular and Non-cellular Microenvironment
Our laboratory has had a longstanding interest in how the interactions between tumors and their microenvironment affect malignant progression. Recently, we have focused on defining the proteolytic pathways that function in the transition of breast cancer from the pre-invasive lesions of ductal carcinoma in situ (DCIS) to invasive ductal carcinomas (IDCs). We use live-cell imaging to visualize, localize and quantify proteolysis as it occurs in real-time and thereby have established roles for lysosomal cysteine proteases both pericellularly and intracellularly in tumor proteolysis. To facilitate these studies, we have developed and optimized 3D organotypic co-culture models that recapitulate the in vivo interactions of mammary epithelial cells or tumor cells with stromal and inflammatory cells. Here we will discuss the background that led to our present studies as well as the techniques and models that we employ. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome.
Identification and Functional Impact of Homo-oligomers of the Human Proton-coupled Folate Transporter
The proton-coupled folate transporter (PCFT; SLC46A1) is a proton-folate symporter that is abundantly expressed in solid tumors and normal tissues, such as duodenum. The acidic pH optimum for PCFT is relevant to intestinal absorption of folates and could afford a means of selectively targeting tumors with novel cytotoxic antifolates. PCFT is a member of the major facilitator superfamily of transporters. Because major facilitator superfamily members exist as homo-oligomers, we tested this for PCFT because such structures could be significant to PCFT mechanism and regulation. By transiently expressing PCFT in reduced folate carrier- and PCFT-null HeLa (R1-11) cells and chemical cross-linking with 1,1-methanediyl bismethanethiosulfonate and Western blotting, PCFT species with molecular masses approximating those of the PCFT dimer and higher order oligomers were detected. Blue native polyacrylamide gel electrophoresis identified PCFT dimer, trimer, and tetramer forms. PCFT monomers with hemagglutinin and His(10) epitope tags were co-expressed in R1-11 cells, solubilized, and bound to nickel affinity columns, establishing their physical associations. Co-expressing YPet and ECFP*-tagged PCFT monomers enabled transport and fluorescence resonance energy transfer in plasma membranes of R1-11 cells. Combined wild-type (WT) and inactive mutant P425R PCFTs were targeted to the cell surface by surface biotinylation/Western blots and confocal microscopy and functionally exhibited a "dominant-positive" phenotype, implying positive cooperativity between PCFT monomers and functional rescue of mutant by WT PCFT. Our results demonstrate the existence of PCFT homo-oligomers and imply their functional and regulatory impact. Better understanding of these higher order PCFT structures may lead to therapeutic applications related to folate uptake in hereditary folate malabsorption, and delivery of PCFT-targeted chemotherapy drugs for cancer.
Cathepsin B Inhibition Limits Bone Metastasis in Breast Cancer
Metastasis to bone is a major cause of morbidity in breast cancer patients, emphasizing the importance of identifying molecular drivers of bone metastasis for new therapeutic targets. The endogenous cysteine cathepsin inhibitor stefin A is a suppressor of breast cancer metastasis to bone that is co-expressed with cathepsin B in bone metastases. In this study, we used the immunocompetent 4T1.2 model of breast cancer which exhibits spontaneous bone metastasis to evaluate the function and therapeutic targeting potential of cathepsin B in this setting of advanced disease. Cathepsin B abundancy in the model mimicked human disease, both at the level of primary tumors and matched spinal metastases. RNAi-mediated knockdown of cathepsin B in tumor cells reduced collagen I degradation in vitro and bone metastasis in vivo. Similarly, intraperitoneal administration of the highly selective cathepsin B inhibitor CA-074 reduced metastasis in tumor-bearing animals, a reduction that was not reproduced by the broad spectrum cysteine cathepsin inhibitor JPM-OEt. Notably, metastasis suppression by CA-074 was maintained in a late treatment setting, pointing to a role in metastatic outgrowth. Together, our findings established a pro-metastatic role for cathepsin B in distant metastasis and illustrated the therapeutic benefits of its selective inhibition in vivo.
