Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P08758 (annexin V)
 9,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Signal transduction pathways involving the c-Raf protein kinase are frequently activated in tumor cells. We have addressed the relevance of this activation by a loss-of-function approach. An anti-sense phosphorothioate oligonucleotide (ODN) specifically targeted against c-raf mRNA (Monia et al., 1996a) was used to block c-Raf protein expression in four different cell lines derived from lung, cervical, prostate and colon carcinomas. Concomitant with the abrogation of c-Raf expression we observed the occurrence of classical apoptotic markers, including chromatin condensation, inter-nucleosomal DNA cleavage, annexin V binding and cleavage of PARP, which was followed by cell death, affecting most of the cell population. This induction of apoptosis occurred independent of the p53 status of the cell. These findings demonstrate that c-Raf can protect tumor cells from undergoing programmed cell death, and suggest that the interference with c-Raf expression or function by ODNs or specific drugs could represent a powerful means for improving the efficacy of anti-cancer therapy.
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PMID:Abrogation of c-Raf expression induces apoptosis in tumor cells. 958 88

The pathogenic role of antiendothelial cell antibodies (AECA) remains unclear. They are frequently associated with antibodies to anionic phospholipids (PL), such as phosphatidylserine (PS), which is difficult to reconcile with the distribution of PL molecular species within the plasma membrane. Since it is already known that PS is transferred to the outer face of the membrane as a preclude to apoptosis, the possibility exists that apoptosis is initiated by AECA. AECA-positive/anti-PL antibody-negative sera from eight patients with systemic sclerosis (SS) and 21 control patients were evaluated. Endothelial cells (EC) were incubated with AECA and the exposure of PS was established through the binding of annexin V. Hypoploid cell enumeration, DNA fragmentation, and optical and ultrastructural analyses of EC were used to confirm apoptosis. Incubation of EC with AECA derived from six of eight patients with SS led to the expression of PS on the surface of the cells. This phenomenon was significantly more frequent in SS (P < 0.04) than in control diseases. The redistribution of plasma membrane PS preceded other events associated with apoptosis: hypoploidy, DNA fragmentation, and morphology characteristic for apoptosis. Apoptosis-inducing AECA did not recognize the Fas receptor. We conclude that AECA may be pathogenic by inducing apoptosis.
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PMID:The binding of some human antiendothelial cell antibodies induces endothelial cell apoptosis. 959 58

Mechanism of cell killing by transfer of Herpes simplex virus type-1 thymidine kinase (HSVtk) and subsequent ganciclovir (GCV) treatment was examined in B16F10 murine melanoma model. While parental B16F10 melanoma cells were resistant to GCV at 100 microM or higher, HSVtk-transduced B16F10 melanoma cell clones became susceptible to GCV with IC50 of 0.1 to 0.3 microM. By means of various parameters including characteristic morphological changes, in situ DNA end-labeling, DNA ladder pattern, flow cytometric detection of sub-G1 DNA content, and annexin V binding of inverted cell surface phosphatidylserine, apoptosis was shown to be associated with the cell killing of ganciclovir on HSVtk-transduced melanoma B16F10 cells. Kinetic analysis showed that the signs of apoptosis were observed not until 60 h of continued GCV treatment and preceded first by a rise in p53 protein level in 12 h and then by S-phase/G2-phase cell cycle arrest associated with corresponding increases in the level of cyclin B1 protein but no apparent change in protein level of Bax or Cdc2. These results suggest that apoptosis occurred as a result of ganciclovir-induced cell cycle arrests rather than direct chemical effect on HSVtk-transduced B16F10 melanoma cells.
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PMID:S- and G2-phase cell cycle arrests and apoptosis induced by ganciclovir in murine melanoma cells transduced with herpes simplex virus thymidine kinase. 963 14

Signals from the IL-7R are essential for normal thymocyte development. We isolated thymocytes from early developmental stages and observed that suspensions of pro-T1, -T2, and -T3 cells rapidly died in culture. Addition of IL-7 promoted their survival, but did not induce cell division. Pro-T4 cells did not undergo rapid cell death, and their survival was therefore independent of IL-7. Death in the absence of IL-7 showed the hallmarks of apoptosis, including DNA fragmentation and annexin V binding; however, caspase inhibitors blocked DNA fragmentation, but did not block cell death. The trophic effect of IL-7 was partially inhibited by blocking protein synthesis. The p53 pathway was not involved in this death pathway, since pro-T cells from p53-/- mice also underwent cell death in the absence of IL-7. The Fas/Fas ligand pathway was not involved in cell death, since Fas-deficient pro-T cells died normally in the absence of IL-7, anti-Fas Abs did not protect cells from death in the absence of IL-7, and Fas expression was undetectable on cells at these stages. The IL-7 trophic affect correlated with increased intracellular levels of Bcl-2 and decreased levels of Bax, whereas no Bcl-X(L), Bcl-w, or Bad was detectable. Thus, maintaining a favorable Bcl-2/Bax ratio may account for the trophic action of IL-7.
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PMID:The trophic action of IL-7 on pro-T cells: inhibition of apoptosis of pro-T1, -T2, and -T3 cells correlates with Bcl-2 and Bax levels and is independent of Fas and p53 pathways. 963 82

