Inhibition of cell invasion by indomethacin on glioma cell lines: in vitro study

Malignant glioma invasion into the surrounding brain tissue is still a major problem for any therapeutical methods. Matrix metalloproteinases (MMPs) have been implicated as important factors in this pathological process. In this study, one of the non-steroidal anti-inflammatory drugs (NSAIDs) indomethacin was employed to investigate the effect of inhibition of cell invasion mediated by MMP-2 and MMP-9 in human malignant glioma cell lines, A172, U87MG, U251MG, and U373MG in vitro. MTT assay was firstly examined to determine non-cytotoxic dose range, then gelatin zymography, matrigel invasion assay, migration assay and MMP-2 activity assay for 24 h exposure in indomethacin were employed to assess the inhibitory effect of indomethacin. MTT assay revealed that dose with 0, 50, and 500 microM/ml were non-cytotoxic. Zymography demonstrated: (a) expression of MMP-2 and MMP-9 activity was downregulated along with elevated dose of indomethacin. (b) MMP-2 activity that changed from pro-MMP-2 to active form of MMP-2 in supernatants of cell lines could not be inhibited by indomethacin. Invasion assay disclosed that the number of invading cells through the matrigel were significantly decreased in a dose dependent manner. Migration assay indicated indomethacin did not affect cells migration. MMP-2 activity assay showed the total and active MMP-2 secretion was suppressed by 500 microM/ml of indomethacin. Our present study is the first report on inhibitive effect of indomethacin mediated by MMP-2 and MMP-9 in invasion assay of glioma cell lines. The current study suggested that non-cytotoxic level of indomethacin was able to reduce the cell invasion of malignant gliomas mediated by MMP-2 and MMP-9, but it did not affected on cell motility. It also lowered down the activity of MMP-2 and MMP-9, and could reduce of MMP-2 secretion of cell lines. Thus, high concentration of indomethacin within non-cytotoxic dose might offer a new therapeutic strategy to impair cell invasion of gliomas.

Could medical intervention work for aortic aneurysms?

BACKGROUND

Aortic aneurysms represent a serious and common condition. Current therapies are based on mechanical treatment. With increased knowledge of the biochemical mechanisms responsible for aneurysm expansion, it may be possible to prevent the growth of small aneurysms.

METHODS

A series of experiments performed in the investigator's laboratory during the past decade is outlined to show the evolution of our concepts of the processes underlying aneurysm formation and progression.

RESULTS

Our understanding of aortic aneurysms has changed dramatically. Once thought to represent a simple degenerative process, aneurysm tissue is highly active metabolically with ongoing synthesis and degradation of matrix proteins. Several members of a family of matrix-degrading enzymes play an important role in this process. These enzymes can be inhibited by the antibiotic doxycycline.

CONCLUSIONS

With a better understanding of aneurysm pathology, it may be possible in the future to inhibit the growth of small aortic aneurysms before they reach a size at which the risk of rupture is significant.

Comparative effects of statin and fibrate on nitric oxide bioactivity and matrix metalloproteinase in hyperlipidemia

OBJECTIVE

Because the lipoprotein effects of statin and fibric acid derivatives therapies differ, we studied the effects of these therapies in patients with hyperlipidemia on lipoproteins, vasomotor function, and plaque stability.

METHODS

We administered simvastatin, 20 mg daily, to 27 patients with hypercholesterolemia and coronary artery disease, or fenofibrate, 200 mg daily, to 27 patients with pure hypertriglyceridemia during 8 weeks.

RESULTS

As expected, simvastatin significantly lowered total cholesterol and low-density lipoprotein cholesterol (LDL-C) more, and fenofibrate decreased triglyceride and increased high-density lipoprotein cholesterol (HDL-C) more than either therapy. Simvastatin and fenofibrate significantly improved the percent flow-mediated dilator response to hyperemia by 183+/-41% and by 30+/-7%, respectively (each P<0.001); however, simvastatin significantly improved more (P<0.001). Simvastatin and fenofibrate significantly lowered plasma levels of tumor necrosis factor alpha (TNF-alpha) by 13+/-4% and by 10+/-4%, respectively (P=0.009 and P=0.006, respectively) with a similar degree (P=0.614). Simvastatin significantly reduced plasma levels of total MMP-9 and TIMP-1 more (P=0.005 and P=0.036, respectively), compared with fenofibrate showing no reduction. There were significant correlations between the degree of changes in TNF-alpha and the degree of changes in MMP-9 activity (r=0.376, P=0.053).

