Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.31 (AMP-activated protein kinase)
 13,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Most cancer cells exhibit increased glycolysis for generation of their energy supply. This specificity could be used to preferentially kill these cells. In this study, we identified the signaling pathway initiated by glycolysis inhibition that results in sensitization to death receptor (DR)-induced apoptosis. We showed, in several human cancer cell lines (such as Jurkat, HeLa, U937), that glucose removal or the use of nonmetabolizable form of glucose (2-deoxyglucose) dramatically enhances apoptosis induced by Fas or by tumor necrosis factor-related apoptosis-inducing ligand. This sensitization is controlled through the adenosine monophosphate (AMP)-activated protein kinase (AMPK), which is the central energy-sensing system of the cell. We established the fact that AMPK is activated upon glycolysis block resulting in mammalian target of rapamycin (mTOR) inhibition leading to Mcl-1 decrease, but no other Bcl-2 anti-apoptotic members. Interestingly, we determined that, upon glycolysis inhibition, the AMPK-mTOR pathway controlled Mcl-1 levels neither through transcriptional nor through posttranslational mechanism but rather by controlling its translation. Therefore, our results show a novel mechanism for the sensitization to DR-induced apoptosis linking glucose metabolism to Mcl-1 downexpression. In addition, this study provides a rationale for the combined use of DR ligands with AMPK activators or mTOR inhibitors in the treatment of human cancers.
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PMID:Glycolysis inhibition sensitizes tumor cells to death receptors-induced apoptosis by AMP kinase activation leading to Mcl-1 block in translation. 1996 61

Although c-Kit is expressed on the surface of myeloma cells in one-third of myeloma patients, the efficacy of imatinib mesylate for patients with myeloma is still controversial. To investigate the combinatorial effect of OSU-03012 and imatinib mesylate, we treated a c-Kit-expressing myeloma cell line, TIB-196, with DMSO, OSU-03012 alone, imatinib mesylate alone and OSU-03012 plus imatinib mesylate. OSU-03012 sensitized TIB-196 cells to imatinib mesylate cytotoxicity. p-STAT3 (Tyr705), as well as down-stream cyclin D1 and Mcl-1, was down regulated. Additionally, there was markedly increased p-AMPK (Thr172) and down-regulation of p-p70S6K (Thr386) in the combination group. Combined treatments targeting c-Kit, AMPK and STAT3 may be a potential strategy for treating patients with myeloma.
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PMID:OSU-03012 sensitizes TIB-196 myeloma cells to imatinib mesylate via AMP-activated protein kinase and STAT3 pathways. 2000 97

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), either alone or in combination with other anticancer drugs, is considered as a new strategy for anticancer therapy. Compound C, a cell-permeable pyrrazolopyrimidine derivative, acts as a potent, selective, reversible ATP-competitive inhibitor of AMP-activated protein kinase (AMPK). In this study, we show that compound C sensitizes Caki human renal cancer cells, but not normal human skin fibroblast cells (HSF) and human mesangial cells, to TRAIL-mediated apoptosis. However, AMPK siRNA failed to affect TRAIL-mediated apoptosis in Caki cells and transduction of dominant negative AMPK rather attenuated TRAIL-induced apoptosis, indicating that the effect of compound C on sensitization of TRAIL-induced apoptosis is independent of AMPK activity. Interestingly, we found that down-regulation of c-FLIP(L) and Mcl-1 contributes to compound C-enhanced TRAIL-induced apoptosis. Reduced expression of c-FLIP(L) and Mcl-1 were caused by the decreased protein stability of c-FLIP(L) and Mcl-1, but not by their transcriptional control, in compound C-treated cells. Pretreatment with N-acetyl-L-cysteine (NAC) significantly inhibited the cell death induced by the combined treatment with compound C and TRAIL as well as recovered the expression levels of c-FLIP(L) and Mcl-1 down-regulated by the combinatory treatment with compound C plus TRAIL, suggesting that compound C-stimulated TRAIL-induced apoptosis appears to be dependent on the generation of reactive oxygen species for down-regulation of c-FLIP(L) and Mcl-1. Taken together, the present study demonstrates that compound C enhances TRAIL-induced apoptosis in human renal cancer cells by ROS-mediated c-FLIP(L) and Mcl-1 down-regulation.
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PMID:Compound C sensitizes Caki renal cancer cells to TRAIL-induced apoptosis through reactive oxygen species-mediated down-regulation of c-FLIPL and Mcl-1. 2045 17

