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PubMed1998

Induction of apoptosis by gemcitabine in BG-1 human ovarian cancer cells compared with induction by staurosporine, paclitaxel and cisplatin.

A variety of chemotherapeutic agents induce cell death via apoptosis. We had shown previously that gemcitabine (2',2'-difluorodeoxycytidine) induced an atypical apoptosis in BG-1 human ovarian cancer cells; therefore, further studies were conducted to characterize more precisely gemcitabine-induced apoptosis in BG-1 cells compared to a general inducer of apoptosis, staurosporine. BG-1 cells exposed to 0.5, 1.0 and 10 microM gemcitabine for 8 h, or staurosporine (1.0 microM) for 6 h, exhibited high molecular weight DNA fragmentation (50 kbp); however, only staurosporine treatment produced internucleosomal DNA fragments (200 bp) in a laddered pattern on the agarose gel. Staurosporine (1.0 microM) rapidly induced phosphatidylserine plasma membrane translocation that increased linearly with time as measured by annexin V-FITC binding, and similar kinetics were observed for caspase activation by staurosporine in BG-1 cells. In contrast, 10 microM gemcitabine increased phosphatidylserine expression in a small fraction of cells (5-10%) vs. untreated controls over the course of 48 h and significant caspase activity was detected within 12 h of drug exposure. Time-lapse video microscopy of BG-1 cells exposed to 1.0 microM staurosporine or 10 microM gemcitabine for up to 72 h showed that the morphologic changes and kinetics of cell death induced by these agents differed significantly. We also evaluated the apoptosis induced by paclitaxel (a mitotic poison) and cisplatin (an agent not dependent on cell cycle functions) in BG-1 cells by these methods because these drugs are used clinically to treat ovarian cancer. Our findings demonstrate that the kinetics of apoptotic cell death induced by gemcitabine and other chemotherapeutic agents should be taken into account when designing treatment strategies for ovarian cancer.

Journal Article↗
PubMed2004

Activation of liver X receptors and retinoid X receptors prevents bacterial-induced macrophage apoptosis.

Microbe-macrophage interactions play a central role in the pathogenesis of many infections. The ability of some bacterial pathogens to induce macrophage apoptosis has been suggested to contribute to their ability to elude innate immune responses and successfully colonize the host. Here, we provide evidence that activation of liver X receptors (LXRs) and retinoid X receptors (RXRs) inhibits apoptotic responses of macrophages to macrophage colony-stimulating factor (M-CSF) withdrawal and several inducers of apoptosis. In addition, combined activation of LXR and RXR protected macrophages from apoptosis caused by infection with Bacillus anthracis, Escherichia coli, and Salmonella typhimurium. Expression-profiling studies demonstrated that LXR and RXR agonists induced the expression of antiapoptotic regulators, including AIM/CT2, Bcl-X(L), and Birc1a. Conversely, LXR and RXR agonists inhibited expression of proapoptotic regulators and effectors, including caspases 1, 4/11, 7, and 12; Fas ligand; and Dnase1l3. The combination of LXR and RXR agonists was more effective than either agonist alone at inhibiting apoptosis in response to various inducers of apoptosis, and it acted synergistically to induce expression of AIM/CT2. Inhibition of AIM/CT2 expression in response to LXR/RXR agonists partially reversed their antiapoptotic effects. These findings reveal unexpected roles of LXRs and RXRs in the control of macrophage survival and raise the possibility that LXR/RXR agonists may be exploited to enhance innate immunity to bacterial pathogens that induce apoptotic programs as a strategy for evading host responses.

Animals↗
PubMed1999

Apoptosis induction by a novel anti-prostate cancer compound, BMD188 (a fatty acid-containing hydroxamic acid), requires the mitochondrial respiratory chain.

