Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.62 (caspase-9)
 7,507 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although histone deacetylase (HDAC) inhibitors are emerging as a promising new treatment strategy in malignancy, how they exert their effect on human non-small cell lung cancer cells is as yet unclear. This study was undertaken to investigate the underlying mechanism of an HDAC inhibitor, Trichostatin A (TSA), -induced apoptosis in a human lung carcinoma cell line A549. The effects of this compound were also tested on cyclooxygenase (COX) activity. Treatment of A549 cells to TSA resulted in the inhibition of viability and the induction of apoptosis in a concentration-dependent manner, which could be proved by trypan blue counts, DAPI staining, agarose gel electrophoresis and flow cytometry analysis. Apoptosis of A549 cells by TSA was associated with a down-regulation of anti-apoptotic Bcl-2 protein and an up-regulation of pro-apoptotic Bax protein. TSA treatment induced the proteolytic activation of caspase-3 and caspase-9, and a concomitant degradation of poly(ADP-ribose)-polymerase protein. Furthermore, TSA decreased the levels of COX-2 mRNA and protein expression without significant changes in the levels of COX-1, which was correlated with an inhibition in prostaglandin E2 synthesis. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of TSA.
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PMID:Induction of apoptosis by trichostatin A, a histone deacetylase inhibitor, is associated with inhibition of cyclooxygenase-2 activity in human non-small cell lung cancer cells. 1601 Apr 30

Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disease caused by polyglutamine-expanded ataxin-3. In the present study, we expressed disease-causing mutant ataxin-3-Q79 in neuronal cultures of cerebellum, striatum and substantia nigra by using recombinant adenoviruses. Subsequently, SCA3 cellular model was used to investigate the molecular mechanism by which ataxin-3-Q79 causes neuronal death. TUNEL staining studies showed that ataxin-3-Q79 induced apoptotic death of cerebellar, striatal or substantia nigra neurons. Ataxin-3-Q79 activated caspase-3 and caspase-9 without inducing the formation of active caspase-8. Ataxin-3-Q79 promoted mitochondrial release of cytochrome c and Smac, which was preceded by the upregulation of Bax protein and downregulation of Bcl-x(L) protein expression. Real-time TaqMan RT-PCR assays demonstrated that ataxin-3-Q79 upregulated Bax mRNA level and downregulated Bcl-xL mRNA expression in striatal, cerebellar and substantia nigra neurons. Our results suggest that polyglutamine-expanded ataxin-3-Q79 activates mitochondrial apoptotic pathway and induces neuronal death by upregulating Bax expression and downregulating Bcl-xL expression.
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PMID:Polyglutamine-expanded ataxin-3 activates mitochondrial apoptotic pathway by upregulating Bax and downregulating Bcl-xL. 1611 67

To elucidate the possible effect of NFkappaB on radioresistance, we used the osteosarcoma cell line Saos2, stably expressing the NFkappaB constitutive inhibitor, mIkappaB (Saos2-mIkappaB) or stably transfected with the empty vector (Saos2-EV). Ionizing radiation induced "intrinsic" apoptosis in Saos2-mIkappaB cells but not in Saos2-EV control cells, with intact NFkappaB activity. We find as expected, that this NFkappaB activity was enhanced following irradiation in the Saos2-EV control cells. On the other hand, inhibition of NFkappaB signaling in Saos2-mIkappaB cells led to the upregulation of the pro-apoptotic systems, such as Bax protein and c-Jun N-terminal Kinase (JNK)/c-Jun/AP1 signaling. Inhibition of NFkappaB resulted in decreased expression of the DNA damage protein GADD45beta, a known inhibitor of JNK. Subsequently, JNK activation of c-Jun/AP-1 proteins increased radiation-induced apoptosis in these mutants. Radiation-induced apoptosis in Saos2-mIkappaB cells was inhibited by the JNK specific inhibitor SP600125 as well as by Bcl-2 over-expression. Furthermore, release of cytochrome-c from mitochondria was increased and caspase-9 and -3 were activated following irradiation in Saos2-mIkappaB cells. Antisense inhibition of GADD45beta in Saos2-EV cells significantly enhanced apoptosis following irradiation. Our results demonstrate that radioresistance of Saos2 osteosarcoma cells is due to NFkappaB-mediated inhibition of JNK. Our study brings new insight into the mechanisms underlying radiation-induced apoptosis of osteosarcoma, and may lead to development of new therapeutic strategies against osteosarcoma.
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PMID:Increased radiation-induced apoptosis of Saos2 cells via inhibition of NFkappaB: a role for c-Jun N-terminal kinase. 1616 36

