351
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Biswas SC, Shi Y, Sproul A, Greene LA. Pro-apoptotic Bim induction in response to nerve growth factor deprivation requires simultaneous activation of three different death signaling pathways. J Biol Chem 2007; 282:29368-74. [PMID: 17702754 DOI: 10.1074/jbc.m702634200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Bim is a pro-apoptotic member of the Bcl-2 family that is induced and contributes to neuron death in response to nerve growth factor (NGF) deprivation. Past work has revealed that Bim is downstream of multiple independent transcriptional pathways in neurons, including those culminating in activation of the c-Jun, FoxO, and Myb transcription factors. This study addresses the issue of whether the three signaling pathways are redundant with respect to Bim induction or whether they act cooperatively. Examination of the proximal Bim promoter reveals binding sites for FoxO, Mybs, and, as shown here, c-Jun. We find that mutation of any one of these types of sites abolishes induction of a Bim promoter-driven reporter in response to NGF deprivation. Moreover, down-regulation of either c-Jun, FoxOs, or Mybs by short hairpin RNAs blocks induction of Bim promoter-reporter activity triggered by withdrawal of NGF. This was the case for reporters driven by either the proximal promoter or a promoter that also includes additional regulatory elements in the first intron of the Bim gene. Such short hairpin RNAs also suppressed the induction of endogenous Bim protein. These findings thus indicate that the Bim promoter acts as a coincidence detector that optimally responds to the simultaneous activation of three different pro-apoptotic transcriptional pathways. Such a mechanism provides a "fail-safe" that prevents neurons from dying by accidental activation of any single pathway. It also permits neurons to utilize individual pathways such as JNK signaling for other purposes without risk of demise.
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Affiliation(s)
- Subhas C Biswas
- Department of Pathology, Center for Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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352
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Barreyro FJ, Kobayashi S, Bronk SF, Werneburg NW, Malhi H, Gores GJ. Transcriptional regulation of Bim by FoxO3A mediates hepatocyte lipoapoptosis. J Biol Chem 2007; 282:27141-27154. [PMID: 17626006 DOI: 10.1074/jbc.m704391200] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Hepatocyte lipoapoptosis, a critical feature of nonalcoholic steatohepatitis, can be replicated in vitro by incubating hepatocytes with saturated free fatty acids (FFA). These toxic FFA induce Bim expression, which is requisite for their cytotoxicity. Because the FoxO3a transcription factor has been implicated in Bim expression, our aim was to determine if FFA induce Bim by a FoxO3a-dependent mechanism. In Huh-7 cells, the saturated FFA, palmitic and stearic acid, increased Bim mRNA 16-fold. Treatment of cells with the saturated FFA induced FoxO3a dephosphorylation (activation) and nuclear translocation and stimulated a FoxO luciferase-based reporter assay; direct binding of FoxO3a to the Bim promoter was also confirmed by a chromatin immunoprecipitation assay. A small interfering RNA-targeted knockdown of FoxO3a abrogated FFA-mediated Bim induction and apoptosis. FoxO3a was activated by a phosphatase 2A-dependent mechanism, since okadaic acid- and small interfering RNA-targeted knockdown of this phosphatase blocked FoxO3a dephosphorylation, Bim expression, and apoptosis. Consistent with these data, phosphatase 2A activity was also stimulated 3-fold by saturated FFA. Immunoprecpitation studies revealed an FFA-dependent association between FoxO3a and protein phosphatase 2A. FFA-mediated FoxO3a activation by protein phosphatase 2A was also observed in HepG2 cells and murine hepatocytes. In conclusion, saturated FFA stimulate protein phosphatase 2A activity, which activates FoxO3a, inducing expression of the intracellular death mediator Bim.
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Affiliation(s)
- Fernando J Barreyro
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Shogo Kobayashi
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Steven F Bronk
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Nathan W Werneburg
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Harmeet Malhi
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Gregory J Gores
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905.
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353
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Takano M, Lu Z, Goto T, Fusi L, Higham J, Francis J, Withey A, Hardt J, Cloke B, Stavropoulou AV, Ishihara O, Lam EWF, Unterman TG, Brosens JJ, Kim JJ. Transcriptional cross talk between the forkhead transcription factor forkhead box O1A and the progesterone receptor coordinates cell cycle regulation and differentiation in human endometrial stromal cells. Mol Endocrinol 2007; 21:2334-49. [PMID: 17609436 DOI: 10.1210/me.2007-0058] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Differentiation of human endometrial stromal cells (HESCs) into decidual cells is associated with induction of the forkhead transcription factor forkhead box O1A (FOXO1). We performed a genomic screen to identify decidua-specific genes under FOXO1 control. Primary HESCs were transfected with small interfering RNA targeting FOXO1 or with nontargeting control small interfering RNA before treatment with a cAMP analogue and the progestin, medroxyprogesterone acetate for 72 h. Total RNA was processed for whole genome analysis using high-density oligonucleotide arrays. We identified 3405 significantly regulated genes upon decidualization of HESCs, 507 (15.3%) of which were aberrantly expressed upon FOXO1 knockdown. Among the most up-regulated FOXO1-dependent transcriptional targets were WNT signaling-related genes (WNT4, WNT16 ), the insulin receptor (INSR), differentiation markers (PRL, IGFBP1, and LEFTY2), and the cyclin-dependent kinase inhibitor p57(Kip2) (CDKN1C). Analysis of FOXO1-dependent down-regulated genes uncovered several factors involved in cell cycle regulation, including CCNB1, CCNB2, MCM5, CDC2 and NEK2. Cell viability assay and cell cycle analysis demonstrated that FOXO1 silencing promotes proliferation of differentiating HESCs. Using a glutathione-S-transferase pull-down assay, we confirmed that FOXO1 interacts with progesterone receptor, irrespectively of the presence of ligand. In agreement, knockdown of PR disrupted the regulation of FOXO1 target genes involved in differentiation (IGFBP1, PRL, and WNT4) and cell cycle regulation (CDKN1, CCNB2 and CDC2) in HESCs treated with either cAMP plus medroxyprogesterone acetate or with cAMP alone. Together, the data demonstrate that FOXO1 engages in transcriptional cross talk with progesterone receptor to coordinate cell cycle regulation and differentiation of HESCs.