We recently developed a class of novel anti-prostate cancer compounds, cyclic hydroxamates that elicit a potent apoptotic response in many tumor cells cultured in vitro (D.G. Tang et al., Biochem. Biophys. Res. Commun., 242: 380-384, 1998). The lead compound, termed BMD188, induces programmed cell death in a variety of prostate cancer cells in vitro as well as in vivo (L. Li et al., Anticancer Res., 19: 51-70, 1999). BMD188 kills androgen-independent prostate cancer cells as well as prostate cancer cells with a multidrug-resistance phenotype. The apoptotic effect of BMD188 in prostate cancer cells does not depend on cell cycle, p53 status, or its purported target, arachidonate 12-lipoxygenase, but does require caspase activation and seems to involve mitochondria. To synthesize more specific and effective anti-prostate cancer hydroxamic acid compounds, it is important to understand their mechanism(s) of action. In the present study, we studied the role of mitochondrial respiratory chain (MRC) in BMD188-induced apoptosis in androgen-independent prostate cancer PC3 cells and compared its effect with that of staurosporine (STS), a widely used apoptosis inducer. Several lines of evidence indicate that BMD188-induced cell death depends on MRC: (a) the death could be significantly inhibited by several complex-specific respiration inhibitors; (b) respiration-deficient rho0 cells were more resistant than wild-type parent cells to apoptosis induction by BMD188; and (c) BMD188 induced a rapid increase in reactive oxygen species in mitochondria, an up-regulation of cytochrome c oxidase subunits, a biphasic alteration (i.e., an early hyperpolarization, followed by later hypopolarization) in the mitochondrial membrane potential (delta psi(m)), dramatic changes in mitochondrial morphology and distribution prior to caspase activation, and an abnormal proliferation of mitochondria at the ultrastructural level. By contrast, STS-induced PC3 apoptosis seemed not to depend on MRC. Taken together, the data suggest that the MRC represents a functional target for anti-prostate cancer hydroxamates.

Antineoplastic Agents↗
PubMed2006

Caspase-3 regulation of diaphragm myonuclear domain during mechanical ventilation-induced atrophy.

RATIONALE: Unloading the diaphragm via mechanical ventilation (MV) results in rapid diaphragmatic fiber atrophy. It is unknown whether the myonuclear domain (cytoplasmic myofiber volume/myonucleus) of diaphragm myofibers is altered during MV. OBJECTIVE: We tested the hypothesis that MV-induced diaphragmatic atrophy is associated with a loss of myonuclei via a caspase-3-mediated, apoptotic-like mechanism resulting in a constant myonuclear domain. METHODS: To test this postulate, Sprague-Dawley rats were randomly assigned to a control group or to experimental groups exposed to 6 or 12 h of MV with or without administration of a caspase-3 inhibitor. MEASUREMENTS AND MAIN RESULTS: After 12 h of MV, type I and type IIa diaphragm myofiber areas were decreased by 17 and 23%, respectively, and caspase-3 inhibition attenuated this decrease. Diaphragmatic myonuclear content decreased after 12 h of MV and resulted in the maintenance of a constant myonuclear domain in all fiber types. Both 6 and 12 h of MV resulted in caspase-3-dependent increases in apoptotic markers in the diaphragm (e.g., number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive nuclei and DNA fragmentation). Caspase-3-dependent increases in apoptotic markers occurred after 6 h of MV, before the onset of myofiber atrophy. CONCLUSIONS: Collectively, these data support the hypothesis that the myonuclear domain of diaphragm myofibers is maintained during prolonged MV and that caspase-3-mediated myonuclear apoptosis contributes to this process.

Animals↗
PubMed1998

Extended therapeutic window for caspase inhibition and synergy with MK-801 in the treatment of cerebral histotoxic hypoxia.

