Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.22.60 (caspase-7)
 920 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Members of the caspase family of cysteine proteases play central roles in coordinating the stereotypical events that occur during apoptosis. Because the major executioner caspases, caspase-3 and caspase-7, exhibit almost indistinguishable activity toward certain synthetic peptide substrates, this has led to the widespread view that these proteases occupy functionally redundant roles within the cell death machinery. However, the distinct phenotypes of mice deficient in either of these caspases, as well as mice deficient in both, is at odds with this view. These distinct phenotypes could be related to differences in the relative expression levels of caspase-3 and caspase-7 in vivo, or due to more fundamental differences between these proteases in terms of their ability to cleave natural substrates. Here we show that caspase-3 and caspase-7 exhibit differential activity toward multiple substrate proteins, including Bid, XIAP, gelsolin, caspase-6, and cochaperone p23. Caspase-3 was found to be generally more promiscuous than caspase-7 and appears to be the major executioner caspase during the demolition phase of apoptosis. Our observations provide a molecular basis for the different phenotypes seen in mice lacking either caspase and indicate that these proteases occupy nonredundant roles within the cell death machinery.
Proc Natl Acad Sci U S A 2008 Sep 02
PMID:Executioner caspase-3 and caspase-7 are functionally distinct proteases. 1872 80

Glioblastoma (GBM) is the most common type of primary brain cancer and carries a dismal prognosis primarily due to the emergence of resistance towards extant radiation, conventional and targeted chemotherapies. Although GBM resists therapy-induced apoptosis, tumors show a seemingly paradoxical propensity for florid intratumoral necrogenesis. This necrosis manifests pathologically as microscopic foci or confluent expanses of necrotic tumor. While it is now well recognized that necrosis is an active cell death process and that apoptosis and necrosis death modalities are intertwined on multiple levels, the precise molecular mechanisms and genetic elements underlying these forms of cell death in GBM remain areas of active investigation. In recent oncogenomic studies, we identified a novel GBM oncoprotein, Bcl2-Like 12 (Bcl2L12), which is significantly expressed in the majority of primary GBM tumor specimens and distantly related to canonical Bcl-2 proteins. Due to its distinctive impact on cell death signaling, Bcl2L12 phenocopies pro-necrotic and anti-apoptotic propensities of high grade glioma: Mechanistically, we determined that unlike prototypic Bcl-2 family members, Bcl2L12 does not safeguard mitochondrial membrane integrity, but instead potently inhibits apoptosis at the level of post-mitochondrial effector caspase-3/7 activation. A combination of enforced expression, RNAi-mediated extinction, co-localization and protein interaction studies revealed that Bcl2L12 inhibits caspases 3 and 7 via distinct mechanisms. Direct physical interaction underlies Bcl2L12's inhibition of caspase-7 processing, whereas Bcl2L12-induced transcriptional upregulation of the small heat shock protein alpha B-crystallin is instrumental to neutralization of caspase-3 activation. Mirroring the cellular phenotype elicited by energy depletion, genetic or pharmacologic inhibition of post-mitochondrial apoptosis signaling molecules, Bcl2L12 promotes necrogenesis in glial cells in the context of a proapoptotic stimulus establishing that it represents a novel regulator of the balance between apoptosis and necrosis in GBM.
Cell Cycle 2008 Sep 15
PMID:What drives intense apoptosis resistance and propensity for necrosis in glioblastoma? A role for Bcl2L12 as a multifunctional cell death regulator. 1876 59