CONCLUSIONS

Simvastatin and fenofibrate demonstrated antiatherosclerotic effects via different mechanisms.

In vivo antitumor effect of ascorbic acid, lysine, proline and green tea extract on human prostate cancer PC-3 xenografts in nude mice: evaluation of tumor growth and immunohistochemistry

BACKGROUND

Matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), Ki 67 (proliferative protein) and constituents of ECM play a critical role in angiogenesis, and are crucial in neoplastic invasion and metastasis. Based on the antitumor properties of certain nutrients, we investigated the effect of a diet containing lysine, proline, arginine, ascorbic acid and green tea extract on the growth of tumors induced by implanting human prostate cancer PC-3 cells in athymic nude mice and on the expression of MMPs, VEGF, Ki 67 and fibronectin in these tumors, as well as the production of mucin (by PAS staining).

MATERIALS AND METHODS

Male nude mice (n =12) were inoculated with 3x10(6) prostate cancer PC-3 cells and randomly divided into two groups; Group A was fed a regular diet and Group B was fed a regular diet supplemented with 0.5% of the nutrient mixture (NM). Four weeks later, tumors were excised, weighed and processed for histology.

RESULTS

The results showed inhibition of tumor growth in Group B. Histological studies revealed inhibition of MMP-9 and VEGF secretion and mitosis in Group B tissues.

CONCLUSION

Nutrient supplementation strongly suppressed the growth of tumors without any adverse effects in nude mice, suggesting strong potential as an anticancer agent.

Extracellular matrix biology: a new frontier in linking the pathology and therapy of hypertension?

The extracellular matrix (ECM) is a vital component of connective tissue, and collagen is a major constituent. There is growing evidence that changes in the composition of the cardiac and vascular matrix occurs during hypertension. Clinically, these effects are manifested as left ventricular hypertrophy and a reduction in arterial compliance and luminal diameter, which results in end organ ischaemia. The matrix metalloproteinases and their inhibitors have a central role in the regulation of the composition of the ECM. In this review, we discuss the mediators that affect the structure of the ECM in hypertension using results from animal and human studies.

Expression of metalloproteinases and inhibitors in the differentiation of P19CL6 cells into cardiac myocytes

P19CL6 are a clonal derivative of P19 embryonal carcinoma cells, a euploid, multipotent mouse cell line, that differentiate efficiently into cardiac myocytes, with spontaneous beating evident within 10 days, following DMSO treatment. Using real-time quantitative RT-PCR we have profiled the expression of the complete matrix metalloproteinase and tissue inhibitor of metalloproteinase gene families during P19CL6 differentiation to cardiac myocytes. The genes subdivide into eight groups based upon their expression profile. Their expression was both qualitatively and quantitatively highly homologous to that seen during mouse heart development.

All-trans-retinoic acid suppresses matrix metalloproteinase activity and increases collagen synthesis in diabetic human skin in organ culture

Diabetes increases susceptibility to chronic skin ulceration. The etiology of chronic wound formation in diabetic individuals is multifactoral but may be accelerated by changes in the structure and function of the skin secondary to impaired fibroblast proliferation, decreased collagen synthesis, and increased matrix metalloproteinase (MMP) expression. This study explored the effects of all-trans-retinoic acid (RA) on cellular and biochemical features of diabetic human skin in organ culture. Two-mm skin biopsies from hip or ankle were obtained from diabetic subjects and incubated for 9 days in the absence or presence of 2 micro mol/L RA. Hip skin from non-diabetic individuals served as control. Following organ culture incubation, untreated and RA-treated tissue was examined histologically after staining with hematoxylin and eosin. In parallel, organ culture-conditioned medium collected on days 5 and 7 was assayed for levels of active and total MMP-1 (interstitial collagenase) and MMP-9 (gelatinase B). The same organ culture fluids were assayed for the presence of soluble collagen. In comparison with skin from non-diabetic individuals, diabetic skin demonstrated no major differences in overall epidermal thickness or collagen production (both were increased in RA-treated tissue as compared to non-RA-treated tissue). In contrast, levels of MMP-9 (active forms) were elevated in organ culture fluid from diabetic skin as compared to non-diabetic control skin. In the presence of RA, active forms of both MMP-1 and MMP-9 were reduced. Together, these data suggest that RA has the capacity to improve structure and function of diabetic skin, and that a major effect is on reduction of collagen-degrading MMPs.