In rats, striatal histotoxic hypoxic lesions produced by the mitochondrial toxin malonate resemble those of focal cerebral ischemia. Intrastriatal injections of malonate induced cleavage of caspase-2 beginning at 6 h, and caspase-3-like activity as identified by DEVD biotin affinity-labeling within 12 h. DEVD affinity-labeling was prevented and lesion volume reduced in transgenic mice overexpressing BCL-2 in neuronal cells. Intrastriatal injection of the tripeptide, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD-fmk), a caspase inhibitor, at 3 h, 6 h, or 9 h after malonate injections reduced the lesion volume produced by malonate. A combination of pretreatment with the NMDA antagonist, dizocilpine (MK-801), and delayed treatment with zVAD-fmk provided synergistic protection compared with either treatment alone and extended the therapeutic window for caspase inhibition to 12 h. Treatment with cycloheximide and zVAD-fmk, but not with MK-801, blocked the malonate-induced cleavage of caspase-2. NMDA injections alone resulted in a weak caspase-2 cleavage. These results suggest that malonate toxicity induces neuronal death by more than one pathway. They strongly implicate early excitotoxicity and delayed caspase activation in neuronal loss after focal ischemic lesions and offer a new strategy for the treatment of stroke.

Amino Acid Chloromethyl Ketones↗
PubMed2005

Biphasic cytochrome c release after transient global ischemia and its inhibition by hypothermia.

Hypothermia is effective in preventing ischemic damage. A caspase-dependent apoptotic pathway is involved in ischemic damage, but how hypothermia inhibits this pathway after global cerebral ischemia has not been well explored. It was determined whether hypothermia protects the brain by altering cytochrome c release and caspase activity. Cerebral ischemia was produced by two-vessel occlusion plus hypotension for 10 mins. Body temperature in hypothermic animals was reduced to 33 degrees C before ischemia onset and maintained for 3 h after reperfusion. Western blots of subcellular fractions revealed biphasic cytosolic cytochrome c release, with an initial peak at about 5 h after ischemia, which decreased at 12 to 24 h, and a second, larger peak at 48 h. Caspase-3 and -9 activity increased at 12 and 24 h. A caspase inhibitor, Z-DEVD-FMK, administered 5 and 24 h after ischemia onset, protected hippocampal CA1 neurons from injury and blocked the second cytochrome c peak, suggesting that caspases mediate this second phase. Hypothermia (33 degrees C), which prevented CA1 injury, did not inhibit cytochrome c release at 5 h, but reduced cytochrome c release at 48 h. Caspase-3 and -9 activity was markedly attenuated by hypothermia at 12 and 24 h. Thus, biphasic cytochrome c release occurs after transient global ischemia and mild hypothermia protects against ischemic damage by blocking the second phase of cytochrome c release, possibly by blocking caspase activity.

Animals↗
PubMed1999

Accumulation of caspase-3 messenger ribonucleic acid and induction of caspase activity in the ovine corpus luteum following prostaglandin F2alpha treatment in vivo.

Caspase-3, a vertebrate homologue of the protein encoded by the Caenorhabditis elegans cell death gene, ced-3, induces apoptosis when overexpressed in eukaryotic cells. Since apoptosis occurs during corpus luteum (CL) regression in many species, including the ewe, these studies were conducted to 1) isolate a cDNA encoding ovine caspase-3, 2) measure steady state amounts of caspase-3 mRNA in the CL during luteolysis induced by prostaglandin F2alpha (PGF2alpha) and during the time of maternal recognition of pregnancy, and 3) measure changes in caspase activity during PGF2alpha-initiated luteal regression. Oligonucleotide primers corresponding to a human caspase-3 cDNA sequence were combined with total RNA from ovine CL in a reverse transcription-polymerase chain reaction-based procedure to amplify a 640-base pair partial cDNA with a nucleotide sequence 86% and 81% identical to the human and rat caspase-3 cDNAs, respectively. CL were collected from ewes at 0, 12, or 24 h after treatment with PGF2alpha on Day 10 of the estrous cycle and from nonpregnant and pregnant ewes on Day 12 or Day 14 of the cycle. Northern blot analysis of total cellular RNA from ovine CL and a radiolabeled ovine caspase-3 cRNA probe indicated the presence of a single mRNA transcript of approximately 2.5 kilobases. Levels of caspase-3 mRNA were approximately 3-fold higher (p < 0.05) in CL at 12 h and 24 h after PGF2alpha in comparison to those levels measured in matched CL from untreated ewes. There were no differences (p > 0.05) in amounts of caspase-3 mRNA in CL on Day 12 or Day 14 of the estrous cycle compared to Day 12 or Day 14 of pregnancy, respectively. Caspase activity in CL (measured by the ability of CL lysates to cleave an artificial caspase substrate) was also significantly (p < 0.05) increased in CL collected after treatment with PGF2alpha compared to CL collected from nontreated ewes. We conclude that physiological cell death during PGF2alpha-induced luteal regression in the ewe is mediated, at least in part, via increased expression and activity of the caspase family of pro-apoptotic proteases.

