Localization of matrix metalloproteinase 9 to the cell surface provides a mechanism for CD44-mediated tumor invasion

Expression of matrix metalloproteinase-2 and -9 and membrane-type 1 matrix metalloproteinase in melanocytic tumors of dogs and canine melanoma cell lines

OBJECTIVE

To evaluate expression of matrix metalloproteinase (MMP)-2 and -9 and membrane-type 1 MMP (MT1-MMP) in melanocytomas and malignant melanomas of dogs, analyze in vitro production of MMPs by canine melanoma cell lines and primary dermal fibroblasts, and investigate mutual communication between tumor cells and fibroblasts and the influence of collagen on MMP regulation.

SAMPLE

35 biopsy specimens from melanocytic tumors and primary dermal fibroblasts of dogs and 3 canine melanoma cell lines (CML-1, CML-10c2, and CML-6M).

PROCEDURES

MMP-2, MMP-9, and MT1-MMP were detected in tumor samples by use of immunohistochemical analysis. In vitro production was analyzed via reverse transcriptase-PCR assay, immunocytochemical analysis, zymography, and immunoblotting.

RESULTS

MMP-9 was overexpressed in malignant melanomas, compared with expression in melanocytomas, whereas no significant differences in MMP-2 and MT1-MMP immunostaining were detected. Stromal cells also often had positive staining results. In vitro, all 3 melanoma cell lines and dermal fibroblasts had evidence of MMP-2 and MT1-MMP, but only melanoma cells had evidence of MMP-9. Coculture of CML-1 or CML-10c2 cells and dermal fibroblasts induced an increase in expression of the active form of MMP-2. Culture of melanoma cells on type I collagen increased the activation state of MT1-MMP.

CONCLUSIONS AND CLINICAL RELEVANCE

MMP-9 expression was increased in malignant melanomas of dogs. Stromal cells were a source for MMPs. Stromal cells, in combination with matrix components such as type I collagen, can interact with tumor cells to regulate MMP production. Information about MMP production and regulation could help in the development of new treatments.

CD44 upregulation in E-cadherin-negative esophageal cancers results in cell invasion

E-cadherin is frequently lost during epithelial-mesenchymal transition and the progression of epithelial tumorigenesis. We found a marker of epithelial-mesenchymal transition, CD44, upregulated in response to functional loss of E-cadherin in esophageal cell lines and cancer. Loss of E-cadherin expression correlates with increased expression of CD44 standard isoform. Using an organotypic reconstruct model, we show increased CD44 expression in areas of cell invasion is associated with MMP-9 at the leading edge. Moreover, Activin A increases cell invasion through CD44 upregulation after E-cadherin loss. Taken together, our results provide functional evidence of CD44 upregulation in esophageal cancer invasion.

Hyaluronan synthase 2 (HAS2) promotes breast cancer cell invasion by suppression of tissue metalloproteinase inhibitor 1 (TIMP-1)

Invasion and metastasis are the primary causes of breast cancer mortality, and increased knowledge about the molecular mechanisms involved in these processes is highly desirable. High levels of hyaluronan in breast tumors have been correlated with poor patient survival. The involvement of hyaluronan in the early invasive phase of a clone of breast cancer cell line MDA-MB-231 that forms bone metastases was studied using an in vivo-like basement membrane model. The metastatic to bone tumor cells exhibited a 7-fold higher hyaluronan-synthesizing capacity compared with MDA-MB-231 cells predominately due to an increased expression of hyaluronan synthase 2 (HAS2). We found that knockdown of HAS2 completely suppressed the invasive capability of these cells by the induction of tissue metalloproteinase inhibitor 1 (TIMP-1) and dephosphorylation of focal adhesion kinase. HAS2 knockdown-mediated inhibition of basement membrane remodeling was rescued by HAS2 overexpression, transfection with TIMP-1 siRNA, or addition of TIMP-1-blocking antibodies. Moreover, knockdown of HAS2 suppressed the EGF-mediated induction of the focal adhesion kinase/PI3K/Akt signaling pathway. Thus, this study provides new insights into a possible mechanism whereby HAS2 enhances breast cancer invasion.

New facets of matrix metalloproteinases MMP-2 and MMP-9 as cell surface transducers: outside-in signaling and relationship to tumor progression

This review focuses on matrix metalloproteinases (MMPs)-2 (gelatinase A) and -9 (gelatinase B), both of which are cancer-associated, secreted, zinc-dependent endopeptidases. Gelatinases cleave many different targets (extracellular matrix, cytokines, growth factors, chemokines and cytokine/growth factor receptors) that in turn regulate key signaling pathways in cell growth, migration, invasion, inflammation and angiogenesis. Interactions with cell surface integral membrane proteins (CD44, αVβ/αβ1/αβ2 integrins and Ku protein) can occur through the gelatinases' active site or hemopexin-like C-terminal domain. This review evaluates the recent literature on the non-enzymatic, signal transduction roles of surface-bound gelatinases and their subsequent effects on cell survival, migration and angiogenesis. Gelatinases have long been drug targets. The current status of gelatinase inhibitors as anticancer agents and their failure in the clinic is discussed in light of these new data on the gelatinases' roles as cell surface transducers - data that may lead to the design and development of novel, gelatinase-targeting inhibitors.

Cell surface glycan-lectin interactions in tumor metastasis

The development of secondary cancers, metastases, requires that a multitude of events are completed in an ordered and sequential manner. This review focuses on the role of cell surface glycans and their binding partners in the metastatic process. A common feature of metastasis is that the steps require adhesive interactions; many of these are mediated by cell surface glycans and their interactions with endogenous carbohydrate binding proteins (lectins). Aberrant glycosylation is a key feature of malignant transformation and the glycans involved influence the adhesive interactions of cancer cells often providing favorable conditions for tumor dissemination. This review focuses on glycans on the cancer cell surface and their association with endogenous lectins. In particular, E-cadherin and siglec-mediated disaggregation of tumor cells from the primary tumor mass; integrins, laminin and CD44-mediated invasion and migration of tumor cells through the connective tissue; the involvement of heparan sulphate in tumor angiogenesis and C-/S-type lectin interactions with the vasculature. The potential role of glycans in cancer cell evasion of immune surveillance is considered.

