Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0344329 (collapse)
 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Various anticancer drugs cause mitochondrial perturbations in association with apoptosis. Here we investigated the involvement of caspase- and Bcl-2-dependent pathways in doxorubicin-induced mitochondrial perturbations and apoptosis. For this purpose, we set up a novel three-color flow cytometric assay using rhodamine 123, annexin V-allophycocyanin, and propidium iodide to assess the involvement of the mitochondria in apoptosis caused by doxorubicin in the breast cancer cell line MTLn3. Doxorubicin-induced apoptosis was preceded by up-regulation of CD95 and CD95L and a collapse of mitochondrial membrane potential (Deltapsi) occurring prior to phosphatidylserine externalization. This drop in Deltapsi was independent of caspase activity, since benzyloxycarbonyl-Val-Ala-dl-Asp-fluoromethylketone did not inhibit it. Benzyloxycarbonyl-Val-Ala-dl-Asp-fluoromethylketone also blocked activation of caspase-8, thus excluding an involvement of the death receptor pathway in Deltapsi dissipation. Furthermore, although overexpression of Bcl-2 in MTLn3 cells inhibited apoptosis, dissipation of Deltapsi was still observed. No decrease in Deltapsi was observed in cells undergoing etoposide-induced apoptosis. Immunofluorescent analysis of Deltapsi and cytochrome c localization on a cell-to-cell basis indicates that the collapse of Deltapsi and cytochrome c release are mutually independent in both normal and Bcl-2-overexpressing cells. Together, these data indicate that doxorubicin-induced dissipation of the mitochondrial membrane potential precedes phosphatidylserine externalization and is independent of a caspase- or Bcl-2-controlled checkpoint.
 ...
PMID:Differential regulation of doxorubicin-induced mitochondrial dysfunction and apoptosis by Bcl-2 in mammary adenocarcinoma (MTLn3) cells. 1210 57

Borrelidin, an antibiotic with anti-angiogenic activity, not only suppresses new capillary tube formation, but also collapses formed capillary tubes in a rat aorta culture model. Since it selectively inhibits threonyl-tRNA synthetase, we examined the effect of threonine on its anti-angiogenic activity. We found that a high concentration of threonine (1 mM) attenuated the ability of borrelidin to inhibit both capillary tube formation in the rat aorta culture model and human umbilical vein endothelial cells (HUVEC) proliferation, yet did not affect the ability of borrelidin to collapse formed capillary tubes or to induce apoptosis in HUVEC. Borrelidin activated caspase-3 and -8, and inhibitors of both caspase-3 and -8 suppressed borrelidin-induced apoptosis in HUVEC. Taken together, these data suggest that the anti-angiogenic effects of borrelidin are mediated through at least two mechanisms, i.e. one threonine-dependent and the other threonine-independent, and borrelidin induces apoptosis in endothelial cells via the caspase-8/-3 pathway.
 ...
PMID:Anti-angiogenesis effects of borrelidin are mediated through distinct pathways: threonyl-tRNA synthetase and caspases are independently involved in suppression of proliferation and induction of apoptosis in endothelial cells. 1456 61

Maintenance of endothelial cell tube integrity is dependent on an intact cytoskeleton. We present data indicating that rapid collapse of endothelial tubular networks in vitro occurs in a dose-dependent manner after administration of microtubule-depolymerizing reagents but not after actin depolymerization. Pretreatment of endothelial cell networks with C3 exoenzyme or recombinant adenoviruses expressing dominant negative RhoA resulted in complete blockade of tube collapse, indicating a role for RhoA in these events. Microtubule depolymerization also resulted in activation of RhoA, whereas increased expression of constitutively active RhoA induced cell rounding and apoptosis of endothelial cells. Furthermore, following treatment with the chemotherapeutic agent vinblastine, rapid capillary tube network collapse occurred followed by endothelial cell apoptosis. Vinblastine, but not control agents, induced cleavage of procaspase-3, procaspase-9, and procaspase-8, along with the known caspase targets p21-activated kinase-2 and gelsolin, indicating that tube collapse caused a defined apoptotic response. Using a model of vascular endothelial growth factor-stimulated angiogenesis in vivo, vinblastine treatment also resulted in collapse and apoptosis of angiogenic blood vessels. Apoptotic endothelial cells stained strongly for cleaved caspase-3, and terminal dUTP nick-end labeling staining revealed fragmented nuclei in vinblastine-treated but not control angiogenic areas. Together, these findings indicate that microtubule-depolymerizing agents directly induce endothelial network collapse in vitro and in vivo leading to endothelial cell apoptosis in a manner dependent on the small GTPase, RhoA. In addition, these findings reveal a novel function for microtubule disrupting chemotherapeutic agents, namely their ability to rapidly collapse newly formed angiogenic vessels, which may contribute to their effectiveness in limiting angiogenesis and tumor growth.
 ...
PMID:Microtubule depolymerization rapidly collapses capillary tube networks in vitro and angiogenic vessels in vivo through the small GTPase Rho. 1469 32