Animals↗
PubMed1997

A sequential two-step mechanism for the production of the mature p17:p12 form of caspase-3 in vitro.

The apoptotic cysteine protease, caspase-3, is expressed in cells as an inactive 32-kDa precursor from which 17 kDa (p17) and 12 kDa (p12) subunits of the mature caspase-3 are proteolytically generated during apoptosis. Two amino acid sequences, ESMD downward arrowS (amino acids 25-29) and IETD downward arrowS (amino acids 172-176), in the precursor have been defined as the cleavage sites for the production of the p17 and p12 subunits. Using a cell-free assay system, we demonstrate that the caspase-3 precursor appears to be cleaved first at the IETD downward arrowS site, producing the p12 subunit and a 20-kDa (p20) peptide. Subsequently, the p20 is cleaved at the ESMD downward arrowS site, generating the mature p17 subunit. The cleavage at the IETD downward arrowS site required a protease activity that was selectively inhibited by the peptide, Ac-IETD-CHO (acetyl-IETD-aldehyde), and other protease inhibitors, such as the cowpox viral serine protease inhibitor, CrmA, and N-alpha-tosyl-L-phenylalanine chloromethyl ketone. The protease that catalyzed the cleavage at the ESMD/S site was selectively inhibited by another peptide, Ac-ESMD-CHO (acetyl-ESMD-aldehyde). More interestingly, the caspase-3 inhibitor, Ac-DEVD-CHO, but not the caspase-1 inhibitor, Ac-YVAD-CHO, also selectively inhibited the protease activity that cleaves at the ESMD downward arrowS site. This indicated that the cleavage at the ESMD downward arrowS site was either autocatalytic or that it required a caspase-3-like activity. In summary, we demonstrate that production of the p17:p12 form of caspase-3 is a sequential two-step process and appears to require two distinct enzymatic activities.

Caspase 3↗
PubMed2005

Impaired rapid eye movement sleep in the Tg2576 APP murine model of Alzheimer's disease with injury to pedunculopontine cholinergic neurons.

Impaired rapid eye movement sleep (REMS) is commonly observed in Alzheimer's disease, suggesting injury to mesopontine cholinergic neurons. We sought to determine whether abnormal beta-amyloid peptides impair REMS and injure mesopontine cholinergic neurons in transgenic (hAPP695.SWE) mice (Tg2576) that model brain amyloid pathologies. Tg2576 mice and wild-type littermates were studied at 2, 6, and 12 months by using sleep recordings, contextual fear conditioning, and immunohistochemistry. At 2 months of age, REMS was indistinguishable by genotype but was reduced in Tg2576 mice at 6 and 12 months. Choline acetyltransferase-positive neurons in the pedunculopontine tegmentum of Tg2576 mice at 2 months evidenced activated caspase-3 immunoreactivity, and at 6 and 12 months the numbers of pedunculopontine tegmentum choline acetyltransferase-positive neurons were reduced in the Tg2576 mice. Other cholinergic groups involved in REMS were unperturbed. At 12 months, Tg2576 mice demonstrated increased 3-nitrotyrosine immunoreactivity in cholinergic projection sites but not in cholinergic soma. We have identified a population of selectively compromised cholinergic neurons in young Tg2576 mice that manifest early onset REMS impairment. The differential vulnerability of these cholinergic neurons to Abeta injury provides an invaluable tool with which to understand mechanisms of sleep/wake perturbations in Alzheimer's disease.