Plasma TGF-β1, MMP-1 and MMP-3 Levels in Chronic Pancreatitis

Chronic pancreatitis (CP) presenting clinically with upper abdominal pain, as well as exocrine and endocrine insufficiencies, is characterized by irreversible morphological and functional alterations in the pancreas. The objective of the present study is to investigate the plasma levels of transforming growth factor-β 1 (TGF-β1), matrix metalloproteinases MMP-1 (collagenase) and MMP-3 (stromelysin) in CP. A total of 71 CP patients and 100 control subjects were considered for the study. Plasma levels of TGF-β1, MMP-1 and MMP-3 were determined by enzyme-linked immunosorbent assay in patients and control subjects. The plasma levels of TGF-β1 and MMP-1 were significantly elevated in patients compared to control group (*P = 0.0301, **P < 0.0001). However, there was no significant difference in the plasma levels of MMP-3 between patients and controls (P = 0.3756). The elevated levels of TGF-β1 and MMP-1 may influence the inflammatory reactions by enhancing the pancreatic stellate cell activation and deposition of extracellular matrix resulting in pancreatic fibrosis. Thus, the present study highlights the role of fibrogenic cytokine marker TGF-β1 and matrix metalloproteinases in the pathogenesis of CP.

Does linezolid modulate lung innate immunity in a murine model of methicillin-resistant Staphylococcus aureus pneumonia?

OBJECTIVES

Methicillin-resistant Staphylococcus aureus is an important cause of mortality among nosocomial infections. Recent investigations suggest that linezolid is superior to vancomycin in achieving clinical cure in patients with nosocomial pneumonia. We hypothesized that linezolid may exhibit anti-inflammatory properties in vivo model of pneumonia.

DESIGN

Prospective interventional study.

SETTING

University affiliated laboratory.

SUBJECTS

BALB/c mice.

INTERVENTIONS

Three groups of BALB/c mice were inoculated with methicillin-resistant S. aureus American Type Culture Collection 33,591 to induce pneumonia. Each group (n = 6) underwent bronchoalveolar lavage at 24 hrs, 48 hrs, and 72 hrs after inoculation after treatment with vancomycin, linezolid, or no antibiotic. Bronchoalveolar lavage fluid levels of monocyte chemotactic protein-5 and interleukin-6 were quantified using cytometric bead array. Metalloproteinase-9 was detected by enzyme-linked immunosorbent assay and gelatin zymography. Neutrophil apoptosis in bronchoalveolar lavage was assessed by annexin V and 7-aminoactinomycin D staining. Neutrophil activity was determined by myeloperoxidase enzyme activity. Phagocytosis of apoptotic neutrophils by linezolid- vs. vancomycin treated-alveolar macrophages was examined in vitro.

MEASUREMENTS AND MAIN RESULTS

Infected mice had a significant reduction in lung bacterial titers compared with controls (p < .05) after treatment with linezolid or vancomycin. There was no difference in bronchoalveolar lavage levels of monocyte chemotactic protein-5 or interleukin-6 between vancomycin- and linezolid-treated groups. Both antimicrobials were comparable in modulating the expression of matrix metalloproteinase-9 in bronchoalveolar lavage. Neutrophil apoptosis was comparable in both vancomycin- and linezolid-treated groups at all three time points. Vancomycin showed lower myeloperoxidase activity compared with linezolid in the first 24 hrs after inoculation (p = .03), but the difference was undetectable at 48 hrs and 72 hrs. Neither compound had an impact on the process of removal of apoptotic neutrophils by alveolar macrophages.

CONCLUSIONS

Linezolid did not display an advantage over vancomycin in modulating pulmonary innate immune response in a murine model of methicillin-resistant S. aureus pneumonia.

Hyaluronan: a Simple Molecule with Complex Character

This review aims to summarize the properties and applications of hyaluronan, a naturally-occurring, anionic polysaccharide. It provides an overview of its physic chemical properties, biosynthesis and biodegradation. It includes a discussion of the principal hyaluronan-binding proteins studied thus far. The existence of such proteins underscores the importance of this polysaccharide in cell-biological processes like cancer, inflammation or wound healing and these properties are discussed. Finally, this review summarizes some of the applications of hyaluronan in medicine, biotechnology and cosmetics.

Prognostic significance of CD44s expression in resected non-small cell lung cancer

Background

CD44s is a cell adhesion molecule known to mediate cellular adhesion to the extracellular matrix, a prerequisite for tumor cell migration. CD44s plays an important role in invasion and metastasis of various cancers. In the present study, we sought to determine whether CD44s is involved in clinical outcomes of patients with resected non-small cell lung cancer (NSCLC).

Methods

Using immunohistochemical staining, we investigated CD44s protein expression using tissue array specimens from 159 patients with resected NSCLC (adenocarcinoma (AC; n = 82) and squamous cell carcinoma (SCC; n = 77). Additionally, the immunoreactivity of cyclooxygenase (COX)-2 was also studied. The clinicopathological implications of these molecules were analyzed statistically.

Results

High CD44s expression was detected more frequently in NSCLC patients with SCC (66/72; 91.7%) than in those with AC histology (P <0.001). Additionally, high CD44s expression was significant correlated with more advanced regional lymph node metastasis (P = 0.021). In multivariate analysis of survival in NSCLC patients with AC histology, significant predictors were lymph node metastasis status (P < 0.001), high-grade tumor differentiation (P = 0.046), and high CD44s expression (P = 0.014). For NSCLC patients with SCC histology, the significant predictor was a more advanced tumor stage (P = 0.015). No significant association was found between CD44s and clinical outcome (P = 0.311).

Conclusions

High CD44s expression was a negative prognostic marker with significance in patients with resected NSCLC, particularly those with AC histology, and was independent of tumor stage.

