Regulation of MMP-9 (gelatinase B) in activated human monocyte/macrophages by two different types of bisphosphonates

Doxycycline-Induced Changes in Circulating MMP or TIMP2 Levels Are Not Associated with Skeletal-Related Event-Free or Overall Survival in Patients with Bone Metastases from Breast Cancer

Doxycycline is often used as a promoter of inducible gene expression in preclinical models; however, it can also have direct effects on tumor growth and survival. This is due in part to its ability to inhibit cell invasion and regulate matrix metalloproteinase (MMP) expression. Given that doxycycline is also osteotropic, a clinical study to assess its effects on modulation of tumor progression or prevention of skeletal-related events (SRE) in patients with bone metastases from breast cancer (the Achilles trial) was undertaken. Patients received 100 mg of oral doxycycline twice daily for 12 weeks, with serum obtained at baseline and 4, 8 and 12 weeks post-initiation of doxycycline treatment. Exploratory analysis of the effects of doxycycline on circulating levels of MMP or tissue inhibitor of matrix metalloproteinase 2 (TIMP2) was performed in enrolled patients. Statistically significant associations were observed between MMP2, MMP9 and TIMP2 at baseline with significant associations maintained between absolute levels and changes in levels of MMP2 and TIMP2 at weeks 4-12 post initiation of doxycycline. Treatment with doxycycline generally resulted in decreases in MMP2 and MMP9 levels with concurrent upregulation of TIMP2 at 12 weeks post-initiation of doxycycline treatment. Despite this, we observed no association with the levels of any of these factors with either SRE-free or overall survival in this patient cohort. In summary, despite observing hypothesized effects of doxycycline administration on surrogate markers of its anti-tumor activity, measures of circulating levels of these biomarkers were not prognostic in this patient population.

Synthesis, antiinflammatory activity, and molecular docking studies of bisphosphonic esters as potential MMP-8 and MMP-9 inhibitors

Bisphosphonic acids (or bisphosphonates) have been successfully used in the clinic treatment of bone diseases for over decades. Additionally, the antiinflammatory activity of these compounds has been gaining attention. In our previous work, we synthesized and in vivo evaluated the bisphosphonic esters 1 and 2, finding a moderate edema inhibition upon oral and topical administration on BALB/c mice. Thus, in this work, the bioisosteric replacement of an amide functional group for an ester afforded the new bisphosphonates 3-6, which had a moderate oral edema inhibition (25 mg/kg dose) and a significant topical antiinflammatory activity (2 mg/ear) on BALB/c mice, with 6 being the most active hit (55.9% edema inhibition), comparable to the positive control (55.5% edema inhibition) on a TPA topical model. Next, to assess the acute toxicity of the synthesized derivatives, test animals were administered with 50-100 mg/kg of 3-6, respectively, by an oral route, and after 14 days, neither lethality nor a significative weight loss were observed. Finally, a structure-activity relationship (SAR) and a molecular docking analysis of 3-6 helped us to explain the trend observed in biological tests. Considering all these aspects, we propose the inhibition of MMP-8 and MMP-9 as a possible action mechanism of the synthesized derivatives.

Intensity-modulated nanoplasmonic interferometric sensor for MMP-9 detection

To elucidate the secretary function of immune cells, we develop a nanoplasmonic circular interferometric biosensor based on intensity interrogation for label-free and dynamic sensing of molecular secretion. Exceptional sensitivity has been demonstrated through coupling free light and surface plasmon polariton (SPPs) waves, which generates a constructive and deconstructive interference pattern with high contrast and narrow linewidth when illuminated by white light. Alternatively, by adopting a narrow-band LED source and a CCD camera in this work, the transmission intensity of multiple sensing units is monitored simultaneously with a simple collinear optical setup. This intensity-modulated sensing platform yields a resolution of 4.1 × 10-5 refractive index unit (RIU) with a high temporal resolution of 1 s and a miniaturized footprint as small as 9.8 × 9.8 μm2 for a single sensing unit. By integrating the signals from multiple sensor units, the resolution of a 12 × 12 sensor array was found to reach 7.3 × 10-6 RIU. We apply this sensor array to detect matrix metalloproteinase 9 (MMP-9) secretion from human monocytic cells, THP-1, at different time points after lipopolysaccharide (LPS) simulation and the results are in good agreement with enzyme-linked immunosorbent assay (ELISA) tests, but without the need for labeling. The spatial, temporal and mass resolutions of the sensor array are found to exceed other label-free technologies. These biomolecular arrays, incorporated in a microfluidic sensor platform, hold great potential for the study the dynamics and interplay of cell secretion signals and achieving a better understanding of single cell functions.

Alteration of macrophage viability, differentiation, and function by bisphosphonates

BACKGROUND

A serious adverse effect of long-term bisphosphonate (BP) administration is bisphosphonate-related osteonecrosis of the jaw (BRONJ). Among different proposed pathogenesis, suppression of immune cells is gaining interest. Because monocytes/macrophages could get access to BP since residing in the blood and bone microenvironment, the aim of this study was to analyze the behaviors of macrophages after BP treatments in vitro.

METHODS

THP-1 cell, an established human monocytic cell model, was used in this study. The effects of BPs, alendronate (ALN) and zoledronic acid (ZA), on macrophage viability, differentiation, and function were investigated. MTT, morphological analysis, flow cytometry, quantitative PCR, and gelatin zymography assay were performed.

RESULTS

BPs impaired macrophage viability at almost all concentration tested (1-100 μM). Cell morphology was altered in the presence of 100 μM BPs. Furthermore, differentiating macrophage viability was also affected by both ALN and ZA at 100 and 10-100 μM, respectively. At high concentration (100 μM), ZA caused a reduction in cell differentiation. On the contrary, ALN and ZA increased matrix metalloproteinase mRNA expressions and activities at low doses (1-10 μM).

