UNIPROT:P08758 - FACTA Search

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Query: UNIPROT:P08758 (annexin V)
9,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Arsenic trioxide (As2O3) has been shown to inhibit the proliferation of hematologic malignant cells. Previously, we reported that As2O3 had an antitumoral effect in head and neck cancer. Here, we investigated the induction of apoptosis and its mechanism in PCI-1 head and neck squamous carcinoma cells, after treatment with As2O3. Treatment with 2 microM of As2O3 caused apoptosis in PCI-1 cells following 3 days of exposure, which was detected by the annexin V-PI and DAPI staining methods. The cell death population was markedly increased, being 88% larger than the As2O3-untreated control cells. To address the mechanism of apoptosis, a Western blot assay was performed, showing that Bax was up-regulated without a change in Bcl-2. Activation of caspase-9 during As2O3-induced apoptosis was substantiated by monitoring the proteolysis of the caspase-9, which was associated with an increase of Apaf-1 and cytochrome c protein. PCI-1 cells rapidly changed the mitochondria membrane potential (DeltaPsim) after addition of As2O3. Furthermore, activation of caspase-3 was demonstrated by monitoring the proteolysis of the caspase-3 and by measuring caspase-3 activity with a fluorogenic substrate, which was associated with the cleavage of poly(ADP-ribose) polymerase. To examine the in vivo effect of As2O3, C3H mouse inoculated with syngenic SCC7 cells was treated by intratumoral injection of As2O3 (300 microg) every day, demonstrating that tumor mass was dramatically reduced on day 4, and revealed induction of apoptosis by TUNEL assay. These results suggest that apoptosis of PCI-1 cells by As2O3 is induced by activation of caspase-3 via cytochrome c, caspase-9 and Apaf-1 complex.
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PMID:Potential role of caspase-3 and -9 in arsenic trioxide-mediated apoptosis in PCI-1 head and neck cancer cells. 1117 89

Arsenicals are toxicants and carcinogens to which large numbers of people risk exposure by contaminated water, air pollution or industrial contact. Several animal studies have determined that inorganic arsenicals are immunotoxic, but the mechanism of immune suppression is not clear. In this study, we show that trivalent arsenic inhibits enzymatic activity of the lysosomal protease cathepsin L (CathL) in the murine antigen-presenting B cell line TA3. CathL plays an important role in antigen processing, the mechanism by which antigen-presenting cells cleave foreign protein antigens to peptides for stimulating a T cell response. Deficient proteolysis may lead to diminished immune responses. Arsenite suppressed enzymatic activity within TA3 cells after 4 h exposure without affecting cell viability. Kinetic analyses revealed that the chemical was a reversible, partially noncompetitive inhibitor of CathL with a Ki of 120 microM. However, an 18 h arsenite exposure triggered massive cell death at concentrations that were substantially lower than those required for enzymatic inhibition. Morphological analysis and annexin V staining showed that arsenite-exposed TA3 cells underwent apoptosis within 18 h, and early stages of apoptosis began by 4 h. These findings suggest that apoptosis may be an important mechanism for arsenic-induced immunosuppression.
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PMID:Immunosuppression by arsenic: a comparison of cathepsin L inhibition and apoptosis. 1135 77

Chronic ingestion of arsenite-contaminated drinking water causes skin, bladder, and liver cancer. The mechanism of arsenite-induced carcinogenesis is unknown. Arsenite is known to disrupt mitosis and to delay transit through M phase in normal diploid fibroblasts. SV40-transformed human fibroblasts were observed to be hypersensitive to the cytotoxic and cytostatic effects of NaAsO(2) compared with normal diploid fibroblasts in concentration-response experiments. Five to 20 microM NaAsO(2) induced cytostasis in cycling normal diploid fibroblasts but not overt lethality in quiescent normal diploid fibroblasts. High concentrations of arsenite were overtly lethal in both cycling and quiescent cells. The IC50 for cycling SV40-transformed fibroblasts was 3.8 and 4.8 microM for the SV40-transformed lines GM4429 and GM0637, respectively, whereas, in cycling normal diploid fibroblasts (GM0024), the IC50 was 24.7 microM. Microscopic examination of NaAsO(2)-treated SV40-transformed fibroblasts suggested a concentration-dependent accumulation of cells in mitosis undergoing apoptosis. Treatment of SV40-transformed fibroblasts with 0-10 microM NaAsO(2) caused a concentration-dependent inhibition of cell proliferation, accumulation of cells having G2/M DNA contents, and increases in the mitotic index. Phase microscopy, annexin V binding, and electron microscopy demonstrated that arrested mitotic cells underwent apoptosis. These results indicate that SV40-transformation sensitizes cells to arsenite-induced mitotic arrest and induction of apoptosis in the mitotic cells.
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PMID:Arsenite disrupts mitosis and induces apoptosis in SV40-transformed human skin fibroblasts. 1196 75