Survivin is a novel target of CD44-promoted breast tumor invasion

The hyaluronan (HA) receptor CD44 plays an essential role in cell-cell or cell-extracellular matrix communications and is a bioactive signal transmitter. Although a number of studies have described the function of CD44 in breast cancer (BC) metastasis, the underlying mechanisms have yet to be determined. By using a validated tetracycline-off-regulated CD44 expression system in the MCF-7 cell line combined with microarray analysis, we identified survivin (SVV) as a potential downstream transcriptional target of CD44. To test the hypothesis that SVV underpins CD44-promoted BC cell invasion, we combined molecular and pharmacologic approaches and showed that CD44 induction increased SVV expression levels, which in turn promotes BC cell invasion. Further, clinical analysis of breast tissue samples showed that SVV expression patterns paralleled those of the standard form of CD44 during breast tumor progression. More interestingly, we identified the PI3K/E2F1 pathway as a potential molecular link between HA/CD44 activation and SVV transcription. In addition to identifying SVV as a target for HA/CD44 signaling, this investigation provides a better understanding of the molecular mechanisms that underpin the novel function of SVV in breast cancer metastasis.

Visualization of CD44 and CD133 in normal pancreas and pancreatic ductal adenocarcinomas: non-overlapping membrane expression in cell populations positive for both markers

Tumor-initiating cells of pancreatic ductal adenocarcinoma (PDAC) have been isolated based on expression of either CD133 or CD44. The authors aimed to visualize pancreatic cells simultaneously expressing both these cell surface markers by employing the same antibodies commonly used in cell-sorting studies. Normal and diseased pancreatic tissue, including 51 PDAC cases, were analyzed. CD44 and CD133 expression was determined by immunohistochemical double staining on formalin-fixed material and subcellular protein distribution evaluated by immunofluorescence/confocal microscopy. In the normal pancreas, CD44 and CD133 were coexpressed in the centroacinar regions but in non-overlapping subcellular compartments. As expected, CD44 was found mainly basolaterally, whereas CD133 was present on the apical/endoluminal membrane. This was also the case in chronically inflamed/atrophic pancreatic tissue and in PDAC. In some malignant ducts, CD44 was found at the apical cell membrane adjacent to but never overlapping with CD133 expression. CD44 level was significantly associated with the patient's lymph node status. In conclusion, a CD44+/CD133+ cell population does exist in the normal and neoplastic pancreas. The preferentially centroacinar localization of the doubly positive cells in the normal parenchyma suggests that this population could be of particular interest in attempts to identify tumor-initiating cells in PDAC.

Extracellular signals in young and aging breast epithelial cells and possible connections to age-associated breast cancer development

Aging of human breast tissue is accompanied by certain structural and functional variations and several studies suggest a possible contribution of these changes to an aging-related breast cancer development. At the cellular level, aging of human mammary epithelial cells is associated with significant morphological and functional alterations such as an increased cell size and a reduced proliferation. Cellular senescence of HMEC cannot be explained by a single mechanism but represents an interaction of numerous extra- and intracellular events and the complexity of such orchestrating pathways is still hardly understood. Besides the contribution of reactive oxygen species and telomere dysfunction to aging, it is the aim of this mini-review, to compare distinct changes to extracellular signals by certain matrix metalloproteinases including MMP-7 and associated growth factor pathways mediated by HB-EGF activation in young and aging HMEC. Such changes can alter hormone receptor levels within aged HMEC, induce tissue fibrosis and promote epithelial-to-mesenchymal transition as a potential prerequisite for breast cancer development. Moreover, an accumulation of aging cells during the normal life span of the breast tissue may also substantially effect and interact with adjacent neighboring populations in the local microenvironment to provide optimized growth conditions which would also support neoplastic cells.

Hyaluronan-CD44 interactions as potential targets for cancer therapy

It is becoming increasingly clear that signals generated in tumor microenvironments are crucial to tumor cell behavior, such as survival, progression and metastasis. The establishment of these malignant behaviors requires that tumor cells acquire novel adhesion and migration properties to detach from their original sites and to localize to distant organs. CD44, an adhesion/homing molecule, is a major receptor for the glycosaminoglycan hyaluronan, which is one of the major components of the tumor extracellular matrix. CD44, a multistructural and multifunctional molecule, detects changes in extracellular matrix components, and thus is well positioned to provide appropriate responses to changes in the microenvironment, i.e. engagement in cell-cell and cell-extracellular matrix interactions, cell trafficking, lymph node homing and the presentation of growth factors/cytokines/chemokines to co-ordinate signaling events that enable the cell responses that change in the tissue environment. The potential involvement of CD44 variants (CD44v), especially CD44v4-v7 and CD44v6-v9, in tumor progression has been confirmed for many tumor types in numerous clinical studies. The downregulation of the standard CD44 isoform (CD44s) in colon cancer is postulated to result in increased tumorigenicity. CD44v-specific functions could be caused by their higher binding affinity than CD44s for hyaluronan. Alternatively, CD44v-specific functions could be caused by differences in associating molecules, which may bind selectively to the CD44v exon. This minireview summarizes how the interaction between hyaluronan and CD44v can serve as a potential target for cancer therapy, in particular how silencing CD44v can target multiple metastatic tumors.

CD44: can a cancer-initiating cell profit from an abundantly expressed molecule?

Can an abundantly expressed molecule be a reliable marker for the cancer-initiating cells (CICs; also known as cancer stem cells), which constitute the minority of cells within the mass of a tumour? CD44 has been implicated as a CIC marker in several malignancies of haematopoietic and epithelial origin. Is this a fortuitous coincidence owing to the widespread expression of the molecule or is CD44 expression advantageous as it fulfils some of the special properties that are displayed by CICs, such as self-renewal, niche preparation, epithelial-mesenchymal transition and resistance to apoptosis?

The role of CD44 and matrix metalloproteinase-9 expression in predicting neck metastasis of supraglottic laryngeal carcinoma

AIM

The aim of this study is to evaluate the role of CD44 and matrix metalloproteinase (MMP)-9 expression in predicting neck metastasis of supraglottic laryngeal carcinoma.

MATERIALS AND METHODS

Two hundred ninety-four supraglottic laryngeal cancers were treated surgically from 1991 to 2005. Ninety-four of the 294 patients had pathologically metastatic lymph node (pN+). Among the 94 patients, 30 pN+ patients were selected via random sampling. Sex-, T value-, and differentiation-matched 30 patients who had pathologically negative neck were also selected. CD44 and MMP-9 antibodies were applied to the tumor representative sections that were derived from paraffin sections by using the streptavidin-biotin method. The association between immunohistochemical results and histopathologic lymph node metastasis was analyzed statistically. The association between immunostaining of CD44 and MMP-9 was also analyzed.