Whether hispidulin, a flavone from traditional Chinese medicine, can modulate the anticancer effects of the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), the cytokine currently in clinical trials was investigated. In the present study, we found that hispidulin potentiated the TRAIL-induced apoptosis in human ovarian cancer cells and converted TRAIL-resistant cells to TRAIL-sensitive cells. When examined for its mechanism, we found that hispidulin was highly effective in activation of caspases 8 and caspase 3 and consequent poly(ADP-ribose) polymerase (PARP) cleavage. Moreover, we found that hispidulin downregulated the expression of Mcl-1, Bcl-2, and Bcl-xL. Whereas the downregulation of Bcl-2 and Bcl-xL was less pronounced, the downregulation of Mcl-1 was quite dramatic and was time-dependent. This sensitization is controlled through the adenosine monophosphate (AMP)-activated protein kinase (AMPK), which is the central energy-sensing system of the cell. Interestingly, we determined that AMPK is activated upon hispidulin treatment, resulting in mammalian target of rapamycin (mTOR) inhibition leading to Mcl-1 decrease. Therefore, our results show a novel mechanism for the sensitization to TRAIL-induced apoptosis linking hispidulin treatment to Mcl-1 downexpression. In addition, this study provides a rationale for the combined use of death receptor (DR) ligands with AMPK activators or mTOR inhibitors in the treatment of human cancers.
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PMID:Hispidulin sensitizes human ovarian cancer cells to TRAIL-induced apoptosis by AMPK activation leading to Mcl-1 block in translation. 2073 85

Beclin 1 usually interacts with several autophagy-inhibitory proteins including the anti-apoptotic proteins from the Bcl-2 family (Bcl-2, Bcl-XL and Mcl-1) and the inositol-1,4,5 trisphosphate (IP 3) receptor, which interacts with Beclin 1 indirectly, via Bcl-2. Beclin 1 possesses a BH3 domain that usually interacts with a hydrophobic cleft, the BH3 receptor domain, contained within Bcl-2 and its homologues. Dissociation of this interaction can be induced by phosphorylation or ubiquitination of the BH3 domain, by post-transcriptional modifications affecting the Bcl-2 protein, as well as by other BH3 domain-containing proteins that have a high affinity for Bcl-2 (or its homologues), and hence liberate Beclin 1 from its restraint. As a result, it has been thought that so-called BH3 mimetics, that is the pharmacological agents that occupy the hydrophobic cleft of Bcl-2, Bcl-XL and Mcl-1, would induce autophagy solely by disrupting the interaction between Beclin 1 and its inhibitors. Unexpectedly, we found that two distinct BH3 mimetics, ABT737 and HA14-1, also stimulate other pro-autophagic pathways and hence activate the nutrient sensors Sirtuin 1 and AMPK, inhibit mTOR, deplete cytoplasmic p53 and trigger the IKK kinase. All these additional activities are required for optimal autophagy induction by BH3 mimetics, pointing to the existence of a coordinated autophagy-regulatory network.
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PMID:BH3 mimetics reveal the network properties of autophagy-regulatory signaling cascades. 2150 85

