Enhancement of MTT, a tetrazolium salt, exocytosis by amyloid beta-protein and chloroquine in cultured rat astrocytes

Malaria pigment accelerates MTT - formazan exocytosis in human endothelial cells

Haemozoin is a by-product of haemoglobin digestion by intraerythrocytic malaria parasites, which induces immunologic responses on different tissues, including endothelial cells. In the present paper, the incubation of human microvascular endothelial cells with haemozoin significantly inhibited MTT reduction, a measure of cytotoxicity, without increasing the release of cytoplasmic lactate dehydrogenase. Moreover, haemozoin did not induce apoptosis or cell cycle arrest nor decreased the number of live cells, suggesting that cells viability itself was not affected and that the inhibition of MTT reduction was only apparent and probably due to accelerated MTT-formazan exocytosis. After 30 min of MTT addition, a significant increase in the % of cells exocytosing MTT formazan crystals was observed in haemozoin-treated cells compared with control cells. Such an effect was partially reversed by the addition of genistein, an inhibitor of MTT-formazan exocytosis. The rapid release of CXCL-8, a preformed chemokine contained in Weibel-Palade bodies, confirmed that haemozoin induces a perturbation of the intracellular endothelial trafficking, including the exocytosis of MTT-formazan containing vesicles. The haem moiety of haemozoin is responsible for the observed effect. Moreover, this work underlines that MTT assay should not be used to measure cytotoxicity induced by haemozoin and other methods should be preferred.

Anterior Gradient 2 is Correlated with EGFR Mutation in Lung Adenocarcinoma Tissues

Background

Epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitor (TKI) has demonstrated a promising therapeutic response in lung adenocarcinoma patients with EGFR gene mutations. However, the predictive factors for this therapy have not been established, except for the EGFR gene mutation status of carcinoma cells.

Methods

We first performed microarray analysis in EGFR-TKI–sensitive lung adenocarcinoma cell lines. The results indicated anterior gradient 2 (AGR2) as a potential surrogate marker of EGFR-TKI. Therefore, we then evaluated the correlation between the status of AGR2 immunoreactivity and clinicopathological factors including overall survival (OS), progression-free survival (PFS) and clinical response to EGFR-TKI, in 147 cases of surgically resected lung adenocarcinoma. The biological significance of AGR2 was further evaluated by transfecting small interfering RNA (siRNA) against AGR2 in these cells.

Results

The status of AGR2 immunoreactivity was significantly higher in lung adenocarcinoma cases with EGFR gene mutations than in those with the wild type (p<0.0001), but there were no significant differences in OS, PFS and response of EGFR-TKI between the AGR2 high and low carcinoma cases. Knockdown of AGR2 gene expression following siRNA transfection resulted in a significantly lower response to EGFR-TKI in EGFR-mutated PC-3.

Conclusions

AGR2 could serve as an adjunctive surrogate protein marker possibly reflecting EGFR gene mutations in lung adenocarcinoma patients. Results from in vitro analysis indicated that AGR2 could be a potential clinical biomarker of EGFR-TKI therapeutic sensitivity in lung adenocarcinoma cells.

In situ fibrillizing amyloid-beta 1-42 induces neurite degeneration and apoptosis of differentiated SH-SY5Y cells

The progression of Alzheimer’s disease is causatively linked to the accumulation of amyloid-β aggregates in the brain, however, it is not clear how the amyloid aggregates initiate the death of neuronal cells. The in vitro toxic effects of amyloid peptides are most commonly examined using the human neuroblastoma derived SH-SY5Y cell line and here we show that differentiated neuron-like SH-SY5Y cells are more sensitive to amyloid peptides than non-differentiated cells, because the latter lack long neurites. Exogenous soluble amyloid-β 1–42 covered cell bodies and whole neurites in differentiated cells with dense fibrils, causing neurite beading and fragmentation, whereas preformed amyloid-β 1–42 fibrils had no toxic effects. Importantly, spontaneously fibrillizing amyloid-β 1–42 peptide exhibited substantially higher cellular toxicity than amyloid-β 1–40, which did not form fibrils under the experimental conditions. These results support the hypothesis that peptide toxicity is related to the active fibrillization process in the incubation mixture.

Culture at a Higher Temperature Mildly Inhibits Cancer Cell Growth but Enhances Chemotherapeutic Effects by Inhibiting Cell-Cell Collaboration

Acute febrile infections have historically been used to treat cancer. To explore the underlying mechanism, we studied chronic effects of fever on cancer cell growth and chemotherapeutic efficacy in cell culture. We found that culturing cancer cells at 39°C mildly inhibited cell growth by arresting the cells at the G1 phase of the cell cycle. When cells were seeded in culture dishes at a lower density, e.g. about 1000–2000 cells per 35-mm dish, the growth inhibition was much greater, manifested as many fewer cell colonies in the 39°C dishes, compared with the results at a higher density seeding, e.g. 20,000 cells per dish, suggesting that cell-cell collaboration as the Allee effect in cell culture is inhibited at 39°C. Withdrawal of cells from serum enhanced the G1 arrest at 39°C and, for some cell lines such as A549 lung cancer cells, serum replenishment failed to quickly drive the cells from the G1 into the S and G2-M phases. Therapeutic effects of several chemotherapeutic agents, including clove bud extracts, on several cancer cell lines were more potent at 39°C than at 37°C, especially when the cells were seeded at a low density. For some cell lines and some agents, this enhancement is long-lasting, i.e. continuing after the cessation of the treatment. Collectively these results suggest that hyperthermia may inhibit cancer cell growth by G1 arrest and by inhibition of cell-cell collaboration, and may enhance the efficacy of several chemotherapeutic agents, an effect which may persist beyond the termination of chemotherapy.

The effect of bortezomib on expression of inflammatory cytokines and survival in a murine sepsis model induced by cecal ligation and puncture

PURPOSE

Although the proteasome inhibitor known as bortezomib can modulate the inflammatory process through the nuclear factor-kappa B signaling pathway, the immunomodulatory effect of pre-incubated bortezomib has not been fully evaluated for inflammation by infectious agents. Therefore, we evaluated the effect of bortezomib on the expression of inflammatory cytokines and mediators in macrophage cell lines and on survival in a murine peritonitis sepsis model.

MATERIALS AND METHODS

Bortezomib was applied 1 hr before lipopolysaccharide (LPS) stimulation in RAW 264.7 cells. The cecal ligation and puncture (CLP) experiments were performed in C57BL/6J mice.

RESULTS

Pre-incubation with bortezomib (25 nM or 50 nM) prior to LPS (50 ng/mL or 100 ng/mL) stimulation significantly recovered the number of viable RAW 264.7 cells compared to those samples without pre-incubation. Bortezomib decreased various inflammatory cytokines as well as nitric oxide production in LPS-stimulated cells. The 7-day survival rate in mice that had received bortezomib at 0.01 mg/kg concentration 1 hr prior to CLP was significantly higher than in the mice that had only received a normal saline solution of 1 mL 1 hr prior to CLP. In addition, the administration of bortezomib at 0.01 mg/kg concentration 1 hr before CLP resulted in a significant decrease in inflammation of the lung parenchyma. Collectively, pretreatment with bortezomib showed an increase in the survival rate and changes in the levels of inflammatory mediators.

CONCLUSION

These results support the possibility of pretreatment with bortezomib as a new therapeutic target for the treatment of overwhelming inflammation, which is a characteristic of severe sepsis.