RESULTS

Overexpression of CD44 and MMP-9 was found to be significantly higher in pN+ patients. There was fair concordance between immunostaining of CD44 and MMP-9.

CONCLUSION

Although wider multiinstitutional and multidisciplinary studies are needed to draw specific conclusions, CD44 and MMP-9 can be useful in the prediction of neck metastasis in the supraglottic laryngeal carcinoma.

CD44 expression is related to poor prognosis of hypopharyngeal squamous cell carcinoma

CONCLUSIONS

CD44 expression in hypopharyngeal squamous cell carcinomas (SCCs) is closely associated with poor prognosis for patients. CD44 may serve as a prognostic marker for hypopharyngeal SCCs.

OBJECTIVES

CD44, an adhesion molecule binding to extracellular matrix, is believed to participate in the progression of malignancies. To clarify the role of CD44 in the progression of hypopharyngeal SCCs, we examined CD44 expression in relation to clinical parameters in hypopharyngeal SCCs.

METHODS

Biopsy specimens of hypopharyngeal SCCs were collected from 40 untreated patients, and their CD44 expression was examined immunohistochemically. Hypopharyngeal SCCs were classified into two groups: CD44-low SCCs comprising < 50% CD44-positive tumor cells and CD44-high SCCs comprising ≥ 50% CD44-positive tumor cells. The relation between CD44 expression and various parameters (clinical T and N stages, distant metastasis, and pathological T and N stages) was analyzed by Fisher's exact test. The relation between CD44 expression and the 5-year disease-free survival (DFS) rate was also analyzed by log rank test.

RESULTS

The CD44 expression in hypopharyngeal SCCs was related to pathological N stage, but not to clinical T and N stages and pathological T stage, of the patients. Distant metastasis during the follow-up occurred more frequently in patients with CD44-high SCCs than those with CD44-low SCCs. The 5-year DFS was significantly lower in the former than in the latter.

The tumor microenvironment in hepatocellular carcinoma: current status and therapeutic targets

A growing body of literature highlights the cross-talk between tumor cells and the surrounding peri-tumoral stroma as a key modulator of the processes of hepatocarcinogenesis, epithelial mesenchymal transition (EMT), tumor invasion and metastasis. The tumor microenvironment can be broadly classified into cellular and non-cellular components. The major cellular components include hepatic stellate cells, fibroblasts, immune, and endothelial cells. These cell types produce the non-cellular components of the tumor stroma, including extracellular matrix (ECM) proteins, proteolytic enzymes, growth factors and inflammatory cytokines. The non-cellular component of the tumor stroma modulates hepatocellular carcinoma (HCC) biology by effects on cancer signaling pathways in tumor cells and on tumor invasion and metastasis. Global gene expression profiling of HCC has revealed that the tumor microenvironment is an important component in the biologic and prognostic classification of HCC. There are substantial efforts underway to develop novel drugs targeting tumor-stromal interactions. In this review, we discuss the current knowledge about the role of the tumor microenvironment in pathogenesis of HCC, the role of the tumor microenvironment in the classification of HCC and efforts to develop treatments targeting the tumor microenvironment.

Comparison of metalloproteinase protein and activity profiling

Proteolytic enzymes play fundamental roles in many biological processes. Members of the matrix metalloproteinase (MMP) family have been shown to take part in processes crucial in disease progression. The current study used the ExcelArray Human MMP/TIMP Array to quantify MMP and tissue inhibitor of metalloproteinase (TIMP) production in the lysates and media of 14 cancer cell lines and 1 normal cell line. The overall patterns were very similar in terms of which MMPs and TIMPs were secreted in the media versus associated with the cells in the individual samples. However, more MMP was found in the media (in both amount and variety). TIMP-1 was produced in all cell lines. MMP activity assays with three different fluorescence resonance energy transfer (FRET) substrates were then used to determine whether protein production correlated with function for the WM-266-4 and BJ cell lines. Metalloproteinase activity was observed for both cell lines with a general MMP substrate (Knight SSP), consistent with protein production data. However, although both cell lines promoted the hydrolysis of a more selective MMP substrate (NFF-3), metalloproteinase activity was confirmed only in the BJ cell line. The use of inhibitors to confirm metalloproteinase activities pointed to the strengths and weaknesses of in situ FRET substrate assays.

CD44 in hematological neoplasias

The CD44 protein family spans a large group of transmembrane glycoproteins acquired by alternative splicing and post-translational modifications. The great heterogeneity in molecular structure is reflected in its various important functions: CD44 mediates (1) interaction between cell and extracellular matrix, (2) signal submission, e.g., by acting as co-receptor for membrane-spanning receptor tyrosine kinases or by association with intracellular molecules initiating several signaling pathways, and (3) anchor function connecting to the cytoskeleton via the ezrin-radixin-moesin protein family. The expression pattern of the different CD44 isoforms display strong variations dependent on cell type, state of activation, and differentiation stage. In hematopoietic cells, CD44 mediates interaction of progenitor cells and bone marrow stroma during hematopoiesis, regulates maturation, and activation-induced cell death in T cells, influences neutrophil and macrophage migration as well as cytokine production, and participates in lymphocyte extravasation and migration. CD44 is involved in development and progress of hematological neoplasias by enhancement of apoptotic resistance, invasiveness, as well as regulation of bone marrow homing, and mobilization of leukemia-initiating cells into the peripheral blood. Thereby altered CD44 expression functions as marker for worse prognosis in most hematological malignancies. Additionally, CD44 expression levels can be used to distinguish between different hematological neoplasias and subtypes. Concerning new treatment strategies, CD44 displays promising potential either by direct targeting of CD44 expressed on the malignant cells or reversing an acquired resistance to primary treatment mediated through altered CD44 expression. The former can be achieved by antibody or hyaluronan-based immunotherapy.