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Affiliation(s)
- Masashi Takano
- Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, United Kingdom
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354
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Goto T, Takano M, Albergaria A, Briese J, Pomeranz KM, Cloke B, Fusi L, Feroze-Zaidi F, Maywald N, Sajin M, Dina RE, Ishihara O, Takeda S, Lam EWF, Bamberger AM, Ghaem-Maghami S, Brosens JJ. Mechanism and functional consequences of loss of FOXO1 expression in endometrioid endometrial cancer cells. Oncogene 2007; 27:9-19. [PMID: 17599040 DOI: 10.1038/sj.onc.1210626] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The forkhead transcription factor FOXO1, a downstream target of phosphatidylinositol-3-kinase/Akt signalling pathway, regulates cyclic differentiation and apoptosis in normal endometrium, but its role in endometrial carcinogenesis is unknown. Screening of endometrial cancer cell lines demonstrated that FOXO1 is expressed in HEC-1B cells, but not in Ishikawa cells, which in turn highly express the FOXO1 targeting E3-ubiquitin ligase Skp2. FOXO1 transcript levels were also lower in Ishikawa cells and treatment with the proteasomal inhibitor was insufficient to restore expression. Lack of FOXO1 expression in Ishikawa cells was not accounted for by differential promoter methylation or activity, but correlated with increased messenger RNA (mRNA) turnover. Comparative analysis demonstrated that HEC-1B cells proliferate slower, but are more resistant to paclitaxel-mediated cell death than Ishikawa cells, which were partially reversed upon silencing of FOXO1 in HEC-1B cells or its re-expression in Ishikawa cells. We further show that FOXO1 is required for the expression of the growth arrest- and DNA-damage-inducible gene GADD45alpha. Analysis of biopsy samples demonstrated a marked loss of FOXO1 and GADD45alpha mRNA and protein expression in endometrioid endometrial cancer compared to normal endometrium. Together, these observations suggest that loss of FOXO1 perturbs endometrial homeostasis, promotes uncontrolled cell proliferation and increases susceptibility to genotoxic insults.
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Affiliation(s)
- T Goto
- 1Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Hospital, London, UK
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355
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Salah Z, Maoz M, Pokroy E, Lotem M, Bar-Shavit R, Uziely B. Protease-activated receptor-1 (hPar1), a survival factor eliciting tumor progression. Mol Cancer Res 2007; 5:229-40. [PMID: 17374729 DOI: 10.1158/1541-7786.mcr-06-0261] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Although ample evidence point to the central involvement of protease activated receptor-1 (PAR1) in tumor progression, little is known about the fate of the tumor when hPar1 is being silenced. We observed that hPar1 antisense clones exhibit low PAR1 levels, attenuated cell proliferation and invasion in vitro, and tumor formation in vivo. These clones showed noticeably reduced paxillin phosphorylation compared with the parental A375SM cells, whereas no change in the integrin levels was noticed. Antisense clones injected into the mice resulted in very few and only occasional small tumors, whereas advanced and vascularized tumors were observed in A375SM cells. The antisense-derived tumor sections expressed active caspase-3, increased terminal deoxynucleotidyl transferase-mediated nick-end labeling staining, and a markedly reduced proliferating cell nuclear antigen level compared with A375SM cell-derived tissue sections. Likewise, ablation of the hPar1 gene in a tetracycline-inducible hPar1 system leads to apoptosis in immature blood vessels, whereas mature vessels were unaffected. The activation of PAR1-induced pAkt/protein kinase B abrogated serum-deprived Bim(EL) induction and also markedly inhibited Bax levels. On the other hand, small interfering RNA silencing of the hPar1 gene induced the expression of Bim(EL), a direct substrate of Akt/protein kinase B and also induced expression of active caspase-9 and caspase-3. These results altogether identify PAR1 as a survival factor that protects cells from undergoing apoptosis. We conclude that whereas PAR1 gene expression correlates with tumor progression, its neutralization effectively initiates an apoptotic pathway leading at least in part to significantly reduced tumor formation.
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Affiliation(s)
- Zaidoun Salah
- Department of Oncology, Hadassah-Hebrew University Hospital, P.O. Box 12000, Jerusalem 91120, Israel
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356
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Lengyel F, Vértes Z, Kovács KA, Környei JL, Sümegi B, Vértes M. Effect of estrogen and inhibition of phosphatidylinositol-3 kinase on Akt and FOXO1 in rat uterus. Steroids 2007; 72:422-8. [PMID: 17433823 DOI: 10.1016/j.steroids.2007.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 02/06/2007] [Accepted: 03/02/2007] [Indexed: 11/26/2022]
Abstract
The importance of FOXO transcription factors in regulating different aspects of cellular homeostasis and apoptosis has become apparent. Akt/protein kinase B has been shown to phosphorylate and inactivate members of FOXO family of transcription factors. Akt and its upstream regulator, phosphatidylinositol-3 kinase (PI3K) are involved in rapid action of estrogen (E2) in different cells and tissues. The aim of the present study was to analyze the E2/PI3K/Akt/FOXO pathway in rat uterus. In response to E2, phosphorylation of Akt/PKB on Ser473 and FOXO1 on Ser256 and Thr24 residues increased but with distinct kinetics, regulating the activation and inactivation of Akt and FOXO1 proteins, respectively. The antiestrogen ICI 182,780 prevented E2 induced Akt activation suggesting that estrogen receptors mediate this effect of E2. Intrauterine injection of Wortmannin caused a decrease in the phosphorylation of Ser473 of Akt, and attenuated phosphorylation of its downstream target FOXO1 at Ser256 and at Thr24. However, the effect of E2 on phosphorylation of Thr24 showed a kinetic pattern distinct from that of Ser256. Our results suggest that the E2/PI3K/Akt/FOXO1 pathway in rat uterus is functioning even at the lack of ovarian hormones and responses to E2 treatment. Estradiol increases Akt phosphorylation through a Wortmannin sensitive way, presumably involving PI3K. The present work shows that PI3K plays a crucial role in the phosphorylation and inactivation of FOXO1 in vivo, indicating that the regulation of this transcription factor is a more complex event in uterine cells requiring further investigations.
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Affiliation(s)
- Ferenc Lengyel
- Institute of Physiology, Pécs University Medical School, Szigeti út 12, Pécs H7624, Hungary.
