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)

Extracellular adenosine reduced viability of RCR-1 rat astrocytoma cells in a dose (0.3-10mM)- and treatment time (24-72h)-dependent manner. In the apoptosis assay using propidium iodide (PI) and annexin V, treatment with adenosine (1mM) for 72h increased the population of PI-negative/annexin V-positive cells, that is related to early apoptosis, and that of PI-positive/annexin V-positive cells, that is related to late apoptosis/secondary necrosis. In addition, nuclei of cells treated with adenosine (1mM) for 72h were reactive to an antibody against single-stranded DNA. Adenosine activated caspase-3, -8 and -9, but mitochondrial membrane potentials were not affected. Adenosine-induced RCR-1 cell death was significantly inhibited by 8-CPT, an antagonist of A(1) adenosine receptors, and forskolin, an adenylate cyclase activator. SQ22536, an adenylate cyclase inhibitor, alternatively, exhibited an effect similar to adenosine. CHA, an agonist of A(1) adenosine receptors, activated caspase-3 and -9, but not caspase-8. Adenosine-induced cytotoxicity of RCR-1 cells was also significantly inhibited by dipyridamole, an inhibitor of adenosine transporter, and AMDA, an inhibitor of adenosine kinase. AICAR, an activator of AMP-activated protein kinase (AMPK), reduced RCR-1 cell viability, but synergistic effect was not obtained with co-treatment with adenosine and AICAR. AICAR activated caspase-3 and -9, but not caspase-8. An additive inhibition was found in the co-presence of 8-CPT and dipyridamole. Extracellular adenosine, thus, appears to activate caspase-9 followed by the effector caspase, caspase-3, at least via two independent pathways linked to A(1) adenosine receptor-mediated adenylate cyclase inhibition and adenosine uptake into cells/conversion to AMP/activation of AMPK, possibly regardless of mitochondrial damage, thereby leading to RCR-1 cell death, dominantly by apoptosis. Moreover, caspase-8 activation could again contribute to adenosine-induced cytotoxicity, although the underlying mechanism is currently unknown. Collectively, the results of the present study may represent a new pathway for caspase activation relevant to diverse adenosine signals in cell death.
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PMID:A(1) adenosine receptor signal and AMPK involving caspase-9/-3 activation are responsible for adenosine-induced RCR-1 astrocytoma cell death. 1646 85

Extracellular adenosine induced apoptosis of HuH-7 cells, a Fas-deficient human hepatoma cell line. The adenosine action was inhibited by dipyridamole, an adenosine transporter inhibitor, or 5'-amino-5'-deoxyadenosine, an inhibitor of adenosine kinase to convert from adenosine to AMP, but it was not affected by inhibitors for adenosine A(1), A(2a), A(2b), and A(3) adenosine receptors. Adenosine activated caspase-3 and -8, but not caspase-9, in HuH-7 cells, and the activation was abolished by dipyridamole. In the real-time RT-PCR and Western blot analysis, extracellular adenosine downregulated mRNA and protein levels for c-FLIP, and the effect was suppressed by dipyridamole. Furthermore, overexpression of c-FLIP short in HuH-7 cells inhibited adenosine-induced caspase-8 activity. Taken together, these results suggest that intracellularly transported adenosine, perhaps converted AMP as the ensuing event, activates caspase-8 and the downstream effector caspase caspase-3 by neutralizing caspase-8 inhibition due to c-FLIP as a consequence of decreased c-FLIP expression, leading to apoptosis. This extends our understanding of adenosine-induced molecular apoptotic pathways.
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PMID:Intracellularly transported adenosine induces apoptosis in HuH-7 human hepatoma cells by downregulating c-FLIP expression causing caspase-3/-8 activation. 1730 86

The naturally occurring cytokinin, ortho-topolin riboside (oTR), has been recently reported to have a strong anticancer effect. However, the molecular mechanism has not been elucidated. From our research we found that oTR strongly inhibited the proliferation of SMMC-7721 cells inducing apoptosis. After oTR treatment, up-regulation of the protein levels of pro-apoptotic Bax and the down-regulation of the anti-apoptotic proteins, Bcl-2 and Bcl-xL was observed, leading to the loss of mitochondrial membrane potential, the release of cytochrome c from the mitochondria into the cytosol, the downstream activation of caspase-9 and caspase-3, as well as the cleavage of poly ADP-ribose-polymerase (PARP), the effect of apoptosis could be blocked by the pan-specific caspase inhibitor z-VAD-fmk and caspase-9-specific inhibitor z-LEHD-fmk. Moreover, oTR was shown to inhibit the activation of the extracellular signal-regulated kinase-1/2 (ERK(1/2)) as well as the Akt pathway. These results suggest that oTR interferes with the mitogen-activated protein kinase (MAPK) and Akt pathways and induces the apoptosis of human SMMC-7721 cells through the activation of intrinsic mitochondria-mediated pathways. However, the apoptosis was completely prevented when cells were treated with A-134974, an inhibitor of adenosine kinase, it indicated that the intracellular phosphorylation of oTR is necessary for its cytotoxic effects to SMMC-7721 cells.
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PMID:Mechanism of apoptotosis induced by ortho-topolin riboside in human hepatoma cell line SMMC-7721. 2246 33