Simvastatin prevents skeletal metastasis of breast cancer by an antagonistic interplay between p53 and CD44

Substantial data from clinical trials and epidemiological studies show promising results for use of statins in many cancers, including mammary carcinoma. Breast tumor primarily metastasizes to bone to form osteolytic lesions, causing severe pain and pathological fracture. Here, we report that simvastatin acts as an inhibitor of osteolysis in a mouse model of breast cancer skeletal metastasis of human mammary cancer cell MDA-MB-231, which expresses the mutant p53R280K. Simvastatin and lovastatin attenuated migration and invasion of MDA-MB-231 and BT-20 breast tumor cells in culture. Acquisition of phenotype to express the cancer stem cell marker, CD44, leads to invasive potential of the tumor cells. Interestingly, statins significantly decreased the expression of CD44 protein via a transcriptional mechanism. shRNA-mediated down-regulation of CD44 markedly reduced the migration and invasion of breast cancer cells in culture. We identified that in the MDA-MB-231 cells, simvastatin elevated the levels of mutated p53R280K, which was remarkably active as a transcription factor. shRNA-derived inhibition of mutant p53R280K augmented the expression of CD44, leading to increased migration and invasion. Finally, we demonstrate an inverse correlation between expression of p53 and CD44 in the tumors of mice that received simvastatin. Our results reveal a unique function of statins, which foster enhanced expression of mutant p53R280K to prevent breast cancer cell metastasis to bone.

Targeting stem cell niches and trafficking for cardiovascular therapy

Regenerative cardiovascular medicine is the frontline of 21st-century health care. Cell therapy trials using bone marrow progenitor cells documented that the approach is feasible, safe and potentially beneficial in patients with ischemic disease. However, cardiovascular prevention and rehabilitation strategies should aim to conserve the pristine healing capacity of a healthy organism as well as reactivate it under disease conditions. This requires an increased understanding of stem cell microenvironment and trafficking mechanisms. Engagement and disengagement of stem cells of the osteoblastic niche is a dynamic process, finely tuned to allow low amounts of cells move out of the bone marrow and into the circulation on a regular basis. The balance is altered under stress situations, like tissue injury or ischemia, leading to remarkably increased cell egression. Individual populations of circulating progenitor cells could give rise to mature tissue cells (e.g. endothelial cells or cardiomyocytes), while the majority may differentiate to leukocytes, affecting the environment of homing sites in a paracrine way, e.g. promoting endothelial survival, proliferation and function, as well as attenuating or enhancing inflammation. This review focuses on the dynamics of the stem cell niche in healthy and disease conditions and on therapeutic means to direct stem cell/progenitor cell mobilization and recruitment into improved tissue repair.

Localizing matrix metalloproteinase activities in the pericellular environment

Matrix metalloproteinases (MMPs) are a group of structurally related proteolytic enzymes containing a zinc ion in the active site. They are secreted from cells or bound to the plasma membrane and hydrolyze extracellular matrix (ECM) and cell surface-bound molecules. They therefore play key roles in morphogenesis, wound healing, tissue repair and remodeling in diseases such as cancer and arthritis. Although the cell anchored membrane-type MMPs (MT-MMPs) function pericellularly, the secreted MMPs have been considered to act within the ECM, away from the cells from which they are synthesized. However, recent studies have shown that secreted MMPs bind to specific cell surface receptors, membrane-anchored proteins or cell-associated ECM molecules and function pericellularly at focussed locations. This minireview describes examples of cell surface and pericellular partners of MMPs, as well as how they alter enzyme function and cellular behaviour.

Platelet-rich fibrin is a Bioscaffold and reservoir of growth factors for tissue regeneration

The platelet-rich fibrin (PRF) is known as a rich source of autologous cytokines and growth factors and universally used for tissue regeneration in current clinical medicine. However, the microstructure of PRF has not been fully investigated nor have been studied the key molecules that differ PRF from platelet-rich plasma. We fabricated PRF under Choukroun's protocol and produced its extract (PRFe) by freezing at -80°C. The conventional histological, immunohistological staining, and scanning electron microscopy images showed the microstructure of PRF, appearing as two zones, the zone of platelets and the zone of fibrin, which resembled a mesh containing blood cells. The PRFe increased proliferation, migration, and promoted differentiation of the human alveolar bone marrow stem cells (hABMSCs) at 0.5% concentration in vitro. From the results of proteome array, matrix metalloproteinase 9 (MMP9) and Serpin E1 were detected especially in PRFe but not in concentrated platelet-rich plasma. Simultaneous elevation of MMP9, CD44, and transforming growth factor β-1 receptor was shown at 0.5% PRFe treatment to the hABMSC in immunoblot. Mineralization assay showed that MMP9 directly regulated mineralization differentiation of hABMSC. Transplantation of the fresh PRF into the mouse calvarias enhanced regeneration of the critical-sized defect. Our results strongly support the new characteristics of PRF as a bioscaffold and reservoir of growth factors for tissue regeneration.

Matrix metalloproteinases in cytotoxic lymphocytes impact on tumour infiltration and immunomodulation

To efficiently combat solid tumours, endogenously or adoptively transferred cytotoxic T cells and natural killer (NK) cells, need to leave the vasculature, traverse the interstitium and ultimately infiltrate the tumour mass. During this locomotion and migration in the three dimensional environment many obstacles need to be overcome, one of which is the possible impediment of the extracellular matrix. The first and obvious one is the sub-endothelial basement membrane but the infiltrating cells will also meet other, both loose and tight, matrix structures that need to be overridden. Matrix metalloproteinases (MMPs) are believed to be one of the most important endoprotease families, with more than 25 members, which together have function on all known matrix components. This review summarizes what is known on synthesis, expression patterns and regulation of MMPs in cytotoxic lymphocytes and their possible role in the process of tumour infiltration. We also discuss different functions of MMPs as well as the possible use of other lymphocyte proteases for matrix degradation.

The protein kinase C cascade regulates recruitment of matrix metalloprotease 9 to podosomes and its release and activation

Podosomes are transient cell surface structures essential for degradation of extracellular matrix during cell invasion. Protein kinase C (PKC) is involved in the regulation of podosome formation; however, the roles of individual PKC isoforms in podosome formation and proteolytic function are largely unknown. Recently, we reported that PDBu, a PKC activator, induced podosome formation in normal human bronchial epithelial cells. Here, we demonstrate that phorbol-12,13-dibutyrate (PDBu)-induced podosome formation is mainly mediated through redistribution of conventional PKCs, especially PKCα, from the cytosol to the podosomes. Interestingly, although blocking atypical PKCζ did not affect PDBu-induced podosome formation, it significantly reduced matrix degradation at podosomes. Inhibition of PKCζ reduced recruitment of matrix metalloprotease 9 (MMP-9) to podosomes and its release and activation. Downregulation of MMP-9 by small interfering RNA (siRNA) or neutralization antibody also significantly reduced matrix degradation. The regulatory effects of PKCζ on matrix degradation and recruitment of MMP-9 to podosomes were PKCζ kinase activity dependent. PDBu-induced recruitment of PKCζ and MMP-9 to podosomes was blocked by inhibition of novel PKC with rottlerin or PKCδ siRNA. Our data suggest that multiple PKC isozymes form a signaling cascade that controls podosome formation and dynamics and MMP-9 recruitment, release, and activation in a coordinated fashion.