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357
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Yu F, Watts RN, Zhang XD, Borrow JM, Hersey P. Involvement of BH3-only proapoptotic proteins in mitochondrial-dependent Phenoxodiol-induced apoptosis of human melanoma cells. Anticancer Drugs 2007; 17:1151-61. [PMID: 17075314 DOI: 10.1097/01.cad.0000231484.17063.9a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Phenoxodiol is a chemically modified analogue of the plant hormone isoflavone with antitumour activities. In the present study, we have examined its ability to induce apoptosis in human melanoma cells and the mechanisms involved. Apoptosis was observed in Phenoxodiol-treated cells by using annexin V/propidium iodide staining and determining mitochondrial membrane potential. To determine which caspase pathways were involved in Phenoxodiol-induced apoptosis, studies were performed using specific caspase inhibitors. Western studies were performed to ascertain which proteins of the apoptosis cascade were affected to cause Phenoxodiol-induced apoptosis. We found that induction of apoptosis by Phenoxodiol was maximal at 48 h with a range of apoptosis of 12+/-4 to 48+/-5% in different melanoma lines. This apoptosis was mainly dependent on activation of caspase-3 and caspase-9. Apoptosis was associated with induction of changes in mitochondrial membrane potential and was inhibited by over-expression of Bcl-2. Variation in sensitivity to Phenoxodiol appeared related to events upstream of the mitochondria and the degree of conformational change in Bax. The p53-regulated BH3-only proteins (Bad, PUMA and Noxa) were increased in the sensitive, but not in the resistant lines, whereas Bim was increased in all the lines tested. Bim appeared, however, to be partially involved because reduction of Bim by RNA interference resulted in decreased levels of apoptosis. Together, these studies suggest that Phenoxodiol induces apoptosis of melanoma cells by induction of p53-dependent BH3 proteins (Bad, PUMA and Noxa) and the p53-independent Bim protein, resulting in activation of Bax and its downstream events.
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Affiliation(s)
- Fu Yu
- Oncology and Immunology Unit, Newcastle Mater Hospital, New South Wales, Australia
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358
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Nguyen DM, Hussain M. The role of the mitochondria in mediating cytotoxicity of anti-cancer therapies. J Bioenerg Biomembr 2007; 39:13-21. [PMID: 17294132 DOI: 10.1007/s10863-006-9055-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Optimal cytotoxic anticancer therapy, at the cellular level, requires effective and selective induction of cell death to achieve a net reduction of biomass of malignant tissues. Standard cytotoxic chemotherapeutics have been developed based on the observations that mitotically active cancer cells are more susceptible than quiescent normal cells to chromosomal, microtubular or metabolic poisons. More recent development of molecularly targeted drugs for cancer focuses on exploiting biological differentials between normal and transformed cells for selective eradication of cancers. The common thread of "standard" and "novel" cytotoxic drugs is their ability to activate the apoptosis-inducing machinery mediated by mitochondria, also known as the intrinsic death signaling cascade. The aim of this article is to provide an overview of the role of the mitochondria, an energy-generating organelle essential for life, in mediating death when properly activated by cytotoxic stresses.
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Affiliation(s)
- Dao M Nguyen
- Section of Thoracic Oncology, Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Room 4W-4-3940, 10 Center Drive, Bethesda, MD 29892, USA.
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359
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Lam EWF, Francis RE, Petkovic M. FOXO transcription factors: key regulators of cell fate. Biochem Soc Trans 2007; 34:722-6. [PMID: 17052182 DOI: 10.1042/bst0340722] [Citation(s) in RCA: 176] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
FOXO (forkhead box O) transcription factors are crucial regulators of cell fate. This function of FOXO proteins relies on their ability to control diverse and at times, opposing cellular functions, such as proliferation, differentiation, DNA repair, defence against oxidative stress damage and apoptosis, in response to hormones, growth factors and other environmental cues. This review discusses our current understanding of the regulation and role of FOXO transcription factors in determining cell fate and highlights their relevance to tumorigenesis and drug resistance.
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Affiliation(s)
- E W-F Lam
- Cancer Research UK Laboratories, Department of Oncology, MRC Cyclotron Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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360
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Piñeiro D, Martín ME, Guerra N, Salinas M, González VM. Calpain inhibition stimulates caspase-dependent apoptosis induced by taxol in NIH3T3 cells. Exp Cell Res 2007; 313:369-79. [PMID: 17145055 DOI: 10.1016/j.yexcr.2006.10.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 10/16/2006] [Accepted: 10/19/2006] [Indexed: 02/05/2023]
Abstract
Taxol is an anticancer drug that triggers apoptosis in a wide spectrum of cancers such as ovarian, breast, lung, head and neck, and bladder carcinoma by both caspase-dependent and -independent apoptosis mechanisms. However, the exact signaling pathways involved in taxol-induced apoptosis strongly depend on the cellular background and they are not completely established yet. In this study we demonstrate that taxol induces caspase-3-independent apoptosis in NIH3T3 cells by a calpain-mediated mechanism. Taxol treatment produced changes in the mitochondrial membrane potential (Delta Psi m) which could be responsible of Ca(2+) release from the mitochondria and the consequent calpain activation. Interestingly, we show that calpain produced proteolysis of caspase-3 and demonstrate that, accordingly, calpain inhibition increased taxol-induced apoptosis. In addition, we reveal that poly (ADP-ribose) polymerase (PARP) was processed by calpain in taxol-treated cells and by caspase-3 after calpain inhibition. In conclusion, these results demonstrate for the first time that calpain could play an important role modulating taxol-induced apoptosis. Further studies are needed to address the potentiality of inducing apoptosis by a combined use of taxol and calpain inhibitors in cells with increased calpain activity.
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Affiliation(s)
- David Piñeiro
- Servicio de Bioquímica-Investigación, Hospital Ramón y Cajal, Ctra Colmenar km 9,100, 28034 Madrid, Spain
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361
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Inta I, Paxian S, Maegele I, Zhang W, Pizzi M, Spano P, Sarnico I, Muhammad S, Herrmann O, Inta D, Baumann B, Liou HC, Schmid RM, Schwaninger M. Bim and Noxa are candidates to mediate the deleterious effect of the NF-kappa B subunit RelA in cerebral ischemia. J Neurosci 2007; 26:12896-903. [PMID: 17167080 PMCID: PMC6674970 DOI: 10.1523/jneurosci.3670-06.2006] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The transcription factor nuclear factor kappaB (NF-kappaB) is well known for its antiapoptotic action. However, in some disorders, such as cerebral ischemia, a proapoptotic function of NF-kappaB has been demonstrated. To analyze which subunit of NF-kappaB is functional in cerebral ischemia, we induced focal cerebral ischemia in mice with a germline deletion of the p52 or c-Rel gene or with a conditional deletion of RelA in the brain. Only RelA deficiency reduced infarct size. Interestingly, expression of the proapoptotic BH3 (Bcl-2 homology domain 3)-only genes Bim and Noxa in cerebral ischemia depended on RelA and the upstream kinase IKK (IkappaB kinase). RelA stimulated Bim and Noxa gene transcription in primary cortical neurons and bound to the promoter of both genes. Thus, the deleterious function in cerebral ischemia is specific for the NF-kappaB subunit RelA and may be mediated through Bim and Noxa.