β2-microglobulin amyloid fibrils are nanoparticles that disrupt lysosomal membrane protein trafficking and inhibit protein degradation by lysosomes

Fragmentation of amyloid fibrils produces fibrils that are reduced in length but have an otherwise unchanged molecular architecture. The resultant nanoscale fibril particles inhibit the cellular reduction of the tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), a substrate commonly used to measure cell viability, to a greater extent than unfragmented fibrils. Here we show that the internalization of β2-microglobulin (β2m) amyloid fibrils is dependent on fibril length, with fragmented fibrils being more efficiently internalized by cells. Correspondingly, inhibiting the internalization of fragmented β2m fibrils rescued cellular MTT reduction. Incubation of cells with fragmented β2m fibrils did not, however, cause cell death. Instead, fragmented β2m fibrils accumulate in lysosomes, alter the trafficking of lysosomal membrane proteins, and inhibit the degradation of a model protein substrate by lysosomes. These findings suggest that nanoscale fibrils formed early during amyloid assembly reactions or by the fragmentation of longer fibrils could play a role in amyloid disease by disrupting protein degradation by lysosomes and trafficking in the endolysosomal pathway.

β-Amyloid1-42, HIV-1Ba-L (clade B) infection and drugs of abuse induced degeneration in human neuronal cells and protective effects of ashwagandha (Withania somnifera) and its constituent Withanolide A

Alzheimer's disease (AD) is characterized by progressive dysfunction of memory and higher cognitive functions with abnormal accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles throughout cortical and limbic brain regions. Withania somnifera (WS) also known as ‘ashwagandha’ (ASH) is used widely in Ayurvedic medicine as a nerve tonic and memory enhancer. However, there is paucity of data on potential neuroprotective effects of ASH against β-Amyloid (1–42) (Aβ) induced neuropathogenesis. In the present study, we have tested the neuroprotective effects of Methanol: Chloroform (3:1) extract of ASH and its constituent Withanolide A (WA) against Aβ induced toxicity, HIV-1_Ba-L (clade B) infection and the effects of drugs of abuse using a human neuronal SK-N-MC cell line. Aβ when tested individually, induced cytotoxic effects in SK-N-MC cells as shown by increased trypan blue stained cells. However, when ASH was added to Aβ treated cells the toxic effects were neutralized. This observation was supported by cellular localization of Aβ, MTT formazan exocytosis, and the levels of acetylcholinesterase activity, confirming the chemopreventive or protective effects of ASH against Aβ induced toxicity. Further, the levels of MAP2 were significantly increased in cells infected with HIV-1_Ba-L (clade B) as well as in cells treated with Cocaine (COC) and Methamphetamine (METH) compared with control cells. In ASH treated cells the MAP2 levels were significantly less compared to controls. Similar results were observed in combination experiments. Also, WA, a purified constituent of ASH, showed same pattern using MTT assay as a parameter. These results suggests that neuroprotective properties of ASH observed in the present study may provide some explanation for the ethnopharmacological uses of ASH in traditional medicine for cognitive and other HIV associated neurodegenerative disorders and further ASH could be a potential novel drug to reduce the brain amyloid burden and/or improve the HIV-1 associated neurocognitive impairments

As2O3 synergistically reactivate latent HIV-1 by induction of NF-κB

None of the current agents can safely and effectively eliminate latent HIV-1 reservoirs, meaning that there is a major barrier to the final cure of AIDS. Arsenic trioxide (As2O3), a drug used to treat acute promyelocytic leukemia (APL), was reported to affect the transcription factors and pathways involved in modulating HIV-1 expression. However, little is known about the effect and molecular basis of As2O3 in inducing HIV-1 expression in latently infected cells. Using the Jurkat T cell model of HIV-1 latency, we found that As2O3 activated latent HIV-1 replication with a similar potency to valproic acid (VPA) and did so in a dose- and time-dependent manner. We also found that As2O3 synergistically reactivated latent HIV-1 transcription with prostratin, tumor necrosis factor alpha (TNF-α) or VPA. Moreover, we provide evidence indicating that As2O3-induced HIV-1 activation involves the nuclear factor kappa B (NF-κB) signaling pathway. In conclusion, we have found that As2O3 can synergistically reactivate latent HIV-1 with other activators, which may provide a new tool to unravel the mechanisms of virus latency and reactivation.

Expression and regulation of apolipoprotein E receptors in the cells of the central nervous system in culture: A review

The importance of apolipoprotein E (apoE) in the central nervous system (CNS) became increasingly clear since the descovery that apoE ε4 allele is a major risk factor for Alzheimer's disease. ApoE is one of the major apolipoproteins that acts as a ligand for the cellular uptake of lipoproteins via apoE receptors, members of low-density lipoprotein receptor (LDLR) family, in the CNS. Recently, LDLR family has been shown to have new functions that modulate intracellular signalling and affect neuronal and glial functions, survival and regeneration. However, the pattern of expression of apoE receptors in the CNS has not been fully clarified yet. The LDLR, very low density lipoprotein receptor (VLDLR), LDLR-related protein (LRP), and apolipoprotein E receptor 2 (apoER2) are known to bind to and internalize apoE-containing lipoproteins. Here we summarize the expression of apoE receptors in the CNS and demonstrate additional our original data on cell type specific expression and regulation of those receptors in the CNS, using in situ hybridization and RT-PCR. The cells used in our study were highly enriched cultures of neurons, astrocytes, microglia and oligodendrocytes isolated from rat brain and neuroblastoma cell line, Neuro2a. All of these four types of receptors were shown to be expressed in neurons, astrocytes, microglia and oligodendrocytes, while LDLR and LRP were expressed in Neuro2a cells. We further examined the regulation of the expression of these receptors by altering the cholesterol content of the cells, and found that only the LDLR expression was downregulated following internalization of lipoprotein cholesterol and upregulated by cholesterol deprivation, in neuronal and astroglial cells. These data together with previous studies suggest that LDLR, VLDL, LRP, and apoER2 may be involved in apoE-mediated lipid uptake and/or intracellualr signalling in the cells of the CNS cells, i.e., neurons, astrocytes, microglia, and oligodendrocytes.

Experimental validation of in silico target predictions on synergistic protein targets

Two relatively recent trends have become apparent in current early stage drug discovery settings: firstly, a revival of phenotypic screening strategies and secondly, the increasing acceptance that some drugs work by modulating multiple targets in parallel (‘multi-target drugs’).

MTT assay for cell viability: Intracellular localization of the formazan product is in lipid droplets

Although MTT is widely used to assess cytotoxicity and cell viability, the precise localization of its reduced formazan product is still unclear. In the present study the localization of MTT formazan was studied by direct microscopic observation of living HeLa cells and by colocalization analysis with organelle-selective fluorescent probes. MTT formazan granules did not colocalize with mitochondria as revealed by rhodamine 123 labeling or autofluorescence. Likewise, no colocalization was observed between MTT formazan granules and lysosomes labeled by neutral red. Taking into account the lipophilic character and lipid solubility of MTT formazan, an evaluation of the MTT reaction was performed after treatment of cells with sunflower oil emulsions to induce a massive occurrence of lipid droplets. Under this condition, lipid droplets revealed a large amount of MTT formazan deposits. Kinetic studies on the viability of MTT-treated cells showed no harmful effects at short times. Quantitative structure-activity relations (QSAR) models were used to predict and explain the localization of both the MTT tetrazolium salt and its formazan product. These predictions were in agreement with experimental observations on the accumulation of MTT formazan product in lipid droplets.

Carcinoembryonic antigen-related cell adhesion molecules as surrogate markers for EGFR inhibitor sensitivity in human lung adenocarcinoma

Background:

Lung adenocarcinoma (LADCA) patients with epidermal growth factor receptor (EGFR) mutations are in general associated with relatively high clinical response rate to EGFR-tyrosine kinase inhibitors (TKIs) but not all responded to TKI. It has therefore become important to identify the additional surrogate markers regarding EGFR-TKI sensitivity.