Apoptosis is frequently regulated by different protein kinases including protein kinase C family enzymes. Both inhibitory and stimulatory effects were demonstrated for several of the different PKC isoforms. Here we show that the novel PKC isoform, PKCeta, confers protection against apoptosis induced by the DNA damaging agents, UVC irradiation and the anti-cancer drug--Camptothecin, of the breast epithelial adenocarcinoma MCF-7 cells. The induced expression of PKCeta in MCF-7 cells, under the control of the tetracycline-responsive promoter, resulted in increased cell survival and inhibition of cleavage of the apoptotic marker PARP-1. Activation of caspase-7 and 9 and the release of cytochrome c were also inhibited by the inducible expression of PKCeta. Furthermore, JNK activity, required for apoptosis in MCF-7, as indicated by the inhibition of both caspase-7 cleavage and cytochrome c release from the mitochondria in the presence of the JNK inhibitor SP600125, was also suppressed by PKCeta expression. Hence, in contrast to most PKC isoforms enhancing JNK activation, our studies show that PKCeta is an anti-apoptotic protein, acting as a negative regulator of JNK activity. Thus, PKCeta could represent a target for intervention aimed to reduce resistance to anti-cancer treatments.
Exp Cell Res 2009 Sep 10
PMID:PKCeta confers protection against apoptosis by inhibiting the pro-apoptotic JNK activity in MCF-7 cells. 1952 67

The toxicity of aggregated beta-amyloid (A beta) has been implicated as a critical cause in the development of Alzheimer's disease (AD). Hibifolin, a flavonol glycoside derived from herbal plants, possessed a strong protective activity against cell death induced by aggregated A beta. Application of hibifolin in primary cortical neurons prevented the A beta-induced cell death in a dose-dependent manner. In cultured cortical neurons, the pre-treatment of hibifolin abolished A beta-induced Ca(2+) mobilization, and also reduced A beta-induced caspase-3 and caspase-7 activation. Moreover, DNA fragmentation induced by A beta could be suppressed by hibifolin. In addition to such protection mechanisms, hibifolin was able to induce Akt phosphorylation in cortical neurons, which could be another explanation for the neuroprotection activity. These results therefore provided the first evidence that hibifolin protected neurons against A beta-induced apoptosis and stimulated Akt activation, which would be useful in developing potential drugs or food supplements for treating AD.
Neurosci Lett 2009 Sep 18
PMID:Hibifolin, a flavonol glycoside, prevents beta-amyloid-induced neurotoxicity in cultured cortical neurons. 1953 22

Apoptotic caspases, such as caspase-7, are stored as inactive protease zymogens, and when activated, lead to a fate-determining switch to induce cell death. We previously discovered small molecule thiol-containing inhibitors that when tethered revealed an allosteric site and trapped a conformation similar to the zymogen form of the enzyme. We noted three structural transitions that the compounds induced: (i) breaking of an interaction between Tyr-223 and Arg-187 in the allosteric site, which prevents proper ordering of the catalytic cysteine; (ii) pinning the L2' loop over the allosteric site, which blocks critical interactions for proper ordering of the substrate-binding groove; and (iii) a hinge-like rotation at Gly-188 positioned after the catalytic Cys-186 and Arg-187. Here we report a systematic mutational analysis of these regions to dissect their functional importance to mediate the allosteric transition induced by these compounds. Mutating the hinge Gly-188 to the restrictive proline causes a massive approximately 6000-fold reduction in catalytic efficiency. Mutations in the Arg-187-Tyr-223 couple have a far less dramatic effect (3-20-fold reductions). Interestingly, although the allosteric couple mutants still allow binding and allosteric inhibition, they partially relieve the mutual exclusivity of binding between inhibitors at the active and allosteric sites. These data highlight a small set of residues critical for mediating the transition from active to inactive zymogen-like states.
J Biol Chem 2009 Sep 18
PMID:Dissecting an allosteric switch in caspase-7 using chemical and mutational probes. 1958 39

