Identification of apoptotic cells by formamide-induced dna denaturation in condensed chromatin

Inducing breast cancer cell death: The impact of taxodone on proliferation through apoptosis

Breast cancer is the most prevalent form of cancer in women and a major contributor to cancer-related fatalities worldwide. Several factors play a role in the development of breast cancer, encompassing age, hormone levels, etc. Taxodone has shown significant anti-tumor properties in both laboratory experiments and living organisms. However, its impact on the human MCF-7 breast cancer cell line has not been researched. This investigation explores the chemo-preventive potential of taxodone in the MCF-7 breast cancer cells. The anticancer potential of taxodone against MCF-7 cells was determined by MTT assay. Further, the induction of apoptosis in MCF-7 breast cancer cells was confirmed via ELISA, which indicated the increased incidences of chromatin condensation and ssDNA breakage in the MCF-7 apoptotic cells upon 24 h of taxodone treatment. The intracellular reactive oxygen species (ROS) level was evaluated using H2DCFDA fluorescent dye to elucidate the mechanism of action triggered upon taxodone treatment. The increasing intercellular ROS level sequentially activated the caspase-mediated apoptosis pathway. Consequently, the outcomes revealed that taxodone decreased the cell viability of MCF-7 dose-dependently. Taxodone triggers apoptosis in MCF-7 cells by increasing intracellular ROS levels and activating the caspase cascade through the mitochondrial apoptosis-induced channel, an early marker of apoptosis onset. Our results indicate that taxodone exhibits anti-proliferative and apoptotic properties against human MCF-7 breast cancer cells, suggesting it to be a natural anticancer agent.

Current trends in luminescence-based assessment of apoptosis

Apoptosis, the most extensively studied type of cell death, is known to play a crucial role in numerous processes such as elimination of unwanted cells or cellular debris, growth, control of the immune system, and prevention of malignancies. Defective regulation of apoptosis can trigger various diseases and disorders including cancer, neurological conditions, autoimmune diseases and developmental disorders. Knowing the nuances of the cell death type induced by a compound can help decipher which therapy is more effective for specific diseases. The detection of apoptotic cells using classic methods has brought significant contribution over the years, but innovative methods are quickly emerging and allow more in-depth understanding of the mechanisms, aside from a simple quantification. Due to increased sensitivity, time efficiency, pathway specificity and negligible cytotoxicity, these innovative approaches have great potential for both in vitro and in vivo studies. This review aims to shed light on the importance of developing and using novel nanoscale methods as an alternative to the classic apoptosis detection techniques.

Augmented Therapeutic Potential of EC-Synthetic Retinoids in Caco-2 Cancer Cells Using an In Vitro Approach

Colorectal cancer therapies have produced promising clinical responses, but tumor cells rapidly develop resistance to these drugs. It has been previously shown that EC19 and EC23, two EC-synthetic retinoids, have single-agent preclinical anticancer activity in colorectal carcinoma. Here, isobologram analysis revealed that they have synergistic cytotoxicity with retinoic acid receptor (RAR) isoform-selective agonistic retinoids such as AC261066 (RARβ2-selective agonist) and CD437 (RARγ-selective agonist) in Caco-2 cells. This synergism was confirmed by calculating the combination index (lower than 1) and the dose reduction index (higher than 1). Flow cytometry of combinatorial IC₅₀ (the concentration causing 50% cell death) confirmed the cell cycle arrest at the SubG₀-G₁ phase with potentiated apoptotic and necrotic effects. The reported synergistic anticancer activity can be attributed to their ability to reduce the expression of ATP-binding cassette (ABC) transporters including P-glycoprotein (P-gp1), breast cancer resistance protein (BCRP) and multi-drug resistance-associated protein-1 (MRP1) and Heat Shock Protein 70 (Hsp70). This adds up to the apoptosis-promoting activity of EC19 and EC23, as shown by the increased Caspase-3/7 activities and DNA fragmentation leading to DNA double-strand breaks. This study sheds the light on the possible use of EC-synthetic retinoids in the rescue of multi-drug resistance in colorectal cancer using Caco-2 as a model and suggests new promising combinations between different synthetic retinoids. The current in vitro results pave the way for future studies on these compounds as possible cures for colorectal carcinoma.

Programmed cell death detection methods: a systematic review and a categorical comparison

Programmed cell death is considered a key player in a variety of cellular processes that helps to regulate tissue growth, embryogenesis, cell turnover, immune response, and other biological processes. Among different types of cell death, apoptosis has been studied widely, especially in the field of cancer research to understand and analyse cellular mechanisms, and signaling pathways that control cell cycle arrest. Hallmarks of different types of cell death have been identified by following the patterns and events through microscopy. Identified biomarkers have also supported drug development to induce cell death in cancerous cells. There are various serological and microscopic techniques with advantages and limitations, that are available and are being utilized to detect and study the mechanism of cell death. The complexity of the mechanism and difficulties in distinguishing among different types of programmed cell death make it challenging to carry out the interventions and delay its progression. In this review, mechanisms of different forms of programmed cell death along with their conventional and unconventional methods of detection of have been critically reviewed systematically and categorized on the basis of morphological hallmarks and biomarkers to understand the principle, mechanism, application, advantages and disadvantages of each method. Furthermore, a very comprehensive comparative analysis has been drawn to highlight the most efficient and effective methods of detection of programmed cell death, helping researchers to make a reliable and prudent selection among the available methods of cell death assay. Conclusively, how programmed cell death detection methods can be improved and can provide information about distinctive stages of cell death detection have been discussed.

Anti-Apoptotic and Anti-Inflammatory Role of Trans ε-Viniferin in a Neuron-Glia Co-Culture Cellular Model of Parkinson's Disease

The polyphenol trans-ε-viniferin (viniferin) is a dimer of resveratrol, reported to hold antioxidant and anti-inflammatory properties. The aims of our study were to evaluate the neuroprotective potential of viniferin in the nerve growth factor (NGF)-differentiated PC12 cells, a dopaminergic cellular model of Parkinson's disease (PD) and assess its anti-inflammatory properties in a N9 microglia-neuronal PC12 cell co-culture system. The neuronal cells were pre-treated with viniferin, resveratrol or their mixture before the administration of 6-hydroxydopamine (6-OHDA), recognized to induce parkinsonism in rats. Furthermore, N9 microglia cells, in a co-culture system with neuronal PC12, were pre-treated with viniferin, resveratrol or their mixture to investigate whether these polyphenols could reduce lipopolysaccharide (LPS)-induced inflammation. Our results show that viniferin as well as a mixture of viniferin and resveratrol protects neuronal dopaminergic cells from 6-OHDA-induced cytotoxicity and apoptosis. Furthermore, when viniferin, resveratrol or their mixture was used to pre-treat microglia cells in our co-culture system, they reduced neuronal cytotoxicity induced by glial activation. Altogether, our data highlight a novel role for viniferin as a neuroprotective and anti-inflammatory molecule in a dopaminergic cellular model, paving the way for nutraceutical therapeutic avenues in the complementary treatments of PD.