Methods:

We first examined the effects of EGFR-TKIs, gefitinib and erlotinib, upon cell proliferation of lung adenocarcinoma cell lines. We then evaluated the gene profiles related to EGFR-TKI sensitivity using a microarray analysis. Results of microarray analysis led us to focus on carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family, CEACAM 3, 5, 6, 7, and 19, as potential further surrogate markers of EGFR-TKI sensitivity. We then examined the correlation between the status of CEACAM 3, 5, 6, 7, and 19 immunoreactivity in LADCA and clinicopathological parameters of individual cases.

Results:

In the cases with EGFR mutations, the status of all CEACAMs examined was significantly higher than that in EGFR wild-type patients, but there were no significant differences in the status of CEACAMs between TKI responder and nonresponder among 22 patients who received gefitinib therapy. However, among 115 EGFR mutation-negative LADCA patients, both CEACAM6 and CEACAM3 were significantly associated with adverse clinical outcome (CEACAM6) and better clinical outcome (CEACAM3).

Conclusion:

CEACAMs examined in this study could be related to the presence of EGFR mutation in adenocarcinoma cells but not represent the effective surrogate marker of EGFR-TKI in LADCA patients. However, immunohistochemical evaluation of CEACAM3/6 in LADCA patients could provide important information on their clinical outcome.

Mitochondrial superoxide production contributes to vancomycin-induced renal tubular cell apoptosis

Vancomycin chloride (VCM), a glycopeptide antibiotic, is widely used for the therapy of infections caused by methicillin-resistant Staphylococcus aureus. However, nephrotoxicity is a major adverse effect in VCM therapy. In this study, we investigated the cellular mechanisms underlying VCM-induced renal tubular cell injury in cultured LLC-PK1 cells. VCM induced a concentration- and time-dependent cell injury in LLC-PK1 cells. VCM caused increases in the numbers of annexin V-positive/PI-negative cells and TUNEL-positive cells, indicating the involvement of apoptotic cell death in VCM-induced renal cell injury. The VCM-induced apoptosis was accompanied by the activation of caspase-9 and caspase-3/7 and reversed by inhibitors of these caspases. Moreover, VCM caused an increase in intracellular reactive oxygen species production and mitochondrial membrane depolarization, which were reversed by vitamin E. In addition, mitochondrial complex I activity was inhibited by VCM as well as by the complex I inhibitor rotenone, and rotenone mimicked the VCM-induced LLC-PK1 cell injury. These findings suggest that VCM causes apoptotic cell death in LLC-PK1 cells by enhancing mitochondrial superoxide production leading to mitochondrial membrane depolarization followed by the caspase activities. Moreover, mitochondrial complex I may play an important role in superoxide production and renal tubular cell apoptosis induced by VCM.

Exocytosis of MTT formazan could exacerbate cell injury

MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] method is one of the most widely used methods to analyze cell proliferation and viability. It is taken up through endocytosis and is reduced by mitochondrial enzymes as well as endosomal/lysosomal compartments, then is transported to cell surfaces to form needle-like MTT formazans; however the effect of MTT itself still remains elusive. Our objective was to investigate the direct effects of MTT on in vitro SH-SY5Y cells. Results showed that the endocytosis of MTT did not cause obvious lesion and induce cell death, but the metabolism and exocytosis of MTT could dramatically damage cells. Our results also indicated that MTT could activate apoptosis related factors such as caspase-8, caspase-3 or accelerate the leakage of cell contents after the appearance of MTT formazan crystals. The present data suggest MTT method should be carefully chosen; otherwise the cell viability would be underestimated and incomparable.

Aquaporin-4 mediates astrocyte response to β-amyloid

It has been demonstrated that the water channel protein aquaporin-4 (AQP4) plays an important role in astrocyte plasticity in response to a variety of injuries or stimuli. However, the potential role of AQP4 in astrocyte response to β-amyloid (Aβ) has not been studied. The purpose of this study was to investigate this issue. Compared to media control, the lower concentrations of Aβ(1-42) (0.1-1 μM) increased AQP4 expression in cultured mouse cortical astrocytes, while the higher concentrations of Aβ(1-42) (10 μM) decreased AQP4 expression. AQP4 gene knockout reduced Aβ(1-42)-induced astrocyte activation and apoptosis, which was associated with a reduction in the uptake of Aβ via decreased upregulation of low-density lipoprotein receptor related protein-1. Moreover, time-course and levels of Aβ(1-42)-induced mitogen-activated protein kinase phosphorylation were altered in AQP4 null astrocytes compared with wild-type controls. Our data reveal a novel role of AQP4 in the uptake of Aβ by astrocytes, indicating that AQP4 is a molecular target for Alzheimer's disease.

Intratumoral localization of aromatase and interaction between stromal and parenchymal cells in the non-small cell lung carcinoma microenvironment

Estrogens produced as a result of intratumoral aromatization has been recently shown to play important roles in proliferation of human non-small cell lung carcinomas (NSCLC), but the details have remained largely unknown. Therefore, in this study, we evaluated the possible roles of intratumoral aromatase in NSCLCs as follows: (a) evaluation of intratumoral localization of aromatase mRNA/protein in six lung adenocarcinoma cases using laser capture microdissection combined with quantitative reverse transcriptase-PCR and immunohistochemistry; (b) examination of the possible effects of isolated stromal cells from lung carcinoma tissues on aromatase mRNA transcript expression in lung carcinoma cell lines (A549 and LK87) through a coculture system; and (c) screening of cytokines derived from stromal LK001S and LK002S cells using cytokine antibody arrays and subsequent evaluation of effects of these cytokines on aromatase expression in A549 and LK87. Both aromatase mRNA and protein were mainly detected in intratumoral carcinoma cells but not in stromal cells. Aromatase expression of A549 and LK87 was upregulated in the presence of LK001S or LK002S cells. Several cytokines such as interleukin-6 (IL-6), oncostatin M, and tumor necrosis factor-alpha, all known as inducible factors of aromatase gene, were detected in conditioned media of LK001S and LK002S cells. Treatment of both oncostatin M and IL-6 induced aromatase gene expression in A549 an LK87, respectively. These results all indicated that intratumoral microenvironments, especially carcinoma-stromal cell interactions, play a pivotal role in the regulation of intratumoral estrogen synthesis through aromatase expression in human lung adenocarcinomas.

Minocycline recovers MTT-formazan exocytosis impaired by amyloid beta peptide

Minocycline, a tetracycline antibiotic, has been reported to exert beneficial effects in models of Alzheimer's disease (AD). To characterize the mechanisms underlying the putative minocycline-related neuroprotection, we studied its effect in an in vitro model of AD. Primary hippocampal cultures were treated with β-amyloid peptide (Aβ) and cell viability was assessed by standard MTT-assay. Incubation with 10 μM Aβ for 24 h significantly inhibits cellular MTT-reduction without inducing morphological signs of enhanced cell death or increase in release of lactate dehydrogenase. This indicates that cell viability was not affected. The inhibition of MTT-reduction by Aβ was due to an acceleration of MTT-formazan exocytosis. Intriguingly, the Aβ-triggered increase in MTT-formazan exocytosis was abolished by co-treatment with minocycline. In vehicle-treated cells minocycline had no effect on formazan exocytosis. This hitherto unrecognized property of minocycline has to be noticed in the elucidation of the underlying mechanism of this promising neuroprotectant.