CONCLUSION

BPs directly acted on macrophage by reducing macrophage survival, inducing morphological alterations, impairing differentiation from monocytes to macrophages, and affecting macrophage function at both mRNA and activity levels.

Zoledronate upregulates MMP-9 and -13 in rat vascular smooth muscle cells by inducing oxidative stress

Background

Bisphosphonates, including zoledronate, target osteoclasts and are widely used in the treatment of osteoporosis and other bone resorption diseases, despite side effects that include damaging the stomach epithelium. Beneficial and adverse effects on other organ systems, including the cardiovascular system, have also been described and could impact on the use of bisphosphonates as therapeutic agents. Vascular smooth muscle cells (VSMCs) are major constituents of the normal vascular wall and have a key role in intimal thickening and atherosclerosis, in part by secreting MMPs that remodel the extracellular matrix and cleave cell surface proteins or secreted mediators. In this study, we investigated the effects of zoledronate on MMP expression.

Methods

Rat VSMCs were stimulated by PDGF (50 ng/mL) plus TNF-α (10 ng/mL) or left unstimulated for a further 24 hours in serum-free medium. In other series of experiments, cells were pre-treated either with SC-514 (50 μM) or with apocynin (20 nM) for 2 hours, then zoledronate (100 μM) was added into 2% fetal calf serum containing medium for 24 hours.

Results and discussion

Using isolated rat VSMCs in culture, zoledronate (100 μM) increased MMP-9 and -13 mRNA expressions but inhibited MMP-2 expression. MMP-9 and MMP-13 up-regulation was shown to depend on the NF-κB pathway; and this was activated by zoledronate. Furthermore, zoledronate elevated the levels of reactive oxygen species detected by either dichlorofluorescein in isolated VSMCs or lucigenin enhanced chemiluminescence in rat aortic rings in vitro. Apocynin, an inhibitor of NADPH oxidase, reversed NF-κB activation and MMP-9 and MMP-13 up-regulation by zoledronate.

Conclusion

We conclude that zoledronate increases MMP-9 and MMP-13 expressions in rat VSMCs dependent upon stimulation of the NF-κB pathway by reactive oxygen species. Effects on MMP expression may contribute to the pharmacologic profile of bisphosphonates.

Liposome encapsulated zoledronate favours M1-like behaviour in murine macrophages cultured with soluble factors from breast cancer cells

Background

Tumour stromal macrophages differentiate to tumour-associated macrophages (TAMs) with characteristics of immunosuppressive M2-type macrophages, having a central role in promoting tumour vascularisation, cancer cell dissemination and in suppressing anti-cancer immune responses. Bisphosphonates (BPs) are a group of drugs commonly used as anti-resorptive agents. Further, nitrogen containing BPs like Zoledronate (ZOL), are known to cause unspecific inflammatory reactions hence the hypothesis that its use could modulate TAMs polarization toward a more inflammatory phenotype.

Methods

We studied the in vitro polarization of J774 murine macrophages upon culture in 4T1 breast cancer cell-conditioned medium (4T1CM) and stimulation with LPS and free and liposome-encapsulated bisphosphonates.

Results

In this system, breast cancer soluble factors reduced the pro-inflammatory activation of macrophages but increased the secretion of matrix metalloproteinases (MMPs). In the presence of 4T1CM, a non-cytotoxic dose of liposome-encapsulated ZOL (ZOL-LIP) enhanced the expression of iNOS and TNF-α, markers of M1 activation, but did not diminish the expression of M2-type markers. In contrast, clodronate treatment either as a free drug (CLO) or liposome-encapsulated (CLO-LIP) decreased the expression of the M1-type markers and was highly cytotoxic to the macrophages.

Conclusions

Breast cancer cells soluble factors modulate macrophages toward M2 activation state. Bisphosphonates may be applied to counteract this modulation. We propose that ZOL-LIP may be suitable for favouring cytotoxic immune responses by TAMs in breast cancer, whereas CLO-LIP may be appropriate for TAM depletion.

Macrophage depletion by free bisphosphonates and zoledronate-loaded red blood cells

Bisphosphonates, besides being important drugs for the treatment of various bone diseases, could also be used to induce apoptosis in macrophage-like and cancer cells. However, their activity in vivo is limited by a short plasma half-life and rapid uptake within bone. Therefore, several delivery systems have been proposed to modify their pharmacokinetic profile and biodistribution. Among these, red blood cells (RBCs) represent one of the most promising biological carriers. The aim of this study was to select the best performing compound among Clodronate, Pamidronate, Ibandronate and Zoledronate in killing macrophages and to investigate RBCs as innovative carrier system to selectively target bisphosphonates to macrophages. To this end, the encapsulation of the selected bisphosphonates in autologous RBCs as well as the effect on macrophages, both in vitro and in vivo were studied. This work shows that, among the tested bisphosphonates, Zoledronate has proven to be the most active molecule. Human and murine RBCs have been successfully loaded with Zoledronate by a procedure of hypotonic dialysis and isotonic resealing, obtaining a dose-dependent drug entrapment with a maximal loading of 7.96±2.03, 6.95±3.9 and 7.0±1.89 µmoles of Zoledronate/ml of packed RBCs for human, Swiss and Balb/C murine RBCs, respectively. Engineered RBCs were able to detach human and murine macrophages in vitro, leading to a detachment of 66±8%, 67±8% and 60.5±3.5% for human, Swiss and Balb/C RBCs, respectively. The in vivo efficacy of loaded RBCs was tested in Balb/C mice administering 59 µg/mouse of RBC-encapsulated Zoledronate. By a single administration, depletion of 29.0±16.38% hepatic macrophages and of 67.84±5.48% spleen macrophages was obtained, confirming the ability of encapsulated Zoledronate to deplete macrophages in vivo. In conclusion, RBCs loaded with Zoledronate should be considered a suitable system for targeted delivery to macrophages, both in vitro and in vivo.