Cell death-inducing properties of selected dendrimers against different breast cancer and leukemia cell lines

Dendrimers represent an opportunity for targeted drug delivery into tumor cells. This is facilitated, for example, by loading of dendrimers with anticancer compounds. However, to assess the effects caused by such conjugates, knowledge of the cytotoxicity of the dendrimers themselves is necessary. The poly(amido amine)-derived dendrimers G₁ (Phe)₆ , G₁ (Dan)₃ , and G₂ were selected due to their different numbers of free amino groups and the poly(propylene imine) (PPI) dendrimer PPI-G₃ served as a reference. The compounds were evaluated for cell-death induction using breast cancer (MCF-7, MDA-MB-231) and leukemia (LAMA-84, K562, SD-1, SUP-B15) cell lines. The compounds exhibited concentration-dependent effects in the low micromolar range against the mammary carcinoma cells. A dependency on the generation, and particularly on the type of dendrimer, was deduced while the quantity of the free amino groups was subsidiary. G₂ revealed to be most cytotoxic, also against all tested leukemia cell lines. The cell line SD-1, however, was susceptible to all dendrimers. The mode of cell death was mainly determined by necrosis, especially at higher concentrations, while apoptosis played a subordinate role. The other dendrimers exerted no antimetabolic effects against LAMA-84, K562, and SUP-B15 cells. Therefore, these dendrimers are generally suitable as nontoxic drug carriers for leukemia cells.

Genotoxic Effects of Exposure to Gasoline Fumes on Petrol Pump Workers

Background:

Petrol pump workers are occupationally exposed to gasoline and its fumes consisting of several mutagenic chemicals.

Objective:

To evaluate the genotoxic effects of exposure to gasoline fumes on petrol pump workers.

Methods:

The study groups included 70 petrol pump workers (exposed group) and 70 healthy age-matched individuals with no known exposure (comparison group). Buccal micronucleus cytome assay (BMCyt) was performed to check the genotoxicity caused due to inhalation of gasoline fumes.

Results:

The frequencies of micronucleated cells, nuclear bud, condensed chromatin cells, karyorrhectic cells, pyknotic cells, and karyolytic cells were significantly higher in the exposed workers compared to the comparison group.

Conclusion:

Exposure to gasoline fumes is associated with increased frequency of cell abnormalities. This may lead to various health consequences including cancer in those occupationally exposed to gasoline fumes.

Flow cytometry in formamide treated cells

The use of formamide for the study in flow cytometry of cell cycle phases, by DNA content measurement in human cancer cell lines, was recently published. In this manuscript, we verify the possibility of extending the procedure to simultaneous analysis of other parameters. The results obtained, here reported, show that the treatment of samples by formamide is compatible with the simultaneous detection of DNA content and surface phenotypes, with quantification of replicating DNA and with measurement of cells with fractional content of DNA. For each of these three applications, we have adapted the procedure to gain simple, reproducible and above all advantageous protocols. Regarding the simultaneous analysis of DNA content and phenotyping the use of formamide achieves optimal DNA stoichiometric staining (C.V. < 3; G2/G1 ratio = 2 ± 0.05) and sufficient maintenance of physical parameters and membrane fluorescence. In the study of duplicating DNA labeled with click chemistry, our procedure eliminates paraformaldehyde (PFA) fixation improving the DNA stoichiometric staining and allows the use of 7-aminoactinomycin D (7-AAD) preserving the Alexa Fluor 488 quantum efficiency. Concerning the detection of cells with fractional content of DNA, permeabilization and fixation by formamide gives the advantage of resolve on linear scale sub-G1 cells from debris and to allow optimal sample recovery (>90%) which is essential in the study of cell necrobiology. Cells treatment by formamide, suitably modified for different applications, can be used to prepare cell samples for flow cytometry analyses that go far beyond stoichiometric staining of DNA.

Unique spectral signatures of the nucleic acid dye acridine orange can distinguish cell death by apoptosis and necroptosis

Cellular injury and death are ubiquitous features of disease, yet tools to detect them are limited and insensitive to subtle pathological changes. Acridine orange (AO), a nucleic acid dye with unique spectral properties, enables real-time measurement of RNA and DNA as proxies for cell viability during exposure to various noxious stimuli. This tool illuminates spectral signatures unique to various modes of cell death, such as cells undergoing apoptosis versus necrosis/necroptosis. This new approach also shows that cellular RNA decreases during necrotic, necroptotic, and apoptotic cell death caused by demyelinating, ischemic, and traumatic injuries, implying its involvement in a wide spectrum of tissue pathologies. Furthermore, cells with pathologically low levels of cytoplasmic RNA are detected earlier and in higher numbers than with standard markers including TdT-mediated dUTP biotin nick-end labeling and cleaved caspase 3 immunofluorescence. Our technique highlights AO-labeled cytoplasmic RNA as an important early marker of cellular injury and a sensitive indicator of various modes of cell death in a range of experimental models.

Oleuropein Prevents Neuronal Death, Mitigates Mitochondrial Superoxide Production and Modulates Autophagy in a Dopaminergic Cellular Model

Parkinson’s disease (PD) is a progressive neurodegenerative disorder, primarily affecting dopaminergic neurons in the substantia nigra. There is currently no cure for PD and present medications aim to alleviate clinical symptoms, thus prevention remains the ideal strategy to reduce the prevalence of this disease. The goal of this study was to investigate whether oleuropein (OLE), the major phenolic compound in olive derivatives, may prevent neuronal degeneration in a cellular dopaminergic model of PD, differentiated PC12 cells exposed to the potent parkinsonian toxin 6-hydroxydopamine (6-OHDA). We also investigated OLE’s ability to mitigate mitochondrial oxidative stress and modulate the autophagic flux. Our results obtained by measuring cytotoxicity and apoptotic events demonstrate that OLE significantly decreases neuronal death. OLE could also reduce mitochondrial production of reactive oxygen species resulting from blocking superoxide dismutase activity. Moreover, quantification of autophagic and acidic vesicles in the cytoplasm alongside expression of specific autophagic markers uncovered a regulatory role for OLE against autophagic flux impairment induced by bafilomycin A1. Altogether, our results define OLE as a neuroprotective, anti-oxidative and autophagy-regulating molecule, in a neuronal dopaminergic cellular model.

Maintenance of somatic tissue regeneration with age in short- and long-lived species of sea urchins

Aging in many animals is characterized by a failure to maintain tissue homeostasis and the loss of regenerative capacity. In this study, the ability to maintain tissue homeostasis and regenerative potential was investigated in sea urchins, a novel model to study longevity and negligible senescence. Sea urchins grow indeterminately, regenerate damaged appendages and reproduce throughout their lifespan and yet different species are reported to have very different life expectancies (ranging from 4 to more than 100 years). Quantitative analyses of cell proliferation and apoptosis indicated a low level of cell turnover in tissues of young and old sea urchins of species with different lifespans (Lytechinus variegatus, Strongylocentrotus purpuratus and Mesocentrotus franciscanus). The ability to regenerate damaged tissue was maintained with age as assessed by the regrowth of amputated spines and tube feet (motor and sensory appendages). Expression of genes involved in cell proliferation (pcna), telomere maintenance (tert) and multipotency (seawi and vasa) was maintained with age in somatic tissues. Immunolocalization of the Vasa protein to areas of the tube feet, spines, radial nerve, esophagus and a sub-population of circulating coelomocytes suggests the presence of multipotent cells that may play a role in normal tissue homeostasis and the regenerative potential of external appendages. The results indicate that regenerative potential was maintained with age regardless of lifespan, contrary to the expectation that shorter lived species would invest less in maintenance and repair.