Neuroprotective activities of activated protein C mutant with reduced anticoagulant activity

The anticoagulant activated protein C (APC) protects neurons and endothelium via protease activated receptor (PAR)1, PAR3 and endothelial protein C receptor. APC is neuroprotective in stroke models. Bleeding complications may limit the pharmacologic utility of APC. Here, we compared the 3K3A-APC mutant with 80% reduced anticoagulant activity and wild-type (wt)-APC. Murine 3K3A-APC compared with wt-APC protected mouse cortical neurons from N-methyl-D-aspartate-induced apoptosis with twofold greater efficacy and more potently reduced N-methyl-D-aspartate excitotoxic lesions in vivo. Human 3K3A-APC protected human brain endothelial cells (BECs) from oxygen/glucose deprivation with 1.7-fold greater efficacy than wt-APC. 3K3A-APC neuronal protection required PAR1 and PAR3, as shown by using PAR-specific blocking antibodies and PAR1- and PAR3-deficient cells and mice. BEC protection required endothelial protein C receptor and PAR1. In neurons and BECs, 3K3A-APC blocked caspase-9 and -3 activation and induction of p53, and decreased the Bax/Bcl-2 pro-apoptotic ratio. After distal middle cerebral artery occlusion (dMCAO) in mice, murine 3K3A-APC compared with vehicle given 4:00 h after dMCAO improved the functional outcome and reduced the infarction volume by 50% within 3 days. 3K3A-APC compared with wt-APC multi-dosing therapy at 12:00 h, 1, 3, 5 and 7 days after dMCAO significantly improved functional recovery and reduced the infarction volume by 75% and 38%, respectively, within 7 days. The wt-APC, but not 3K3A-APC, significantly increased the risk of intracerebral bleeding as indicated by a 50% increase in hemoglobin levels in the ischemic hemisphere. Thus, 3K3A-APC offers a new approach for safer and more efficacious treatments of neurodegenerative disorders and stroke with APC.

Species-dependent neuroprotection by activated protein C mutants with reduced anticoagulant activity

Activated protein C (APC) is a protease with anticoagulant and cytoprotective activities. APC is neuroprotective in rodent models of stroke. But, an APC variant with reduced anticoagulant activity, 3K3A-APC, compared to wild-type APC shows greater neuroprotection with no risk for bleeding in stroke models. To determine whether 3K3A-APC exhibits species-dependent neuroprotection similar to that as seen with wild-type APC, we studied murine and human recombinant 3K3A-APC mutants which show approximately 80% reduced anticoagulant activity. Murine 3K3A-APC (0.2 mg/kg i.v.) administered at 4 h after embolic stroke improved substantially functional outcome and reduced by 80% the infract volume 7 days after stroke. Human 3K3A-APC was neuroprotective after embolic stroke in mice, but at significantly higher concentrations (i.e. 2 mg/kg i.v.). Species-dependent neuroprotection, i.e. murine > human 3K3A-APC, was confirmed in a mouse model of permanent middle cerebral artery occlusion. Human 3K3A-APC had by fivefold greater cytoprotective activity than murine 3K3A-APC in oxygen-glucose deprivation model in human brain endothelial cells, whereas murine 3K3A-APC was by 2.5-fold more potent than human 3K3A-APC in a mouse model of NMDA-induced neuronal apoptosis. Thus, 3K3A-APC exhibits species-dependent neuroprotection which should be taken into account when designing human trials for ischemic stroke with APC mutants.

Amphotericin B-induced renal tubular cell injury is mediated by Na+ Influx through ion-permeable pores and subsequent activation of mitogen-activated protein kinases and elevation of intracellular Ca2+ concentration

Amphotericin B (AMB) is one of the most effective antifungal agents; however, its use is often limited by the occurrence of adverse events, especially nephrotoxicity. The present study was designed to determine the possible mechanisms underlying the nephrotoxic action of AMB. The exposure of a porcine proximal renal tubular cell line (LLC-PK1 cells) to AMB caused cell injury, as assessed by mitochondrial enzyme activity, the leakage of lactate dehydrogenase, and tissue ATP depletion. Propidium iodide uptake was enhanced, while terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling was not affected by AMB, suggesting a lack of involvement of apoptosis in AMB-induced cell injury. The cell injury was inhibited by the depletion of membrane cholesterol with methyl-beta-cyclodextrin, which lowered the extracellular Na(+) concentration or the chelation of intracellular Ca(2+). The rise in the intracellular Ca(2+) concentration may be mediated through the activation of the ryanodine receptor (RyR) on the endoplasmic reticulum and the mitochondrial Na(+)-Ca(2+) exchanger, since cell injury was attenuated by dantrolene (an RyR antagonist) and CGP37157 (an Na(+)-Ca(2+) exchanger inhibitor). Moreover, AMB-induced cell injury was reversed by PD169316 (a p38 mitogen-activated protein [MAP] kinase inhibitor), c-Jun N-terminal kinase inhibitor II, and PD98059 (a MEK1/2 inhibitor). The phosphorylations of these MAP kinases were enhanced by AMB in a calcium-independent manner, suggesting the involvement of MAP kinases in AMB-induced cell injury. These findings suggest that Na(+) entry through membrane pores formed by the association of AMB with membrane cholesterol leads to the activation of MAP kinases and the elevation of the intracellular Ca(2+) concentration, leading to renal tubular cell injury.

Sex steroid receptors expression and hormone-induced cell proliferation in human osteosarcoma

Sex steroid receptors including estrogen receptors (ER), progesterone receptors (PR), and androgen receptors (AR) have been sporadically reported in human osteosarcoma or its cell lines. Therefore, sex steroids have been considered to play some roles in human osteosarcoma, but no systematic and detailed studies regarding the correlation between the status of these receptors in sarcoma cells and clinicopathological parameters have been reported. We examined the existence of ER, PR and AR in 28 cases of osteosarcoma using immunohistochemistry. We then characterized the potential influence of sex steroids on cell proliferation of osteosarcoma cells using MG-63 human osteosarcoma cell line, which expressed all of these receptors. ER-beta and PR were detected in the great majority of the cases (23 and 24 cases, respectively) but ER-alpha and aromatase were not detected in all the cases, and AR was detected only in eight cases. There was a significant positive correlation between ER-beta and Ki-67 (MIB1) labeling indexes. The absence of aromatase in tumors also suggests the relative importance of concentrations of circulating sex steroids. Proliferation of MG-63 cells was significantly stimulated by estradiol, progesterone, and 5 alpha-dihydrotestosterone (DHT), and was significantly suppressed by the addition of fulvestrant (ICI), mifepristone (RU), and hydroxiflutamide, blockers for ER, PR and AR, respectively. Sex steroids, particularly estrogen and progesterone, are considered to play important roles in the regulation of cell proliferation in human osteosarcoma. In addition, these data suggest the potential for a novel endocrine therapy in osteosarcoma using clinically available inhibitors of progesterone and estrogen actions.

Combined treatment with L-carnitine and a pan-caspase inhibitor effectively reverses amiodarone-induced injury in cultured human lung epithelial cells

Amiodarone is an effective class III antiarrhythmic drug, however, the pulmonary toxicity is one of the most life-threatening complications of its use. The present study was designed to determine the mechanisms underlying pulmonary toxicity of amiodarone. In cultured human lung epithelial cells A549, amiodarone caused cell injury characterized by mitochondrial membrane depolarization, ATP depletion, enhanced propidium iodide (PI) uptake and increase in the number of Annexin-V positive cells, although the population of PI-stained cells appeared earlier and was not identical to that of Annexin-V stained cells, suggesting that the apoptosis and necrosis appeared in different cells. The apoptosis was accompanied with the activation of caspase-2, -3 and -8 but not caspase-9, and reversed by these caspase inhibitors. However, the caspase inhibitors had no influence on mitochondrial membrane potential or PI uptake after exposure of A549 cells to amiodarone. In contrast, mitochondrial cofactors such as L-carnitine and acetyl-L: -carnitine attenuated mitochondrial membrane depolarization, abrogated cellular ATP depletion and reversed PI uptake without affecting Annexin-V positive cells. These finding suggest that different intracellular events operate to cause apoptosis and necrosis after exposure of pulmonary epithelial cells to amiodarone.