Expression patterns of stromal MMP-2 and tumoural MMP-2 and -9 are significant prognostic factors in invasive ductal carcinoma of the breast

Matrix metalloproteinases (MMPs) are matrix-degrading enzymes that play a pivotal role in aggressive behaviours, such as rapid tumour growth, invasion, and metastasis, of several types of solid tumours. In particular, stromal MMP-2 plays important roles in the progression of malignant tumours, but most clinical studies have focused on tumoural MMP-2 and -9 expression, and not stromal MMP-2 expression. One hundred and seventy-seven cases diagnosed as invasive ductal carcinoma of the breast between 2000 and 2005 were included in this study. Expressions of tumoural MMP-2 and -9 and stromal MMP-2 were analysed by immunostaining on a tissue microarray. Subsequently, the associations between those results and various clinicopathological parameters were evaluated. Stromal MMP-2 expression correlated significantly with clinicopathological parameters such as advanced T category, larger tumour size, high histological grade, tumour necrosis, ER- and PR-negative, and HER-2-positive (all p < 0.05). In univariate and multivariate analyses, overall survival was linked with stromal MMP-2 expression as well as dual expression of stromal MMP-2 and tumoural MMP-2 and -9 (all p < 0.05). Stromal MMP-2 expression may play a crucial role in predicting aggressive clinical behaviour in breast cancer patients.

Effect of bisphosphonates on the rapidly growing male murine skeleton

Bisphosphonates are effective for preventing and treating skeletal disorders associated with hyperresorption. Their safety and efficacy has been studied in adults where the growth plate is fused and there is no longitudinal bone growth and little appositional growth. Although bisphosphonate use in the pediatric population was pioneered for compassionate use in the treatment of osteogenesis imperfecta, they are being increasingly used for the treatment and prevention of bone loss in children at risk of hyperresorptive bone loss. However, the effect of these agents on the growing skeleton in disorders other than osteogenesis imperfecta has not been systematically compared. Studies were, therefore, undertaken to examine the consequences of bisphosphonate administration on the growth plate and skeletal microarchitecture during a period of rapid growth. C57Bl6/J male mice were treated from 18 to 38 days of age with vehicle, alendronate, pamidronate, zoledronate, or clodronate at doses selected to replicate those used in humans. Treatment with alendronate, pamidronate, and zoledronate, but not clodronate, led to a decrease in the number of chondrocytes per column in the hypertrophic chondrocyte layer. This was not associated with altered hypertrophic chondrocyte apoptosis or vascular invasion at the growth plate. The effects of pamidronate on trabecular microarchitecture were less beneficial than those of alendronate and zoledronate. Pamidronate did not increase cortical thickness or cortical area/total area relative to control mice. These studies suggest that bisphosphonate administration does not adversely affect skeletal growth. Long-term investigations are required to determine whether the differences observed among the agents examined impact biomechanical integrity of the growing skeleton.

Optofluidic platform for real-time monitoring of live cell secretory activities using Fano resonance in gold nanoslits

An optofluidic platform for real-time monitoring of live cell secretory activities is constructed via Fano resonance in a gold nanoslit array. Large-area and highly sensitive gold nanoslits with a period of 500 nm are fabricated on polycarbonate films using the thermal-annealed template-stripping method. The coupling between gap plasmon resonance in the slits and surface plasmon polariton Bloch waves forms a sharp Fano resonance with intensity sensitivity greater than 11 000% per refractive index unit. The nanoslit array is integrated with a cell-trapping microfluidic device to monitor dynamic secretion of matrix metalloproteinase 9 (MMP-9) from human acute monocytic leukemia cells in situ. Upon continuous lipopolysaccharide (LPS) stimulation, MMP-9 secretion is detected within 2 h due to ultrahigh surface sensitivity and close proximity of the sensor to the target cells. In addition to the advantage of detecting early cell responses, the sensor also allows interrogation of cell secretion dynamics. Furthermore, the average secretion per cell measured using our system well matches previous reports while it requires orders of magnitude less cells. The optofluidic platform may find applications in fundamental studies of cell functions and diagnostics based on secretion signals.

Vascular endothelial growth factor expression and inhibition in uveal melanoma cell lines

Background:

Uveal melanoma (UM) is a disease that affects approximately five people per million in the United States. This disease metastasises predominantly to the liver, and treatment options following the clinical detection of these sequelae are limited. Vascular endothelial growth factor-A (VEGF-A) is the primary activator of tumour angiogenesis and functions by binding to VEGF-Receptor 2 (VEGF-R2) and is often required for tumour growth beyond 2–3 mm. The purpose of this study was to investigate the expression of VEGF-A and the primary VEGF-R2 in three UM cell lines. Furthermore, we investigated the effects of VEGF-A inhibition on receptor activation and production of other cytokines. Finally, the effects of VEGF-A inhibition on the proliferation, migration, and invasion in the cell lines were ascertained.

Materials:

Three UM cell lines (92.1, OCM-1, and UW-1) were incubated with and without the addition of 100 μg/mL of bevacizumab. VEGF-A expression under both conditions was determined by sandwich enzyme-linked immunosorbent assay (ELISA), and phosphorylated VEGF-R2 expression was determined using western blot. The effects of VEGF-A inhibition on 20 cytokines (IL-1a, IL-2, IL-5, IL-8, IL-12p70, GM-CSF, IFNy, CCL3, MMP-9, TNF-a, IL-1b, IL-4, IL-6, IL-10, IL-13, GRO, MCP-1, MIP-1b, and RANTES) were determined using a multiplex sandwich ELISA. Proliferation rates before and after treatment were evaluated via sulforhodamine B assay, and migration and invasion assays implementing the Boyden chamber technique, the latter with artificial extracellular matrix, were used to assess their respective abilities. The Student’s t-test was used to compare changes in cytokine expression following VEGF-A inhibition. Analysis of variance was used to compare changes in the functional abilities of three uveal melanoma cell lines following VEGF-A inhibition. A P-value < 0.05 was considered statistically significant.