In pneumococcal meningitis a novel water-soluble inhibitor of matrix metalloproteinases and TNF-α converting enzyme attenuates seizures and injury of the cerebral cortex

Matrix metalloproteinases (MMPs) and TNF-alpha converting enzyme (TACE) contribute to the pathophysiology of bacterial meningitis. To date, MMP-inhibitors studied in models of meningitis were compromised by their hydrophobic nature. We investigated the pharmacokinetics and the effect of TNF484, a water-soluble hydroxamate-based inhibitor of MMP and TACE, on disease parameters and brain damage in a neonatal rat model of pneumococcal meningitis. At 1 mg/kg q6h TNF484 reduced soluble TNF-alpha and the collagen degradation product hydroxyproline in the cerebrospinal fluid. Clinically, TNF484 attenuated the incidence of seizures and was neuroprotective in the cortex. Water-soluble MMP-inhibitors may hold promise in the therapy of bacterial meningitis.

Release of soluble CD40L from platelets is regulated by glycoprotein IIb/IIIa and actin polymerization

OBJECTIVES

The purpose of this study was to examine the effects of glycoprotein (GP) IIb/IIIa antagonists (abciximab, eptifibatide, and tirofiban) and other inhibitors on translocation of CD40L from intraplatelet stores to the platelet surface and on the release of soluble CD40L (sCD40L) from platelets.

BACKGROUND

CD40L is a proinflammatory and prothrombotic ligand in the tumor necrosis factor family.

METHODS

Platelet surface CD40L was measured by flow cytometry, and sCD40L was measured by enzyme-linked immunosorbent assay.

RESULTS

Translocation of CD40L from intraplatelet stores to the platelet surface was not inhibited by GP IIb/IIIa antagonists. However, release of sCD40L from the surface of activated platelets was inhibited by GP IIb/IIIa antagonists in a dose-dependent manner, in concert with inhibition of PAC1 binding to platelets (a surrogate marker for fibrinogen binding). Release of sCD40L from activated platelets was also markedly reduced in Glanzmann platelets (deficient in GP IIb/IIIa). Ethylenediaminetetraacetic acid was an effective inhibitor of sCD40L release, but only when added before platelet activation. Both cytochalasin D (an inhibitor of actin polymerization) and GM6001 (an inhibitor of matrix metalloproteinases [MMPs]) inhibited the release of sCD40L from platelets when added before, as well as 3 min after, platelet activation. However, neither cytochalasin D nor GM6001 affected translocation of CD40L to the platelet surface.

CONCLUSIONS

The GP IIb/IIIa antagonists inhibit release of sCD40L from activated platelets. Release of sCD40L from platelets is regulated, at least in part, by GP IIb/IIIa, actin polymerization, and an MMP inhibitor-sensitive pathway. In addition to their well-characterized inhibition of platelet aggregation, GP IIb/IIIa antagonists may obviate the proinflammatory and prothrombotic effects of sCD40L.

Involvement of matrix metalloproteinases and tenascin-C in elastin calcification

Elastin degeneration and calcification occur in many cardiovascular diseases, including medial arterial elastocalcinosis, atherosclerosis, and bioprosthetic heart valve mineralization. In the present study, we tested the hypothesis that the onset and progression of elastin-oriented calcification is associated with matrix remodeling and elastin degradation events. We studied whether aluminum ions inhibit elastin calcification by reducing elastin degradation and altering remodeling events. Subdermal implantation of pure elastin in juvenile rats resulted in a time-dependent calcification of elastin, reaching high levels 21 days after implantation. In situ hybridization showed that elastin calcification was associated with an up-regulation of matrix metalloproteinase (MMP) mRNA expression, specifically MMP-9 and MMP-2. Gelatin zymography demonstrated increased MMP-9 and MMP-2 enzyme activities in early stages of elastin calcification. Calcified elastin displayed a time-dependent pattern of tenascin-C (TN-C) and alkaline phosphatase (AP) expression. Pretreatment of pure elastin with aluminum ions prior to implantation resulted in complete inhibition of elastin calcification. Aluminum ion binding to elastin was found to protect elastin against MMP-mediated degradation in vitro. Noncalcified, explanted aluminum-pretreated elastin exhibited reduced activities of MMPs. TN-C expression in elastin implants exhibited a time-dependent pattern that was also affected by pretreatment of elastin with aluminum ions. In conclusion, elastin calcification is accompanied by matrix remodeling events, and the efficacy of aluminum pretreatment in inhibiting elastin calcification may be related in part to its effects on elastin remodeling.