Cucurbitacin E has neuroprotective properties and autophagic modulating activities on dopaminergic neurons

Natural molecules are under intensive study for their potential as preventive and/or adjuvant therapies for neurodegenerative disorders such as Parkinson's disease (PD). We evaluated the neuroprotective potential of cucurbitacin E (CuE), a tetracyclic triterpenoid phytosterol extracted from the Ecballium elaterium (Cucurbitaceae), using a known cellular model of PD, NGF-differentiated PC12. In our postmitotic experimental paradigm, neuronal cells were treated with the parkinsonian toxin 1-methyl-4-phenylpyridinium (MPP⁺) to provoke significant cellular damage and apoptosis or with the potent N,N-diethyldithiocarbamate (DDC) to induce superoxide (O₂^•−) production, and CuE was administered prior to and during the neurotoxic treatment. We measured cellular death and reactive oxygen species to evaluate the antioxidant and antiapoptotic properties of CuE. In addition, we analyzed cellular macroautophagy, a bulk degradation process involving the lysosomal pathway. CuE showed neuroprotective effects on MPP⁺-induced cell death. However, CuE failed to rescue neuronal cells from oxidative stress induced by MPP⁺ or DDC. Microscopy and western blot data show an intriguing involvement of CuE in maintaining lysosomal distribution and decreasing autophagy flux. Altogether, these data indicate that CuE decreases neuronal death and autophagic flux in a postmitotic cellular model of PD.

Assessment of antimicrobial (host defense) peptides as anti-cancer agents

Cationic antimicrobial (host defense) peptides (CAPs) are able to kill microorganisms and cancer cells, leading to their consideration as novel candidate therapeutic agents in human medicine. CAPs can physically associate with anionic membrane structures, such as those found on cancer cells, causing pore formation, intracellular disturbances, and leakage of cell contents. In contrast, normal cells are less negatively-charged and are typically not susceptible to CAP-mediated cell death. Because the interaction of CAPs with cells is based on charge properties rather than cell proliferation, both rapidly dividing and quiescent cancer cells, as well as multidrug-resistant cancer cells, are targeted by CAPs, making CAPS potentially valuable as anti-cancer agents. CAPs often exist as families of peptides with slightly different amino acid sequences. In addition, libraries of synthetic peptide variants based on naturally occurring CAP templates can be generated in order to improve upon their action. High-throughput screens are needed to quickly and efficiently assess the suitability of each CAP variant. Here we present the methods for assessing CAP-mediated cytotoxicity against cancer cells (suspension and adherent) and untransformed cells (measured using the tritiated thymidine-release or MTT assay), and for discriminating between cell death caused by necrosis (measured using lactate dehydrogenase- or (51)Cr-release assays), or apoptosis and necrosis (single-stranded DNA content measured by flow cytometry). In addition the clonogenic assay, which assesses the ability of single transformed cells to multiply and produce colonies, is described.

Resveratrol protects DAergic PC12 cells from high glucose-induced oxidative stress and apoptosis: effect on p53 and GRP75 localization

Resveratrol (RESV), a polyphenolic natural compound, has long been acknowledged to have cardioprotective and antiinflammatory actions. Evidence suggests that RESV has antioxidant properties that reduce the formation of reactive oxygen species leading to oxidative stress and apoptotic death of dopaminergic (DAergic) neurons in Parkinson’s disease (PD). Recent literature has recognized hyperglycemia as a cause of oxidative stress reported to be harmful for the nervous system. In this context, our study aimed (a) to evaluate the effect of RESV against high glucose (HG)-induced oxidative stress in DAergic neurons, (b) to study the antiapoptotic properties of RESV in HG condition, and c) to analyze RESV’s ability to modulate p53 and GRP75, a p53 inactivator found to be under expressed in postmortem PD brains. Our results suggest that RESV protects DAergic neurons against HG-induced oxidative stress by diminishing cellular levels of superoxide anion. Moreover, RESV significantly reduces HG-induced apoptosis in DAergic cells by modulating DNA fragmentation and the expression of several genes implicated in the apoptotic cascade, such as Bax, Bcl-2, cleaved caspase-3, and cleaved PARP-1. RESV also prevents the pro-apoptotic increase of p53 in the nucleus induced by HG. Such data strengthens the correlation between hyperglycemia and neurodegeneration, while providing new insight on the high occurrence of PD in patients with diabetes. This study enlightens potent neuroprotective roles for RESV that should be considered as a nutritional recommendation for preventive and/or complementary therapies in controlling neurodegenerative complications in diabetes.

Early methyl donor deficiency may induce persistent brain defects by reducing Stat3 signaling targeted by miR-124

The methyl donors folate (vitamin B9) and vitamin B12 are centrepieces of the one-carbon metabolism that has a key role in transmethylation reactions, and thus in epigenetic and epigenomic regulations. Low dietary intakes of folate and vitamin B12 are frequent, especially in pregnant women and in the elderly, and deficiency constitutes a risk factor for various diseases, including neurological and developmental disorders. In this respect, both vitamins are essential for normal brain development, and have a role in neuroplasticity and in the maintenance of neuronal integrity. The consequences of a methyl donor deficiency (MDD) were studied both in vivo in rats exposed in utero, and in vitro in hippocampal progenitors (H19-7 cell line). Deficiency was associated with growth retardation at embryonic day 20 (E20) and postnatally with long-term brain defects in selective areas. mRNA and protein levels of the transcription factor Stat3 were found to be decreased in the brains of deprived fetuses and in differentiating progenitors (62 and 48% for total Stat3 protein, respectively), along with a strong reduction in its phosphorylation at both Tyr⁷⁰⁵ and Ser⁷²⁷ residues. Vitamin shortage also affected upstream kinases of Stat3 signaling pathway (phospho-Erk1/2, phospho-Src, phospho-JNK, and phospho-p38) as well as downstream target gene products (Bcl-2 and Bcl-xL), thus promoting apoptosis. Conversely, the expression of the Stat3 regulator miR-124 was upregulated in deficiency conditions (≥65%), and its silencing by using siRNA partly restored Stat3 signaling in hippocampal neurons by increasing specifically the phosphorylation of Erk1/2 and Src kinases. Furthermore, miR-124 siRNA improved the phenotype of deprived cells, with enhanced neurite outgrowth. Taken together, our data suggest that downregulation of Stat3 signaling by miR-124 would be a key factor in the deleterious effects of MDD on brain development.

Activation of GSK-3β and caspase-3 occurs in Nigral dopamine neurons during the development of apoptosis activated by a striatal injection of 6-hydroxydopamine

The 6-Hydroxydopamine (6-OHDA) rat model of Parkinson's disease is essential for a better understanding of the pathological processes underlying the human disease and for the evaluation of promising therapeutic interventions. This work evaluated whether a single striatal injection of 6-OHDA causes progressive apoptosis of dopamine (DA) neurons and activation of glycogen synthase kinase 3β (GSK-3β) and caspase-3 in the substantia nigra compacta (SNc). The loss of DA neurons was shown by three neuron markers; tyrosine hydroxylase (TH), NeuN, and β-III tubulin. Apoptosis activation was determined using Apostain and immunostaining against cleaved caspase-3 and GSK-3β pY216. We also explored the possibility that cleaved caspase-3 is produced by microglia and astrocytes. Our results showed that the 6-OHDA caused loss of nigral TH(+) cells, progressing mainly in rostrocaudal and lateromedial directions. In the neostriatum, a severe loss of TH(+) terminals occurred from day 3 after lesion. The disappearance of TH(+) cells was associated with a decrease in NeuN and β-III tubulin immunoreactivity and an increase in Apostain, cleaved caspase-3, and GSK-3β pY216 in the SNc. Apostain immunoreactivity was observed from days 3 to 21 postlesion. Increased levels of caspase-3 immunoreactivity in TH(+) cells were detected from days 1 to 15, and the levels then decreased to day 30 postlesion. The cleaved caspase-3 also collocated with microglia and astrocytes indicating its participation in glial activation. Our results suggest that caspase-3 and GSK-3β pY216 activation might participate in the DA cell death and that the active caspase-3 might also participate in the neuroinflammation caused by the striatal 6-OHDA injection.