Results:

All three cell lines produced copious amounts of VEGF-A in culture (92.1, 11785.5 ± 231.8 pg/μL; OCM-1, 4608.0 ± 324.0 pg/μL; UW-1, 8309.3 ± 634.5 pg/μL), which was reduced to undetectable levels following the administration of bevacizumab (P< 0.05). Similarly, detectable phosphorylated VEGF-R2 was present in all cells, which was reduced significantly in all cell lines following bevacizumab treatment (107525.2 ± 8602.0 versus 1024.5 ± 98.2, 46587.3 ± 4192.9 versus 12821.1 ± 1666.7, and 60394.3 ± 4026.4 versus 6908.2 ± 607.2; 92.1, OCM-1, and UW-1, respectively; P< 0.05). Of the cytokines investigated, only MMP-9 and CCL3 were ubiquitously altered across all three cell lines following bevacizumab treatment; they were upregulated (CCL3: 1072.50 ± 18.77 pg/mL versus 1281.00 ± 72.34 pg/mL; 22.5 ± 7.85 pg/mL versus 62.00 ± 9.16 pg/mL; 20.33 ± 6.35 pg/mL versus 35.00 ± 6.22 pg/mL; control versus bevacizumab; MMP-9: 25.50 ± 5.47 pg/mL versus 88.25 ± 13.38 pg/mL; 19.75 ± 4.14 pg/mL versus 45.25 ± 8.36 pg/mL; 3.25 ± 1.09 pg/mL versus 19.25 ± 3.77 pg/mL; control versus bevacizumab; 92.1, OCM-1, and UW-1, respectively; P< 0.05). Bevacizumab significantly reduced the proliferation of one cell line (92.1: 0.405 ± 0.012 versus 0.509 ± 0.033; bevacizumab versus control; values OD; P< 0.05), the migration of two cell lines (92.1: 0.071 ± 0.003 versus 0.115 ± 0.003; OCM-1: 0.049 ± 0.005 versus 0.117 ± 0.014; bevacizumab versus control; values OD; P< 0.05), and did not significantly affect invasion.

Conclusion:

Despite the significant reduction in phosphorylated VEGF-R2 levels, bevacizumab did not have a dramatic impact on the functional abilities of the three UM cell lines studied. Our results indicate that compensatory mechanisms, such as the upregulation of MMP-9 and CCL-3, following bevacizumab administration may mitigate its effects on these abilities.

Regulation of MMP-9 by a WIN-binding site in the monocyte-macrophage system independent from cannabinoid receptors

The cannabinoid system is known to be involved in the regulation of inflammatory processes. Therefore, drugs targeting cannabinoid receptors are considered as candidates for anti-inflammatory and tissue protective therapy. We demonstrated that the prototypical cannabinoid agonist R(+)WIN55,212-2 (WIN) reduced the secretion of matrix metalloproteinase-9 (MMP-9) in a murine model of cigarette-smoke induced lung inflammation. In experiments using primary cells and cell lines of the monocyte-macrophage-system we found that binding of the cannabinoid-receptor agonist WIN to a stereo-selective, specific binding site in cells of the monocyte-macrophage-system induced a significant down-regulation of MMP-9 secretion and disturbance of intracellular processing, which subsequently down-regulated MMP-9 mRNA expression via a ERK1/2-phosphorylation-dependent pathway. Surprisingly, the anti-inflammatory effect was independent from classical cannabinoid receptors. Our experiments supposed an involvement of TRPV1, but other yet unidentified sites are also possible. We conclude that cannabinoid-induced control of MMP-9 in the monocyte-macrophage system via a cannabinoid-receptor independent pathway represents a general option for tissue protection during inflammation, such as during lung inflammation and other diseases associated with inflammatory tissue damage.

Differentiation and gene expression profile of tumor-associated macrophages

Tumor microenvironment is composed of proliferating neoplastic cells, a vascular network of endothelial cells, extra cellular matrix produced by fibroblasts, cellular compartments of adaptive immunity like lymphocytes and dendritic cells as well as cells of innate immunity, e.g., natural killer cells and macrophages. Many pre-clinical and clinical studies demonstrate an inversed correlation between macrophage infiltrate and patients' prognosis indicating a macrophage supporting role for tumor progression as producers of growth and angiogenic factors and as regulators of tissue remodelling. Based on in vitro models, macrophages have been classified in pro-inflammatory, classically activated macrophages (M1; stimulated by IFN-γ or LPS) and anti-inflammatory, alternatively activated macrophages (M2; stimulated by either IL-4/IL-13, IL-1β/LPS in combination with immune complexes or by IL-10/TGFβ/glucocorticoids). Tumor escape has been linked with a switch from M1 activation in the early tumor initiation process towards M2-like phenotype during tumor progression, a process that highlights the heterogeneity and plasticity of macrophage activation and which offers a possible therapeutic target directed against reversing the TAM phenotype in the tumor. Here, we review different tumor-environmental stimuli and signalling cascades involved in this switch in differentiation and the so connected gene regulation in TAMs. In addition, therapeutic applications deducted from this differentiation and gene regulatory processes are presented. Data from pre-clinical as well as clinical studies clearly support the notion, that TAMs are excellent novel therapeutic targets for the fight against cancer.

Effects of alendronate on human osteoblast-like MG63 cells and matrix metalloproteinases

OBJECTIVE

The objective of this study was to examine the effects of alendronate on the expression and activity of matrix metalloproteinases (MMPs) and the expression of the tissue inhibitors of MMPs (TIMPs) from human osteoblast-like MG63 cells.