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Affiliation(s)
- Ioana Inta
- Department of Neurology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Stephan Paxian
- Molecular Neurology Unit, Department of Neurology, University of Muenster, 48129 Muenster, Germany
| | - Ira Maegele
- Department of Neurology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Wen Zhang
- Department of Neurology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Marina Pizzi
- Division of Pharmacology and Experimental Therapeutics, Department of Biomedical Sciences and Biotechnologies, School of Medicine, University of Brescia, 25123 Brescia, Italy
| | - PierFranco Spano
- Division of Pharmacology and Experimental Therapeutics, Department of Biomedical Sciences and Biotechnologies, School of Medicine, University of Brescia, 25123 Brescia, Italy
| | - Ilenia Sarnico
- Division of Pharmacology and Experimental Therapeutics, Department of Biomedical Sciences and Biotechnologies, School of Medicine, University of Brescia, 25123 Brescia, Italy
| | - Sajjad Muhammad
- Department of Neurology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Oliver Herrmann
- Department of Neurology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Dragos Inta
- Department of Neurology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Bernd Baumann
- Department of Physiological Chemistry, University of Ulm, 89081 Ulm, Germany
| | - Hsiou-Chi Liou
- Department of Medicine, Division of Immunology, Weill Medical College of Cornell University, New York, New York 10021, and
| | - Roland M. Schmid
- Department of Internal Medicine II, Technical University of Munich, 81675 Munich, Germany
| | - Markus Schwaninger
- Department of Neurology, University of Heidelberg, 69120 Heidelberg, Germany
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362
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Kashiwagi H, McDunn JE, Goedegebuure PS, Gaffney MC, Chang K, Trinkaus K, Piwnica-Worms D, Hotchkiss RS, Hawkins WG. TAT-Bim Induces Extensive Apoptosis in Cancer Cells. Ann Surg Oncol 2007; 14:1763-71. [PMID: 17206479 DOI: 10.1245/s10434-006-9298-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 11/07/2006] [Accepted: 11/09/2006] [Indexed: 11/18/2022]
Abstract
BACKGROUND Suppression of apoptosis is central to the development of cancer and is associated with resistance to modern adjuvant treatments. Therefore, molecules and pathways of apoptotic processes are critical targets for the development of anti-cancer therapeutics. Since apoptosis is executed by intracellular proteins, molecular approaches must incorporate a method to deliver the treatment into the tumor cells. METHODS We utilized a peptide that contains two domains, a peptide transduction domain derived from the HIV-1 TAT protein and a biological effector domain, the BH3 domain from the pro-apoptotic Bcl-2 family member Bim. We examined whether this construct (TAT-Bim) induced apoptosis in several cancer cell lines (T-cell lymphoma (EL4), pancreatic cancer (Panc-02), and melanoma (B16)) and whether TAT-Bim treatment synergized with radiation. A mutant TAT-Bim peptide with no biologic activity (TAT-Bim-inactive) was used as a control. C57/BL6 mice were challenged with syngeneic cancer cell lines and the effects of intratumoral TAT-Bim injection on tumor growth and host survival were determined. RESULTS TAT-Bim was internalized by all cancer cells within two hours. TAT-Bim resulted in apoptosis in a dose dependent fashion in all cell lines and sublethal irradiation augmented the effects of TAT-Bim induced apoptosis. TAT-Bim significantly slowed tumor growth in murine models of pancreatic cancer and melanoma. CONCLUSION TAT-Bim exemplifies a strategy for cancer therapy that involves inducing apoptosis by antagonizing the endogenous anti-apoptotic machinery. Small peptide therapeutics, in combination with traditional adjuvant therapies such as radiation, may provide a valuable 'second hit' and drive tumor cells into programmed cell death.
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Affiliation(s)
- Hiroyuki Kashiwagi
- Department of Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
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363
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Riou C, Yassine-Diab B, Van grevenynghe J, Somogyi R, Greller LD, Gagnon D, Gimmig S, Wilkinson P, Shi Y, Cameron MJ, Campos-Gonzalez R, Balderas RS, Kelvin D, Sekaly RP, Haddad EK. Convergence of TCR and cytokine signaling leads to FOXO3a phosphorylation and drives the survival of CD4+ central memory T cells. ACTA ACUST UNITED AC 2006; 204:79-91. [PMID: 17190839 PMCID: PMC2118424 DOI: 10.1084/jem.20061681] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The molecular events involved in the establishment and maintenance of CD4+ central memory and effector memory T cells (TCM and TEM, respectively) are poorly understood. In this study, we demonstrate that ex vivo isolated TCM are more resistant to both spontaneous and Fas-induced apoptosis than TEM and have an increased capacity to proliferate and persist in vitro. Using global gene expression profiling, single cell proteomics, and functional assays, we show that the survival of CD4+ TCM depends, at least in part, on the activation and phosphorylation of signal transducer and activator of transcription 5a (STAT5a) and forkhead box O3a (FOXO3a). TCM showed a significant increase in the levels of phosphorylation of STAT5a compared with TEM in response to both IL-2 (P < 0.04) and IL-7 (P < 0.002); the latter is well known for its capacity to enhance T cell survival. Moreover, ex vivo TCM express higher levels of the transcriptionally inactive phosphorylated forms of FOXO3a and concomitantly lower levels of the proapoptotic FOXO3a target, Bim. Experiments aimed at blocking FOXO3a phosphorylation confirmed the role of this phosphoprotein in protecting TCM from apoptosis. Our results provide, for the first time in humans, an insight into molecular mechanisms that could be responsible for the longevity and persistence of CD4+ TCM.
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Affiliation(s)
- Catherine Riou
- Laboratoire d'Immunologie, Centre de Recherche, Hôpital Saint-Luc du Centre Hospitalier de l'Université de Montréal (CHUM), Montréal, Québec H2X 1P1, Canada
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364
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Rosivatz E, Matthews JG, McDonald NQ, Mulet X, Ho KK, Lossi N, Schmid AC, Mirabelli M, Pomeranz KM, Erneux C, Lam EWF, Vilar R, Woscholski R. A small molecule inhibitor for phosphatase and tensin homologue deleted on chromosome 10 (PTEN). ACS Chem Biol 2006; 1:780-90. [PMID: 17240976 DOI: 10.1021/cb600352f] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phosphatase and tensin homologue deleted on chromosome 10 (PTEN), a phosphoinositide 3-phosphatase, is an important regulator of insulin-dependent signaling. The loss or impairment of PTEN results in an antidiabetic impact, which led to the suggestion that PTEN could be an important target for drugs against type II diabetes. Here we report the design and validation of a small- molecule inhibitor of PTEN. Compared with other cysteine-based phosphatases, PTEN has a much wider active site cleft enabling it to bind the PtdIns(3,4,5)P3 substrate. We have exploited this feature in the design of vanadate scaffolds complexed to a range of different organic ligands, some of which show potent inhibitory activity. A vanadyl complexed to hydroxypicolinic acid was found to be a highly potent and specific inhibitor of PTEN that increases cellular PtdIns(3,4,5)P3 levels, phosphorylation of Akt, and glucose uptake in adipocytes at nanomolar concentrations. The findings presented here demonstrate the applicability of a novel and specific chemical inhibitor against PTEN in research and drug development.