Arsenic trioxide (As(2)O(3)) is an effective treatment for acute promyelocytic leukemia (APL), but is less effective against other leukemias. Although the response of APL cells to As(2)O(3) has been linked to degradation of the PML/RARalpha fusion oncoprotein, there is evidence that PML/RARalpha expression is not the only mediator of arsenic sensitivity. Indeed, we found that exogenous expression of PML/RARalpha did not sensitize a non-APL leukemic line to As(2)O(3). To evaluate possible other determinants of sensitivity of leukemic cells to As(2)O(3), we derived two arsenic-resistant NB4 subclones. Despite being approximately 10-fold more resistant to arsenic than their parental cell line, PML/RARalpha protein was still degraded by As(2)O(3) in these cells, providing further evidence that loss of expression of the oncoprotein does not confer arsenic sensitivity. Both arsenic-resistant clones contained high glutathione (GSH) levels, however, and we found that GSH depletion coupled with As(2)O(3) treatment dramatically inhibited their growth. Annexin V-staining and TUNEL analysis confirmed a synergistic induction of apoptosis. In addition, these cells failed to accumulate ROS in response to arsenic treatment, in contrast to their arsenic-sensitive parental cells, unless cotreated with buthionine sulfoximine. While other malignant cells did not show a good correlation between arsenic sensitivity and GSH content, GSH depletion nevertheless sensitized all cell lines examined, regardless of their initial response to arsenic alone. These findings suggest that PML/RARalpha expression is not a determinant of arsenic sensitivity, and further support the coupling of GSH depletion and arsenic treatment as a novel treatment for human malignancies that are unresponsive to arsenic alone.
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PMID:Glutathione depletion overcomes resistance to arsenic trioxide in arsenic-resistant cell lines. 1275 Jul 8

Arsenic trioxide (As2O3) can induce clinical remission in patients with acute promyelocytic leukemia (APL), including those who have relapsed after treatment with all-trans-retinoic acid (RA). In vitro studies with the APL-derived NB4 cell line showed that As2O3 exerts a dose-dependent dual effect, which induces apoptosis at 1 microM, whereas at a lower concentration of 0.1 microM, a partial differentiation of APL is observed. In non-APL cells, interferon (IFN) alpha and 1 microM As2O3 act synergistically to induce apoptosis. In this report, we show that in NB4 cells and in two RA-resistant NB4-derived cell lines, NB4-R1 and NB4-R2, IFNalpha or IFNgamma combined with 0.1 microM As2O3 lead to an increased maturation effect. Moreover, IFNgamma alone is able to differentiate RA-sensitive and -resistant cells with a higher maturation effect on NB4-R2 cells. In contrast, all these cells underwent apoptosis in the presence of the cytokine and a higher concentration of As2O3. IFNgamma boosted As2O3-induced apoptosis in APL cells as tested by TUNEL, Annexin V staining and activation of caspase 3. As2O3 differently altered IFN-induced gene products; it downregulated PML/RARalpha and PML, did not alter PKR and Stat1, and upregulated interferon regulatory family (IRF)-1. Synergism by IFNgamma and arsenic on IRF-1 expression is mediated by a composite element in the IRF-1 promoter that includes an IFNgamma-activation site (GAS) overlapped by a nonconsensus site for nuclear factor kappa B (NFkappaB). Arsenic has no effect on NFkappaB, whereas it enhances the activation of Stat1 by IFNgamma in NB4 cells leading to an increase in IRF-1 expression.
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PMID:Arsenic enhances the activation of Stat1 by interferon gamma leading to synergistic expression of IRF-1. 1466 93