The radioprotective agent, amifostine, suppresses the reactivity of intralysosomal iron

Amifostine (2-[(3-aminopropyl)amino]ethane-thiol dihydrogen phosphate ester; WR-2721) is a radioprotective agent used clinically to minimize damage from radiation therapy to adjacent normal tissues. This inorganic thiophosphate requires dephosphorylation to produce the active, cell-permeant thiol metabolite, WR-1065. The activation step is presumably catalyzed by membrane-bound alkaline phosphatase, activity of which is substantially higher in the endothelium of normal tissues. This site-specific delivery may explain the preferential protection of normal versus neoplastic tissues. Although it was developed several decades ago, the mechanisms through which this agent exerts its protective effects remain unknown. Because WR-1065 is a weak base (pKa = 9.2), we hypothesized that the drug should preferentially accumulate (via proton trapping) within the acidic environment of intracellular lysosomes. These organelles contain abundant 'loose' iron and represent a likely initial target for oxidant- and radiation-mediated damage. We further hypothesized that, within the lysosomal compartment, the thiol groups of WR-1065 would interact with this iron, thereby minimizing iron-catalyzed lysosomal damage and ensuing cell death. A similar mechanism of protection via intralysosomal iron chelation has been invoked for the hexadentate iron chelator, desferrioxamine (DFO; although DFO enters the lysosomal compartment by endocytosis, not proton trapping). Using cultured J774 cells as a model system, we found substantial accumulation of WR-1065 within intracellular granules as revealed by reaction with the thiol-binding fluorochrome, BODIPY FL L-cystine. These granules are lysosomes as indicated by co-localization of BODIPY staining with LysoTracker Red. Compared to 1 mM DFO, cells pre-treated with 0.4 microM WR-1065 are protected from hydrogen peroxide-mediated lysosomal rupture and ensuing cell death. On a molar basis in this experimental system, WR-1065 is approximately 2500 times more effective than DFO in preventing oxidant-induced lysosomal rupture and cell death. This increased effectiveness is most likely due to the preferential concentration of this weak base within the acidic lysosomal apparatus. By electron spin resonance, we found that the generation of hydroxyl radical, which normally occurs following addition of hydrogen peroxide to J774 cells, is totally blocked by pretreatment with either WR-1065 or DFO. These findings suggest a single and plausible explanation for the radioprotective effects of amifostine and may provide a basis for the design of even more effective radio- and chemoprotective drugs.

Ethanol-induced apoptosis in human liver adenocarcinoma cells (SK-Hep1): Fas- and mitochondria-mediated pathways and interaction with MAPK signaling system

For studying molecular mechanisms regulating the fate of ethanol-treated hepatocytes, involvement of Fas in ethanol-induced apoptosis was examined in human liver adenocarcinoma (SK-Hep1) cells in which the function of Fas-associated death domain (FADD) protein was knocked down by transfection. In FADD-knocked down cells, while ethanol-induced increase in generation of reactive oxygen species (ROS) was unaffected, apoptosis was significantly suppressed, demonstrating the involvement of Fas in ethanol-induced hepatocyte apoptosis more directly than in the past reports. On the other hand, effects of mitogen-activated protein kinase (MAPK), which is well known to determine the fate of various cells, on ethanol-induced apoptosis have not been examined in SK-Hep1 cells. Of three major MAPKs, only p38 MAPK and JNK were found activated by 200 mM ethanol treatment. When cells were incubated with inhibitors of p38 MAPK and JNK, ethanol-induced apoptosis was decreased while ROS generation was unaffected, and examination of pro-apoptotic Bax and anti-apoptotic Bcl-2 levels showed decrease of the former and increase of the latter. We concluded that oxidative stress inflicted by ROS triggered Fas-mediated and mitochondria-mediated apoptotic pathways in ethanol-treated SK-Hep1 cells, and that p38 MAPK and JNK were promoting mitochondrial pathway, suggesting interaction between apoptosis and MAPK signaling systems.

Homocysteinylation of neuronal proteins contributes to folate deficiency-associated alterations of differentiation, vesicular transport, and plasticity in hippocampal neuronal cells

Despite the key role in neuronal development of a deficit in the methyl donor folate, little is known on the underlying mechanisms. We therefore studied the consequences of folate deficiency on proliferation, differentiation, and plasticity of the rat H19-7 hippocampal cell line. Folate deficit reduced proliferation (17%) and sensitized cells to differentiation-associated apoptosis (+16%). Decreased production (-58%) of S-adenosylmethionine (the universal substrate for transmethylation reactions) and increased expression of histone deacetylases (HDAC4,6,7) would lead to epigenomic changes that may impair the differentiation process. Cell polarity, vesicular transport, and synaptic plasticity were dramatically affected, with poor neurite outgrowth (-57%). Cell treatment by an HDAC inhibitor (SAHA) led to a noticeable improvement of cell polarity and morphology, with longer processes. Increased homocysteine levels (+55%) consecutive to folate shortage produced homocysteinylation, evidenced by coimmunoprecipitations and mass spectrometry, and aggregation of motor proteins dynein and kinesin, along with functional alterations, as reflected by reduced interactions with partner proteins. Prominent homocysteinylation of key neuronal proteins and subsequent aggregation certainly constitute major adverse effects of folate deficiency, affecting normal development with possible long-lasting consequences.

Cryopreservation increases apoptosis in human menisci

PURPOSE

Removal of the meniscus leads to progressive degenerative arthritis of the knee on a long-term basis; therefore, meniscal allograft transplantation has been proposed as an alternative to meniscectomy. Preservation methods are required to build up operational stocks and to provide living grafts of a practical size at the right time for patients. Methods for meniscus preservation have been published, and relevant literature confirms that using standard cryopreservation, the chondrocyte survival in situ is inadequate and extremely variable and the cryoinjury mechanisms are not completely established. The aim of the present study is to further investigate possible cellular injury caused by cryopreservation by analysing apoptosis and ultrastructural damage to menisci.

METHODS

Seven human menisci that were cryopreserved by standard method were used. All tissue samples were processed simultaneously for routine light microscopy, scanning and transmission electron microscopy as well as apoptosis assessment by the use of ISOL method.

RESULTS

With respect to cellularity, significant differences (P < 0.05) between the fresh (14.6 ± 3.5) (mean ± SD) and cryopreserved menisci (9.2 ± 2.8) (mean ± SD) were observed. Apoptosis using ISOL method was observed in fibrochondrocytes of fresh and cryopreserved menisci. The quantitative analysis revealed significant differences (P < 0.05) between fresh meniscus samples, where the apoptotic index was 0.8 ± 2.3% (mean ± SD), and cryopreserved meniscus samples, where this index was 50 ± 18.1% (mean ± SD).

CONCLUSION

The results suggest that apoptosis occurs during meniscus cryopreservation. The major findings of this study are cellular damage in meniscus cryopreservation suggesting apoptosis-mediated cell loss. The findings reported herein encourage to further investigations in preservation procedures to enhance maximum long-term clinical survival.