Nodular basal cell carcinoma is associated with increased hyaluronan homeostasis

BACKGROUND

Basal cell carcinoma (BCC) is one of the most frequent forms of malignancy in humans. Although BCC is a tumour of low degree of malignancy, if left untreated, it can be locally aggressive, eat away at tissues and cause ulceration. Nodular is the most common subtype of BCC (>50%). Although apparently non-invasive, micronodular, a certain subgroup of nodular, is likely to recur. Glycosaminoglycans (GAGs), such as hyaluronic acid (HA), are extracellular matrix molecules of high importance in malignant transformation, metastasis and other complex remodelling processes.

OBJECTIVES

To investigate the expression of GAGs and their metabolizing enzymes in nodular BCC, when compared with adjacent healthy human skin tissue specimens.

METHODS

Total GAGs were isolated and purified from nodular BCC and normal adjacent human skin tissue specimens. GAGs were subsequently fractionated by electrophoresis on cellulose acetate membranes and characterized using specific GAG-degrading enzymes. The content of HA in total GAGs was measured using ELISA and the expression of HA synthases (HAS), hyaluronidases (HYAL) and HA receptors (CD44 and receptor hyaluronic acid-mediated motility (RHAMM) was assessed using RT-PCR.

RESULTS

Nodular BCC is associated with increased levels of HA concomitant with upregulation of gene expression of HAS3, HYAL3 and RHAMM, when compared with normal adjacent skin.

CONCLUSION

These results indicate that HA homeostasis in nodular BCC shows distinct features which may be helpful in understanding the complex behaviour of nodular subtype of BCC, thus eventually leading to new treatment strategies.

Role of matrix metalloproteinase-9 dimers in cell migration: design of inhibitory peptides

Non-proteolytic activities of matrix metalloproteinases (MMPs) have recently been shown to impact cell migration, but the precise mechanism remains to be understood. We previously demonstrated that the hemopexin (PEX) domain of MMP-9 is a prerequisite for enhanced cell migration. Using a biochemical approach, we now report that dimerization of MMP-9 through the PEX domain appears necessary for MMP-9-enhanced cell migration. Following a series of substitution mutations within the MMP-9 PEX domain, blade IV was shown to be critical for homodimerization, whereas blade I was required for heterodimerization with CD44. Blade I and IV mutants showed diminished enhancement of cell migration compared with wild type MMP-9-transfected cells. Peptides mimicking motifs in the outermost strands of the first and fourth blades of the MMP-9 PEX domain were designed. These peptides efficiently blocked MMP-9 dimer formation and inhibited motility of COS-1 cells overexpressing MMP-9, HT-1080, and MDA-MB-435 cells. Using a shRNA approach, CD44 was found to be a critical molecule in MMP-9-mediated cell migration. Furthermore, an axis involving a MMP-9-CD44-EGFR signaling pathway in cell migration was identified using antibody array and specific receptor tyrosine kinase inhibitors. In conclusion, we dissected the mechanism of pro-MMP-9-enhanced cell migration and developed structure-based inhibitory peptides targeting MMP-9-mediated cell migration.

Hyaluronic acid metabolism is increased in unstable plaques

BACKGROUND

Hyaluronic acid is expressed in atherosclerotic lesions, but its exact role in atherosclerotic disease remains unknown. As degradation of hyaluronic acid by hyaluronidase into low molecular weight hyaluronic acid (LMW-HA) is associated with inflammation and Matrix Metalloproteinase (MMP)-9 activity, we hypothesized that hyaluronic acid metabolism is increased in plaques with unstable characteristics like large lipid core, high number of macrophages, MMP-9 activity, low collagen and smooth muscle cell content.

MATERIALS AND METHODS

Protein was isolated from 68 carotid artery specimens. The adjacent plaque segment was characterized for the histological parameters: lipid core, macrophage, collagen, smooth muscle cell (SMC) content and the amount of intra-plaque thrombus. Hyaluronidase activity, total hyaluronic acid and LMW-HA expression, the standard hayaluronic acid receptor CD44s and the VEGF-A binding isoform CD44v3, MMP-9 activity and the plaque instability associated growth factor Vascular Endothial Growth Factor (VEGF)-A were analysed and correlated with histological characteristics.

RESULTS

Hyaluronidase activity, LMW-HA and CD44 expression (CD44s, CD44v3) levels were increased in atheromatous plaques compared with fibrous plaques. Total hyaluronic acid did not correlate with plaque instability. MMP-9 activity correlated with CD44s, hyaluronidase and LMW-HA expression. CD44v3 correlated with the angiogenic factor VEGF-A. In vitro stimulation of macrophages with LMW-HA increased MMP-9 activity.

CONCLUSIONS

We show for the first time that increased hyaluronic acid metabolism and elevated CD44 levels are associated with plaque destabilization potentially by increased MMP-9 activity and stimulation of angiogenesis.

Cancer stem cells in pancreatic cancer

Pancreatic cancer is an aggressive malignant solid tumor well-known by early metastasis, local invasion, resistance to standard chemo- and radiotherapy and poor prognosis. Increasing evidence indicates that pancreatic cancer is initiated and propagated by cancer stem cells (CSCs). Here we review the current research results regarding CSCs in pancreatic cancer and discuss the different markers identifying pancreatic CSCs. This review will focus on metastasis, microRNA regulation and anti-CSC therapy in pancreatic cancer.