More than other tissues, skin is exposed to numerous external stresses generating ROS that, in addition to endogenous oxygen radicals, cause keratinocyte alterations and contribute in part to photocarcinogenesis and aging. Recent evidence suggests a differentiation-dependent susceptibility of keratinocytes to apoptosis. We explored hydrogen peroxide-induced cell death in normal human keratinocytes according to their differentiation. On H(2)O(2)-exposed skin explants, caspase-3 was strongly activated in basal keratinocytes double stained with beta(1) integrin, whereas DNA fragmentation occurred in suprabasal cells only without caspase-3 activation. In addition, isolated basal keratinocytes, selected by adhesion to type IV collagen, were more sensitive than nonadherent cells to H(2)O(2)-induced apoptosis with regard to mitochondrial transmembrane potential (Deltapsi(mt)) collapse and membrane integrity. Similarly, necrotic/late apoptotic cells were present at low levels only in the adherent epidermal population. Furthermore, in primary cultures of undifferentiated keratinocytes H(2)O(2)-induced cell death appeared via a mitochondrial failure. Deltapsi(mt) collapse was associated with a strong early activation of the initiatory caspase-8, then the executive caspase-3, and, to a lesser extent, the inflammatory caspase-1. Finally, undifferentiated basal cells possess a higher sensitivity than differentiated suprabasal cells to H(2)O(2)-induced cell death, and apoptosis in human keratinocytes occurs via different pathways depending on the cell's differentiation state.
 ...
PMID:Hydrogen peroxide-induced cell death in normal human keratinocytes is differentiation dependent. 1562 60

The mechanisms involved in the apoptotic effect of LCY-2-CHO [9-(2-chlorobenzyl)-9H-carbazole-3-carbaldehyde], a synthetic carbazole derivative identified as an anti-inflammatory compound, were studied. Cell cycle analysis by propidium iodide staining in human THP-1 monocytic leukemia cells showed the ability of LCY-2-CHO to increase cell population in sub-G1 stage with time- and concentration-dependent manners. LCY-2-CHO-mediated cell death was also demonstrated by DNA laddering and was not related to the release of lactate dehydrogenase. Apoptosis in THP-1 cells induced by LCY-2-CHO was accompanied by the Bid cleavage, collapse of mitochondrial transmembrane potential, the release of cytochrome c and the activation of caspase-3. The apoptotic effect of LCY-2-CHO was diminished by the presence of zVEID-fmk (caspase-6 inhibitor), zIETD-fmk (caspase-8 inhibitor), and zVAD-fmk (non-selective caspase inhibitor), but was not altered by several antioxidants, and cathepsin inhibitor. The Bid cleavage and loss of mitochondrial transmembrane potential, but not the cytochrome c release, were reversed by zIETD-fmk. Comparing the cell selectivity of LCY-2-CHO, we found T-cell acute lymphoblastic CEM leukemia cells were sensitive to 1 microM LCY-2-CHO, acute myeloid leukemia HL-60 cells underwent apoptosis at 10 microM, while adherent cancer cells, such as PC3, HT29 and MCF-7, were resistant to 30 microM LCY-2-CHO within 24-h incubation. Taken together in the present study, we demonstrated LCY-2-CHO might be apoptotic for malignant hematopoietic cells but not anchorage-dependent cells. This action is mediated by an intrinsic caspase-dependent apoptotic event involving mitochondria.
 ...
PMID:Cell apoptosis induced by a synthetic carbazole compound LCY-2-CHO is mediated through activation of caspase and mitochondrial pathways. 1589 95