Synchronizing cell cycle of goat fibroblasts by serum starvation causes apoptosis

Cell cycle stage and synchronization of donor cells are important factors influencing the success of somatic cell nuclear transfer. This study examined whether serum starvation has any effect on specific cell death. We also studied the effects of serum starvation, culture to confluence, and full confluency (confluent + 72 h) on cell cycle characteristics and apoptosis of goat dermal fibroblast cells. The cells were obtained from the ear of a 1.5-year-old female goat. The following experimental groups were analysed for fibroblast cells: (i) normally growing, (ii) confluent, (iii) full confluency, (iv) cells starved for 48 h and (v) cells starved for 72 h. Analysis of cell cycle distribution by flow cytometry showed that 4.56 and 51.88% of normal cycling cells were at the G0 and G1 phases respectively. In the confluent group, 80% of the cells were arrested in the G0/G1 phase. Serum starvation for 48 and 72 h arrested 84.78% and 90.1% cells at the G0/G1 phase respectively which showed a significant difference when compared with the control group (p < 0.05). Double staining by PI and FITC distinguishes G0 phase from G1 phase. In the full confluency group, 91.53% of cells were at G0/G1 stage, but in contrast to the serum starved group, this high percentage of G0/G1 cells was mainly associated with G1 cells. Under normal culture conditions, 6.39% of cells underwent early apoptosis. In the confluent group 8.93% of cells showed early apoptosis. Serum starvation for 48 and 72 h caused early apoptosis in 8.91 and 39.83% of the cells respectively. Full confluency treatment did not increase the number of apoptotic cells significantly (8.67%). After 72 h, serum starvation significantly increased early apoptosis (p < 0.05). In conclusion, the use of full confluency is suitable for cell cycle synchronization because it arrests cells at the G0/G1 phase and also induces less apoptosis in comparison with the serum starvation group.

A new Phaseolus vulgaris lectin induces selective toxicity on human liver carcinoma Hep G2 cells

We describe here the purification and characterization of a new Phaseolus vulgaris lectin that exhibits selective toxicity to human hepatoma Hep G2 cells and lacks significant toxicity on normal liver WRL 68 cells. This polygalacturonic acid-specific lectin (termed BTKL) was purified from seeds of P. vulgaris cv. Blue tiger king by liquid chromatography techniques. The 60-kDa dimeric lectin showed strong and broad-spectrum hemagglutinating activity toward human, rabbit, rat, and mouse erythrocytes. Bioinformatic analysis unveils substantial N-terminal sequence similarity of BTKL to other Phaseolus lectins. Among a number of tumor cells tested, BTKL exhibits potent anti-Hep G2 activity which is associated with (1) induction of DNA fragmentation, (2) production of apoptotic bodies and chromatin condensation, (3) triggering of cell apoptosis and necrosis, and (4) depolarization of mitochondrial membrane (low ΔΨm). Furthermore, BTKL could induce inducible nitric oxide synthase (iNOS) expression and subsequent nitric oxide production in vitro in mouse macrophages, which may contribute to its antitumor activity. In addition, BTKL could bring about a significant dose-dependent increase in the production of mRNAs of proinflammatory cytokines including interleukin-1 beta, interleukin-2, tumor necrosis factor alpha, and interferon-gamma. In sum, the antitumor activity and mechanism of BTKL provided here suggest that it has potential therapeutic value for human liver cancer.

Ionising irradiation-induced inhibition of differentiation of C3H10T1/2 cells to the osteoblastic lineage

PURPOSE

Previous studies using mouse osteoblast derived MC3T3-E1 and mouse myoblast derived C2C12 cells have not completely explained the mechanisms responsible for osteoradionecrosis. Thus, the aim of this study was to advance the in vitro experimental approaches for investigations of osteoradionecrosis.

MATERIALS AND METHODS

The pluripotent stem cell line, mouse embryo derived C3H10T1/2, was treated with all-trans-retinoic acid after irradiation (1, 3 and 6 Gy), and cell growth, cell cycle distribution, apoptosis, and alkaline phosphatase (ALP) activity were assessed.

RESULTS

We demonstrated that ionising radiation inhibited the growth and decreased ALP activity in C3H10T1/2 cells. The decrease in cell growth was not due to apoptosis but was due to cell cycle delay. The decrease in ALP activity persisted in cells that were induced to an osteoblastic lineage 24 h after irradiation.

CONCLUSIONS

Our results suggested that C3H10T1/2 cells are suitable for investigating the effects of ionising irradiation on osteoblast precursor cells.

Measurement of telomere length using PNA probe by cytometry

Peptide nucleic acid (PNA) probes hybridize to denatured telomeric sequences in cells permeabilized in hot formamide. In reported protocols, the hybridization was conducted in solutions with high formamide concentrations to avoid the DNA renaturation that can hamper binding of the oligo-PNA probe to specific sequences. We postulated that telomeric DNA, confined in the nuclear microvolume, is not able to properly renature after hot formamide denaturation. Therefore, to improve hybridization conditions between the probe and the target sequences, it might be possible to add probe to sample after the complete removal of formamide.

Differentiation and neural integration of hippocampal neuronal progenitors: signaling pathways sequentially involved

In the context of their potential implication in regenerative strategies, we characterized cell mechanisms underlying the fate of embryonic rat hippocampal H19-7 progenitors in culture upon induction of their differentiation, and tested their capacities to integrate into a neuronal network in vitro. Without addition of growth factors, nearly 100% of cells expressed various neuronal markers, with a progressive rise of the expression of Synapsin I and II, suggesting that cells developed as mature neurons with synaptogenic capacities. Fully differentiated neurons were identified as glutamatergic and expressed the receptor-associated protein PSD-95. Quantification of ATP showed that 60% of cells died within 24 h after differentiation. Cell death was shown to imply Erk1/2-dependent intrinsic mitochondrial apoptosis signaling pathway, with activation of caspase-9 and -3, finally leading to single-strand DNA. Surviving neurons displayed high levels of Akt, phospho-Akt, and antiapoptotic proteins such as Bcl-2 and Bcl-XL, with decreased caspase activation. In the absence of trophic support, the proapoptotic death-associated protein (DAP) kinase was dramatically stimulated by 24 h postdifferentiation, along with increased levels of p38 and phospho-p38, and caspase reactivation. These findings show that different signaling pathways are sequentially triggered by differentiation, and highlight that ultimate cell death would involve p38 and DAP kinase activation. This was supported by the improvement of cell survival at 24-h postdifferentiation when cells were treated by PD169316, a specific inhibitor of p38. Finally, when seeded on rat hippocampal primary cultured neurons, a significant number of differentiated H19-7 cells were able to survive and to develop cell-cell communication.

Cisplatin triggers atrophy of skeletal C2C12 myotubes via impairment of Akt signalling pathway and subsequent increment activity of proteasome and autophagy systems

Cisplatin (cisPt) is an antineoplastic drug which causes an array of adverse effects on different organs and tissues, including skeletal muscle. In this work we show that cisPt behaves as a potent trigger to activate protein hypercatabolism in skeletal C2C12 myotubes. Within 24h of 50 μM cisPt administration, C2C12 myotubes displayed unchanged cell viability but showed a subset of hallmark signs typically recognized during atrophy, including severe reduction in body size, repression of Akt phosphorylation, transcriptional up-regulation of atrophy-related genes, such as atrogin-1, gabarap, beclin-1 and bnip-3, and loss of myogenic markers. As a consequence, proteasomal activity and formation of autophagosomes were remarkably increased in cisPt-treated myotubes, but forced stimulation of Akt pathway, as obtained through insulin administration or delivery of a constitutively activated Akt form, was sufficient to counter the cisPt-induced protein breakdown, leading to rescue of atrophic size. Overall, these results indicate that cisPt induces atrophy of C2C12 myotubes via activation of proteasome and autophagy systems, suggesting that the Akt pathway represents one sensitive target of cisPt molecular action in skeletal muscle.