Involvement of both tumor necrosis factor-α-induced necrosis and p53-mediated caspase-dependent apoptosis in nephrotoxicity of cisplatin

We previously reported that necrosis occurs predominantly in porcine renal tubular LLC-PK1 cells, when the cells were exposed transiently to a high concentration of cisplatin. Moreover, we demonstrated that generation of reactive oxygen species and subsequent production of tumor necrosis factor-alpha (TNF-alpha) through phosphorylation of p38 MAPK are implicated in the pathogenesis of cisplatin-induced renal cell injury. However, some TUNEL-positive cells appeared in renal proximal tubules of rats after systemic injection of cisplatin, suggesting an involvement of apoptosis. In the present study, we found in LLC-PK1 cells that both apoptosis and necrosis were elicited when the cells were exposed to 200 microM cisplatin for 1 h followed by incubation for 24 h in the presence of 20 microM cisplatin. The cisplatin-induced necrosis was largely attenuated by the antioxidant N-acetylcysteine, while apoptosis was prevented by the specific inhibitors for caspases-2, -8, and -3 and a p53 inhibitor pifithrin-alpha but not by the p38 MAPK inhibitor SB203580. On the other hand, SB203580 attenuated the cisplatin-induced increase in TNF-alpha production. These findings suggest that p53-mediated activations of caspases-2, -8 and -3 play a key role in cisplatin-induced renal cell apoptosis, while oxidative stress-induced TNF-alpha synthesis via p38 MAPK phosphorylation contributed to the necrosis.

Formation of Amyloids by Aβ-(1–42) on NGF-differentiated PC12 Cells: Roles of Gangliosides and Cholesterol

The conversion of soluble, non-toxic amyloid beta-protein (Abeta) to aggregated, toxic Abeta could be the key step in the development of Alzheimer's disease. Liposomal studies have proposed that Abeta-(1-40) preferentially recognizes a cholesterol-dependent cluster of gangliosides and a conformationally altered form of Abeta promotes the aggregation of the protein. Cell experiments using fluorescein-labeled Abeta-(1-40) supported this model. Here, the interaction of native Abeta-(1-42) with unfixed rat pheochromocytoma PC12 cells was visualized using the amyloid-specific dye Congo red. Abeta-(1-42) preferentially bound to ganglioside and cholesterol-rich domains of cell membranes and formed amyloids in a time-dependent manner. These observations corroborate the model involving ganglioside-mediated accumulation of Abeta. The NGF-induced differentiation of PC12 cells into neuron-like cells caused a marked increase in both gangliosides and cholesterol, and thereby greatly potentiated the accumulation and cytotoxicity of Abeta-(1-42). NGF-differentiated cells exposed to Abeta-(1-42) had degenerated neurites, in which ganglioside and cholesterol-rich domains were localized, preceding cell death. A reduction in the amount of cholesterol by the cholesterol synthesis inhibitor compactin almost nullified the formation of amyloids by Abeta-(1-42). Our system using NGF-differentiated PC12 cells and Congo red is useful for screening inhibitors of the formation of amyloids by and cytotoxicity of Abeta.

Biomimicking Extracellular Matrix: Cell Adhesive RGD Peptide Modified Electrospun Poly(D,L-lactic-co-glycolic acid) Nanofiber Mesh

A cell adhesive peptide, Arg-Gly-Asp (RGD), was immobilized onto the surface of electrospun poly(D,L-lactic-co-glycolic acid) PLGA nanofiber mesh in an attempt to mimic an extracellular matrix structure. A blend mixture of PLGA and PLGA-b-PEG-NH(2) di-block copolymer dissolved in a 1:1 volume mixture of dimethylformamide and tetrahydrofuran was electrospun to produce a nanofiber mesh with functional primary amino groups on the surface. Various electrospinning parameters, such as polymer concentration and the blend ratio, were optimized to produce a nanofiber mesh with desirable morphology, surface characteristics, and fiber diameter. A cell adhesive peptide, GRGDY, was covalently grafted onto the aminated surface of the electrospun mesh under a hydrating condition. The amounts of surface primary amino groups and grafted RGD peptides were quantitatively determined. Cell attachment, spreading, and proliferation were greatly enhanced in the RGD modified electrospun PLGA nanofiber mesh compared with that of the unmodified one.

Dysregulation of the Hedgehog pathway in human hepatocarcinogenesis

Hedgehog (Hh) pathway activation promotes tumors in several endodermally derived tissues, but its role in the pathogenesis of hepatocellular carcinoma (HCC) is unknown. Although normal hepatocytes lack Hh signaling, activation of the Hh pathway in endodermal progenitors is required for liver development. Thus, we hypothesized that hepatocarcinogenesis may involve regulation of Hh signaling. This pathway is activated when Hh ligand binds to its receptor, Patched (PTC). In an unoccupied state, PTC normally functions as a tumor suppressor that inhibits Smoothened (SMO), a proto-oncoprotein, from activating downstream components and transcription of target genes. Here we show that in HCCs, overexpression of the Smo proto-oncogene, as well as an increase in the stoichiometric ratio of Smo to Ptc mRNA levels, correlated with tumor size, a prognostic indicator in HCC biology. In one tumor we identified a novel Smo mutation in an evolutionarily conserved residue. We also demonstrated that HCC cell lines (HepG2 and Hep3B) expressed Hh pathway components and activated Hh transcriptional targets. In Hep3B cells, cyclopamine, an inhibitor of wild-type SMO, had no effect, but KAAD-cyclopamine, a blocker of oncogenic SMO, inhibited Hh signaling activity by 50%, decreased expression of the hepatocarcinogenic oncogene, c-myc, by 8-fold, and inhibited the growth rate of Hep3B cells by 94%. These data support our hypothesis that Hh signaling is dysregulated in human hepatocarcinogenesis. We demonstrate that overexpression and/or tumorigenic activation of the Smo proto-oncogene mediates c-myc overexpression which plays a critical role in hepatocarcinogenesis and suggests that Smo is a prognostic factor in HCC tumorigenesis.

A prostacyclin analog prevents radiocontrast nephropathy via phosphorylation of cyclic AMP response element binding protein

We reported previously that radiocontrast medium induces caspase-dependent apoptosis and that cAMP analogs inhibit cell injury in cultured renal tubular cells. In the present study, cellular mechanisms underlying the protective effects of cAMP were determined. Ioversol, a radiocontrast medium, caused cell injury accompanied by decreases in Bcl-2, increases in Bax, and caspase activation in LLC-PK1 cells. Both cell injury and cellular events induced by ioversol were inhibited by dibutyryl cAMP and the prostacyclin analog beraprost. Dibutyryl cAMP increased phosphorylation of Akt and CREB, both of which were reversed by H89, wortmannin and the Akt inhibitor SH-6. The protective effect of dibutyryl cAMP was also reversed by these kinase inhibitors. In dominant-negative CREB-transfected cells, dibutyryl cAMP no longer prevented cell injury or inhibited changes in mRNA expression of Bcl-2 and Bax. In mice with unilateral renal occlusion, ioversol increased urinary excretion of N-acetyl-beta-d-glucosaminidase with concomitant decreases in Bcl-2 mRNA, increases in Bax mRNA, activation of caspase-3, and induction of apoptosis in tubular and interstitial cells. Beraprost completely reversed these in vivo effects of ioversol. These findings suggest that elevation of endogenous cAMP effectively prevents radiocontrast nephropathy through activation of A kinase/PI 3-kinase/Akt followed by CREB phosphorylation and enhanced expression of Bcl-2.