Alzheimer Disease↗
PubMed2000

Cleavage of Bax-alpha and Bcl-x(L) during carboplatin-mediated apoptosis in squamous cell carcinoma cell line.

Although carboplatin (CBDCA) has been used for the treatment of several types of tumors, the complete response rate has been limited, probably because of inherent or CBDCA-induced resistance. As a first step to overcome these problems, we tried to elucidate the mechanisms of CBDCA-mediated cytotoxicity in the squamous cell carcinoma cell line MIT7. The treatment of cells with CBDCA resulted in apoptosis in a dose-dependent manner, as assessed by the propidium iodide staining method and DNA degradation in a nucleosomal pattern. The induction of apoptosis was accompanied by the decline of mitochondrial membrane potential (Deltapsi(m) ) at 12 h following CBDCA stimulation. Variant forms of p18 Bax-alpha and p16 Bcl-x(L) were generated with the down-regulation of both Bax-alpha (p21) and Bcl-x(L) (p31) at 36 and 48 h following CBDCA stimulation, suggesting that the modulation of Bcl-2 family proteins Bax-alpha and Bcl-x(L) play some role in CBDCA-mediated apoptosis. The activation of caspase-3 and -8 occurred at 12 and 24 h following the stimulation, respectively. The pretreatment of cells with pan-caspase inhibitor Z-VAD-fmk markedly prevented CBDCA-mediated cytotoxicity/apoptosis and the modulation of Bcl-2 family proteins (generation of p18 Bax-alpha and p16 Bcl-x(L) ) with only slight prevention of decline of Deltapsi(m). Taken together, these results may suggest that activation of several caspases, including caspase-3 and -8, plays some role in CBDCA-mediated apoptosis, probably through the modification of Bcl-2 family proteins, Bax-alpha and Bcl-x(L). Moreover, caspase activation may occur downstream of membrane depolarization.

Antineoplastic Agents↗
PubMedDate not supplied

The effect of 3-(5-nitro-2-thienyl)-9-chloro-5-morpholin-4-yl[1,2,4]triazolo[4,3-c]quinazoline on cell growth, cell cycle, induction of DNA fragmentation, and activity of caspase 3 in murine leukemia L1210 cells and fibroblast NIH-3T3 cells.

Quinazolines are multitarget agents, which have broad spectrum of biological activity, and some of them are now in cancer clinical testing. 3-(5-nitro-2-thienyl)-9-chloro-5-morpholin-4-yl[1,2,4]triazolo[4,3-c]quinazoline is a new synthetically prepared derivative, which in our previous study showed cytotoxic effects on cancer cell lines HeLa and B16. Quinazoline, at micromolar concentrations, induced morphological changes and necrosis of B16 cells, and at nanomolar concentrations it produced changes of F-actin cytoskeleton. It did not cause changes in the cell cycle, did not induce apoptotic cell death in B16 cells, did not have a mutagenic effect, and did not even behave as a typical intercalating agent. Little significant reduction of tumor volume in intramuscular transplanted B16 cells was observed. The aim of the present study was to examine the cytotoxic effect of 3-(5-nitro-2-thienyl)-9-chloro-5-morpholin-4-yl[1,2,4]triazolo[4,3-c]quinazoline on murine leukemia L1210 cells and fibroblast NIH-3T3 cells. Induction of cell morphology and cell cycle changes, induction of apoptosis and caspase 3 activity were studied. Quinazoline acted cytotoxically on both cell lines. The sensitivity of leukemia L1210 cells to the quinazoline was higher than that of fibroblast NIH-3T3. The IC(100) was 12 microM for L1210 cells and 24 microM for NIH-3T3 cells. No effect of quinazoline on the cell cycle profile of L1210 and NIH-3T3 was detected, however, quinazoline induced an increase of the sub-G(0) cell fraction, apoptotic DNA fragmentation, and apoptotic morphological changes at a concentration of 12 microM. This quinazoline concentration induced caspase 3 activity. Our results demonstrated that induction of apoptotic cell death via activation of caspase 3 contributed to the cytotoxic effects of 3-(5-nitro-2-thienyl)-9-chloro-5-morpholin-4-yl[1,2,4]triazolo[4,3-c]quinazoline in murine leukemia L1210 cells.