Caspase-7 is an executioner caspase that plays a key role in apoptosis, cancer, and a number of neurodegenerative diseases. The mechanism of caspase-7 activation by granzyme B and caspase-3 has been well characterized. However, whether other proteases such as calpains activate or inactivate caspase-7 is not known. Here, we present that recombinant caspase-7 is directly cleaved by calpain-1 within the large subunit of caspase-7 to produce two novel products, large subunit p18 and p17. This new form of caspase-7 has a 6-fold increase in V(max) when compared with the previously characterized p20/p12 form. Zymography revealed that the smaller caspase-7 product (p17) is 18-fold more active than either the caspase-3-cleaved product (p20) or the larger calpain-1 product of caspase-7 (p18). Mass spectrometry and site-directed mutagenesis identified the calpain cleavage sites within the caspase-7 large subunit at amino acid 36 and 45/47. These proteolysis events occur in vivo as indicated by the accumulation of caspase-7 p18 and p17 subunits in cortical neurons undergoing Ca(2+) dysregulation. Further, cleavage at amino acid 45/47 of caspase-7 by calpain results in a reduction in nuclear localization when compared with the caspase-3 cleavage product of caspase-7 (p20). Our studies suggest the calpain-activated form of caspase-7 has unique enzymatic activity, localization, and binding affinity when compared with the caspase-activated form.
J Biol Chem 2009 Sep 11
PMID:Calpain-1 cleaves and activates caspase-7. 1961 26

Taxane and vinblastine represent two classes of microtubules-targeted agents for cancer chemotherapy. Although taxol and vinblastine are widely used for cancer treatment, resistance to these agents is frequently encountered in the clinic. An ongoing question has been what mechanisms are involved in the resistance of tumour cells to microtubules-targeted agents or how the clinical effectiveness can be improved. There is increasing evidence that microtubules interact with the endoplasmic reticulum (ER). Here, we have shown that taxol and vinblastine induce multiple arms of the ER stress response, including up-regulation of glucose-regulated protein 78 (GRP78) expression, X-box binding protein 1 splicing and eukaryotic initiation factor 2alpha phosphorylation. Abrogation of GRP78 induction sensitizes breast cancer cells to taxol and vinblastine. Treatment with (-)-epigallocatechin gallate (EGCG), a known GRP78 inhibitor, synergistically promotes taxol- and vinblastine-induced cell death. GRP78 knockdown or EGCG potentiates taxol- and vinblastine-induced activation of pro-apoptosis arms of the ER stress response, such as JNK phosphorylation, caspase-7 and PARP cleavage. Inhibition of JNK and caspase-7 abrogates EGCG sensitization of breast cancer cells to taxol and vinblastine. We conclude that induction of the unfolded protein response represents a novel mechanism underlying the efficacy and resistance to microtubules-targeted agents. Combination of compounds capable of suppressing GRP78 might be a novel approach for improving the effectiveness of microtubules-targeted chemotherapy.
J Cell Mol Med 2009 Sep
PMID:Blockade of GRP78 sensitizes breast cancer cells to microtubules-interfering agents that induce the unfolded protein response. 1967 93

Suppressor of cytokine signaling-3 (SOCS-3) acts as a negative feedback regulator of the Janus-activated kinase/signal transducers and activators of transcription factors signaling pathway and plays an important role in the development and progression of various cancers. To better understand the role of SOCS-3 in prostate cancer, SOCS-3 expression was down-regulated in DU-145, LNCaP-IL-6+, and PC3 cells by consecutive SOCS-3 small interfering RNA transfections. SOCS-3 mRNA and protein expression as measured by quantitative reverse transcription-PCR and Western blot, respectively, were decreased by approximately 70% to 80% compared with controls. We observed a significant decrease in cell proliferation and viability in all SOCS-3-positive cell lines but not in the parental LNCaP cell line, which is SOCS-3 negative. In this study, we show that down-regulation of SOCS-3 leads to an increased cell death in prostate cancer cell lines. We found a considerable increase in the activation of the proapoptotic caspase-3/caspase-7, caspase-8, and caspase-9. A significant up-regulation of cleaved poly(ADP-ribose) polymerase and inhibition of Bcl-2 expression was observed in all SOCS-3-positive cell lines. Overexpression of Bcl-2 could rescue cells with decreased SOCS-3 levels from going into apoptosis. Tissue microarray data prove that SOCS-3 is highly expressed in castration-refractory tumor samples. In conclusion, we show that SOCS-3 is an important protein in the survival machinery in prostate cancer and is overexpressed in castration-resistant tumors. SOCS-3 knockdown results in an increase of cell death via activation of the extrinsic and intrinsic apoptosis pathways.
Cancer Res 2009 Sep 15
PMID:Down-regulation of suppressor of cytokine signaling-3 causes prostate cancer cell death through activation of the extrinsic and intrinsic apoptosis pathways. 1973 59