The role of neural stem cells for in vitro models of schizophrenia: neuroprotection via Akt/ERK signal regulation

Recent neuroimaging studies have revealed progressive morphological brain changes during the course of schizophrenia, and the neurotrophic and neurogenetic effects of atypical antipsychotics are believed to prevent or retard these brain volume reductions. In addition to drug-induced neural stem cell (NSC) activation, transplantation of exogenous NSCs has been proposed as a possible approach to repair the damaged brain in psychiatric disease. NSC transplantation embraces not only neuron replacement but also enhanced neuroprotection of existing neurons with the goal of restoring the impaired brain. However, little is known about the cell-cell interactions of exogenous NSCs with existing neurons, or about their neuroprotective actions especially in psychiatric diseases. In the present study, we used cortical neuron cultures to examine the neurotrophism and neuroprotection of exogenous NSCs against the neuronal damage induced by exposure to the NMDA receptor antagonist, MK-801. We also investigated their role in serum/nutrient deprivation stress. The exogenous NSCs exerted neuroprotective effects against both types of apoptotic injuries considered as in vitro schizophrenic disease models. Exogenous NSCs also altered cellular survival signaling in injured neurons by indirect cell-cell contact in an injury-dependent manner. In MK-801 exposure, NSCs increased phosphorylated Akt (p-Akt) and ERK (p-ERK), both of which were reduced by this stress. While, in serum/nutrient deprivation, NSCs increased p-Akt, but decreased p-ERK which was increased by this damage. Our results demonstrate that exogenous NSCs have anti-apoptotic activities and can rescue cortical neurons by directing cellular survival signaling of neurons into the proper direction, without cell contact.

Prevention of apnea-induced apoptosis in NREM- and REM-generating nuclei of adult guinea pigs

The present study was designed to investigate the effects of recurrent periods of apnea/hypoxia on the morphology of neurons in sites that control NREM and REM sleep. In addition, we determined whether the administration of a GABA agonist, eszopiclone, was capable of preventing the degenerative, i.e., apoptotic, sequelae of hypoxia in these sleep-promoting neurons. Adult guinea pigs were divided into control (normoxic) and hypoxic groups; a separate group of hypoxic animals was administered eszopiclone. Recurrent periods of hypoxia and normoxia lasted for a duration of 3h. Subsequently, the brains were sectioned, and areas in the CNS that control NREM sleep as well as REM sleep were examined after staining with an antibody raised against single-stranded DNA, which labels apoptotic neurons. In the group of control (normoxic) animals, apoptotic neurons were not observed in CNS regions that control NREM or REM sleep. In hypoxic animals, a large number of apoptotic neurons were found in the preceding regions. In the hypoxic animals that were administered eszopiclone, there were almost no apoptotic neurons in the brain regions that control NREM or REM sleep. These results demonstrate that recurrent periods of apnea induce extensive apoptosis in CNS nuclei that control NREM and REM sleep and that eszopiclone is capable of preventing neuronal degeneration in these sites. We suggest that the degeneration of neurons in sites that control the states of sleep is responsible for those sleep disturbances that arise as a consequence of hypoxia in individuals with sleep-related breathing disorders.

Silver nanoparticle exposure causes apoptotic response in the earthworm Lumbricus terrestris (Oligochaeta)

In terrestrial ecotoxicology there is a serious lack of data for potential hazards posed by engineered nanoparticles (ENPs). This is partly due to complex interactions between ENPs and the soil matrix, but also to the lack of suitable toxicological end points in organisms that are exposed to ENPs in a relevant manner. Earthworms are key organisms in terrestrial ecosystems, but so far only physiological end points of low sensitivity have been used in ecotoxicity studies with ENPs. We exposed the earthworm Lumbricus terrestris to silver nanoparticles and measured their impact on apoptosis in different tissues. Increased apoptotic activity was detected in a range of tissues both at acute and sublethal concentrations (down to 4 mg/kg soil). Comparing exposure in water and soil showed reduced bioavailability in soil reflected in the apoptotic response. Apoptosis appears to be a sensitive end point and potentially a powerful tool for quantifying environmental hazards of ENPs.

Curcumin-induced apoptosis in PC3 prostate carcinoma cells is caspase-independent and involves cellular ceramide accumulation and damage to mitochondria

Curcumin, the principal curcuminoid of tumeric, has potent anticancer activity. To determine the mechanism of curcumin-induced cytotoxicity in prostate cancer cells, we exposed PC3 prostate carcinoma cells to 25 to 100 microM curcumin for 24 to 72 h. Curcumin treatment of PC3 cells caused time- and dose-dependent induction of apoptosis and depletion of cellular reduced glutathione (GSH). Exogenous GSH and its precursor N-acetyl-cysteine, but not ascorbic acid (AA) or ebselen, decreased curcumin accumulation in PC3 cells and also prevented curcumin-induced DNA fragmentation. The failure of AA and ebselen to protect PC3 cells from curcumin-induced apoptosis argued against the involvement of reactive oxygen species; rather, GSH-mediated inhibition of curcumin-induced cytotoxicity was due to reduced curcumin accumulation in PC3 cells. Curcumin-treated PC3 cells showed apoptosis-inducing cellular ceramide accumulation and activation of p38 mitogen-activated protein kinase (MAPK) and c-jun N-terminal kinase (JNK). Caspase-3, caspase-8, and caspase-9 were activated, and cytochrome c and apoptosis-inducing factor (AIF) were released from mitochondria following curcumin treatment. Interestingly, curcumin-induced apoptosis was not prevented by p38 MAPK, JNK, or caspase inhibition. We conclude that curcumin-induced cytotoxicity was due to cellular ceramide accumulation and damage to mitochondria that resulted in apoptosis mediated by AIF and other caspase-independent processes.

Apnea produces neuronal degeneration in the pons and medulla of guinea pigs

Obstructive sleep apnea and other sleep-related breathing disorders result in recurrent periods of oxygen deprivation (hypoxia), hypercapnia and an increase in the cellular production of reactive oxygen species (oxidative stress-related injury). Individuals with these disorders suffer from a variety of cellular abnormalities that result in cardiopulmonary dysfunctions, disturbances in sleep and other pathologies. In the present experiment, using an animal model of sleep apnea, we determined that the degeneration of neurons and glia, due to apoptosis, occurs in specific regions of the pons and medulla. Adult guinea pigs, which were divided into control (normoxic) and experimental (hypoxic) groups, were anesthetized with alpha-chloralose and immobilized with Flaxedil. Apnea (hypoxia) was induced by ventilatory arrest in order to desaturate the oxyhemoglobin to 75% SpO(2). A sequence of apnea, followed by ventilation with recovery to >95% SpO(2), was repeated for a period of 3h. At the end of the period of recurrent apnea, the animals were perfused and brain sections were immunostained with a mouse monoclonal antibody raised against single-stranded DNA (ssDNA). Apoptotic neurons and glia, which were not found in the control group of animals, were present in brainstem regions in hypoxic group of animals; these regions involved in the control of respiration (e.g., the parafacial respiratory group and the ventral respiratory group), cardiovascular functions (e.g., the nucleus ambiguus, the nucleus tractus solitarius and the dorsal motor nucleus of the vagus) as well as REM sleep (the nucleus pontis oralis) and wakefulness (e.g., the dorsal raphe and locus ceruleus). We suggest apoptotic neurons and glia in critical areas of the pons and medulla results in many of the comorbidities experienced by patients with sleep-disordered breathing pathologies.