Overexpression of matrix metalloproteinase 9 in tumor epithelial cells correlates with colorectal cancer metastasis

Colorectal cancer mortality largely reflects metastasis, the spread of the disease to distant organs. Matrix metalloproteinase 9 (MMP-9) is a key regulator of metastasis and a target for anticancer strategies in colon cancer. Here, the overexpression of MMP-9 in pure tumor epithelial, but nor stromal, cell populations was associated with metastatic progression of colorectal cancer, as defined by reverse transcriptase-polymerase chain reaction (qRT-PCR) and confirmed by immunostaining. Thus, cancer cell MMP-9 represents a novel, selective prognostic and predictive factor that may be exploited for more effective disease stage stratification and therapeutic regimen selection in patients with colorectal cancer.

Quantifying the proteolytic release of extracellular matrix-sequestered VEGF with a computational model

Background

VEGF proteolysis by plasmin or matrix metalloproteinases (MMPs) is believed to play an important role in regulating vascular patterning in vivo by releasing VEGF from the extracellular matrix (ECM). However, a quantitative understanding of the kinetics of VEGF cleavage and the efficiency of cell-mediated VEGF release is currently lacking. To address these uncertainties, we develop a molecular-detailed quantitative model of VEGF proteolysis, used here in the context of an endothelial sprout.

Methodology and Findings

To study a cell's ability to cleave VEGF, the model captures MMP secretion, VEGF-ECM binding, VEGF proteolysis from VEGF₁₆₅ to VEGF₁₁₄ (the expected MMP cleavage product of VEGF₁₆₅) and VEGF receptor-mediated recapture. Using experimental data, we estimated the effective bimolecular rate constant of VEGF₁₆₅ cleavage by plasmin to be 328 M⁻¹s⁻¹ at 25°C, which is relatively slow compared to typical MMP-ECM proteolysis reactions. While previous studies have implicated cellular proteolysis in growth factor processing, we show that single cells do not individually have the capacity to cleave VEGF to any appreciable extent (less than 0.1% conversion). In addition, we find that a tip cell's receptor system will not efficiently recapture the cleaved VEGF due to an inability of cleaved VEGF to associate with Neuropilin-1.

Conclusions

Overall, VEGF₁₆₅ cleavage in vivo is likely to be mediated by the combined effect of numerous cells, instead of behaving in a single-cell-directed, autocrine manner. We show that heparan sulfate proteoglycans (HSPGs) potentiate VEGF cleavage by increasing the VEGF clearance time in tissues. In addition, we find that the VEGF-HSPG complex is more sensitive to proteases than is soluble VEGF, which may imply its potential relevance in receptor signaling. Finally, according to our calculations, experimentally measured soluble protease levels are approximately two orders of magnitude lower than that needed to reconcile levels of VEGF cleavage seen in pathological situations.

The stem cell code in oral epithelial tumorigenesis: 'the cancer stem cell shift hypothesis'

Tumors of the oral cavity provide an ideal model to study various stages of epithelial tumor progression. A group of cancer cells termed cancer stem cells (CSCs) eludes therapy, persists and initiates recurrence augmenting malignant spread of the disease. Hitherto, accurate identification and separation of such minimal residual cells have proven futile due to lack of identifiable traits to single out these cells from the heterogeneous tumor bulk. In this review we have compiled comprehensive evidence from comparative phenotypic and genotypic studies on normal oral mucosa as well as tumors of different grades to elucidate that differential expression patterns of putative stem cells markers may identify 'minimal residual disease' in oral squamous cell carcinoma. We propose the "cancer stem cell shift hypothesis" to explain the exact identity and switch-over, tumor-promoting mechanisms adapted by putative CSCs with correlation to tumor staging.

Effects of hepatic ischemia/reperfusion injury on tumor proliferation and metastasis

Hepatic ischemia/reperfusion injury (HIRI) is a common pathophysiological process encountered in liver surgery. It has significant effects on the migration, adhesion, colonization and growth of circulating tumor cells by affecting the expression of some cytokines such as chemokines, adhesion molecules, matrix metalloproteinases, and vascular endothelial growth factor. Therefore, HIRI is highly correlated with the postoperative recurrence and metastasis of liver cancer.

CD44, a therapeutic target for metastasising tumours

Members of the CD44 family of transmembrane glycoproteins, in particular CD44v6 isoforms, were shown to be metastatic determinants of rat pancreatic tumour cells back in the early 1990s. Furthermore, the expression of several CD44 proteins correlates with aggressive stages of various human cancers. Because of the frequent and homogeneous expression of CD44v6 isoforms in squamous cell carcinoma, antibodies recognising these proteins were used in clinical trials for patients suffering from head and neck squamous cell carcinoma (HNSCC). Although the phase I clinical trials looked promising, the studies were abruptly ended after the death of a patient. Despite the termination of the trials, CD44 certainly remains a valid target for anti-cancer therapy. In this review, alternative strategies targeting CD44 functions are presented. These functions include the binding to hyaluronan (HA), the collaboration with osteopontin and the contribution of CD44 isoforms to receptor tyrosine kinase (RTKs) activation. These new attempts led to the development of peptides that interfere for example with HA binding and that might be used to induce apoptosis in mammary carcinoma or to prevent homing of leukaemia stem cells. Other peptides block RTK activation and thereby inhibit tumour angiogenesis and metastatic spread.

CD44 attenuates activation of the hippo signaling pathway and is a prime therapeutic target for glioblastoma

Glioblastoma multiforme (GBM) is the most aggressive brain tumor that, by virtue of its resistance to chemotherapy and radiotherapy, is currently incurable. Identification of molecules whose targeting may eliminate GBM cells and/or sensitize glioblastoma cells to cytotoxic drugs is therefore urgently needed. CD44 is a major cell surface hyaluronan receptor and cancer stem cell marker that has been implicated in the progression of a variety of cancer types. However, the major downstream signaling pathways that mediate its protumor effects and the role of CD44 in the progression and chemoresponse of GBM have not been established. Here we show that CD44 is upregulated in GBM and that its depletion blocks GBM growth and sensitizes GBM cells to cytotoxic drugs in vivo. Consistent with this observation, CD44 antagonists potently inhibit glioma growth in preclinical mouse models. We provide the first evidence that CD44 functions upstream of the mammalian Hippo signaling pathway and that CD44 promotes tumor cell resistance to reactive oxygen species-induced and cytotoxic agent-induced stress by attenuating activation of the Hippo signaling pathway. Together, our results identify CD44 as a prime therapeutic target for GBM, establish potent antiglioma efficacy of CD44 antagonists, uncover a novel CD44 signaling pathway, and provide a first mechanistic explanation as to how upregulation of CD44 may constitute a key event in leading to cancer cell resistance to stresses of different origins. Finally, our results provide a rational explanation for the observation that functional inhibition of CD44 augments the efficacy of chemotherapy and radiation therapy.