MATERIALS AND METHODS

MG63 cells were exposed to various concentrations of alendronate. Cell proliferation and cytotoxicity were evaluated by water-soluble tetrazolium-1 and lactate dehydrogenase, respectively. MG63-mediated collagen degradation was assessed utilising Type I collagen assays. Conditioned media and membrane extracts were collected for Western blot analyses of select MMPs and TIMPs. Gelatin zymography gels were incubated with alendronate to assess its effects on MMP-2 activity.

RESULTS

Alendronate affected MG63 proliferation and cytotoxicity at concentrations equal to/or greater than 10(-5) M (all p < 0.05). There were no significant differences in the collagen degrading ability of treated cells at non-toxic levels vs. untreated cells. Alendronate had no effects on the expression of MMP-2 or MT1-MMP (membrane type-1 MMP) in the conditioned media or membrane extracts, and of MMP-1 or TIMP-2 in the conditioned media. TIMP-2 in the membrane extracts was not detectable. MMP-2 activity in the zymograms was inhibited by 10(-3) and 10(-2) M alendronate.

CONCLUSION

Alendronate at 10(-5) M or higher was toxic to the cells. Alendronate at 10(-8) to 10(-6) M did not alter the expression of MMP-1, MMP-2, MT1-MMP or TIMP-2, as well as did not alter collagen degradation. Alendronate inhibited MMP-2 activity at 10(-3) and 10(-2) M in the zymograms. In conclusion, non-toxic levels of alendronate (10(-8) to 10(-6) M) did not alter MMP expression in MG63 cells or inhibit MMP-2 activity.

Tumour macrophages as potential targets of bisphosphonates

Tumour cells communicate with the cells of their microenvironment via a series of molecular and cellular interactions to aid their progression to a malignant state and ultimately their metastatic spread. Of the cells in the microenvironment with a key role in cancer development, tumour associated macrophages (TAMs) are among the most notable. Tumour cells release a range of chemokines, cytokines and growth factors to attract macrophages, and these in turn release numerous factors (e.g. VEGF, MMP-9 and EGF) that are implicated in invasion-promoting processes such as tumour cell growth, flicking of the angiogenic switch and immunosuppression. TAM density has been shown to correlate with poor prognosis in breast cancer, suggesting that these cells may represent a potential therapeutic target. However, there are currently no agents that specifically target TAM's available for clinical use.

Bisphosphonates (BPs), such as zoledronic acid, are anti-resorptive agents approved for treatment of skeletal complication associated with metastatic breast cancer and prostate cancer. These agents act on osteoclasts, key cells in the bone microenvironment, to inhibit bone resorption. Over the past 30 years this has led to a great reduction in skeletal-related events (SRE's) in patients with advanced cancer and improved the morbidity associated with cancer-induced bone disease. However, there is now a growing body of evidence, both from in vitro and in vivo models, showing that zoledronic acid can also target tumour cells to increase apoptotic cell death and decrease proliferation, migration and invasion, and that this effect is significantly enhanced in combination with chemotherapy agents. Whether macrophages in the peripheral tumour microenvironment are exposed to sufficient levels of bisphosphonate to be affected is currently unknown. Macrophages belong to the same cell lineage as osteoclasts, the major target of BPs, and are highly phagocytic cells shown to be sensitive to bisphosphonates in model studies; In vitro, zoledronic acid causes increased apoptotic cell death; in vivo the drug has been shown to inhibit the production of pro-angiogenic factor MMP-9, as well as most recent evidence showing it can trigger the reversal of the TAMs phenotype from pro-tumoral M2 to tumoricidal M1. There is thus accumulating evidence supporting the hypothesis that effects on TAMs may contribute to the anti-tumour effect of bisphosphonates. This review will focus in detail on the role of tumour associated macrophages in breast cancer progression, the actions of bisphosphonates on macrophages in vitro and in tumour models in vivo and summarise the evidence supporting the potential for the targeting of tumour macrophages with bisphosphonates.

Chronic wound fluid--thinking outside the box

Chronic wounds are associated with an altered wound milieu that results from an imbalance in extracellular matrix (ECM) homeostasis. This alteration is characterized by an increased destruction and degradation of components of the ECM with a concomitant lack of synthesis of these elements. Traditionally wound fluid has been considered a reflection of the internal wound milieu. It has been used to monitor and reflect on the chronic status of a wound or to measure the efficacy of wound treatment. However, on closer inspection of chronic wound fluid, certain components of the fluid, particularly matrix metalloproteinases (MMPs) and their subcomponents (MMP-9) have been found to exist at higher levels in wound fluid than in the corresponding wound. There is mounting evidence that much of the destructive effects observed in chronic wounds may be compounded by components of the wound exudate which are corrosive in nature resulting in a continuum of ECM breakdown. Isolation of these components has identified MMPs, in particular MMP-9 as dominant in this destructive process. Additionally an association has been made between high bacterial levels and elevated MMP9 in chronic wounds. Agents that have efficacy against MMP-9 and significant antibacterial potency thus provide a dual defense against chronic wounds. It is likely that these agents cause a change in the chronic wound fluid components that more closely resemble the balance of proteases and growth factors seen acute wounds, thus triggering a positive wound healing process. Nanocrystalline silver appears to fulfill these criteria. A strategy is suggested whereby wound fluid is directly targeted to diminish the corrosive wound fluid elements in an attempt to break the ongoing destructive inflammatory cycle. This presents a relatively new treatment paradigm attempting to influence wound healing by working from without to initiate changes within.