Although reactive oxygen species (ROS) have been implicated in cadmium (Cd)-induced hepatotoxicity, the role of ROS in this pathway remains unclear. Therefore, we attempted to determine the molecular mechanisms relevant to Cd-induced cell death in HepG2 cells. Cd was found to induce apoptosis in the HepG2 cells in a time- and dose-dependent fashion, as confirmed by DNA fragmentation analysis and TUNEL staining. In the early stages, both rapid and transient ROS generation triggered apoptosis via Fas activation and subsequent caspase-8-dependent Bid cleavage, as well as by calpain-mediated mitochondrial Bax cleavage. The timing of Bid activation was coincided with the timing at which the mitochondrial transmembrane potential (MMP) collapsed as well as the cytochrome c (Cyt c) released into the cytosol. Furthermore, mitochondrial permeability transition (MPT) pore inhibitors, such as cyclosporin A (CsA) and bongkrekic acid (BA), did not block Cd-induced ROS generation, MMP collapse and Cyt c release. N-acetylcysteine (NAC) pretreatment resulted in the complete inhibition of the Cd-induced apoptosis via catalase upregulation and subsequent Fas downregulation. NAC treatment also completely blocked the Cd-induced intracellular ROS generation, MMP collapse and Cyt c release, indicating that Cd-induced mitochondrial dysfunction may be regulated indirectly by ROS-mediated signaling pathway. Taken together, a rapid and transient ROS generation by Cd triggers apoptosis via caspase-dependent pathway and subsequent mitochondrial pathway. NAC inhibits Cd-induced apoptosis through the blocking of ROS generation as well as the catalase upregulation.
 ...
PMID:A rapid and transient ROS generation by cadmium triggers apoptosis via caspase-dependent pathway in HepG2 cells and this is inhibited through N-acetylcysteine-mediated catalase upregulation. 1616 29

The combination of irinotecan (CPT-11) and 5-fluorouracil (5-FU) is currently used in the treatment of advanced colorectal carcinoma. When compared to both agents alone, CPT-11 followed by 5-FU treatment demonstrated a synergistic effect. This observation can be related to increased in apoptosis induction after caspase activation. Several studies have demonstrated that changes in mitochondrial membrane potential occur earlier in apoptosis. In this study, we verified whether the collapse in mitochondrial membrane and the activation of caspases is responsible for increased apoptosis observed with CPT-11/5-FU treatment. Thus, HT-29 and SNU-C4 human colon carcinoma cell lines were exposed for 24 h to each drug alone, and to various combinations and treatment sequences, and assessed for colony formation, changes in the mitochondrial membrane potential, and the activities of caspase-3, -8, and -9. The CPT-11/5-FU treatment induced apoptosis in both cell lines; however, the most pronounced effect was observed in HT-29 cells. In these cells, both caspase-3 and -9 were involved in the activation of apoptosis after CPT-11/5-FU treatment. Moreover, in these cells, a reduction of 50% in mitochondrial membrane potential was observed with this treatment. On the other hand, in the SNU-C4 cell line in addition to caspase-3 and-9, caspase-8 seems to be important to apoptosis after CPT-11/5-FU treatment. Furthermore, in this cell line we did not observe alterations in mitochondrial membrane potential. In spite of the differences among the cell lines, these results indicated that the increase in apoptosis in HT-29 cells observed with CPT-11 followed by 5-FU treatment could be explained by a disruption in mitochondria membrane potential that induced caspases activation.
 ...
PMID:Irinotecan/5-fluorouracil combination induces alterations in mitochondrial membrane potential and caspases on colon cancer cell lines. 1649 56