Protection of rat primary hippocampal cultures from Aβ cytotoxicity by pro-inflammatory molecules is mediated by astrocytes

The brain of Alzheimer's disease patients shows abundant dystrophic neurites in close proximity to fibrillar beta-amyloid (A beta) plaques, and activated glial cells. We evaluated the influence of pro-inflammatory molecules (LPS + IFN-gamma) on A beta(1-42) neurotoxicity. 2 microM A beta(1-42) induced apoptosis of hippocampal cells and LPS + IFN-gamma reduced the apoptosis induced by A beta. However, LPS + IFN-gamma prevented apoptosis only in hippocampal cultures containing astrocytes. Also, LPS + IFN-gamma induced the secretion of TGF beta, a cytokine having neuroprotective effects, only in hippocampal cultures that contained astrocytes. Astrocytes had a regulatory effect over microglial and neuronal responses to A beta. The results suggest that LPS + IFN-gamma, traditionally considered as pro-apoptotic, reduced apoptosis induced by A beta through the activation of neuroprotective mechanisms mediated by astrocytes. We propose that astrocytes are pivotal in the modulation of inflammation of the CNS. The impairment of the regulatory functions performed by activated astrocytes could represent an important pathogenic mechanism for neurodegenerative diseases.

Growth inhibitory effect of alk(en)yl thiosulfates derived from onion and garlic in human immortalized and tumor cell lines

Two alk(en)yl thiosulfates, sodium n-propyl thiosulfate (NPTS) and sodium 2-propenyl thiosulfate (2PTS), are natural constituents of onion and garlic, respectively, which were identified originally as causative agents of onion- and garlic-induced hemolytic anemia in dogs. As a continuation of our studies on the beneficial functions of NPTS and 2PTS, in the present study, we investigated the antitumor effects of these compounds. They were shown to inhibit the in vitro proliferation of three human tumorigenic cell lines, WiDr, 293 and HL-60, in a dose-dependent manner. Overall, NPTS seemed to have weak activity for inhibiting cell growth compared with 2PTS, though not in WiDr cells, which were sensitive to both compounds. NPTS and 2PTS caused oxidative damage to HL-60 cells and induced apoptosis. The extent of apoptosis was approximately proportional to that of the oxidative damage and also to that of the cytotoxicity caused by these compounds. These results suggest that the alk(en)yl thiosulfates have an antitumor effect through the induction of apoptosis initiated by oxidative stress.

Analysis of gene expression induced by diethylstilbestrol (DES) in human primitive Müllerian duct cells using microarray

The Mullerian ducts are strongly influenced by natural estrogen, estradiol (E2) and diethylstilbestrol (DES) in their development. We screened E2 and DES responsive genes using a microarray analysis in human primitive Mullerian duct cell line, EMTOKA cells expressed estrogen receptor (ER) beta. c-myc oncogene and other target genes expression was detected in cells treated by high-dose DES, but ER antagonist ICI 182,780 could not prevent c-myc induction above. Results of our present study suggested the presence of ER independent pathway in oncogenes induction process by high-dose DES treatment in a human primitive Mullerian duct cell line.

Mishandling of the therapeutic peptide glucagon generates cytotoxic amyloidogenic fibrils

PURPOSE

Some therapeutic peptides exhibit amyloidogenic properties that cause insolubility and cytotoxicity against neuronal cells in vitro. Here, we characterize the conformational change in monomeric therapeutic peptide to its fibrillar aggregate in order to prevent amyloidogenic formation during clinical application.

METHODS

Therapeutic peptides including glucagon, porcine secretin, and salmon calcitonin were dissolved in acidic solution at concentrations ranging from 1 mg/ml to 80 mg/ml and then aged at 37 degrees C. Amyloidogenic properties were assessed by circular dichroism (CD), electron microscopy (EM), staining with beta-sheet-specific dyes, and size-exclusion chromatography (SEC). Cytotoxic characteristics were determined concomitantly.

RESULTS

By aging at 2.5 mg/ml or higher for 24 h, monomeric glucagon was converted to fibrillar aggregates consisting of a beta-sheet-rich structure with multimeric states of glucagon. Although no aggregation was observed by aging at the clinical concentration of 1 mg/ml for 1 day, 30-day aging resulted in the generation of fibrillar aggregates. The addition of anti-glucagon serum significantly inhibited fibrillar conversion of monomeric glucagon. Glucagon fibrils induced significant cell death and activated an apoptotic enzyme, caspase-3, in PC12 cells and NIH-3T3 cells. Caspase inhibitors attenuated this toxicity in a dose-dependent manner, indicating the involvement of apoptotic signaling pathways in the fibrillar formation of glucagon. On the contrary to glucagon, salmon calcitonin exhibited aggregation at a much higher concentration of 40 mg/ml and secretin showed no aggregation at the concentration as high as 75 mg/ml.

CONCLUSIONS

These results indicated that glucagon was self-associated by its beta-sheet-rich intermolecular structure during the aging process under concentrated conditions to induce fibrillar aggregates. Glucagon has the same amyloidogenic propensities as pathologically related peptides such as beta-amyloid (Abeta)1-42 and prion protein fragment (PrP)106-126 including conformational change to a beta-sheet-rich structure and cytotoxic effects by activating caspases. These findings suggest that inappropriate preparation and application of therapeutic glucagon may cause undesirable insoluble products and side effects such as amyloidosis in clinical application.

Sympathetic nervous system regulation of liver repair

This chapter reviews recent evidence that the sympathetic nervous system (SNS) regulates liver repair by modulating the phenotypes of hepatic stellate cells (HSCs), the liver's principal fibrogenic cells, and hepatic epithelial progenitors, i.e., oval cells. SNS nerve fibers touch HSCs and these cells express adrenoceptors, suggesting that HSCs may be targets for SNS neurotransmitters. HSCs also contain catecholamine biosynthetic enzymes, release norepinephrine (NE), and are growth-inhibited by adrenoceptor antagonists. In addition, HSCs from mice with reduced levels of NE grow poorly in culture and exhibit inhibited activation during liver injury. Finally, growth and injury-related fibrogenic responses are rescued by adrenoceptor agonists. Thus, certain SNS inhibitors (SNSIs) protect experimental animals from cirrhosis. Conversely, SNSIs enhance the hepatic accumulation of oval cells (OCs) in injured livers. This response is associated with improved liver injury. Because SNSIs do not affect the expression of cytokines, growth factors, or growth factor receptors that are known to regulate OCs, and OCs express adrenoceptors, it is conceivable that catecholamines influence OCs by direct interaction with OC adrenoceptors. Given evidence that the SNS regulates the viability and activation of HSCs and OCs differentially, SNSIs may be novel therapies to improve the repair of damaged livers.

A practical note on the use of cytotoxicity assays

In this study, four cytotoxicity detection assays and four cytotoxic mechanisms were compared in one cellular system. Cellular responses and their effects were characterized. The assays used are based on different modes of detection like LDH release, MTT metabolism, neutral red uptake and the ATP content of treated cells. As cytotoxic mechanisms were used the model agents triton X-100, chloroquine and sodium azide (which are common in cell culture) as well as an ion channel (NMDA) mediated excitotoxicity cell death (which is specific for the cell line used). We found major differences in the calculated EC(50)-values for the cytotoxic effect of choroquine (0.1 up to 200 mM) and for sodium azide (4 up to 1300 mM) depending on the assay used. Therefore, it is important to choose a suitable cytotoxicity assay depending on the supposed cell death mechanism. As this study compares the strengths and weaknesses of the most common assays, it can help to find the appropriate one.