The anti-tumor drug Flavopiridol is a potent inhibitor of cyclin-dependent kinases (cdks). As a consequence, Flavopiridol-treated cells arrest in both G1 and G2, but Flavopiridol has also been shown to be cytotoxic for some tumor cell lines. The underlying molecular events are, however, unclear. We now show that Flavopiridol induces apoptosis in human umbilical vein endothelial cells (HUVECs), as judged by the occurrence of classical apoptotic markers, including chromatin condensation, internucleosomal cleavage, DNA fragmentation (TUNEL assay), annexin V binding and poly(ADP-ribose) polymerase (PARP)-cleavage. Such induction of apoptosis occurs with equal efficiency in both proliferating and G0/G1-arrested cells. Because growth-arrested HUVECs lack cdk2 activity and contain high levels of the cdk inhibitor p27, our observations suggest that cell cycle regulated cdks may not be the only critical target for Flavopiridol-induced apoptosis. Surprisingly, A549 lung carcinoma cells were clearly dependent on cell proliferation for the induction of cell death, pointing to cell type-related differences in the mechanism of Flavopiridol action.
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PMID:Cell cycle-independent induction of apoptosis by the anti-tumor drug Flavopiridol in endothelial cells. 963 6

This study determined the occurrence of two molecular markers of apoptosis, chromosomal DNA strand breaks and oolemma phosphatidylserine redistribution, in >200 uninseminated and unfertilized human oocytes, and >800 newly ovulated and cultured mouse oocytes. DNA breaks were analysed by terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL) and phosphatidylserine by annexin V staining, with imaging by conventional epifluorescence and scanning laser confocal fluorescence microscopy. More than 300 intact and 500 fragmented mouse oocytes were examined at 24 h intervals during 6 days of culture in three different types of medium. For the human, 205 oocytes were examined at retrieval or at 24 h intervals during 7.5 days of culture in two types of medium. The perifollicular vascularity and the dissolved oxygen content of follicular fluid were determined for most of the follicles from which human oocytes were derived. The results demonstrate that TUNEL fluorescence of metaphase II (MII) chromosomes and annexin V staining of the oolemma in newly ovulated and cultured mouse and human oocytes are rare, and, when detected, are not spatially or temporally related. This finding also applied to mouse oocytes that fragmented during culture and exhibited morphological features that grossly resembled apoptotic body formation. In contrast, TUNEL but not annexin V staining occurred in the first polar body of a relatively high proportion of newly ovulated mouse oocytes, but was rarely detected in newly aspirated human oocytes. For the human, the occurrence of MII chromosomal TUNEL fluorescence was patient-specific and unrelated to perifollicular vascularity or dissolved oxygen content of the corresponding follicular fluid. The pattern of chromosomal TUNEL fluorescence observed in the first polar body and in the MII chromosomes of a very small number of mouse and human oocytes, especially after many days of culture, suggests that DNA strand breaks may not arise by apoptosis-associated endonuclease digestion. The results with these two markers suggest that it is premature to conclude that apoptosis occurs in ovulated oocytes or that such a mechanism is involved in the elimination or prevention of fertilization of oocytes with cytoplasmic or chromosomal defects.
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PMID:DNA strand breaks and phosphatidylserine redistribution in newly ovulated and cultured mouse and human oocytes: occurrence and relationship to apoptosis. 964 66

Vector-mediated transfer of prodrug-activating genes provides a promising means of cancer gene therapy. In a search for more selective and more potent bioactivating enzymes for gene therapy of malignant brain tumors, the toxicity-generating capacity of the rabbit cytochrome P450 isozyme CYP4B1 was investigated. Rabbit CYP4B1, but not rat or human isozymes, efficiently converts the inert prodrugs, 2-aminoanthracene (2-AA) and 4-ipomeanol (4-IM), into highly toxic alkylating metabolites. Toxicity of these two prodrugs was evaluated in culture in parental and genetically modified rodent (9L) and human (U87) glioma cell lines stably expressing CYP4B1, and in vivo in a subcutaneous 9L tumor model in nude mice. The most sensitive CYP4B1-expressing glioma clone, 9L4B1-60, displayed an LD50 of 2.5 microM for 2-AA and 4-IM after 48 h of prodrug incubation, whereas 20 times higher prodrug concentrations did not cause any significant toxicity to control cells. Substantial killing of control tumor cells by 2-AA was achieved by co-culturing these cells with CYP4B1-expressing cells at a ratio of 100:1, and toxic metabolites could be transferred through medium. In both CYP4B1-expressing cells and co-cultured control cells, prodrug bioactivation was associated with DNA fragmentation, as assayed by fluorescent TUNEL assays and by annexin V staining. Alkaline elution of cellular DNA after exposure to 4-IM revealed extensive protein-DNA crosslinking with single-strand breakage. Growth of 9L-4B1 tumors in nude mice was inhibited by intraperitoneal injection of 4-IM with minimal side effects. Potential advantages of the CYP4B1 gene therapy paradigm include: the low concentrations of prodrug needed to kill sensitized tumor cells; low prodrug conversion by human isozymes, thus reducing toxicity to normal cells; a tumor-killing bystander effect that can occur even without cell-to-cell contact; and the utilization of lipophilic prodrugs that can penetrate the blood-brain barrier.
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PMID:New prodrug activation gene therapy for cancer using cytochrome P450 4B1 and 2-aminoanthracene/4-ipomeanol. 965 Jun 11