Expression of matrix metalloproteinase-9 and significance of a macrophage assay in eosinophilic granuloma

Although most cases of eosinophilic granuloma (an immune-mediated lesion) do not behave in an aggressive manner, occasionally, recurrence after treatment has been observed. This study aims to investigate the significance and relationship of matrix metalloproteinase-9 (MMP-9) and infiltration of macrophages in eosinophilic granulomas (EGs). The immunohistochemical strept avidin-biotin complex method was used to detect the expression of MMP-9 and CD-68 (for labeling macrophages) in 13 cases of EG. Three of whom showed local recurrence. The results showed that many of the Langerhans histiocytic cells, which reacted positively with MMP-9 protein antibody, were immunolabeled with CD-68 antibody. The results showed that there is a highly significant relationship between the expression of MMP-9 and macrophage count in EGs (P < .001), with recurrent lesions showing a higher mean expression of both MMP-9 and CD-68. In conclusion, there may be a cooperation between macrophages and MMP-9 in EGs, which correlates well with local recurrence. Their expression may therefore provide some prognostic indication of the possible aggressive and recurrence behavior of this lesion.

Activation of Src kinase by protein-tyrosine phosphatase-PEST in osteoclasts: comparative analysis of the effects of bisphosphonate and protein-tyrosine phosphatase inhibitor on Src activation in vitro

PTP-PEST is involved in the regulation of sealing ring formation in osteoclasts. In this article, we have shown a regulatory role for PTP-PEST on dephosphorylation of c-Src at Y527 and phosphorylation at Y418 in the catalytic site. Activation of Src in osteoclasts by over-expression of PTP-PEST resulted in the phosphorylation of cortactin at Y421 and WASP at Y294. Also enhanced as a result, is the interaction of Src, cortactin, and Arp2 with WASP. Moreover, the number of osteoclasts displaying sealing ring and bone resorbing activity was increased in response to PTP-PEST over-expression as compared with control osteoclasts. Cells expressing constitutively active-Src (527YDeltaF) simulate the effects mediated by PTP-PEST. Treatment of osteoclasts with a bisphosphonate alendronate or a potent PTP inhibitor PAO decreased the activity and phosphorylation of Src at Y418 due to reduced dephosphorylation state at Y527. Therefore, Src-mediated phosphorylation of cortactin and WASP as well as the formation of WASP.cortactin.Arp2 complex and sealing ring were reduced in these osteoclasts. Similar effects were observed in osteoclasts treated with an Src inhibitor PP2. We have shown that bisphosphonates could modulate the function of osteoclasts by inhibiting downstream signaling mediated by PTP-PEST/Src, in addition to its effect on the inhibition of the post-translational modification of small GTP-binding proteins such as Rab, Rho, and Rac as shown by others. The promising effects of the inhibitors PP2 and PAO on osteoclast function suggest a therapeutic approach for patients with bone metastases and osteoporosis as an alternative to bisphosphonates.

Review: Finding the Culprit: A Review of the Influences of Proteases on the Chronic Wound Environment

Chronic leg ulcers are a complex medical condition with varied underlying causes and requiring diverse treatment strategies. It is generally accepted that chronic ulcers occur when the normal wound healing process is interrupted. These wounds are characterized by excessive protease activity, abundant granulation tissue, and decreased levels of growth factors, resulting in an overall poor prognosis for the patient. Many studies have focused on identifying the key proteases, specifically matrix metalloproteinases (MMPs), responsible for an ulcer's chronicity. Of note, the results of these studies are often conflicting. This report therefore focuses on a review of this literature to identify which MMPs are important in terms of ulcer prognosis and healing outcome. This has revealed that MMPs are clearly important in many biological processes in wound healing, hence are critical to consider when developing improved therapies to enhance both ulcer healing times and ulcer healing outcomes.

Increased matrix metalloproteinase-9 (MMP-9) activity observed in chronic wound fluid is related to the clinical severity of the ulcer

BACKGROUND

The pathology of chronic wounds is often characterized by elevated levels of proinflammatory cytokines [e.g. tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta], proteases [e.g. matrix metalloproteinases (MMPs)] and neutrophil elastase. MMPs specifically have been implicated by a number of studies as the major protease family responsible for the degradation of key factors critical to the ulcer's ability to heal.

OBJECTIVES

To assess individual MMPs in chronic wound fluid (CWF) in order to develop improved treatments for chronic ulcers.

METHODS

Collagen type I and IV zymography, immunoprecipitation followed by a substrate activity assay, and an indirect enzyme-linked immunosorbent assay were all used to analyse MMP levels in CWF.

RESULTS

Our studies demonstrate that there is excessive protease activity in CWF compared with both human serum and acute wound fluid (AWF), which can be specifically attributed to MMPs as determined through a MMP-inhibitor study. Multiple MMPs were immunoprecipitated from the CWF samples and MMP-9 was identified as the predominant protease in CWF, with significantly elevated activity levels in CWF compared with AWF. In addition, the clinical status of the ulcer is directly associated with the amounts of MMP-9 present in the wound fluid. Therefore, this study suggests that higher levels of MMP-9 in chronic wound fluid correlate with a clinically worse wound.

CONCLUSIONS

In view of these results, it is hypothesized that a specific inhibitor of MMP-9 could potentially be more therapeutically effective than general MMP inhibitors in modulating chronic ulcers towards a healing state.

Attenuation of protease activity in chronic wound fluid with bisphosphonate-functionalised hydrogels

Chronic ulcers are an important and costly medical issue, imposing considerable pain, reduced mobility and decreased quality of life. The common pathology in these chronic wounds is excessive proteolytic activity, resulting in degradation of key factors critical to the ulcer's ability to heal. Matrix metalloproteinases (MMPs), a large family of zinc-dependent endopeptidases, have been shown to have increased activity in chronic wound fluid (CWF), with many authors suggesting that they need to be inhibited for the ulcer to heal. The studies we report here show that the excessive MMP activity in CWF can be inhibited with the bisphosphonate alendronate, in the form of a sodium salt, a functionalised analogue, and tethered to a poly(2-hydroxy methacrylate) (PHEMA) hydrogel. Furthermore, these functionalised alendronate hydrogels appear to be biologically inert as assessed in a three-dimensional ex vivo human skin equivalent model. Together, these results highlight the potential use of a tethered MMP inhibitor to inhibit protease activity in wound fluid. This approach may improve wound healing as it still allows MMPs to remain active in the upper cellular layers of the ulcer bed where they perform vital roles in wound healing; thus may offer an attractive new device-orientated wound therapy.