Hypothesis: is antibiotic use associated with breast cancer?

The hypothesis that antibiotic use may increase cancer risk was first proposed several decades ago and some research suggests an increased risk of breast cancer among women with conditions likely to require long-term antibiotic use (e.g., acne, recurrent urinary-tract infections, UTI). However, this hypothesis has not been verified and the possible biological mechanisms are not entirely clear. A recent cohort study in Finland reported an increased risk of breast-cancer associated with antibiotic use for UTI. The effect of antibiotics on the ability of intestinal microflora to metabolise phytochemicals from edible plants into compounds that may protect against cancer was proposed as a potential mechanism. We extend this hypothesis by proposing that antibiotic use may be associated with breast-cancer risk through effects on immune and inflammatory factors, such as cytokines, T lymphocytes, prostaglandins, and matrix metalloproteinases, as well as disruption of phytochemical and oestrogen metabolism by intestinal microflora. We suggest that some mechanisms may increase breast-cancer risk, while others may decrease risk, depending on the antibiotic classification.

Serum profiles of matrix metalloproteinases and their tissue inhibitor in patients with acute coronary syndromes. The effects of short-term atorvastatin administration

There is increasing evidence that abnormal cytokine expression and increased metalloproteinase activity are implicated in the pathophysiology of acute coronary syndromes. This study investigates the serum profiles of representative metalloproteinases (MMP-1, -2, -9) and their tissue inhibitor (TIMP-1) in patients with myocardial infarction (MI) and unstable angina (UA) in relation to circulating proinflammatory cytokine (TNF-alpha and IL-6) activity. Furthermore, we examined the effects of a 30-day treatment with atorvastatin on serum levels of these inflammatory factors. Serum concentrations of MMP-1, -2, -9, TIMP-1, IL-6 and TNF-alpha were measured (enzyme-linked immunosorbent assay (ELISA) method) in 23 acute myocardial infarction patients and 20 unstable angina patients on 0 day, 1st, 3rd, 7th and 30th day after admission. Sixteen normal volunteers were used as healthy controls. Additionally, 12 patients of myocardial infarction group and 11 patients of unstable angina group were treated with atorvastatin (20 mg/day) for 30 days in a randomized design. In patients with myocardial infarction and unstable angina, serum levels of MMP-2, -9, TIMP-1, TNF-alpha and IL-6 were significantly higher than those of healthy controls in all time frames (p<0.05). In the group of unstable angina patients, we observed a statistically significant reduction in the levels of MMP-9, TIMP-1 and IL-6 after the 30-day atorvastatin administration. Our results suggest that serum MMPs, TIMP-1 and proinflammatory cytokines play an important role in the pathophysiology of the acute coronary syndromes. The reduction of these factors by short-term atorvastatin administration may provide a new insight into the pleiotropic effects of statins on unstable coronary artery disease.

Minocycline inhibits smooth muscle cell proliferation, migration and neointima formation after arterial injury

The tetracyclines are antimicrobials that also inhibit expression of certain matrix metalloproteinases (MMPs). We conducted a series of experiments to determine if minocycline could inhibit MMP expression and limit human aortic smooth muscle cell (SMC) proliferation and migration. Analysis of SMC proliferation was performed after cells were grown in minocycline-incubated media. SMC migration activity was assayed in a micro-Boyden chamber. Western blotting revealed that minocycline reduced SMC production of MMP-2 in a dose dependent manner. Increasing doses of minocycline progressively reduced SMC proliferation to 49% of control values and limited SMC migration to 15% of control. When administered to rats with balloon injured carotid arteries, intraperitoneal doses of minocycline (70-100 mg/kg) reduced neointima formation by 76%, but were associated with liver toxicity. Higher doses were lethal and lower doses were ineffective. Minocycline, applied to injured arteries in a pluronic gel with a low pH, was also ineffective. In summary, minocycline lowers MMP-2 expression, reduces SMC proliferation and migration, and inhibits neointimal hyperplasia, but its efficacy is limited by systemic toxicity.