Chlorambucil-induced apoptosis was assessed by three different flow cytometric methods in B-cell chronic lymphocytic leukaemia (B-CLL) cells cultured in vitro and the results were compared with those derived from the morphological assessment of the same samples. Spontaneous apoptosis was consistently observed in the control cultures in the absence of drug but this accounted for less than 12% of all cells in every case. The methods under investigation were the Annexin V labelling assay, the terminal deoxynucleotidyl transferase (TdT) end-labelling assay and the labelling of a 38 kDa mitochondrial membrane protein (7A6 antigen) which is exposed on cells undergoing apoptotic cell death (Apo2.7 assay). The Annexin V assay consistently stained a higher percentage of cells and with a greater separation between the positive and negative cell populations. We conclude that the phosphatidyl serine translocation to the outer leaflet of the cell membrane following an apoptotic signal, as labelled by Annexin V, probably occurs before the development of the DNA strand breaks or the exposure of 7A6 antigen in those cells triggered to die by apoptosis.
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PMID:Flow cytometric assessment of three different methods for the measurement of in vitro apoptosis. 965 30

Upon transforming growth factor-beta (TGF-beta) treatment, Ramos cells, a B-cell lymphoma cell line, undergo apoptosis, as measured by annexin V labeling, DNA fragmentation, and propidium iodide staining. Apoptosis could be observed by 24 h after TGF-beta exposure and occurred before the development of a significant blockage of cell cycle progression. TGF-beta-mediated apoptosis was also accompanied by a strong induction of caspase-3 subfamily activity. Incubation of cells with the caspase inhibitor Z-VAD.FMK at 20 microM, but not at 10 microM, prevented TGF-beta-induced apoptosis from occurring. By comparison, caspase-3 subfamily activity was 87% inhibited at 10 microM Z-VAD.FMK and completely inhibited at 20 microM. Because of TGF-beta's well-established role of regulating gene transcription, the mRNA levels for proteins associated with apoptosis (Fas- and Fas-associated proteins, Bcl-2 family members, IAP proteins, and I kappa B) were also studied. After 24 h of TGF-beta treatment, the most significant mRNA changes occurred with Bcl-XL (two-fold decrease) and Bik (twofold increase). TGF-beta treatment also resulted after 48 h in a fivefold decrease in Bcl-XL protein levels, based on immunoblotting analysis. Therefore, TGF-beta-mediated apoptosis involves the activation of caspases. In addition, TGF-beta transcriptionally regulates Bcl-2 family members, Bcl-XL and Bik, to further influence the apoptosis process.
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PMID:Transforming growth factor-beta-mediated apoptosis in the Ramos B-lymphoma cell line is accompanied by caspase activation and Bcl-XL downregulation. 966 22

Ceramide, a stress-induced second messenger, has been associated with apoptosis in several malignant and non-malignant cell lines. We have shown that photodynamic treatment (PDT), using the phthalocyanine photosensitizer Pc 4 (HOSiPcOSi[CH3]2[CH2]3N[CH3]2), causes increased ceramide generation and subsequent induction of apoptosis in L5178Y-R (LY-R) mouse lymphoma cells. To test further if ceramide generation accompanies photocytotoxicity, we treated various cell lines with a PDT dose producing a 99-99.9% loss of clonogenicity. Like LY-R cells, human leukemia (U937) cells underwent rapid DNA fragmentation initiating within 1 h after PDT. Similarly, Chinese hamster ovary (CHO) cells showed rapid DNA laddering, beginning 1 h following the treatment. In contrast, mouse radiation-induced fibrosarcoma (RIF-1) cells showed no apoptosis within 24 h post-PDT, as judged by the absence of 50 kbp and oligonucleosome size DNA fragments, as well as no annexin V binding to cells with preserved membrane integrity. Using the same doses of PDT, we observed a time-dependent ceramide accumulation in all three cell lines. While a significant increase in ceramide levels was reached within 1 and 10 min in U937 and CHO cells, respectively, elevated ceramide production was measured only after 30 min in RIF-1 cells. In addition, exogenous N-acetyl-sphingosine was able to mimic PDT-induced apoptosis in U937 and CHO cells. We suggest that ceramide accumulation is associated with PDT-induced apoptosis and photocytotoxicity.
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PMID:Association of ceramide accumulation with photodynamic treatment-induced cell death. 967 55


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