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Affiliation(s)
- Erika Rosivatz
- Division of Cell and Molecular Biology, Imperial College London, Exhibition Road, London SW7 2AZ, U.K.
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365
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McCarty MF, Block KI. Preadministration of high-dose salicylates, suppressors of NF-kappaB activation, may increase the chemosensitivity of many cancers: an example of proapoptotic signal modulation therapy. Integr Cancer Ther 2006; 5:252-68. [PMID: 16880431 DOI: 10.1177/1534735406291499] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
NF-kappaB activity is elevated in a high proportion of cancers, particularly advanced cancers that have been treated previously. Cytotoxic treatment selects for such up-regulation inasmuch as NF-kappaB promotes transcription of a large number of proteins that inhibit both the intrinsic and extrinsic pathways of apoptosis; NF-kappaB also boosts expression of mdr1, which expels many drugs from cells. Indeed, high NF-kappaB activity appears to be largely responsible for the chemo- and radioresistance of many cancers. Thus, agents that suppress NF-kappaB activity should be useful as adjuvants to cytotoxic cancer therapy. Of the compounds that are known to be NF-kappaB antagonists, the most practical for current use may be the nonsteroidal anti-inflammatory drugs aspirin, salicylic acid, and sulindac, each of which binds to and inhibits Ikappa kinase- beta, a central mediator of NF-kappa activation; the low millimolar plasma concentrations of salicylate required for effective inhibition of this kinase in vivo can be achieved with high-dose regimens traditionally used to manage rheumatic disorders. The gastrointestinal toxicity of such regimens could be minimized by using salsalate or enteric-coated sodium salicy-late or by administering misoprostol in conjunction with aspirin therapy. Presumably, best results would be seen if these agents were administered for several days prior to a course of chemo- or radiotherapy, continuing throughout the course. This concept should first be tested in nude mice bearing xenografts of chemoresistant human tumors known to have elevated NF-kappa activity. Ultimately, more complex adjuvant regimens can be envisioned in which salicylates are used in conjunction with other NF-kappa antagonists and/or agents that target other mediators of down-regulated apoptosis in cancer, such as Stat3; coadministration of salicylate and organic selenium may have intriguing potential in this regard. These strategies may also have potential as adjuvants to metronomic chemotherapy, which seeks to suppress angio-genesis by targeting cycling endothelial cells in tumors.
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Affiliation(s)
- Mark F McCarty
- Block Center for Integrative Cancer Care, Evanston, Illinois 60201, USA
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366
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Butt AJ, Roberts CG, Seawright AA, Oelrichs PB, Macleod JK, Liaw TYE, Kavallaris M, Somers-Edgar TJ, Lehrbach GM, Watts CK, Sutherland RL. A novel plant toxin, persin, with in vivo activity in the mammary gland, induces Bim-dependent apoptosis in human breast cancer cells. Mol Cancer Ther 2006; 5:2300-9. [PMID: 16985064 DOI: 10.1158/1535-7163.mct-06-0170] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Phytochemicals have provided an abundant and effective source of therapeutics for the treatment of cancer. Here we describe the characterization of a novel plant toxin, persin, with in vivo activity in the mammary gland and a p53-, estrogen receptor-, and Bcl-2-independent mode of action. Persin was previously identified from avocado leaves as the toxic principle responsible for mammary gland-specific necrosis and apoptosis in lactating livestock. Here we used a lactating mouse model to confirm that persin has a similar cytotoxicity for the lactating mammary epithelium. Further in vitro studies in a panel of human breast cancer cell lines show that persin selectively induces a G2-M cell cycle arrest and caspase-dependent apoptosis in sensitive cells. The latter is dependent on expression of the BH3-only protein Bim. Bim is a sensor of cytoskeletal integrity, and there is evidence that persin acts as a microtubule-stabilizing agent. Due to the unique structure of the compound, persin could represent a novel class of microtubule-targeting agent with potential specificity for breast cancers.
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Affiliation(s)
- Alison J Butt
- Cancer Research Program, Garvan Institute of Medical Research, St. Vincent's Hospital, Darlinghurst, New South Vales 2010, Australia.
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367
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Kato M, Yuan H, Xu ZG, Lanting L, Li SL, Wang M, Hu MCT, Reddy MA, Natarajan R. Role of the Akt/FoxO3a pathway in TGF-beta1-mediated mesangial cell dysfunction: a novel mechanism related to diabetic kidney disease. J Am Soc Nephrol 2006; 17:3325-35. [PMID: 17082237 DOI: 10.1681/asn.2006070754] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Diabetic nephropathy (DN) is characterized by mesangial cell (MC) expansion and accumulation of extracellular matrix proteins. TGF-beta is increased in MC under diabetic conditions and in DN and activates key signaling pathways, including the phosphoinositide-3-kinase/Akt (PI3K/Akt) pathway. FoxO transcription factors play roles in cell survival and oxidative stress and are negatively regulated by Akt-mediated phosphorylation. We tested whether phosphorylation-mediated inactivation of FoxO3a by TGF-beta can mediate MC survival and oxidative stress. TGF-beta treatment significantly increased levels of p-Akt (activation) and p-FoxO3a (inactivation) in cultured MC. This FoxO3a inactivation was accompanied by significant decreases in the expression of two key FoxO3a target genes, the proapoptotic Bim and antioxidant manganese superoxide dismutase in MC. TGF-beta treatment triggered the nuclear exclusion of FoxO3a, significantly inhibited FoxO3a transcriptional activity, and markedly protected MC from apoptosis. A PI3K inhibitor blocked these TGF-beta effects. It is interesting that p-Akt and p-FoxO3A levels also were increased in renal cortical tissues from rats and mice at 2 wk after the induction of diabetes by streptozotocin, thus demonstrating in vivo significance. In summary, TGF-beta and diabetes can increase FoxO3a phosphorylation and transcriptional inactivation via PI3K/Akt. These new results suggest that Akt/FoxO pathway regulation may be a novel mechanism by which TGF-beta can induce unopposed MC survival and oxidant stress in early DN, thereby accelerating renal disease.