Long-acting analogue of vasoactive intestinal peptide, [R15, 20, 21, L17]-VIP-GRR (IK312532), protects rat alveolar L2 cells from the cytotoxicity of cigarette smoke

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) act as neurotransmitters in numerous biological responses. We previously reported that the replacement of Lys by Arg, and Met by Leu in VIP (IK312532; [Arg15, 20, 21, Leu17]-VIP) resulted in a significant improvement in metabolic stability and biological activity. In the present study, we investigated the effect of VIP and its related peptides including long-acting VIP derivative (IK312532) and PACAP27 on the cytotoxicity of cigarette smoke extract (CSE), a causative factor of chronic obstructive pulmonary disease (COPD), in rat alveolar L2 cells. RT-PCR displayed the dominant expression of mRNA for the VIP-specific VPAC2 receptor in L2 cells, and VIP and the related peptides showed the specific binding activity and potent stimulation of adenylate cyclase. CSE at a concentration of 0.1% or higher induced significant apoptotic death of L2 cells. Interestingly, the addition of neuropeptides at a concentration of 10(-11) M or higher in L2 cells with CSE (0.25%) resulted in significant attenuation of cell death with the deactivation of CSE-evoked caspase-3 activity. IK312532 was much stable against the enzymatic digestion compared to VIP, and the protective effect of IK312532 was 1.6-fold higher than that of VIP. Taken together with our previous report showing that IK312532 has long-acting relaxant activity in the lung, IK312532 may be a potential candidate for drug treatment of asthma and COPD.

Novel heparan sulfate mimetic compounds as antitumor agents

Heparan sulfate glycosaminoglycans (HSGAGs) are involved in tumor cell growth, adhesion, invasion, and migration, due to their interactions with various proteins. In this study, novel HSGAG-mimetic compounds (KI compounds) were designed and synthesized. As a result of cell-based assays, KI-105 was found to exert potent inhibitory activities against migration and invasion of human fibrosarcoma HT1080 cells. The present results indicate that a novel invasion/migration inhibitor, KI-105, can increase the adherence of HT1080 cells. It was conceivable that this cellular effect was caused by an increase in the amount of cell-surface HSGAGs and focal adhesions. Although further investigations are needed to decipher the molecular mechanism of KI-105, it is suggested that heparanase and Cdc42 are involved in its biological effects.

Structure-based design of a selective heparanase inhibitor as an antimetastatic agent

Heparanase is an endo-β-d-glucuronidase that degrades heparan sulfate glycosaminoglycans in the extracellular matrix and the basement membrane and is well known to be involved in tumor cell invasion and angiogenesis. We have focused on heparanase as a target for antitumor agents, especially antimetastatic agents. (R)-3-hexadecanoyl-5-hydroxymethyltetronic acid (RK-682) was found to display an inhibitory activity against heparanase in our screening of natural sources. Because RK-682 has been reported to show inhibitory activities against several enzymes, we have tried to develop selective heparanase inhibitors using the method of rational drug design. Based on the structure of the heparanase/RK-682 complex, we speculated that selective inhibitory activity against heparanase could be acquired by arylalkylation, namely, by benzylation of the 4-position of RK-682. Among the rationally designed 4-alkyl-RK-682 derivatives, 4-benzyl-RK-682 has been found to possess a selective inhibitory activity for heparanase (IC50 for heparanase, 17 μmol/L; IC50 for other enzymes, &gt;100 μmol/L). 4-Benzyl-RK-682 also inhibited the invasion and migration of human fibrosarcoma HT1080 cells (IC50 for invasion, 1.5 μmol/L; IC50 for migration, 3.0 μmol/L). On the other hand, RK-682 had no inhibitory effect on the invasion and migration of HT1080 cells at doses of up to 100 μmol/L.

Cyclic AMP reverses radiocontrast media-induced apoptosis in LLC-PK1 cells by activating A kinase/PI3 kinase

BACKGROUND

Radiographic contrast material is one of agents that are prone to cause nephropathy, although little is known about cellular mechanisms underlying contrast media-induced renal failure. The present study was designed to determine the role of caspase in contrast media-induced renal injury. The modulation by cyclic adenosine monophosphate (cAMP) of cell injury was subsequently examined.

METHODS

LLC-PK1 cells (a proximal renal tubular cell line of porcine origin) were exposed to diverse contrast media for 30 minutes followed by incubation for 24 hours in normal medium. Cell viability was assessed by mitochondrial enzyme activity and propidium iodide stain. Apoptosis was determined by DNA electrophoresis and annexin V stain. Caspase activity was measured fluorometrically. The mRNA for bax and bcl-2 was determined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Iodinated and magnetic resonance contrast media reduced cell viability due to apoptosis. The cell damage induced by a non-ionic contrast medium ioversol was inhibited by specific inhibitors for caspase-3 and -9 but not caspase-8. Ioversol enhanced the activities of caspase-3 and -9, but to a lesser extent, caspase-8. The bax mRNA was enhanced, while bcl-2 mRNA was reduced, after exposure to ioversol. All of these actions of ioversol were reversed by dibutyl cAMP in the manner sensitive to a protein kinase A inhibitor H89 and a phosphatidylinositol 3 (PI3) kinase inhibitor wortmannin.

CONCLUSION

We demonstrated for the first time that cAMP reversed caspase-dependent apoptotic renal cell damage caused by contrast media. Both protein kinase A and PI3 kinase might be involved in protective effect of cAMP.

Immortalization of human nucleus pulposus cells by a recombinant SV40 adenovirus vector: establishment of a novel cell line for the study of human nucleus pulposus cells

STUDY DESIGN

Establishment and characterization of a de novo cell line derived from human nucleus pulposus cells using a recombinant simian virus 40 (SV40) adenovirus vector.

OBJECTIVES

To assess the feasibility of human nucleus pulposus cell line procurement and to evaluate the character of the resultant outcome to better understand the nature of human nucleus pulposus cells.

SUMMARY OF BACKGROUND DATA

Despite recent advances in disc cell biologic research, the fundamental nature of nucleus pulposus cells, especially in the context of human cell lines, is still not well understood. Therefore, a broad-based analysis of these cells is of significant necessity. Because of the limited amount of existing human cells, establishment of an immortal cell line would greatly facilitate resource supply.

METHODS

After release of informed consent, tissue samples of nucleus pulposus were obtained from the lumbar intervertebral disc of a 19-year-old man undergoing anterior fusion for burst fracture. Samples with no apparent damage were selected and digested enzymatically for primary culture and then were infected with recombinant SV40 adenovirus vector (Ad/SV40). The infected cells were maintained in culture for more than 40 population doublings, after which they were considered immortalized. Next, confirmation of expression of T antigen was performed and resultant immortalized cell lines were designated and classified as human nucleus pulposus cell line derived from Ad/SV40 infection-1 (HNPSV-1). HNPSV-1 cells were characterized and compared with their mother cells under two designated culture conditions: monolayer and three-dimensional. Morphologic and immunocytochemical analyses were performed at various intervals. Cell proliferation, DNA synthesis, proteoglycan synthesis, gene expression profiling, and karyotypic analyses were also performed. Moreover, HNPSV-1 cells were injected into rabbit discs to assess the presence of tumorigenesis.

RESULTS

Recombinant SV40 adenovirus vector infected nucleus pulposus cells with relatively high efficiency (90%> at multiplicity of infection 100). HNPSV-1 demonstrated marked prolongation of cell life with continuous cell doublings for over 5 months (60-100 cell population doublings). Despite significant increase in cell proliferation and DNA synthesis when compared with its mother cells, resultant cell lines expressed strikingly similar cell morphology and functional characteristics. Atypical karyotypes were noted; however, no apparent tumorigenesis was seen in rabbit discs 24 weeks after injection of HNPSV-1.

CONCLUSIONS

HNPSV-1 was successfully established using recombinant SV40 adenovirus vector. Results showed that human nucleus pulposus cells are capable of immortalization with maintenance of original cell characteristics. It is anticipated that these cells will be useful for in vitro studies of the biologic nature of human nucleus pulposus cells.