Animals↗
PubMed2003

Premature keratinocyte death and expression of marker proteins of apoptosis in human skin after UVB exposure.

Epidermal keratinocytes undergo a process of terminal differentiation or cornification that in many aspects resembles apoptosis. It is characterized by the elimination of cell nuclei within the granular layer, whereas the cytoplasm is transformed into horn cells. Premature death of keratinocytes can be induced by extrinsic factors such as UV irradiation. We investigated the time-dependent expression of apoptotic marker proteins in the skin of one healthy human volunteer after irradiation with a fourfold minimal erythema dose (MED) of UVB. The data were supplemented by including healthy skin areas of biopsies from patients UVB-irradiated for therapeutic reasons. Punch biopsies were analysed by in situ end-labelling (ISEL) for DNA strand breaks and by immunohistochemistry for expression of p53, bcl-2, active caspase-3 and its proform, and deoxyribonuclease I (DNase I). Keratinocytes with pyknotic nuclei were first detected 6 h after UVB exposure, and apoptotic keratinocytes (sunburn cells) 12 h after exposure. These aggregated to sunburn bodies after 24 h. In control skin, nuclei with DNA strand breaks were only occasionally detected in the granular layer but 6 h after UVB irradiation in the spinous layer. After 12 h, many sunburn cells were ISEL-positive and positively stained for active caspase-3, P53, and DNase I. Morphometric evaluation of the immunohistochemical data demonstrated that maximal upregulation of P53, DNase I and activation of caspase-3 occurred 12 h after irradiation and in advance of the peak of apoptotic cell death reached after 24 h as verified by ISEL. In contrast, strong Bcl-2 immunostaining appeared restricted to presumed melanocytes and basal cells but was not increased after UVB irradiation.

Adult↗
PubMed1998

Taxanes propagate apoptosis via two cell populations with distinctive cytological and molecular traits.

Taxol and Taxotere propagate apoptosis in Jurkat T cells via molecular signals that coincide with the appearance of two distinct cell populations. Cell cycle arrest in G2-M phase and activation of cell cycle-dependent kinases begin within 2 h and extend to most cells by 16 h. Phosphorylation of Bcl-2 also begins within 2 h and intensifies from 2-16 h. Cell cycle arrest, activation of mitotic kinases, and phosphorylation of Bcl-2 coincided with the appearance of a population of metastable cells that accumulate YO-PRO-1 dye, are resistant to the caspase inhibitor carbobenzoxy-L-aspartyl-alpha-[(2,6-dichlorobenzoyl)oxy]methane, and have intact genomic DNA. Phosphorylation and deactivation of kinases that relay survival/mitogenesis signals in T cells begin after 8 h and are prominent by 12-16 h. Deactivated kinases include c-Raf-1, p44 extracellular receptor kinase, and the tyrosine kinases c-Lck and ZAP-70. Activation of Mr 40,000 and Mr 52,000 kinases is also prominent by 12-16 h. The modulation of all these kinases coincided with the activation of caspase-3 at 12 h and the appearance of a population of apoptotic cells that accumulate YO-PRO-1, are susceptible to the caspase inhibitor carbobenzoxy-L-aspartyl-alpha-[(2,6-dichloro-benzoyl)oxy]methane, and contain fragmented genomic DNA. This distinctive apoptosis signaling pathway may help account for the superior cytotoxic efficacy of taxanes in certain types of cancer.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Preliminary evaluation of caspases-dependent apoptosis signaling pathways of free and HPMA copolymer-bound doxorubicin in human ovarian carcinoma cells.