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Affiliation(s)
- Mitsuo Kato
- Department of Diabetes, Beckman Research Institute of the City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
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368
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Leao M, Anderton E, Wade M, Meekings K, Allday MJ. Epstein-barr virus-induced resistance to drugs that activate the mitotic spindle assembly checkpoint in Burkitt's lymphoma cells. J Virol 2006; 81:248-60. [PMID: 17035311 PMCID: PMC1797259 DOI: 10.1128/jvi.01096-06] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Epstein-Barr virus (EBV) is associated with a number of human cancers, and latent EBV gene expression has been reported to interfere with cell cycle checkpoints and cell death pathways. Here we show that latent EBV can compromise the mitotic spindle assembly checkpoint and rescue Burkitt's lymphoma (BL)-derived cells from caspase-dependent cell death initiated in aberrant mitosis. This leads to unscheduled mitotic progression, resulting in polyploidy and multi- and/or micronucleation. The EBV latent genes responsible for this phenotype are expressed from the P3HR1 strain of virus and several viruses with similar genomic deletions that remove the EBNA2 gene. Although EBNA2 and the latent membrane proteins are not expressed, the EBNA3 proteins are present in these BL cells. Survival of the EBV-positive cells is not consistently associated with EBV lytic gene expression or with the genes that are expressed in EBV latency I BL cells (i.e., EBNA1, EBERs, and BARTs) but correlates with reduced expression of the cellular proapoptotic BH3-only protein Bim. These data suggest that a subset of latent EBV gene products may increase the likelihood of damaged DNA being inherited because of the impaired checkpoint and enhanced survival capacity. This could lead to greater genetic diversity in progeny cells and contribute to tumorigenesis. Furthermore, since it appears that this restricted latent EBV expression interferes with the responses of Burkitt's lymphoma-derived cells to cytotoxic drugs, the results of this study may have important therapeutic implications in the treatment of some BL.
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Affiliation(s)
- Maria Leao
- Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, United Kingdom
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369
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Wu W, Zou M, Brickley DR, Pew T, Conzen SD. Glucocorticoid Receptor Activation Signals through Forkhead Transcription Factor 3a in Breast Cancer Cells. Mol Endocrinol 2006; 20:2304-14. [PMID: 16690749 DOI: 10.1210/me.2006-0131] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
Activation of the glucocorticoid receptor (GR) plays a critical role in the stress response of virtually all cell types. Despite recent advances in large-scale genomic and proteomic data acquisition, identification of physiologically relevant molecular events downstream of nuclear hormone receptor activation remains challenging. By analyzing gene expression changes 30 min after dexamethasone (Dex) treatment, we previously found that immediate induction of serum and glucocorticoid-regulated kinase-1 (SGK-1) expression is required for GR-mediated mammary epithelial cell survival signaling. We now report that activation of the GR mediates Forkhead transcription factor 3a (FOXO3a) phosphorylation and inactivation in mammary epithelial cells. GR-mediated induction of SGK-1 expression is required for FOXO3a inactivation; additional growth factor stimulation is not required. To further explore the gene expression changes that occur downstream of GR-mediated FOXO3a inactivation, we analyzed temporal gene expression data and selected GR-down-regulated genes containing core FOXO3a binding motifs in their proximal promoters. This approach revealed several previously unrecognized transcriptional target genes of FOXO3a, including IGF binding protein-3 (IGFBP-3). Endogenous IGFBP-3 expression was confirmed to be dependent on the GR-SGK-1-FOXO3a signaling pathway. Moreover, GR activation decreased FOXO3a-induced apoptosis in SK-BR-3 breast cancer cells. Collectively, our data suggest that GR-mediated FOXO3a inactivation is an important mechanism contributing to glucocorticoid-mediated mammary epithelial cell survival.
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Affiliation(s)
- Wei Wu
- Department of Medicine and Committee on Cancer Biology, MC 2115, University of Chicago, Chicago, Illinois 60637, USA
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370
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Hersey P. Apoptosis and melanoma: how new insights are effecting the development of new therapies for melanoma. Curr Opin Oncol 2006; 18:189-96. [PMID: 16462190 DOI: 10.1097/01.cco.0000208794.24228.9f] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE OF REVIEW Melanoma has proven resistant to most available chemotherapy and immunotherapy. Despite a range of different biochemical targets, most agents kill cancer cells by induction of apoptosis. RECENT FINDINGS Investigation of this process has provided insights into the resistance mechanisms in cancer cells and to development of a range of new agents that target apoptosis pathways. These include agents which inhibit antiapoptotic B cell lymphoma-2 family proteins and inhibitor of apoptosis proteins. In addition, a range of signal pathway inhibitors have become available that are able to inhibit signal pathways known to be associated with resistance to apoptosis. SUMMARY Evaluation of most of these reagents are at a preclinical level but studies on some pathway inhibitors have passed from phase II into phase III studies. Similarly, evaluation of antisense reagents are at an advanced stage. These early trials show much promise and suggest this approach to development of new therapies will lead to much needed advances in treatment of this disease.
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Affiliation(s)
- Peter Hersey
- Oncology and Immunology Unit, David Maddison Clinical Sciences Building, Newcastle, New South Wales, Australia.
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371
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Abstract
Apoptosis or programmed cell death is a key regulator of physiological growth control and regulation of tissue homeostasis. One of the most important advances in cancer research in recent years is the recognition that cell death mostly by apoptosis is crucially involved in the regulation of tumor formation and also critically determines treatment response. Killing of tumor cells by most anticancer strategies currently used in clinical oncology, for example, chemotherapy, gamma-irradiation, suicide gene therapy or immunotherapy, has been linked to activation of apoptosis signal transduction pathways in cancer cells such as the intrinsic and/or extrinsic pathway. Thus, failure to undergo apoptosis may result in treatment resistance. Understanding the molecular events that regulate apoptosis in response to anticancer chemotherapy, and how cancer cells evade apoptotic death, provides novel opportunities for a more rational approach to develop molecular-targeted therapies for combating cancer.
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Affiliation(s)
- S Fulda
- University Children's Hospital, Ulm, Germany.
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372
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Chong ZZ, Li F, Maiese K. Group I metabotropic receptor neuroprotection requires Akt and its substrates that govern FOXO3a, Bim, and beta-catenin during oxidative stress. Curr Neurovasc Res 2006; 3:107-17. [PMID: 16719794 PMCID: PMC2040240 DOI: 10.2174/156720206776875830] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Metabotropic glutamate receptors are expressed throughout the nervous system, but their function as well as their ability to promote neuronal survival rests heavily upon the intracellular mechanisms governed by this family of G-proteins. In this regard, we examined one of the primary pathways that can oversee cell survival, namely protein kinase B (Akt1), and its functional integration with some of its substrates that may work in concert with group I metabotropic glutamate receptor (mGluRI) activation to protect primary hippocampal neurons during oxidative stress. We demonstrate that neuroprotection against free radical injury through mGluRI activation with DHPG requires the activation of Akt1, since loss of Akt1 activity assessed through its GSK-3alpha/beta substrate by pharmacological blockade of the phosphatidylinositide-3-kinase pathway or the gene silencing of Akt1 expression prevents neuronal protection during mGluRI activation. Closely coupled to the robust neuroprotection by mGluRI activation are the inhibitory phosphorylation and prevention of caspase 3 cleavage of the Forkhead transcription factor FOXO3a, the down-regulation of Bim expression, and the protection of beta-catenin by Akt1 against phosphorylation and degradation to promote its translocation from the cytoplasm to the nucleus and allow it to assist with a "pro-survival" cellular program. Further insight into the cellular mechanisms that determine neuronal protection by the metabotropic glutamate system will foster the successful therapeutic development of mGluRs for neurodegenerative disorders.