Fucoidan is an active component of seaweed that has been shown to inhibit proliferation and induce apoptotic cell death in several tumor cells. However, the detailed mechanisms underlying this process have not yet been elucidated. In the present report, we investigated the effect of fucoidan on the induction of apoptosis in human breast cancer MCF-7 cells. Our data demonstrated that fucoidan reduced the viable cell number of MCF-7 cells in a dose- and time-dependent manner. In contrast, fucoidan did not affect the viable cell number of normal human mammary epithelial cells. Results from the apoptosis assay demonstrated that fucoidan induced internucleosomal DNA fragmentation, chromatin condensation, activation of caspase-7, -8, and -9, and cleavage of poly(ADP ribose) polymerase. Furthermore, expression of Bid was decreased, whereas truncated Bid was increased by fucoidan treatment. There was also a decline in cytosolic Bax and a striking increase of cytosolic cytochrome c. Caspase-8-specific inhibitor, z-ITED-fmk, canceled the cytotoxicity of fucoidan, activation of caspase-7, -8, and -9, and a series of changes in Bax, Bid, and cytochrome c. However, caspase-9-specific inhibitor exerted a moderate inhibitory effect on the cytotoxicity of fucoidan. These data indicated that fucoidan could induce apoptotic cell death through a caspase-8-dependent pathway in MCF-7 cells.
J Agric Food Chem 2009 Sep 23
PMID:Fucoidan induces apoptosis through activation of caspase-8 on human breast cancer MCF-7 cells. 1975 76

Glycyrrhiza uralensis (licorice) is one of the most frequently prescribed ingredients in Oriental medicine, and licorice extract has been shown to exert anti-carcinogenic effects. However, its use as a cancer chemopreventive agent is rather limited, due to the fact that its principal component, glycyrrhizin, is known to induce hypertension. This study determined the effects of a hexane/ethanol extract of G. uralensis (HEGU), which contains undetectable amounts of glycyrrhizin, on the apoptosis of androgen-insensitive DU145 cells. HEGU induced apoptosis and increased the levels of cleaved caspase-9, caspase-7, caspase-3 and poly (ADP-ribose) polymerase (PARP). HEGU also induced mitochondrial membrane depolarization and cytochrome c release to the cytosol. HEGU increased the levels of Fas, death receptor 4 (DR4), cleaved caspase-8, Mcl-1S, and truncated Bid proteins. A caspase-8 inhibitor suppressed HEGU-induced apoptosis. An active fraction of HEGU was separated via column chromatography and the structure of the active compound isoangustone A was identified via 1H-NMR and 13C-NMR. Isoangustone A increased apoptotic cells, the cleavage of PARP and caspases, and the levels of DR4 and Mcl-1S. Transfection with DR4 small interfering RNA attenuated HEGU- and isoangustone A-induced apoptosis. These results demonstrate that the activation of DR4 contributes to HEGU- and isoangustone A-induced apoptosis of DU145 cells.
Mol Nutr Food Res 2010 Sep
PMID:Isoangustone A present in hexane/ethanol extract of Glycyrrhiza uralensis induces apoptosis in DU145 human prostate cancer cells via the activation of DR4 and intrinsic apoptosis pathway. 2022 24


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