Trimidox (3,4,5-trihydroxybenzamidoxime) has been shown to reduce the activity of ribonucleotide reductase accompanied by growth inhibition and the differentiation of mammalian cells. Here we examine the induction of apoptosis by trimidox in several human leukaemia cell lines, focusing on the release of cytochrome c and the activation of caspase proteases in the human B cell line NALM-6. Induction of apoptosis by trimidox (300 microM) was detected in NALM-6, HL-60 (premyelocytic leukaemia cells), MOLT-4 (an acute lymphoblastic leukaemia cells), Jurkat (a T-cell leukaemia cells), U937 (expressing many monocyte-like characteristics), and K562 (erythroleukaemia). NALM-6 was most affected by trimidox among leukaemia cells; therefore, we employed NALM-6 cells in the subsequent experiments. The cells showed a time-dependent increase in DNA damage after trimidox (250 microM) treatment. A significant increase in the amount of cytochrome c release was detected after treatment with trimidox. Bcl-2 and Bax protein expressions were not changed by trimidox. Caspase-3 and -9 were activated by incubation with trimidox, whereas caspase-8 was not. Furthermore, trimidox-induced apoptosis was prevented by a broad-spectrum caspase inhibitor, a caspase-3, and a caspase-9 inhibitor, but not by a caspase-8 inhibitor. Inhibition of c-Jun NH2-terminal kinase (JNK) by SP600125 appreciably protected cells from trimidox-induced apoptosis, but no effect inhibition of p38 mitogen-activated protein kinase (MAPK) by SB203580. In contrast, extracellular signal-regulated kinase (ERK) inhibitors U0126 and PD98059 strongly potentiated the apoptotic effect of trimidox. This report shows that the induction of apoptosis by trimidox occurs through a cytochrome c-dependent pathway, which sequentially activates caspase-3 and caspase-9.
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PMID:Trimidox induces apoptosis via cytochrome c release in NALM-6 human B cell leukaemia cells. 1643 90

Inhibitor of differentiation/DNA binding (Id) proteins comprise a class of helix-loop-helix transcription factors involved in proliferation, differentiation, apoptosis, and carcinogenesis. We have shown that while Id2 is induced by UVB in primary keratinocytes, Id3 is upregulated only in immortalized cells. We have now determined that the consequences of ectopic expression of Id3 protein are strikingly different between immortalized and primary keratinocytes. Overexpression of Id3 induces a significant increase in apoptotic cells as revealed by Annexin V positivity as well as proteolytic processing of caspase-3 in immortalized, but not in primary keratinocytes. Id3-green fluorescent protein (GFP)-positive cells exhibited a fivefold increase in apoptotic nuclear fragmentation compared to Id3-GFP-negative cells. These apoptotic responses were accompanied by activation of caspase-3, as shown by immunocytochemical staining with antibodies to active caspase-3. Immunostaining with antibodies to the active form of caspase-9 as well as to the active form of Bax further revealed that induction of apoptosis in Id3-overexpressing keratinocytes occurred via a mitochondrial-caspase-9-mediated pathway. Coexpression of dominant-negative caspase-9 with Id3 significantly suppressed apoptotic nuclear fragmentation, indicating that caspase-9 activation is essential for Id3-induced cell death. This response was also markedly attenuated by coexpression with the Bax antagonist antiapoptotic protein Bcl2, confirming a role for Bax activation in this apoptotic response. Id3-induced Bax activation may result from increased expression of Bax protein. Furthermore, reduction of Id3 expression by small interfering RNAs abrogated the UVB-induced proteolytic activation of caspase-3 in these cells. These data together suggest that UVB-induced apoptosis of immortalized keratinocytes is at least in part due to Id3 upregulation in these cells.
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PMID:Id3 induces a caspase-3- and -9-dependent apoptosis and mediates UVB sensitization of HPV16 E6/7 immortalized human keratinocytes. 1644 66

Aging is characterized by loss of myocytes, remodeling, and impaired contractile function in the heart. The rate of programmed cell death, or "apoptosis," in the left ventricle increases with age, and contributes to a 30% reduction in myocytes. Aging may preferentially target the Bcl-2 pathway of apoptosis in the heart. Exercise can protect cardiac function of the aging heart, although the mechanisms are poorly understood. We tested the hypothesis that 12 wk of exercise training would attenuate age-induced increases in remodeling, apoptosis, and Bax/Bcl-2 ratio in rat left ventricle. We found that exercise training provided significant protection against loss of cardiac myocytes, reduction in number of myonuclei, reactive hypertrophy of remaining myocytes, and increased connective tissue in left ventricle of the aging rat heart. Exercise training significantly attenuated age-induced increases of apoptosis in the left ventricle, as indicated by lower DNA fragmentation, TUNEL-positive staining, and caspase-3 cleavage, when compared with left ventricles from the age-matched sedentary group. Further, exercise training in the aging reduced caspase-9 levels and Bax/Bcl-2 ratio by lowering Bax protein expression while increasing Bcl-2 levels. These are the first data to demonstrate protective effects of endurance exercise training against elevated apoptosis and remodeling in the aging heart.
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PMID:Exercise training attenuates age-induced elevation in Bax/Bcl-2 ratio, apoptosis, and remodeling in the rat heart. 1645 53