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Affiliation(s)
- Zhao Zhong Chong
- Division of Cellular and Molecular Cerebral Ischemia, Wayne State University School of Medicine, Detroit, MI 48201, USA
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373
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Yano T, Ito K, Fukamachi H, Chi XZ, Wee HJ, Inoue KI, Ida H, Bouillet P, Strasser A, Bae SC, Ito Y. The RUNX3 tumor suppressor upregulates Bim in gastric epithelial cells undergoing transforming growth factor beta-induced apoptosis. Mol Cell Biol 2006; 26:4474-88. [PMID: 16738314 PMCID: PMC1489128 DOI: 10.1128/mcb.01926-05] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Genes involved in the transforming growth factor beta (TGF-beta) signaling pathway are frequently altered in several types of cancers, and a gastric tumor suppressor RUNX3 appears to be an integral component of this pathway. We reported previously that apoptosis is notably reduced in Runx3-/- gastric epithelial cells. In the present study, we show that a proapoptotic gene Bim was transcriptionally activated by RUNX3 in the gastric cancer cell lines SNU16 and SNU719 treated with TGF-beta. The human Bim promoter contains RUNX sites, which are required for its activation. Furthermore, a dominant negative form of RUNX3 comprised of amino acids 1 to 187 increased tumorigenicity of SNU16 by inhibiting Bim expression. In Runx3-/- mouse gastric epithelium, Bim was down-regulated, and apoptosis was reduced to the same extent as that in Bim-/- gastric epithelium. We confirmed comparable expression of TGF-beta1 and TGF-beta receptors between wild-type and Runx3-/- gastric epithelia and reduction of Bim in TGF-beta1-/- stomach. These results demonstrate that RUNX3 is responsible for transcriptional up-regulation of Bim in TGF-beta-induced apoptosis.
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Affiliation(s)
- Takashi Yano
- Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Singapore
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374
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Pierce J, Rir-Sima-Ah J, Estrada I, Wilder J, Strasser A, Tesfaigzi Y. Loss of pro-apoptotic Bim promotes accumulation of pulmonary T lymphocytes and enhances allergen-induced goblet cell metaplasia. Am J Physiol Lung Cell Mol Physiol 2006; 291:L862-70. [PMID: 16782750 DOI: 10.1152/ajplung.00516.2005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Immunological tolerance during prolonged exposure to allergen is accompanied by a shift in the lymphocyte content and a reduction of goblet cell metaplasia (GCM). Bim initiates negative selection of autoreactive T and B cells and shut down of T cell immune responses in vivo. The present study investigated whether Bim plays a role in the resolution of GCM during prolonged exposure to allergen. Loss of Bim increased T lymphocyte numbers in the bronchoalveolar lavage at 4 and 15 days of allergen exposure. The numbers of pulmonary CD4(+)8(-), CD4(-)8(+), and gammadelta T cells were significantly higher in naive and allergen-challenged bim(-/-) mice compared with wild-type (WT) littermates. When activated, pulmonary bim(-/-) T cells produced increased levels of IFNgamma compared with bim(+/+) T cells. No differences were noted in the total numbers of epithelial cells per millimeter of basal lamina between bim(+/+) and bim(-/-) mice, and the rate of resolution over 15 days of exposure was similar in both groups of mice. However, GCM was significantly enhanced and expression of IL-13Ralpha2 was reduced in bim(-/-) mice compared with WT mice at 4 days. Furthermore, treatment of bronchiolar explant cultures with increasing IFNgamma levels reduced immunostaining for IL-13Ralpha2. Collectively, these studies suggest that, during prolonged exposure to allergen, Bim plays no role in the resolution of GCM, but increased IFNgamma levels in bim(-/-) mice may be responsible for reduced expression of IL-13Ralpha2 and enhanced GCM despite similar levels of IL-13 in bim(+/+) and bim(-/-) mice.
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Affiliation(s)
- Joseph Pierce
- Lovelace Respiratory Research Institute, 2425 Ridgecrest Dr., SE, Albuquerque, NM 87108, USA
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375
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Li Z, Zhang J, Liu Z, Woo CW, Thiele CJ. Downregulation of Bim by brain-derived neurotrophic factor activation of TrkB protects neuroblastoma cells from paclitaxel but not etoposide or cisplatin-induced cell death. Cell Death Differ 2006; 14:318-26. [PMID: 16778834 DOI: 10.1038/sj.cdd.4401983] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Chemoresistance and increased expression of TrkB and brain-derived neurotrophic factor (BDNF) are biomarkers of poor prognosis in tumors from patients with neuroblastoma (NB). Previously, we found BDNF activation of TrkB through PI3K/Akt protects NB from etoposide/cisplatin-induced cell death. In this study, the role of Bim, a proapoptotic protein, was investigated. Bim was involved in paclitaxel but not etoposide or cisplatin-induced cell death in NB cells. Pharmacological and genetic studies showed that BDNF-induced decreases in Bim were regulated by MAPK and not PI3K/Akt pathway. Both MAPK and PI3K pathways were involved in BDNF protection of NB cells from paclitaxel-induced cell death, while PI3K predominantly mediated BDNF protection of NB cells from etoposide or cisplatin-induced cell death. These data indicate that different chemotherapeutic drugs induce distinct death pathways and growth factors utilize different signal transduction pathways to modulate the effects of chemotherapy on cells.