Arsenic trioxide (As2O3) is an effective drug for treatment of acute promyelocytic leukemia (APL) and malignant tumors. However, it is not commonly known to researchers that sensitivity has been associated with As2O3 concentration in target cells. Cell lines and cell strains of leukemia and solid cancer cells were treated with different concentrations of As2O3, and the concentrations were compared to apoptosis detected by FITC-annexin V and propidium iodide (PI) double staining. Results showed that intracellular and intercellular concentrations of arsenic in different cell lines differed. Our study noted that the cell lines had concentrations of arsenic trioxide in decreasing order, as follows: APL primary cell > K562 > CML primary cell > HL-60 > AML-M2 primary cell > HeLa > H-22. Higher intracellular As2O3 concentrations in cell lines APL, NB4, and K562 can be obtained by treating in culture medium with lower As2O3 concentration for longer times than the transient higher concentration. These results indicate that different leukemia and solid carcinoma cell lines have different intracellular arsenic concentrations, which correlate with different sensitivities to As2O3 in clinical treatment. The intracellular As2O3 concentration is higher; in addition, we note apoptosis, a very important observation in our study. As2O3 inhibited the growth of these cell lines significantly. Novel techniques by maintaining continuous low but effective arsenic levels inside the target leukemic cells in APL may improve the complete remission rate and overall survival with minimum cost and drug toxicity.
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PMID:Significance of intracellular arsenic trioxide for therapeutic response in acute promyelocytic leukemia. 1568 19

Arsenic trioxide (ATO) induces apoptosis in a range of solid tumors and leukemia cells, and has been clinically applied for the treatment of acute promyelocytic leukemia with confirmed efficacy. Acute megakaryocytic leukemia (AMKL) is an aggressive malignancy with poor prognosis, if bone marrow transplantation is not possible. In this study, we applied flow cytometry, Western blot analysis and microarray techniques to investigate the effects of ATO on apoptosis and the cell division cycle of AMKL cell lines CHRF-288-11 and MEG-01. Our data demonstrated that ATO is a potent agent against AMKL as indicated by apoptotic markers, Annexin V and caspase-3. ATO activated the intrinsic (mitochondrial) pathway of apoptosis, which involved disrupting mitochondrial membrane potential, increased Bax/Bcl-2 ratio and caspase-9 activation, as well as the extrinsic (death receptor) pathway mediated by Fas and caspase-8 activation. We provided the first evidence that ATO stimulated expressions of CD137 mRNA and protein, which might be relevant to the extrinsic mechanism. ATO induced delays of cell cycle progression at S phase and arrest at G2/M phase of AMKL cells, but caspase-3 expression appeared not to be phase-specific. The multiple-signaling mechanism of ATO warrants it a potential agent to incorporate in the treatment regimen of AMKL.
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PMID:Arsenic trioxide mediates intrinsic and extrinsic pathways of apoptosis and cell cycle arrest in acute megakaryocytic leukemia. 1601 Apr 37

Arsenic trioxide (As2O3) has recently been used to treat acute promyelocytic leukaemia and has activity in vitro against several solid tumour cell lines where the induction of differentiation and apoptosis are the prime effects. The mechanism of As2O3-induced cell death has yet to be clarified, especially in solid cancers. In the present study, the human breast cancer cell line MCF-7 was examined as a cellular model for As2O3 treatment. The involvement of extracellular signal-regulated kinase (ERK), p38 and c-Jun N-terminal kinase (JNK) was investigated in As2O3-induced cell death. 3. It was found that As2O3 activates the prosurvival mitogen-activated protein kinase kinase (MEK)/ERK pathway in MCF-7 cells, which, conversely, may compromise the efficacy of As2O3. Hence, a combination treatment of As2O3 and MEK inhibitors was investigated to determine whether this treatment could lead to enhanced growth inhibition and apoptosis in MCF-7 cells. 4. Inhibition of MEK/ERK with the pharmacological inhibitors U0126 (10 micromol/L) or PD98059 (20 micromol/L) together with As2O3 (2 and 5 micromol/L) resulted in a significant enhancement of growth inhibition in breast cancer MCF-7 cells as determined by the 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay and [Methyl-3H]-thymidine incorporation. Furthermore, the results demonstrated that combined treatment with As2O3 and the MEK1/2 inhibitor U0126 could augment breast cancer MCF-7 cell apoptosis approximately twofold compared with the effects of the two drugs alone, as determined by Hoechst 33258 or annexin V/propidium iodide (PI) staining and flow cytometry. 5. In addition, As2O3 activated p38 in a dose-dependent manner, but had no effect on JNK1/2. Treatment with a p38 inhibitor did not prevent As2O3-induced apoptosis. 6. In conclusion, the results of the present study showed that enhanced apoptosis is detected in breast cancer MCF-7 cells in the presence of As2O3 and an MEK inhibitor, which may be a new promising adjuvant to current breast cancer treatments.
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PMID:Inhibition of mitogen-activated protein kinase kinase enhances apoptosis induced by arsenic trioxide in human breast cancer MCF-7 cells. 1644 69