Tyrosine phosphatase inhibition induces loss of blood–brain barrier integrity by matrix metalloproteinase-dependent and -independent pathways

Tight junctions between endothelial cells of brain capillaries form the structural basis of the blood-brain barrier (BBB), which controls the exchange of molecules between blood and CNS. Regulation of cellular barrier permeability is a vital and complex process involving intracellular signalling and rearrangement of tight junction proteins. We have analysed the impact of tyrosine phosphatase inhibition on tight junction proteins and endothelial barrier integrity in a primary cell culture model based on porcine brain capillary endothelial cells (PBCEC) that closely mimics the BBB in vitro. The tyrosine phosphatase inhibitor phenylarsine oxide (PAO) induced increased matrix metalloproteinase (MMP) activity, which was paralleled by severe disruption of cell-cell contacts and proteolysis of the tight junction protein occludin. ZO-1 and claudin-5 were not affected. Under these conditions, the transendothelial electrical resistance (TEER) was markedly reduced. PAO-induced occludin proteolysis could be prevented by different MMP inhibitors. Pervanadate (PV) reduced the TEER similar to PAO, but did not increase MMP activity. Cell-cell contacts of PV-treated cells appeared unaffected, and occludin proteolysis did not occur. Our results suggest that tyrosine phosphatase inhibition can influence barrier properties independent of, but also correlated to MMPs. Evidence is given for a role of MMPs in endothelial tight junction regulation at the BBB in particular and probably at tight junctions (TJs) in general.

Human immunodeficiency virus type 1 Tat and methamphetamine affect the release and activation of matrix-degrading proteinases

Human immunodeficiency virus (HIV) dementia (HIVD) is associated with an increase in the number of activated monocytes within the central nervous system (CNS), a pathological feature that may be more remarkable in the setting of superimposed substance abuse. Monocytes may transport HIV to the brain, and, moreover, activated and/or infected monocytes have been shown to release a number of potent neurotoxins. Although the mechanisms responsible for the increase in the CNS ingress of monocytes are multiple, blood-brain barrier (BBB)-degrading matrix metalloproteinases (MMPs) are likely to play an important role. The current study investigates the effects of the HIV-1-encoded protein Tat, and the drug of abuse methamphetamine, on MMP release from brain derived cells. The release of urokinase plasminogen activator (uPA), an activator of MMPs, was also investigated. Mixed human neuron/astrocyte cultures were stimulated with Tat or methamphetamine, and supernatants were analyzed by enzyme-linked immunosorbent assay (ELISA) and/or gelatin substrate zymography. Results showed that Tat and methamphetamine increased the release of MMP-1 from these cultures. Tat also increased supernatant levels of active MMP-2. In addition, both Tat and methamphetamine stimulated the release of the MMP activator uPA, and in a manner that was sensitive to inhibition with pertussis toxin. Together, these results suggest that in HIVD, Tat and methamphetamine may contribute to CNS inflammation by stimulating increased release and/or activation of matrix-degrading proteinases through mechanisms that include Gi/Go-coupled signaling. These results also suggest a potential mechanism for acceleration of HIVD with methamphetamine use.

Inhibition of lymphangiogenesis-related properties of murine lymphatic endothelial cells and lymph node metastasis of lung cancer by the matrix metalloproteinase inhibitor MMI270