The mitochondrial pathway of swine influenza virus (SIV)-induced apoptosis was investigated using porcine kidney (PK-15) cells, swine testicle (ST) cells, and HeLa cervical carcinoma cells which are known not to support viral replication. As judged by cell morphology, annexin V staining, and DNA fragmentation, PK-15 and ST cells infected with three different subtypes of SIV (H1N1, H3N2, and H1N2) were obviously killed by apoptosis, not necrosis. SIV infection in PK-15 and HeLa cells was shown to decrease the cellular levels of Bcl-2 protein compared to that of mock-infected control cells at 24 h post-infection, whereas expression levels of Bax protein increased in the PK-15 cells, but did not increase in HeLa cells by SIV infection. Cytochrome c upregulation was also observed in cytosolic fractions of the PK-15 and HeLa cells infected with SIV. Apoptosome (a multi-protein complex consisting of cytochrome c, Apaf-1, caspase-9, and ATP) formation was confirmed by immunoprecipitation using cytochrome c antibody. Furthermore, SIV infection increased the cellular levels of TAJ, an activator of the JNK- stressing pathway, and the c-Jun protein in the PK-15 and HeLa cells. Taken together, these results suggest that the mitochondrial pathway should be implicated in the apoptosis of PK-15 cells induced by SIV infection.
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PMID:Activation of the intrinsic mitochondrial apoptotic pathway in swine influenza virus-mediated cell death. 1652 May 48

Deletion at chromosome 3p21.3 is the earliest and the most frequently observed genetic alteration in lung cancer, suggesting that the region contains tumor suppressor gene(s) (TSG). Identification of those genes may lead to the development both of biomarkers to identify high-risk individuals and novel therapeutics. Previously, we cloned the H37/Luca15/RBM5 gene from 3p21.3 and showed its TSG characteristics. To investigate the physiologic function of H37 in the lung and its mechanism of tumor suppression, we have stably transfected H37 into A549 non-small cell lung cancer cells. A549/H37 cells show significant growth inhibition compared with the vector controls by in vitro and in vivo cell proliferation assays. Using this lung cancer cell model, we have found that the molecular mechanism of H37 tumor suppression involves both cell cycle (G(1)) arrest and apoptosis. To further define H37's function in cell cycle/apoptotic pathways, we investigated differential expression profiles of various cell cycle and apoptosis regulatory proteins using Western blot analysis. Both cyclin A and phophorylated RB levels were decreased in H37-transfected cells, whereas expression of Bax protein was increased. Mitochondrial regulation of apoptosis further downstream of Bax was investigated, showing change in the mitochondrial membrane potential, cytochrome c release into the cytosol, and enhanced caspase-9 and caspase-3 activities. We also report that H37 may mediate apoptosis in a p53-independent manner, and Bax knockdown by small interfering RNA suggests Bax plays a functional role downstream of H37. Lastly, we proposed a tumor suppression model of H37 as a post-transcriptional regulator for cell cycle/apoptotic-related proteins.
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PMID:3p21.3 tumor suppressor gene H37/Luca15/RBM5 inhibits growth of human lung cancer cells through cell cycle arrest and apoptosis. 1658 63

We examined in vitro sensitivity of B-CLL cells exposed to cladribine, mafosfamide, mitoxantrone and combinations ofcladribine with mafosfamide and/or mitoxantrone. The results revealed that each applied treatment of leukemic cells, besides having a cytotoxic effect, affected the events associated with apoptosis. All drugs used alone, and cladribine combinations with mafosfamide and/or mitoxantrone induced DNA fragmentation and the changes in expression/proteolysis level of caspase-3, caspase-9 precursors, PARP-1, lamin B, Bax and Bcl-2; however, each to a different degree. The exposure of leukemic cells to both cladribine combinations induced stronger effects. Moreover, the data showed that the expression of regulatory antiapoptotic protein Bcl-2 generally decreased in drug-treated B-CLL cells, whereas proapoptotic polypeptide Bax increased, resulting in enhancement of Bax-Bcl-2 ratios in comparison with untreated cells. Drug-treatment of the studied cells induced the translocation of Bax protein from the cytosol to the cellular pellet, containing mitochondria, where this polypeptide indicated the capacity for oligomerization. These observations suggest that the examined drugs are able to induce apoptosis of B-CLL cells via the mitochondria pathway.
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PMID:In vitro sensitivity of B-cell chronic lymphocytic leukemia to cladribine and its combinations with mafosfamide and/or mitoxantrone. 1708 66

Through protein-protein binding assays, we found that HCV core protein interacted with 14-3-3epsilon protein. Interestingly, the expression of HCV core protein induced apoptosis in 293T cells. The apoptosis induced by core expression is accompanied by translocation of Bax from cytosol to mitochondria, disruption of mitochondrial membrane potential, cytochrome c release, and activation of caspase-9 and caspase-3. Furthermore, over-expression of 14-3-3epsilon inhibited the core-induced apoptosis and Bax translocation to mitochondria. These results indicate that HCV core protein induces the Bax-mediated apoptosis by interacting with 14-3-3epsilon protein in 293T cells. As a mechanism of apoptosis induction by HCV core, we propose that the interaction of HCV core with 14-3-3epsilon causes the dissociation of Bax from the Bax/14-3-3epsilon complex in cytosol, and the free Bax protein provokes activation of the mitochondrial apoptotic pathway.
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PMID:Interaction of HCV core protein with 14-3-3epsilon protein releases Bax to activate apoptosis. 1714 Nov 94


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