Enteric neuroglial apoptosis in inflammatory bowel diseases

BACKGROUND

Enteric nervous system abnormalities have been described in patients with inflammatory bowel diseases. However, the mechanisms responsible for these abnormalities remain to date largely unknown.

AIMS

We investigated the potential role of apoptotic phenomena in enteric neurons and enteroglial cells in patients with inflammatory bowel diseases.

PATIENTS AND METHODS

Full-thickness surgical specimens of 19 patients undergoing surgery for medically refractory disease (9 from the ileum of patients with Crohn's disease, 10 from the colon of patients with ulcerative colitis) were assessed for the presence of enteric neurons and enteroglial cells and for their apoptosis by two immunohistochemical methods, one also able to distinguish apoptosis from necrosis. The results were compared with those obtained in control specimens.

RESULTS

Concerning Crohn's disease, the ileal segments displayed a significant increase of apoptotic enteric neurons and enteroglial cells in both the submucous and the myenteric plexus compared to controls. In patients with ulcerative colitis, compared to controls, apoptotic phenomena were significantly reduced in enteric neurons, whereas they were increased in the enteroglial cell population (submucous and myenteric plexus).

CONCLUSIONS

In patients with inflammatory bowel disease apoptotic phenomena involve both enteric neurons and enteroglial cells, and may play a role in the abnormalities of the enteric nervous system. The importance of these findings in the pathophysiology of these conditions remains to be determined.

The role of Curcuma longa against doxorubicin (adriamycin)-induced toxicity in rats

The major component, called curcumin, of turmeric (Curcuma longa L.) (Family Zingiberaceae) powder is responsible for its biological actions. The present study aimed to prove the protective effect of turmeric extract against doxorubicin (DOX)-induced cardiac, hepatic, and renal toxicity as evaluated in rats. Body weight and urine volume of the animal groups under investigation were recorded daily throughout the experimental period. Also, the cardiac, hepatic, and renal toxicities were determined by estimating the changes in serum activities of the enzymes lactate dehydrogenase (LDH) and creatine kinase (CK), serum levels of alanine aminotransferase, aspartate aminotransferase, nitric oxide, albumin, and calcium, and kidney and liver tissue activities of superoxide dismutase and glutathione peroxidase, as well as the contents of glutathione and malondialdehyde. Hyperlipidemia was also determined, and protein and albumin changes in urine were estimated. Biochemical and histopathological findings demonstrate that turmeric extract has multiple therapeutic activities that are beneficially protective, and it has an ameliorative effect against DOX-induced cardiac toxicity and hepatotoxicity and blocks DOX-induced nephrosis. Similarly, turmeric extract inhibited the DOX-induced increase in plasma cholesterol, LDH, and CK. The present findings conclude that the turmeric extract has multiple therapeutic activities that block the cardiac, hepatic, and renal toxicities induced by DOX, and it also possibly acts as a free radical scavenger.

Chondrocyte apoptosis after simulated intraarticular fracture: a comparison of histologic detection methods

Accurate evaluation of programmed cell death, or apoptosis, in chondrocytes is essential to studying cartilage injury. We evaluated four methods of detecting chondrocyte-programmed cell death in formalin-fixed, paraffin-embedded cartilage after experimental osteochondral fracture. Human osteochondral explants were subjected to experimental fracture in a manner known to induce high levels of chondrocyte-programmed cell death. After 4 days in culture, specimens were fixed and analyzed for programmed cell death using: (1) terminal deoxynucleotidyl transferase end labeling; (2) DNA denaturation analysis using an antibody specific for single-stranded DNA; (3) immunohistochemistry using antisera specific for active caspase-3; and (4) in situ oligonucleotide ligation. Quantitative analysis of programmed cell death levels for each technique was performed comparing injured and uninjured areas of cartilage. We observed differences between injured and uninjured areas of cartilage using the four methods. Human cartilage fixed in zinc-formalin and embedded in paraffin is amenable to programmed cell death analysis using any of four independent methods, each of which ostensibly has some advantages in terms of assaying different steps along the apoptotic pathway. Using the protocols described in this article, investigators may have additional tools to identify and quantify chondrocytes undergoing programmed cell death after experimental cartilage injury.

HDL antielastase activity prevents smooth muscle cell anoikis, a potential new antiatherogenic property

Various studies using proteomic approaches have shown that HDL can carry many proteins other than its constitutive apolipoprotein A-I (apoA-I). Using mass spectrometry and Western blotting, we showed the presence of alpha(1)-antitrypsin (AAT) (SERPINA1, serpin peptidase inhibitor, clade A, an elastase inhibitor) in HDL, isolated either by ultracentrifugation or by selected-affinity immunosorption using an anti-apoA-I column. Furthermore, we report that HDL possesses potent antielastase activity. We further showed that only HDL but not LDL is able to bind AAT. HDL-associated AAT was able to inhibit extracellular matrix degradation, cell detachment, and apoptosis induced by elastase in human vascular smooth muscle cells (VSMCs) and in mammary artery cultured ex vivo. Degradation of fibronectin by elastase used as a marker of pericellular proteolysis was prevented by addition of HDL. Elastase present in aortic abdominal aneurysm (AAA) thrombus samples was also able to induce apoptosis of VSMCs in culture. This phenomenon was prevented by addition of HDL but not of LDL. Finally, we report that the proportion of AAT in HDL isolated from patients with an AAA is decreased relative to that from matched control subjects, suggesting a reduced capacity of HDL to inhibit elastase in these patients. In conclusion, our data provide evidence of a new potential antiatherogenic property of HDL attributable to AAT and its antielastase activity.

Deficiency of nicotinamide adenine dinucleotide phosphate, reduced form oxidase enhances hepatocellular injury but attenuates fibrosis after chronic carbon tetrachloride administration

Reactive oxygen species (ROS) activate hepatic stellate cells and enhance fibrogenesis. This study determined the role of nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase deficiency in the development of hepatocellular necrosis, inflammation, and apoptosis in relation to fibrosis produced by chronic carbon tetrachloride (CCl(4)) administration. Wild-type (WT) mice or mice with deficiency of the gp91(phox) subunit of NADPH complex (gp91(phox(-/-) )) were subjected to biweekly CCl(4) injections over 8 weeks, whereas controls were given isovolumetric injections of olive oil. Serum aspartate aminotransferase (AST) was higher after CCl(4) administration in gp91(phox(-/-) ) than in WT mice, correlating with increased necrosis on liver histology. By contrast, more hepatocyte apoptosis was found after CCl(4) in the WT than in the gp91(phox(-/-) ) mice, which was associated with changes in components of the mitochondrial pathway of apoptosis, namely, an increase in the pro-apoptotic BAX protein in the WT, but not in the gp91(phox(-/-) ) mice and also a lower cytosolic cytochrome c in the gp91(phox(-/-) ) mice. There were fewer stellate cells and less fibrosis after CCl(4) in the gp91(phox(-/-) ) as compared with the WT mice. The increase in alpha(1)(I) collagen messenger RNA (mRNA), however, was greater after CCl(4) in the gp91(phox(-/-) ) mice. Matrix metalloproteinase-2 (MMP-2) and MMP-9 mRNA increased more in the gp91(phox(-/-) ) than in WT mice after CCl(4.) Tissue inhibitor of metalloproteinase 1 (TIMP-1) and TIMP-2 increased after CCl(4) only in the gp91(phox(-/-) ) mice.