Based on a previous report on the effect of a matrix metalloproteinase (MMP) inhibitory compound, MMI270, in regulating tumor-induced angiogenesis, as well as recent findings concerning functional correlations among tumor metastasis, angiogenesis and lymphangiogenesis, we investigated the anti-metastatic efficacy of MMI270 in a murine model of lymph node metastasis of lung cancer, and analyzed whether this inhibitor could also regulate lymphangiogenesis-related properties of murine lymphatic endothelial cells (LECs) and invasive properties of Lewis lung cancer (LLC) cells. The observation that MMI270 led to a significant decrease in the weight of tumor-metastasized lymph nodes of mice led us to test its anti-lymphangiogenic and anti-invasive effects in vitro. Murine LECs were characterized by an in vitro tube formation assay, by semi-quantitative RT-PCR assay to examine the expression of mRNAs for flt-4, Flk-1, Tie-1, Tie-2, CD54/ICAM1, vWF, MMPs and uPA, and by western blotting to confirm the protein expression of flt-4 and CD31/PECAM. This is the first report on the expression of MMP-2, MMP-9 and MT1-MMP in murine LECs, as well as on the inhibition of their enzymatic activity, and of the invasive ability and tube-forming property of LECs by an MMP inhibitor. Furthermore, MMI270 was shown to strongly inhibit the activity of MMP-2 and -9 produced by LLC cells and the invasion of these cells through Matrigel. In summary, the present results indicate that MMI270, apart from its anti-tumor angiogenic application, might be useful as an anti-metastatic drug, on the basis of its downregulatation of both the lymphangiogenesis-related properties of LECs and the invasive properties of LLC cells in vitro.

Involvement of matrix metalloproteinases and their inhibitors in peripheral synovitis and down-regulation by tumor necrosis factor ? blockade in spondylarthropathy

OBJECTIVE

To investigate the role of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in spondylarthropathy (SpA) synovitis.

METHODS

Paired samples of synovial biopsy tissue as well as serum and synovial fluid (SF) from 41 patients with SpA and 20 patients with rheumatoid arthritis (RA) and serum samples from 20 healthy controls were analyzed by immunohistochemistry and enzyme-linked immunosorbent assay for the presence of MMPs 1, 2, 3, and 9 and TIMPs 1 and 2. In addition, sera from 16 patients with ankylosing spondylitis (AS) and peripheral synovitis and 17 patients with AS and exclusively axial involvement were analyzed. An additional cohort of SpA patients was analyzed at baseline and after 12 weeks of infliximab treatment.

RESULTS

Staining for MMPs and TIMPs showed a cellular and interstitial pattern in the synovial lining and sublining layers that was similar between the RA and SpA patients. Involvement of MMPs and TIMPs in SpA synovitis was suggested by the correlation with cellular infiltration, vascularization, and cartilage degradation. Higher serum levels of MMPs 3 and 9 were revealed in SpA and RA patients as compared with healthy controls. Production of MMP-3, but not MMP-9, in the serum reflected the presence of peripheral synovitis, as indicated by 1) the correlation between serum levels, SF levels (which were 1,000-fold higher than the serum levels), and synovial expression of MMP-3, 2) the increased levels of MMP-3 in AS patients with peripheral disease and not exclusively axial involvement, and 3) the correlation of serum and SF MMP-3 with parameters of synovial, but not systemic, inflammation. The modulation of the MMP/TIMP system by tumor necrosis factor alpha (TNFalpha) blockade was confirmed by the down-regulation of all MMPs and TIMPs in the synovium and a pronounced and rapid decrease of serum MMP-3.

CONCLUSION

MMPs and TIMPs are highly expressed in SpA synovitis and mirror both the inflammatory and tissue-remodeling aspects of the local disease process. Serum MMP-3, originating from the inflamed joint, represents a valuable biomarker for peripheral synovitis. Modulation of the MMP/TIMP system by infliximab could contribute to the antiinflammatory and tissue-remodeling effects of TNFalpha blockade in SpA.

Apoptotic induction by BE16627B on human malignant glioma cell lines by an anti-matrix metalloproteinase agent