The purpose of the study was to examine the role of caspases in signaling pathways of apoptosis induced by free doxorubicin (DOX) and HPMA copolymer-bound DOX (P(GFLG)-DOX) in human ovarian carcinoma cells. Sensitive A2780 and DOX resistant A2780/AD cells were exposed to different doses of drugs within 12, 18, 24 and 36 h. Caspase activity, expression of genes encoding human caspases 1-10, Apaf-1 and bcl-2 proteins and apoptosis were studied. In sensitive cells both free and P(GFLG)-DOX activated caspases 3, 7 and 9. In addition, P(GFLG)-DOX activated caspases 6 and 8. In resistant cells apoptosis induced by free DOX depended on the activation of caspases 2, 7 and 9, while caspase 3 was not involved; this explains the low degree of apoptosis induced by free DOX in resistant cells. P(GFLG)-DOX triggered the additional caspases 3, 6 and 8. A more pronounced degree of caspase activation and apoptosis after the action of P(GFLG)-DOX depended on the inhibition of bcl-2-encoded cellular defensive mechanisms and a more significant activation of Apaf-1. It was concluded that HPMA copolymer-bound DOX induced additional caspase-dependent apoptosis signaling pathways and the degree of the induction was higher, which led to more pronounced apoptosis when compared to free DOX.

Antibiotics, Antineoplastic↗
PubMed1999

Immunohistochemical localization of interleukin-1beta, interleukin-1 receptor antagonist and interleukin-1beta converting enzyme/caspase-1 in the rat brain after peripheral administration of kainic acid.

The temporal and anatomical distribution of members of the interleukin-1 system in the rat brain following intraperitoneal kainic acid administration was studied in relation to neurodegeneration as detected with in situ end labelling. Kainic acid administration (10 mg/kg, i.p.) resulted in the induced expression of interleukin-1beta, interleukin- receptor antagonist and caspase-1p10 immunoreactivity in areas known to display neuronal and tissue damage upon excitotoxic lesions. The induction of these proteins was transient. Interleukin-1 immunoreactivity appeared at 5 h, and the interleukin-1 receptor antagonist-immunoreactive cells were first detected at 12 h, whereas the induction of caspase- 1p10 expression was first detected 24 h after kainic acid injection. Double labelling with the microglial marker Ox42 confirmed that both interleukin-1beta and interleukin-1 receptor antagonist were mainly localized in microglial cells. The regional distribution of in situ end-labelled neurons was similar to the distribution of cells expressing interleukin-1beta and interleukin-1 receptor antagonist, whereas the distribution of caspase-1 was more limited. The in situ end-labelled neurons, were, similarly to the interleukin-1beta-positive cells, first detected at 5 h, which is earlier than the induction of caspase-1. Our results show that the induction of IL-1beta and IL-1 receptor antagonist proteins after kainic acid are closely associated with the temporal as well as the anatomical distribution of in situ end-labelled neurons, whereas the induction of caspase-1 protein exhibited a delayed temporal profile and limited distribution. Since cytokine production occurs in activated microglial cells, the inflammatory component seems to be a strong mediator of this type of excitotoxic damage. The late onset of the caspase-1 expression would seem to indicate that this enzyme has no fundamental role in directly causing neuronal cell death induced by systemic kainic acid.

Animals↗
PubMed2004

[An immunohistochemical study on the expression of caspase-3 in the skin wound healing].

OBJECTIVE: To investigate the expression of caspase-3 during skin wound healing and explore the applicability of caspase-3 to determination of wound age. METHODS: The expression of caspase-3 were performed on 33 mice skin incised wounds at different posttraumatic intervals and 3 mice as control by immunohistochemical technique. RESULTS: Expression of caspase-3 was detectable in polymorphonuclear cells (PMNs) in the wound specimens aged 6 h. In the wound specimens aged from 12 h to 24 h after injury, caspase-3 was identified in a large number of infiltrating PMNs and part of mononuclear cells (MNCs). Afterwards, the MNCs and fibroblastic cells (FBCs) accounted in the most part of the caspase-3 positive cells. Morphometrically, the ratio of the number of the caspase-3 stained PMNs, MNCs and FBCs to total number of the cells in the wounds was evaluated and calculated. The ratio of the caspase-3 positive cells was low in the wound specimens aged from 0 h to 3 h (4.53 +/- 6.53)%, and maximized in the wound specimens aged 3 day (62.66 +/- 4.84)%. Thereafter, the ratio decreased and minimized in the specimens aged 14 day (21.56 +/- 4.54)%. CONCLUSION: The results suggest that caspase-3 may play an important role in inducing neutrophil, macrophage and fibroblast apoptosis during skin wound healing. Furthermore, caspase-3 may be used as a marker for the wound age determination.