Apoptotic injury in cultured human hepatocytes induced by HMG-CoA reductase inhibitors

Hepatotoxicity is the major complaint during therapy with lipid-lowering agents such as statins, although the cellular mechanisms underlying the statin-induced liver injury are not fully understood. Using cultured human hepatocytes, we investigated the effects of lipophilic as well as hydrophilic statins on the cell viability. Lipophilic statins, including simvastatin, lovastatin, cerivastatin, fluvastatin and atorvastatin, reduced the viability of hepatocytes as assessed by the mitochondrial enzyme activity to reduce WST-8, however, a hydrophilic pravastatin did not cause cell injury. The simvastatin-induced loss of cell viability was attenuated by mevalonate or geranylgeranyl pyrophosphate. Simvastatin-induced DNA fragmentation and increased the number of cells stained with annexin V and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling, both of which were reversed by caspase inhibitors such as zDEVD-fmk, zLEHD-fmk and zIETD-fmk. Consistent with these data, the activities of caspase-3, caspase-9 and caspase-8 were elevated by simvastatin. Simvastatin reduced the protein content and mRNA expression for bcl-2 without affecting bax mRNA expression. On the other hand, both lipophilic and hydrophilic statins significantly reduced the content of endogenous cholesterol. These findings suggest that lipophilic statins cause an apoptotic injury in human hepatocytes by stimulating caspase-3 subsequent to the activation of caspase-9 and caspase-8, in which the inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase may be involved.

A prostacyclin analog beraprost sodium attenuates radiocontrast media-induced LLC-PK1 cells injury

BACKGROUND

We previously reported that the apoptotic injury in a porcine renal tubular cell line LLC-PK1 cells induced by radiographic contrast media is attenuated by dibutyl cyclic adenosine monophosphate (cAMP) in a manner dependent on protein kinase A (PKA). The present study was designed to determine whether the elevation of endogenous cAMP with beraprost sodium, a prostacyclin analog, reduces the contrast material-induced renal tubular injury.

METHODS

The cell injury was induced by the exposure to ioversol for 30 minutes followed by further incubation for 24 hours in the absence of the contrast medium, and assessed by propidium iodide uptake and WST-8 assay. Apoptosis was determined by annexin V stain and DNA electrophoresis. Caspase activity was assessed by the enzymatic degradation of specific substrate peptides. Bax and bcl-2 mRNA expression were determined by reverse transcription-polymerase chain reaction (RT-PCR). The phosphorylation of cAMP-responsive element binding protein (CREB) was measured by an immunofluorescent method.

RESULTS

Beraprost sodium (10 to 1000 nmol/L) attenuated concentration dependently the ioversol-induced decrease in cell viability, in which the protective effect of beraprost sodium was dependent on the elevation of cellular cAMP content. The phosphorylation of CREB was enhanced by beraprost sodium in PKA-dependent manner. In addition, beraprost sodium reversed the ioversol-induced increase in bax mRNA with a concomitant decrease in bcl-2 mRNA and subsequent activation of caspase-3 and -9, thereby resulting in the inhibition of the nuclear damage.

CONCLUSION

Beraprost sodium reversed the contrast media-induced renal tubular cells in culture by activating cAMP/protein kinase A-dependent phosphorylation of CREB and subsequent enhancement of bcl-2 expression.

Vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide attenuate the cigarette smoke extract-induced apoptotic death of rat alveolar L2 cells

Chronic obstructive pulmonary disease is a major clinical disorder usually associated with cigarette smoking. A central feature of chronic obstructive pulmonary disease is inflammation coexisting with an abnormal protease/antiprotease balance, leading to apoptosis and elastolysis. In an in vitro study of rat lung alveolar L2 cells, cigarette smoke extract (CSE) induced apoptotic cell death. Exposure of L2 cells to CSE at a concentration of 0.25% resulted in a 50% increase of caspase-3 and matrix metalloproteinase (MMP) activities. Specific inhibitors for caspases and MMPs attenuated the cytotoxicity of CSE. RT-PCR amplification identified VPAC2 receptors in L2 cells. A radioligand-binding assay with (125)I-labeled vasoactive intestinal peptide (VIP) found high affinity and saturable (125)I-labeled VIP-binding sites in L2 cells. VIP and pituitary adenylate cyclase-activating polypeptide (PACAP27) were approximately equipotent for both VIP receptor binding and stimulation of cAMP production in L2 cells. Both neuropeptides, at concentrations higher than 10(-13) m, produced a concentration-dependent inhibition of CSE-induced cell death in L2 cells. VIP, at 10(-7) m, reduced CSE-stimulated MMP activity and caspase-3 activation. The present study has shown that VIP and PACAP27 significantly attenuate the cytotoxicity of CSE through the activation of VPAC2 receptor, and the protective effect of VIP may partly be the result of a reduction in the CSE-induced stimulation of MMPs and caspases.

Rational design and synthesis of novel heparan sulfate mimetic compounds as antiadhesive agents

A biological evaluation of the antiadhesive activity of novel heparan sulfate glycosaminoglycans mimetic compounds (KI-compounds) is described. In an adhesion assay, KI-111 [2-(4-fluoro-3-nitrobenzoyl)benzoic acetic anhydride] was found to exert potent inhibitory activities against the adhesion of human fibrosarcoma HT1080 cells and HeLa cells to fibronectin. Cell growth, migration, and invasion of HT1080 cells were also inhibited by KI-111 at almost equal concentrations.

Cytoplasmic vacuolation in cultured rat astrocytes induced by an organophosphorus agent requires extracellular signal-regulated kinase activation

There are various toxic chemicals that cause cell death. However, in certain cases deleterious agents elicit various cellular responses prior to cell death. To determine the cellular mechanisms by which such cellular responses are induced is important, but sufficient attention has not been paid to this issue to date. In this study, we showed the characteristic effects of an organophosphorus (OP) agent, bis(pinacolyl methyl)phosphonate (BPMP), which we synthesized for the study of OP nerve agents, on cultured rat astrocytes. Morphologically, BPMP induced cytoplasmic vacuolation and stellation in the rat astrocytes. Cytoplasmic vacuolation is a cell pathological change observed, for example, in vacuolar degeneration, and stellation has been reported in astrocytic reactions against various stimuli. By pretreatment with cycloheximide, a protein synthesis inhibitor, stellation was inhibited, although vacuolation was not. Cell staining with a mitochondrion-selective dye indicated that the vacuolation probably occurs in the mitochondria that are swollen and vacuolatred in the center. Interestingly, the extracellular signal-regulated kinase (ERK) cascade inhibitor inhibited vacuolation and, to some extent, stellation. These results suggest that the ERK signaling cascade is important for the induction of mitochondrial vacuolation. We expect that a detailed study of these astrocytic reactions will provide us new perspectives regarding the variation and pathological significance of cell morphological changes, such as vacuolar degeneration, and also the mechanisms underlying various neurological disorders.

Backscattered light confocal imaging of intracellular MTT-formazan crystals

Metabolically active animal and plant cells reduce MTT tetrazolium salt to a corresponding nonfluorescent formazan. Reduction of MTT by viable cells is exploited in a number of tests widely used in biological research. The aim of this study was to optimize a microscopy method of detecting small crystals of MTT-formazan formed in intact cells maintained in in vitro cultures. We examined scattering properties of small intracellular crystals of MTT formazan and found that the efficiency of light scattering was dependent on wavelength. Small (<3 microm) crystals of MTT-formazan, formed in viable cells, scattered red, but not blue, light. Large crystals, which are formed later at a stage when cells begin to lose viability, scattered both red and blue light. We conclude that optimal detection of early stages of crystallization of MTT-formazan in living cells is possible using confocal microscopy of red, but not blue, scattered light. High contrast and resolution of images can be achieved by filtering out interference effects in the frequency domain.