Efficacy and safety of intravenous bisphosphonates in patients with bone metastases caused by metastatic breast cancer

Solid tumors frequently metastasize to bone. This results in debilitating skeletal complications such as intractable bone pain, pathologic fractures, spinal cord compression, and hypercalcemia. Patients frequently require palliative radiation therapy or orthopedic surgery. Bisphosphonates have been shown to delay the incidence and decrease the frequency of skeletal-related events. Zoledronic acid is the only bisphosphonate that has provided benefits for patients with bone metastases secondary to a broad range of solid tumors. Among patients with metastatic breast or prostate cancer, zoledronic acid has demonstrated significant reductions in pain and skeletal morbidity compared with placebo. Zoledronic acid has also shown significant reductions in skeletal morbidity in patients with lung cancer or other solid tumors compared with placebo. Zoledronic acid is generally well tolerated. Flu-like symptoms which are manageable with standard treatment can occur. Renal monitoring is recommended, with dose reductions for patients with renal dysfunction. Osteonecrosis has been reported in patients receiving bisphosphonates and might be avoidable with appropriate dental care.

Mechanisms of osteopontin and CD44 as metastatic principles in prostate cancer cells

BACKGROUND

The expression level of osteopontin correlates with the metastatic potential of several tumors. Osteopontin is a well-characterized ligand for the alphavbeta3 integrin. The present study was undertaken to elucidate the possible role of osteopontin/alphavbeta3 signaling in prostate cancer cell migration.

RESULTS

We generated stable prostate cancer cell (PC3) lines that over-express osteopontin (PC3/OPN), mutant OPN in the integrin binding-site (PC3/RGDDeltaRGA), and null for OPN (PC3/SiRNA). The following observations were made in PC3/OPN cells as compared with PC3 cells: 1) an increase in multinucleated giant cells and RANKL expression; 2) an increase in CD44 surface expression, interaction of CD44/MMP-9 on the cell surface, MMP-9 activity in the conditioned medium, and cell migration; 3) western blot analysis of concentrated conditioned medium exhibited equal levels of MMP-9 protein in all PC3 cells. However, zymography analysis demonstrated that the levels of MMP-9 activity in the conditioned media reflect the CD44 surface expression pattern of the PC3 cell lines; 4) although MMP-9 and MMP-2 are secreted by PC3 cells, only the secretion of MMP-9 is regulated by OPN expression. A strong down regulation of the above-mentioned processes was observed in PC3/OPN (RGA) and PC3/SiRNA cells. PC3/OPN cells treated with bisphosphonate (BP) reproduce the down-regulation observed in PC3/OPN (RGA) and PC3/SiRNA cells.

CONCLUSION

Rho signaling plays a crucial role in CD44 surface expression. BPs inhibits the mevalonate pathway, which in turn, prevents the prenylation of a number of small GTPases. Attenuation of Rho GTPase activation by BPs may have contributed to the down regulation of cell surface CD44/MMP-9 interaction, MMP-9 activation/secretion, and cell migration. Taken together, these observations suggest that CD44 surface expression is an important event in the activation of MMP-9 and migration of prostate cancer cells. The various steps involved in the above mentioned signaling pathway and/or the molecules regulating the activation of MMP-9 are potential therapeutic target.

Monocyte/macrophage infiltration in tumors: modulators of angiogenesis

The role of a tumor immune infiltrate in cancer progression and metastasis has been debated frequently. Although often considered to be associated with improved prognosis and leading to the enhanced survival of cancer patients, inflammatory cells have also been described to assist the tumor's capabilities to progress, proliferate, and metastasize. Tumor-associated macrophages (TAMs), for example, have been shown to be symbiotically related to tumor cells: Tumor cells recruit TAMs and provide them with survival factors, and TAMs in turn produce a variety of angiogenic factors in response to the tumor microenvironment. This review will describe the composition of an immune infiltrate in tumors and the angiogenic and angiostatic properties of the cells present. Special emphasis will be on the angiogenesis-associated activities of TAMs. The development of immunotherapy and gene therapy using TAMs to mediate tumor cytotoxicity or to deliver gene constructs will be discussed as well. As immunotherapy has so far not been as effective as anticipated, a combination therapy in which angiostatic agents are used as well is put forward as a novel strategy to treat cancer.

Autoactivation profiles of calcium-dependent matrix metalloproteinase-2 and -9 in inflammatory synovial fluid: effect of pyrophosphate and bisphosphonates

BACKGROUND

The presence of matrix metalloproteinase-2 and -9 (MMP-2, MMP-9), gelatinase A and B, in synovial fluid is typical in inflammatory connective tissue diseases especially rheumatoid arthritis (RA). Because MMPs are synthesized as latent proforms, a pathophysiologic understanding of MMP regulation has focused on mechanisms of activation that remain to date largely unresolved.

METHODS

Synovial fluid was collected by aseptic aspiration from RA patients and incubated with and without physiologic levels of calcium and other modifiers (pyrophosphate, bisphosphonates, and the tissue inhibitors of MMPs (TIMPs), under conditions that activate MMPs. MMP-2 and -9 were then characterized by substrate gel electrophoresis (gelatin zymography) to resolve both latent and activated 'partially proteolyzed' forms.