We have elucidated the pharmacological action of the anti-matrix metalloproteinase inhibitor BE16627B on glioma cells. The study was limited to the noncytotoxic dose range. The aim of the study was to investigate whether the cytotoxicity of BE16627B, an anti-MMP agent, is related to apoptosis in the human malignant glioma cell lines U87MG, U251MG, and U373MG. MTT assay was performed to detect the cytotoxic dose range. Agarose gel electrophoresis was performed with purified genomic DNA following exposure to 20 to 500 microM BE16627B for 24 h, compared with 0 microM for the control group. Transmission electron microscopy (TEM) was employed to study nuclear fragmentation following exposure to 0, 20, and 500 microM of the agent for 24 h. An in situ endolabeling assay was performed to determine the index of apoptotic induction. MTT assay revealed that concentrations of 100 microM and above were cytotoxic. DNA laddering was demonstrated in agarose gel electrophoresis. TEM disclosed condensing and fragmentation of the chromatin. None of these changes were observed in the control group and the noncytotoxic dose group. The in situ endolabeling study disclosed that the apoptotic index was significantly elevated by cytotoxic doses of this agent (U373MG; control, 4.0%; 500 microM, 68.5%). These results indicated that cytotoxic concentrations of BE16627B induced apoptosis in human malignant glioma cell lines. In our previous report, this agent inhibited activity of MMP in noncytotoxic concentrations. Further study should be done to determine the pharmacological action of toxic BE16627B.

Inhibition of alpha-ketoglutarate dehydrogenase complex promotes cytochrome c release from mitochondria, caspase-3 activation, and necrotic cell death

Mitochondrial dysfunction has been implicated in cell death in many neurodegenerative diseases. Diminished activity of the alpha-ketoglutarate dehydrogenase complex (KGDHC), a key and arguably rate-limiting enzyme of the Krebs cycle, occurs in these disorders and may underlie decreased brain metabolism. The present studies used alpha-keto-beta-methyl-n-valeric acid (KMV), a structural analogue of alpha-ketoglutarate, to inhibit KGDHC activity to test effects of reduced KGDHC on mitochondrial function and cell death cascades in PC12 cells. KMV decreased in situ KGDHC activity by 52 +/- 7% (1 hr) or 65 +/- 4% (2 hr). Under the same conditions, KMV did not alter the mitochondrial membrane potential (MMP), as assessed with a method that detects changes as small as 5%. KMV also did not alter production of reactive oxygen species (ROS). However, KMV increased lactate dehydrogenase (LDH) release from cells by 100 +/- 4.7%, promoted translocation of mitochondrial cytochrome c to the cytosol, and activated caspase-3. Inhibition of the mitochondrial permeability transition pore (MPTP) by cyclosporin A (CsA) partially blocked this KMV-induced change in cytochrome c (-40%) and LDH (-15%) release, and prevented necrotic cell death. Thus, impairment of this key mitochondrial enzyme in PC12 cells may lead to cytochrome c release and caspase-3 activation by partial opening of the MPTP before the loss of mitochondrial membrane potentials.

Tumor necrosis factor-alpha (TNF-alpha) stimulates chemotactic response in mouse myogenic cells

Migration of transplanted myogenic cells occurs during both embryogenesis and regeneration of skeletal muscles and is important for successful myoblast transplantation, but little is known about factors that promote chemotaxis of these cells. Tumor necrosis factor-alpha (TNF-alpha) is known to induce chemotactic effect on several cell types. In this study, we investigated its influence on the in vitro and in vivo motility of C2C12 and primary myoblasts. In the in vitro test performed in the blind-well Boyden chambers, we showed that TNF-alpha (50-400 U/ml) significantly enhanced the ability of myogenic cells to migrate. The dose-response curve for this factor was bell shaped, with maximum activity in the 200 U/ml range. In the in vivo test, intramuscular administration of TNF-alpha was performed by an Alzet pump connected to a perforated polyethylene microtube inserted in the tibialis anterior (TA) of CD1 mice. In these experiments, myoblasts were injected under the muscle epimysium. The recipient mice were immunosuppressed with FK506. Our results showed that, 5 days after myoblast transplantation, cells migrated further in the muscles infused with TNF-alpha than in the muscles not exposed to TNF-alpha. TNF-alpha not only has a chemotactic activity but may also modify cell migration via its action on matrix metalloproteinase (MMP) expression. The proteolytic activities of the MMPs secreted in the muscles were thus also assessed by gelatin zymography. The results showed an increased of MMP-2 and MMP-9 transcripts in the TNF-alpha-infused muscles injected with myogenic cells. Myoblast migration during transplantation may be enhanced by overlapping gradients of several effector molecules such as TNF-alpha, interferon-gamma (INF-gamma), and interleukins, released at the site of muscle injury. We propose that TNF-alpha may promote myoblast migration directly through chemotactic activity and indirectly by enhancing MMP activity at the site of muscle injury.