CONCLUSION

Decreased hepatic fibrosis after chronic CCl(4) administration in mice with NADPH oxidase deficiency occurs in the setting of greater necrosis and inflammation but decreased apoptosis.

Sodium azide induces necrotic cell death in rat squamous cell carcinoma SCC131

Sodium azide (NaN(3)) is widely used in industry and agriculture, and also in laboratories as a potent preservative. NaN(3) induces cell death when applied to cultured cells. However, whether the mode of cell death is apoptosis or necrosis remains a subject of debate. There have been no previous reports on NaN(3)-induced cell death in squamous cell carcinoma (SCC), and so we studied the mode of cell death induced by NaN(3) using the rat SCC cell line, SCC131. In this experiment, SCC131 cells died 48-72 h after NaN(3) treatment with concentrations greater than 5 mM. The NaN(3) treatment reduced the mitochondrial membrane potential and ATP content. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and DNA ladder detection assay indicated that no DNA fragmentation occurred. In addition, phosphatidyl serine did not appear on the cell surface, according to the findings of dye-uptake bioassay and flow cytometric analysis of Annexin V labeling. Electron microscopic analysis revealed that the NaN(3)-treated cells showed mitochondrial swelling and rupture of the cell membrane. In conclusion, NaN(3) induces necrotic cell death in SCC131. This experimental model may be used in the study of necrotic cell death.

Hyaluronan induces cell death in activated T cells through CD44

In the immune system, leukocyte activation induces CD44 to bind hyaluronan, a component of the extracellular matrix. Here we used gain and loss of hyaluronan-binding mutants of CD44 to examine the consequence of hyaluronan binding in T cells. Jurkat T cells transfected with CD44 mutated at S180, which prevented the addition of chondroitin sulfate, displayed constitutively high levels of hyaluronan binding. These cells were more susceptible to activation-induced cell death, whereas cells expressing a CD44 mutant unable to bind hyaluronan (R41A) were resistant to cell death. In TCR or PMA activated Jurkat T cells, hyaluronan induced rapid cell death. This depended on the level of hyaluronan binding by the cell, and the amount and size of hyaluronan. High molecular mass hyaluronan had the greatest effect and cell death occurred independently of Fas and caspase activation. In splenic T cells, high hyaluronan binding occurred in a subpopulation of cells undergoing activation-induced cell death. In addition, hyaluronan induced cell death in approximately 10% of reactivated splenic T cells when Fas-dependent apoptosis was prevented by Ab blocking or in Fas negative MRL/lpr T cells. This demonstrates that hyaluronan can induce cell death in activated, high hyaluronan binding T cells via a Fas-independent mechanism.

Chondrocyte apoptosis: implications for osteochondral allograft transplantation

Osteochondral allograft transplantation is a useful technique to manage larger articular cartilage injuries. One factor that may compromise the effectiveness of this procedure is chondrocyte cell death that occurs during the storage, preparation, and implantation of the osteochondral grafts. Loss of viable chondrocytes may negatively affect osteochondral edge integration and long-term function. A better understanding of the mechanisms responsible for chondrocyte loss could lead to interventions designed to decrease cell death and improve results. Recent studies indicate that apoptosis, or programmed cell death, is responsible for much of the chondrocyte death associated with osteochondral allograft transplantation. Theoretically, some of these cells can be rescued by blocking important apoptotic mediators. We review the role of apoptosis in cartilage degeneration, focusing on apoptosis associated with osteochondral transplantation. We also review the pathways thought to be responsible for regulating chondrocyte apoptosis, as well as experiments testing inhibitors of the apoptotic pathway. These data suggest that key contributors to the apoptotic process can be manipulated to enhance chondrocyte survival. This knowledge may lead to better surgical outcomes for osteochondral transplantation.

Lack of inducible nitric oxide synthase leads to increased hepatic apoptosis and decreased fibrosis in mice after chronic carbon tetrachloride administration

The role of nitric oxide (NO) in liver injury and fibrosis is unclear. The purpose of this study was to determine whether inducible NO synthase deficiency (iNOS(-/-)) affects liver injury and fibrosis produced in mice by chronic carbon tetrachloride (CCl(4)) administration. Wild-type (WT) or iNOS(-/-) mice were subjected to biweekly CCl(4) injections over 8 weeks, whereas controls were given isovolumetric injections of olive oil. Serum aminotransferases were lower after CCl(4) in the iNOS(-/-) than in the WT mice, which correlated with decreased necrosis on liver histology. There was increased apoptosis, a lower number of stellate cells, and a lesser degree of fibrosis after CCl(4) in the iNOS(-/-) as compared with the WT mice. alpha(1)(I) collagen messenger RNA (mRNA) was markedly increased after CCl(4) in the WT and to a significantly lesser extent in the iNOS(-/-) mice. Liver matrix metalloproteinase-9 (MMP-9) mRNA and MMP-2 mRNA were increased more in the WT than in the iNOS(-/-) mice after CCl(4). Also tissue inhibitor metalloproteinase 1 (TIMP-1) mRNA was increased to a much greater extent in the WT than in the iNOS(-/-) mice after CCl(4) (P < 0.05). However, MMP-9 and TIMP-1 protein, determined by western blot, were similarly increased after CCl(4) in both groups of mice.

CONCLUSION

NO protects against CCl(4)-induced apoptosis. In the absence of iNOS, there is decreased necrosis, increased apoptosis, and reduced liver fibrosis.

Enhanced inhibition of adipogenesis and induction of apoptosis in 3T3-L1 adipocytes with combinations of resveratrol and quercetin

Certain flavonoids have been shown to have specific effects on biochemical and metabolic functions of adipocytes. In this study, we investigated the effects of combinations of resveratrol and quercetin on adipogenesis and apoptosis in 3T3-L1 cells. In maturing preadipocytes resveratrol and quercetin at 25 microM individually suppressed intracellular lipid accumulation by 9.4+/-3.9% (p<0.01) and 15.9+/-2.5%, respectively, (p<0.001). The combination of resveratrol and quercetin at the same dose, however, decreased lipid accumulation by 68.6+/-0.7% (p<0.001). In addition, combinations of resveratrol and quercetin at 25 microM significantly decreased the expression of peroxisome proliferators-activated receptor gamma (PPAR gamma) and CCAAT/enhancer-binding protein (C/EBP)alpha, both of which act as key transcription factors. In mature adipocytes resveratrol and quercetin at 100 microM individually decreased viability by 18.1+/-0.6% (p<0.001) and 15.8+/-1% (p<0.001) and increased apoptosis (100 microM) by 120.5+/-8.3% (p<0.001) and 85.3+/-10% (p<0.001) at 48 h, respectively. Combinations of resveratrol and quercetin further decreased viability (73.5+/-0.9%, p<0.001) and increased apoptosis (310.3+/-9.6%, p<0.001) more than single compounds alone. The combination of resveratrol and quercetin at 100 muM increased release of cytochrome c from mitochondria to cytosol and decreased ERK 1/2 phosphorylation. Taken together, our data indicate that combinations of resveratrol and quercetin can exert potential anti-obesity effects by inhibiting differentiation of preadipocytes and inducing apoptosis of mature adipocytes.