RESULTS

Gelatin zymography revealed that RA synovial fluid contained latent neutrophil MMP-9 (92, 130, 225 kDa) and fibroblast MMP-2 (72 kDa). A small amount of activated MMP-2 (64 kDa) was also noted. Incubation of synovial fluid without calcium resulted in MMP-9 activation to 87, 116, and 209 kDa forms. MMP-9 activation was, however, substantially delayed in the presence of physiologic calcium (2.5 mmol/l). MMP-2 did not demonstrate any appreciable activation with or without physiologic calcium. MMP-9 activation likely occurred via an autoactivation mechanism since it was susceptible to inhibition by the tissue inhibitor of MMP-9 (TIMP-1). Pyrophosphate and bisphosphonates (alendronate and risedronate) were ineffective in blocking synovial fluid MMP-9 autoactivation. Some early MMP-9 activation was noted with alendronate despite the presence of physiologic calcium.

DISCUSSION

Although RA synovial fluid contained abundant MMP-2 and MMP-9, only MMP-9 underwent autoactivation to lower molecular weight forms. MMP-9 was transiently stable in the presence of physiologic calcium concentration, whereas autoactivation was more pronounced without exogenous calcium. The apparent lack of MMP-2 autoactivation with or without calcium, likely resulted from the coexistence of its bound endogenous inhibitor, TIMP-2. The role of differential autoactivation of MMPs activity in inflammatory arthritic disease is discussed.

Clodronate : a review of its use in the prevention of bone metastases and the management of skeletal complications associated with bone metastases in patients with breast cancer

Clodronate (clodronate disodium, Bonefos) is a non-nitrogen-containing bisphosphonate that inhibits osteoclast activity, and thereby inhibits bone resorption. Clodronate has been extensively used in patients with advanced breast cancer, and is generally well tolerated. In patients with primary breast cancer, clodronate is currently the only bisphosphonate shown to improve survival rates and to reduce the incidence of bone metastases in randomised controlled trials. Further trials in patients with early breast cancer are warranted to confirm results to date and to determine the optimal duration of treatment, as well as the efficacy of the drug compared with other bisphosphonates. In the meantime, clodronate is a well established bisphosphonate which has shown beneficial effects in the prevention of bone metastases and on survival in patients with primary breast cancer.

Evolving Role of Bisphosphonates in Women Undergoing Treatment for Localized and Advanced Breast Cancer

Breast cancer commonly metastasizes to bone, producing hypercalcemia, pathologic fractures, spinal compression, and pain that increase morbidity and affect the patient's mobility and quality of life. The use of bisphosphonates like pamidronate and zoledronic acid inhibits osteolytic activity caused by bone metastases. The use of bisphosphonates to prevent bone loss and preserve bone health in the adjuvant setting in women with breast cancer undergoing hormonal therapy with aromatase inhibitors or ovarian suppression is being actively investigated. Interestingly, clodronate, an oral bisphosphonate, has been shown in 2 trials to decrease the risk of recurrence in women with early-stage breast cancer, suggesting a direct or indirect antitumor effect of bisphosphonates. Trials to confirm the antitumor effects of bisphosphonates are currently ongoing. Prolonged intravenous bisphosphonate use has been associated with a rare risk of osteonecrosis of the jaw. Recommendations for management of this condition are discussed.

Interleukin-18 (IL-18) and matrix metalloproteinase-9 (MMP-9) in post-menopausal osteoporosis

This survey covered 60 post-menopausal women with osteoporosis. The patients were divided into three equal groups, and each group was treated with one of the three so-called anti-resorptive drugs, namely alendronate (10 mg/day) risedronate (5 mg/day) and raloxifene (60 mg/day) for 12 months. The Elisa technique was used to measure circulating IL-18 and MMP-9. Lumbar bone mineral density (BMD) levels were determined by using dexa mineralometry (Lunar DPX) at baseline and after 12 months of treatment. The results showed comparable responses of the patients treated with alendronate or risedronate, being a significant increase in BMD, an increase in circulating IL-18, and only slight modifications in circulating MMP-9 levels. After 12 months of treatment with raloxifene, there were minimal, non-significant increases in BMD, slight modifications in IL-18 levels, and a significant reduction in circulating MMP-9 levels. The conclusions can be drawn that all three drugs, albeit through different mechanisms, can be considered valid treatments for post-menopausal osteoporosis. Although measurements of circulating IL-8 and MMP-9 levels allowed us to differentiate the effects of the three drugs used, as of today, they have no real role in the diagnosis and/or follow-up of osteoporosis.

An amino-bisphosphonate targets MMP-9-expressing macrophages and angiogenesis to impair cervical carcinogenesis

A mouse model involving the human papillomavirus type-16 oncogenes develops cervical cancers by lesional stages analogous to those in humans. In this study the angiogenic phenotype was characterized, revealing intense angiogenesis in high-grade cervical intraepithelial neoplasias (CIN-3) and carcinomas. MMP-9, a proangiogenic protease implicated in mobilization of VEGF, appeared in the stroma concomitant with the angiogenic switch, expressed by infiltrating macrophages, similar to what has been observed in humans. Preclinical trials sought to target MMP-9 and angiogenesis with a prototypical MMP inhibitor and with a bisphosphonate, zoledronic acid (ZA), revealing both to be antiangiogenic, producing effects comparable to a Mmp9 gene KO in impairing angiogenic switching, progression of premalignant lesions, and tumor growth. ZA therapy increased neoplastic epithelial and endothelial cell apoptosis without affecting hyperproliferation, indicating that ZA was not antimitotic. The analyses implicated cellular and molecular targets of ZA's actions: ZA suppressed MMP-9 expression by infiltrating macrophages and inhibited metalloprotease activity, reducing association of VEGF with its receptor on angiogenic endothelial cells. Given its track record in clinical use with limited toxicity, ZA holds promise as an "unconventional" MMP-9 inhibitor for antiangiogenic therapy of cervical cancer and potentially for additional cancers and other diseases where MMP-9 expression by infiltrating macrophages is evident.