Apoptosis provoked by glucose shortage in dividing T cells is mediated via the BH3-only protein Noxa and inhibition of its binding partner Mcl-1. It is unknown how signals from cellular metabolism can affect the balance between Mcl-1 and Noxa and to what extent other Bcl-2 members are involved in this apoptosis cascade. Here, we defined the mechanism underlying apoptosis in relation to various types of metabolic stress. First, we established that the Noxa/Mcl-1 balance is regulated by glucose deprivation as well as by general metabolic stress, via changes in proteasome-mediated degradation of Mcl-1. Second, in contrast with cytokine-deprivation, no transcriptional modulation of Mcl-1, Puma, Bim or Noxa was observed during glucose deprivation. Third, no changes in PKB or GSK3 activity occurred and no clear role for AMPK was detected. Fourth, apoptosis triggered by nutrient deprivation was executed without signs of overt autophagy and independent of ROS production or p38 MAP kinase activity. Lastly, apoptosis under nutrient limitation could also be delayed by knock-down of Bim or overexpression of Bcl-2. In conclusion, Noxa functions in a specific apoptotic pathway that integrates overall nutrient stress, independent from attenuated PI3K/PKB signaling and without clear involvement of autophagy.
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PMID:Apoptosis induced by overall metabolic stress converges on the Bcl-2 family proteins Noxa and Mcl-1. 2151 46

We investigated the molecular mechanisms responsible for fisetin-induced apoptosis in U266 cells. Fisetin elicited the cytotoxicity in U266 cells, manifested as an increased fraction of the cells with sub-G1 content or stained positively with TUNEL labeling. Fisetin enhanced caspase-3 activation, downregulation of Bcl-2 and Mcl-1(L), and upregulation of Bax, Bim and Bad. Fisetin activated AMPK as well as its substrate acetyl-CoA carboxylase (ACC), along with a decreased phosphorylation of AKT and mTOR. Fisetin also stimulated generation of ROS in U266 cells. Conversely, compound C or N-acetyl-L-cystein blocked fisetin-induced apoptosis. Our data suggest that fisetin-induced apoptosis in U266 cells is through ROS and AMPK pathways.
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PMID:Activation of reactive oxygen species/AMP activated protein kinase signaling mediates fisetin-induced apoptosis in multiple myeloma U266 cells. 2226 40

Twist1 is highly expressed in primary and metastatic non-small cell lung cancer (NSCLC), and thus acts as a critical target for lung cancer chemotherapy. In the current study, we investigated the underlying mechanism initiated by silencing of Twist1 that sensitizes NSCLC cells to cisplatin. Silencing of Twist1 triggered ATP depletion, leading to AMP-activated protein kinase (AMPK)-activated mammalian target of rapamycin (mTOR) inhibition in NSCLC cells. AMPK-induced mTOR inhibition, in turn, resulted in downregulation of ribosome protein S6 kinase 1 (S6K1) activity. Downregulation of mTOR/S6K1 reduced Mcl-1 protein expression, consequently promoting sensitization to cisplatin. Overexpression of Mcl-1 reduced PARP cleavage induced by cisplatin and Twist1 siRNA, suggesting that this sensitization is controlled through Mcl-1 expression. Interestingly, cells treated with Twist1 siRNA displayed upregulation of p21(Waf1/CIP1), and suppression of p21(Waf1/CIP1) with specific siRNA further enhanced the cell death response to cisplatin/Twist1 siRNA. In conclusion, silencing of Twist1 sensitizes lung cancer cells to cisplatin via stimulating AMPK-induced mTOR inhibition, leading to a reduction in Mcl-1 protein. To our knowledge, this is the first report to provide a rationale for the implication of cross-linking between Twist1 and mTOR signaling in resistance of NSCLC to anticancer drugs.
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PMID:Silencing of Twist1 sensitizes NSCLC cells to cisplatin via AMPK-activated mTOR inhibition. 2267 93