CD95/Fas and CD40 receptors are important regulators of cell survival during germinal center reaction. In this study we used a human follicular lymphoma cell line, HF1A3, to study molecular mechanisms of CD95-mediated apoptosis and CD40-induced rescue from apoptosis. CD95 stimulation induced activation of caspase-8 and -3, collapse of mitochondrial membrane potential (DeltaPsim), release of cytochrome c and fragmentation of nuclear DNA. All these apoptotic events were abrogated, when cells were pretreated with CD40 antibodies before CD95 stimulation. CD40 induced a rapid up regulation of both short and long isoforms of c-FLIP, as these proteins were detectable 4h after receptor stimulation. The induction of c-FLIP as well as the anti-apoptotic function of CD40 was completely abolished when NF-kappaB activity was inhibited by a selective inhibitor PDTC. We conclude that the anti-apoptotic signaling of CD40 involves NF-kappaB-mediated induction of c-FLIP proteins which can interfere with caspase-8 activation. However, it remains to be seen whether c-FLIP proteins are the only one ones involved in CD40-mediated protection.
 ...
PMID:The CD40-induced protection against CD95-mediated apoptosis is associated with a rapid upregulation of anti-apoptotic c-FLIP. 1690 43

The invasive character of gliomas depends on proteolytic cleavage of the surrounding extracellular matrix. Cathepsin B and urokinase-type plasminogen activator receptor (uPAR) together are known to be overexpressed in gliomas and, as such, are attractive targets for gene therapy. In the present study, we used plasmid constructs to induce the RNA interference (RNAi)-mediated down-regulation of uPAR and cathepsin B in SNB19 human glioma cells. We observed that the simultaneous down-regulation of uPAR and cathepsin B induces the up-regulation of proapoptotic genes and initiates a collapse in mitochondrial Deltapsi. Cathepsin B and uPAR down-regulated cells showed increases in the expression of activated caspase-8 and DFF40/caspase-activated DNase. Nuclear translocation of AIF and Fas ligand translocation to the cell membrane were also observed. Ki67 and X-linked inhibitor of apoptosis protein levels decreased, thereby indicating apoptosis. These results suggest the involvement of uPAR-cathepsin B complex on the cell surface and its role in maintaining the viability of SNB19 glioma cells. In conclusion, RNAi-mediated down-regulation of uPAR and cathepsin B initiates a partial extrinsic apoptotic cascade accompanied by the nuclear translocation of AIF. Our study shows the potential of RNAi-mediated down-regulation of uPAR and cathepsin B in developing new therapeutics for gliomas.
 ...
PMID:RNA interference-mediated simultaneous down-regulation of urokinase-type plasminogen activator receptor and cathepsin B induces caspase-8-mediated apoptosis in SNB19 human glioma cells. 1717 24

Ultraviolet (UV) irradiation is a DNA-damaging agent that triggers apoptosis through both the membrane death receptor and mitochondrial apoptotic signaling pathways. Bid, a pro-apoptotic Bcl-2 family member, is important in most cell types to apoptosis in response to DNA damage. In this study, a recombinant plasmid, YFP-Bid-CFP, comprised of yellow and cyan fluorescent protein and a full length Bid, was used as a fluorescence resonance energy transfer analysis (FRET) probe. Using the FRET technique based on YFP-Bid-CFP, we found that Bid activation was initiated at 9+/-1 h after UV irradiation, and the average duration of the activation was 75+/-10 min. Bid activation coincided with a collapse of the mitochondrial membrane potential with an average duration of 50+/-10 min. When cells were pretreated with Z-IETD-fmk (caspase-8 specific inhibitor) the process of Bid activation was completely inhibited, but the apoptosis was only partially affected. Z-DEVD-fmk (caspase-3 inhibitor) and Z-FA-fmk (non asp specific inhibitor) did not block Bid activation. Furthermore, the endogenous Bid activation with or without Z-IETD-fmk in response to UV irradiation was confirmed by Western blotting. In summary, using the FRET technique, we observed the dynamics of Bid activation during UV-induced apoptosis and found that it was a caspase-8 dependent event.
 ...
PMID:Fluorescence resonance energy transfer analysis of bid activation in living cells during ultraviolet-induced apoptosis. 1721 57


<< Previous 1 2 3 4 5 6 Next >>