Animals↗
PubMed2006

Doxazosin induces apoptosis of benign and malignant prostate cells via a death receptor-mediated pathway.

Quinazoline-based alpha1-adrenoceptor antagonists such as doxazosin and terazosin have been previously shown to induce apoptosis in prostate cancer cells via an alpha1-adrenoceptor-independent pathway, involving activation of transforming growth factor-beta1 (TGF-beta1) signaling. In this study, the molecular events initiating this apoptotic effect were further investigated in vitro using the human androgen-independent prostate cancer cells PC-3 and the human benign prostate epithelial cells BPH-1. Quantitative microarray assays were done in PC-3 and BPH-1 cells after treatment with doxazosin (25 micromol/L, 6 and 24 hours) to identify the early gene changes. Transient changes in the expression of several apoptosis regulators were identified, including up-regulation of Bax and Fas/CD95 and down-regulation of Bcl-xL and TRAMP/Apo3. Moreover, there were significant changes in the expression pattern of signaling components of the extracellular matrix such as integrins alpha2, alphaV, beta1, and beta8. Western blot analysis revealed activation of caspase-8 and caspase-3 within the first 6 to 12 hours of treatment with doxazosin in both PC-3 and BPH-1 cells. Doxazosin-induced apoptosis was blocked by specific caspase-8 inhibitors, supporting the functional involvement of caspase-8 in doxazosin-induced apoptosis. The effect of doxazosin on recruitment of Fas-associated death domain (FADD) and procaspase-8 to the Fas receptor was examined via analysis of death-inducing signaling complex formation. Doxazosin increased FADD recruitment and subsequent caspase-8 activation, implicating Fas-mediated apoptosis as the underlying mechanism of the effect of doxazosin in prostate cells. These results show that doxazosin exerts its apoptotic effects against benign and malignant prostate cells via a death receptor-mediated mechanism with a potential integrin contribution towards cell survival outcomes.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Spatiotemporal evidence of apoptosis-mediated ischemic injury in organotypic hippocampal slice cultures.

Oxygen-glucose deprivation (OGD) induced neuron-specific cell death in organotypic hippocampal slice cultures. Neuronal death was first evident in the CA1 region 24 h after the injury as assessed by propidium iodide (PI) labeling, and continued to extend to the CA3/4 region up to 72 h. At 6 days post-OGD, PI labeling was weak and diffuse with no clear demarcation of pyknotic nuclei. To characterize biochemical changes produced by OGD, cellular efflux of three key amino acid neurotransmitters was evaluated. OGD elicited large increases in the release of GABA and aspartate (55- and 4.5-fold increase over basal, respectively), while there were no detectable changes in extracellular glutamate levels. In order to ascertain the existence of the synaptic pool of glutamate, sister cultures were treated with sodium azide. This evoked a strong increase in glutamate release, suggesting the intactness of the glutamate system. Further studies revealed a time-dependent activation of caspase 3 following OGD, shown by immunoblot analysis as well as by confocal laser scanning microscopy. While we did not observe the activation of caspases 1, 2, or 8 in our model, the activation of caspase 9 was evident, peaking at 12 h post-OGD. Despite no apparent increase in glutamate release by ischemic slices, treatment with a N-methyl-D-aspartate (NMDA) antagonist or an alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) antagonist significantly reduced neuronal death. Furthermore, a pan-caspase inhibitor (zVAD-fmk), but not the caspase 3 inhibitor (DEVD-fmk), provided partial neuroprotection. Inhibition of a Ca(2+)-dependent cysteine protease, calpain, by MDL28170 also elicited partial neuroprotective effects.

Animals↗