The purine analog fludarabine (Fd) is an essential therapeutic for chronic lymphocytic leukemia (CLL). Innate or acquired resistance to Fd is a significant clinical problem and is largely mediated by increased expression of BCL-2 family members. The antiapoptotic BCL-2 family proteins inhibit both apoptosis and autophagy, therefore, downregulation of antiapoptotic BCL-2 family proteins and enhanced autophagy must coexist in cells dying in response to an apoptosis inducing therapeutic. However, in the drug-resistant cells that have an increased dependence on antiapoptotic proteins, whether autophagy is also inhibited remains unclear. Here, we examined the role of the BCL-2 family in regulating cell death and autophagy in leukemic cell lines and their derivative isogenic Fd-resistant (FdR) cells. MCL-1 degradation following Fd treatment freed the proapoptotic effectors BIM and BECN1, thus leading to cell death-associated autophagy in Fd-sensitive cells. However, in FdR cells, low BIM expression and BECN1 sequestration by MCL-1 prevented cell death. Consistently, in sensitive cells inhibition of apoptosis using siBIM and of both the early-phase autophagy nucleation steps by siBECN1, shATG7 or 3-methyladenine and the late-phase autophagy by shLAMP2, significantly reduced Fd-induced cell death. Paradoxically, FdR cells were addicted to basal autophagy, which was dependent on AMP-activated protein kinase (AMPK) but not BECN1. Moreover, in FdR cells, inhibition of autophagy by shLAMP2, but not siBECN1, enhanced cell death. The BH3-mimetic obatoclax released BIM and BECN1 from MCL-1 in Fd-sensitive and BECN1 from MCL-1 in FdR cells, and was effective at killing both Fd-sensitive and - resistant leukemic cells, including primary CLL cells. Therefore, a differential regulation of autophagy through BECN1 and AMPK signaling in Fd-sensitive and - resistant cells determines the different possible outcomes of autophagy inhibition. These findings suggest effective means to overcome Fd resistance by induction of BIM-dependent apoptosis and activation of BECN1-dependent autophagy.
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PMID:BECN1 and BIM interactions with MCL-1 determine fludarabine resistance in leukemic B cells. 2368 Dec 23

The secondary EGF receptor (EGFR) T790M is the most common mechanism of resistance to reversible EGFR-tyrosine kinase inhibitors (TKI) in patients with non-small cell lung cancer (NSCLC) with activating EGFR mutations. Although afatinib (BIBW2992), a second-generation irreversible EGFR-TKI, was expected to overcome the acquired resistance, it showed limited efficacy in a recent phase III clinical study. In this study, we found that the inhibition of glycolysis using 2-deoxy-d-glucose (2DG) improves the efficacy of afatinib in H1975 and PC9-GR NSCLC cells with EGFR T790M. Treatment with the combination of 2DG and afatinib induced intracellular ATP depletion in both H1975 and PC9-GR cells, resulting in activation of AMP-activated protein kinase (AMPK). AMPK activation played a central role in the cytotoxicity of the combined treatment with 2DG and afatinib through the inhibition of mTOR. The alteration of the AMPK/mTOR signaling pathway by the inhibition of glucose metabolism induced specific downregulation of Mcl-1, a member of the antiapoptotic Bcl-2 family, through translational control. The enhancement of afatinib sensitivity by 2DG was confirmed in the in vivo PC9-GR xenograft model. In conclusion, this study examined whether the inhibition of glucose metabolism using 2DG enhances sensitivity to afatinib in NSCLC cells with EGFR T790M through the regulation of the AMPK/mTOR/Mcl-1 signaling pathway. These data suggest that the combined use of an inhibitor of glucose metabolism and afatinib is a potential therapeutic strategy for the treatment of patients with acquired resistance to reversible EGFR-TKIs due to secondary EGFR T790M.
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PMID:Glycolysis inhibition sensitizes non-small cell lung cancer with T790M mutation to irreversible EGFR inhibitors via translational suppression of Mcl-1 by AMPK activation. 2388 84


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