Characterization of the expression of variant and standard CD44 in prostate cancer cells: identification of the possible molecular mechanism of CD44/MMP9 complex formation on the cell surface

CD44 is a glycosylated adhesion molecule and osteopontin is one of its ligand. CD44 undergoes alternative splicing to produce variant isoforms. Our recent studies have shown an increase in the surface expression of CD44 isoforms (sCD44 and v4-v10 variant CD44) in prostate cancer cells over-expressing osteopontin (PC3/OPN). Formation of CD44/MMP9 complex on the cell surface is indispensable for MMP9 activity. In this study, we have characterized the expression of variant CD44 using RT-PCR, surface labeling with NHS-biotin, and immunoblotting. Expression of variant CD44 encompassing v4-v10 and sCD44 at mRNA and protein levels are of the same levels in PC3 and PC3/OPN cells. However, an increase in the surface expression of v6, v10, and sCD44 in PC3/OPN cells suggest that OPN may be a ligand for these isoforms. We then proceeded to determine the role of sCD44 in MMP9 activation. Based on our previous studies in osteoclasts, we hypothesized that phosphorylation of CD44 has a role on its surface expression and subsequent activation of MMP9. We have prepared TAT-fused CD44 peptides comprising unphosphorylated and constitutively phosphorylated serine residues at positions Ser323 and Ser325. Transduction of phosphopeptides at Ser323 and Ser323/325 into PC3 cells reduced the surface levels of CD44, MMP9 activity, and cell migration; but had no effect on the membrane localization of MMP9. However, MMP9 knock-down PC3 cells showed reduced CD44 at cellular and surface levels. Thus we conclude that surface expression of CD44 and activation of MMP9 on the cell surface are interdependent.

Syndecan-2 functions as a docking receptor for pro-matrix metalloproteinase-7 in human colon cancer cells

Although elevated syndecan-2 expression is known to be crucial for the tumorigenic activity in colon carcinoma cells, how syndecan-2 regulates colon cancer is unclear. In human colon adenocarcinoma tissue samples, we found that both mRNA and protein expression of syndecan-2 were increased, compared with the neighboring normal epithelium, suggesting that syndecan-2 plays functional roles in human colon cancer cells. Consistent with this notion, syndecan-2-overexpressing HT-29 colon adenocarcinoma cells showed enhanced migration/invasion, anchorage-independent growth, and primary tumor formation in nude mice, paralleling their morphological changes into highly tumorigenic cells. In addition, our experiments revealed that syndecan-2 enhanced both expression and secretion of matrix metalloproteinase-7 (MMP-7), directly interacted with pro-MMP-7, and potentiated the enzymatic activity of pro-MMP-7 by activating its processing into the active MMP-7. Collectively, these data strongly suggest that syndecan-2 functions as a docking receptor for pro-MMP-7 in colon cancer cells.

Sensing invasion: cell surface receptors driving spreading of glioblastoma

Glioblastoma multiforme (GBM) is the most common malignant brain tumour in adults. One main source of its high malignancy is the invasion of isolated tumour cells into the surrounding parenchyma, which makes surgical resection an insufficient therapy in nearly all cases. The invasion is triggered by several cell surface receptors including receptor tyrosine kinases (RTKs), G protein-coupled receptors (GPCRs), TGF-beta receptor, integrins, immunoglobulins, tumour necrosis factor (TNF) family, cytokine receptors, and protein tyrosine phosphatase receptors. The cross-talk between cell-surface receptors and the redundancy of downstream effectors make analysis of invasive signals even more complex. Therapies involving inhibition of single receptors do not give promising outcomes and a thorough knowledge of invasive signals of common and exclusive signalling components is required for design of best combinatory treatment schemes to fight the disease.

Proteoglycan signaling co-receptors: roles in cell adhesion, migration and invasion

Signaling co-receptors are diverse, multifunctional components of most major signaling pathways, with roles in mediating and regulating signaling in both physiological and pathophysiological circumstances. Many of these signaling co-receptors, including CD44, glypicans, neuropilins, syndecans and TssRIII/betaglycan are also proteoglycans. Like other co-receptors, these proteoglycan signaling co-receptors can bind multiple ligands, promoting the formation of receptor signaling complexes and regulating signaling at the cell surface. The proteoglycan signaling co-receptors can also function as structural molecules to regulate adhesion, cell migration, morphogenesis and differentiation. Through a balance of these signaling and structural roles, proteoglycan signaling co-receptors can have either tumor promoting or tumor suppressing functions. Defining the role and mechanism of action of these proteoglycan signaling co-receptors should enable more effective targeting of these co-receptors and their respective pathways for the treatment of human disease.

Pleiotropic roles of matrix metalloproteinases in tumor angiogenesis: contrasting, overlapping and compensatory functions

A number of extensive reviews are available discussing the roles of MMPs in various aspects of cancer progression from benign tumor formation to overt cancer present with deadly metastases. This review will focus specifically on the evidence functionally linking the MMPs and tumor-induced angiogenesis in various in vivo models. Emphasis has been placed on the cellular origin of the MMPs in tumor tissue, the requirement of proMMP activation and the resulting proteolytic activity for the induction and progression of tumor angiogenesis, and the pleiotropic roles for some of the MMPs. The functional mechanisms of the angiogenic MMPs are discussed as well as their catalytic detection in complex biological systems. In addition, the contribution of active MMPs to metastatic spread and establishment of secondary metastasis will be discussed in view of the findings indicating that MMPs are involved in the preparation of pre-metastatic niches. Finally, the most recent evidence, indicating the pro-metastatic consequences of anti-angiogenic therapies employing MMP inhibitors will be presented as examples highlighting possible outcomes of interfering with the pleiotropic nature of the MMP functionality.