We investigated the in vitro effects of arsenic trioxide on cell growth, cell cycle regulation, and apoptosis in As4.1 juxtaglomerular cells. Arsenic trioxide inhibited the growth of As4.1 cells with an IC(50) of approximately 5 microM. Arsenic trioxide induced S phase arrest of the cell cycle and very efficiently stimulated apoptosis in As4.1 cells, as evidenced by flow cytometric detection of sub-G(1) DNA content, annexin V binding assay, and 4'-6-diamidino-2-phenylindole staining. This apoptotic process was accompanied by the loss of mitochondrial transmembrane potential (DeltaPsi(m)), a decrease in Bcl-2, the activation of caspase-3, and cleavage of poly(ADP-ribose) polymerase. However, all of the caspase inhibitors tested in this experiment failed to rescue As4.1 cells from arsenic trioxide-induced cell death in view of sub-G(1) cells and annexin V positive-staining cells. However, a caspase-8 inhibitor (Z-IETD-FMK) noticeably decreased the loss of DeltaPsi(m) in arsenic trioxide-treated cells. When we examined the changes in reactive oxygen species (ROS), H(2)O(2), or O(2)(*-) in arsenic trioxide-treated cells, H(2)O(2) was significantly decreased and O(2)(*-) was increased. In addition, we detected a decreased GSH content in arsenic trioxide-treated cells. Taken together, we have demonstrated that arsenic trioxide as a ROS generator potently inhibited the growth of As4.1 JG cells through S phase arrest of the cell cycle and caspase-independent apoptosis.
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PMID:Arsenic trioxide inhibits growth of As4.1 juxtaglomerular cells via cell cycle arrest and caspase-independent apoptosis. 1750 98

Chronic lymphocytic leukemia (CLL) cells are characterized by defective apoptosis which leads to their extended survival. Arsenic trioxide (As(2)O(3)) was reported to induce cell death in many malignant cells, but the specific pathway of As(2)O(3)-induced apoptosis/necrosis remains controversial. Our aim was to determine if As(2)O(3) kills CLL cells through apoptosis and whether this is accompanied by reduction in Bcl-2 levels. Cells from nine patients with CLL were incubated with increasing concentrations of As(2)O(3) (0.5-2 microM) for 2, 7, or 14 days. Cells viability was measured using Alamar Blue assay and apoptosis using human Annexin V-FITC and propidium iodine (PI) kit (BMS306FI; Bender MedSystems, Vienna, Austria). Intracellular Bcl-2, Bax, and caspase-3 levels were measured by flow cytometry. As(2)O(3) significantly reduced CLL cell viability (P < 0.01) and induced apoptotic cell death in a time- and dose-dependent manner. After 7 days, CLL cells showed a significant decrease in mean fluorescence intensity (MFI) of Bcl-2 on flow cytometry study. Bax and caspase-3 levels showed significant decrease in MFI only after prolonged incubations (7 and 14 days) and mostly at higher concentrations of As(2)O(3). The mechanism underlying the reduction in viability of CLL cells incubated with As(2)O(3) is mediated by induction of apoptosis maybe through the down-regulation of Bcl-2. Further studies are needed to elucidate the potential therapeutic role of As(2)O(3) in CLL.
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PMID:Arsenic-trioxide-induced apoptosis of chronic lymphocytic leukemia cells. 1920 92

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