Transforming growth factor-beta1 inhibits tumor growth in a mouse melanoma model by down-regulating the plasminogen activation system

The degradation of basement membranes by tumor cells involves secretion and activation of proteinases, such as matrix metalloproteinases (MMPs) and the plasminogen activation system (uPA, tPA, PAI-1), and results from an imbalance between their inhibitors and activators, controlled by various growth factors or cytokines. Among them, the TGF-beta family is one of the most intriguing because it has been reported either to decrease or promote cancer progression. In the present paper, we studied the effect of TGF-beta1 in a mouse melanoma model. In vivo, TGF-beta1 inhibited tumor growth after subcutaneous injection of B16F1 cells in syngenic mice. In vitro, TGF-beta1 did not alter B16F1 cell proliferation, but strongly decreased their migration through Matrigel-coated membranes. The protease production was analyzed by zymography, Western blot, or RT-PCR. MMP-2 and TIMP-2 expression were not altered by TGF-beta1. In contrast, TGF-beta1 triggered a large decrease of uPA and tPA, as well as a decrease of uPA and uPAR mRNAs. By Western blot and RT-PCR analyses, TGF-beta1 was shown to induce a strong increase of PAI-1 synthesis. Collectively, these results suggest that TGF-beta1 may inhibit melanoma tumor growth by specifically decreasing plasmin activity of tumor cells and play a protective role during the earliest stages of tumor progression.

Protective role of tuftsin fragment 1-3 in an animal model of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) causes morbidity and mortality and commonly follows the reperfusion after an ischemic event. Tissue plasminogen activator (tPA), a fibrinolytic serine protease, is routinely given for the treatment of stroke. However, tPA also can promote neuronal death, suggesting that caution should be exercised when using it. Furthermore, tPA upon brain injury mediates microglial activation and modulates neuronal survival. To investigate the role of tPA and microglia during brain hemorrhage, we induced experimentally ICH by intracerebral injection of collagenase. Seven days after the introduction of ICH, it persisted in tPA-deficient (tPA(-/-)) mice but is drastically reduced in size in wild-type mice. Three weeks after ICH, there are still red blood cells in tPA(-/-) but not in wild-type animals. Activated microglia persist around the injury site. When microglial activation is inhibited by tuftsin fragment 1-3 macrophage/microglial inhibitory factor (MIF), the stroke injury volume is significantly reduced, and the neurobehavioral deficits exhibited by the mice are improved. Our results suggest that endogenous tPA assists in the clearance of intracerebral hemorrhage, presumably by affecting microglial activation, and MIF could be a valuable neuroprotective agent for the treatment of ICH.

Transforming growth factor-beta induces expression of vascular endothelial growth factor in human retinal pigment epithelial cells: involvement of mitogen-activated protein kinases

Vascular endothelial growth factor (VEGF) is a major agent in choroidal and retinal neovascularization, events associated with age-related macular degeneration (AMD) and diabetic retinopathy. Retinal pigment epithelium (RPE), strategically located between retina and choroid, plays a critical role in retinal disorders. We have examined the effects of various growth factors on the expression and secretion of VEGF by human retinal pigment epithelial cell cultures (HRPE). RT-PCR analyses revealed the presence of three isoforms of mRNA corresponding to VEGF 121, 165, and 189 that were up regulated by TGF-beta1. TGF-beta1, beta2, and beta3 were the potent inducers of VEGF secretion by HRPE cells whereas bFGF, PDGF, TGF-alpha, and GM-CSF had no effects. TGF-beta receptor type II antibody significantly reversed induction of VEGF secretion by TGF-beta. In contrast activin, inhibin and BMP, members of TGF-beta super family, had no effects on VEGF expression in HRPE. VEGF mRNA levels and protein secretion induced by TGF-beta were significantly inhibited by SB203580 and U0126, inhibitors of MAP kinases, but not by staurosporine and PDTC, protein kinase C and NF-kappaB pathway inhibitors, respectively. TGF-beta also induced VEGF expression by fibroblasts derived from human choroid of eye. TGF-beta induction of VEGF secretion by RPE and choroid cells may play a significant role in choroidal neovascularization (CNV) in AMD. Since the secretion of VEGF by HRPE is regulated by MAP kinase pathways, MAP kinase inhibitors may have potential use as therapeutic agents for CNV in AMD.