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Affiliation(s)
- Z Li
- Cell & Molecular Biology Section, Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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376
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Kajihara T, Jones M, Fusi L, Takano M, Feroze-Zaidi F, Pirianov G, Mehmet H, Ishihara O, Higham JM, Lam EWF, Brosens JJ. Differential expression of FOXO1 and FOXO3a confers resistance to oxidative cell death upon endometrial decidualization. Mol Endocrinol 2006; 20:2444-55. [PMID: 16709600 DOI: 10.1210/me.2006-0118] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The integrity of the feto-maternal interface is critical for survival of the conceptus. This interface, consisting of the maternal decidua and the invading placental trophoblast, is exposed to profound changes in oxygen tension during pregnancy. We demonstrate that human endometrial stromal cells become extraordinarily resistant to oxidative stress-induced apoptosis upon decidualization in response to cAMP and progesterone signaling. This differentiation process is associated with the induction of the forkhead transcription factor FOXO1, which in turn increases the expression of the mitochondrial antioxidant manganese superoxide dismutase. However, silencing of FOXO1 did not increase the susceptibility of decidualized cells to oxidative cell death. Comparative analysis demonstrated that hydrogen peroxide, a source of free radicals, strongly induces FOXO3a mRNA and protein expression in undifferentiated human endometrial stromal cells but not in decidualized cells. Expression of a constitutively active FOXO3a mutant elicited apoptosis in decidualized cells. Furthermore, silencing of endogenous FOXO3a in undifferentiated cells abrogated apoptosis induced by hydrogen peroxide. These results suggest that the induction of FOXO1 may enhance the ability of decidualized cells to prevent oxidative damage while the simultaneous repression of FOXO3a expression disables the signaling pathway responsible for oxidative cell death. The differential regulation of FOXO expression provides the decidua with a robust system capable of coping with prolonged episodes of oxidative stress during pregnancy.
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Affiliation(s)
- Takeshi Kajihara
- Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Hospital, London W12 0NN, United Kingdom
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377
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Relling DP, Esberg LB, Fang CX, Johnson WT, Murphy EJ, Carlson EC, Saari JT, Ren J. High-fat diet-induced juvenile obesity leads to cardiomyocyte dysfunction and upregulation of Foxo3a transcription factor independent of lipotoxicity and apoptosis. J Hypertens 2006; 24:549-61. [PMID: 16467659 DOI: 10.1097/01.hjh.0000203846.34314.94] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Obesity is associated with dyslipidemia, which leads to elevated triglyceride and ceramide levels, apoptosis and compromised cardiac function. METHODS To determine the role of high-fat diet-induced obesity on cardiomyocyte function, weanling male Sprague-Dawley rats were fed diets incorporating 10% of kcal or 45% of kcal from fat. Mechanical function of ventricular myocytes was evaluated including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90) and maximal velocity of shortening and relengthening (+/- dl/dt). Intracellular Ca properties were assessed using fluorescent microscopy. RESULTS High-fat diet induced hyperinsulinemic insulin-resistant obesity with depressed PS, +/- dl/dt, prolonged TPS/TR90 reduced intracellular Ca release and Ca clearing rate in the absence of hypertension, diabetes, lipotoxicity and apoptosis. Myocyte responsiveness to increased stimulus frequency and extracellular Ca was compromised. SERCA2a and phospholamban levels were increased, whereas phosphorylated phospholamban and potassium channel (Kv1,2) were reduced in high-fat diet group. High-fat diet upregulated the forkhead transcription factor Foxo3a, and suppressed mitochondrial aconitase activity without affecting expression of the caloric sensitive gene silent information regulator 2 (Sir2), protein nitrotyrosine formation, lipid peroxidation and apoptosis. Levels of endothelial nitric oxide synthase (NOS), inducible NOS, triglycerides and ceramide were similar between the two groups. CONCLUSIONS Collectively, our data show that high-fat diet-induced obesity resulted in impaired cardiomyocyte function, upregulated Foxo3a transcription factor and mitochondrial damage without overt lipotoxicity or apoptosis.
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Affiliation(s)
- David P Relling
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine, Grand Forks, North Dakota, USA
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378
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Herdman ML, Marcelo A, Huang Y, Niles RM, Dhar S, Kiningham KK. Thimerosal Induces Apoptosis in a Neuroblastoma Model via the cJun N-Terminal Kinase Pathway. Toxicol Sci 2006; 92:246-53. [PMID: 16624850 DOI: 10.1093/toxsci/kfj205] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The cJun N-terminal kinase (JNK)-signaling pathway is activated in response to a variety of stimuli, including environmental insults, and has been implicated in neuronal apoptosis. In this study, we investigated the role that the JNK pathway plays in neurotoxicity caused by thimerosal, an ethylmercury-containing preservative. SK-N-SH cells treated with thimerosal (0-10 microM) showed an increase in the phosphorylated (active) form of JNK and cJun with 5 and 10 microM thimerosal treatment at 2 and 4 h. To examine activator protein-1 (AP-1) transcription, cells were transfected with a pGL2 vector containing four AP-1 consensus sequences and then treated with thimerosal (0-2.5 microM) for 24 h. Luciferase studies showed an increase in AP-1 transcriptional activity upon thimerosal administration. To determine the components of the AP-1 complex, cells were transfected with a dominant negative to either cFos (A-Fos) or cJun (TAM67). Reporter analysis showed that TAM67, but not A-Fos, decreased AP-1 transcriptional activity, indicating a role for cJun in this pathway. To assess which components are essential to apoptosis, cells were treated with a cell-permeable JNK inhibitor II (SP600125) or transfected with TAM67, and the downstream effectors of apoptosis were analyzed. Cells pretreated with SP600125 showed decreases in activation of caspases 9 and 3, decreases in degradation of poly(ADP-ribose) polymerase (PARP), and decreased levels of proapoptotic Bim, in comparison to cells treated with thimerosal alone. However, cells transfected with TAM67 showed no changes in those same components. Taken together, these results indicate that thimerosal-induced neurotoxicity occurs through the JNK-signaling pathway, independent of cJun activation, leading ultimately to apoptotic cell death.
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Affiliation(s)
- Michelle L Herdman
- Department of Pharmacology, Joan C. Edwards School of Medicine, Marshall University, 1542 Spring Valley Drive, Huntington, WV 25704, USA
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379
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Sunters A, Madureira PA, Pomeranz KM, Aubert M, Brosens JJ, Cook SJ, Burgering BMT, Coombes RC, Lam EWF. Paclitaxel-induced nuclear translocation of FOXO3a in breast cancer cells is mediated by c-Jun NH2-terminal kinase and Akt. Cancer Res 2006; 66:212-20. [PMID: 16397234 DOI: 10.1158/0008-5472.can-05-1997] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The microtubule-targeting compound paclitaxel is often used in the treatment of endocrine-resistant or metastatic breast cancer. We have previously shown that apoptosis of breast cancer cells in response to paclitaxel is mediated by induction of FOXO3a expression, a transcription factor downstream of the phosphatidylinositol-3-kinase/Akt signaling pathway. To further investigate its mechanism of action, we treated MCF-7 cells with paclitaxel and showed a dose-dependent increase in nuclear localization of FOXO3a, which coincided with decreased Akt signaling but increased c-Jun NH2-terminal kinase 1/2 (JNK1/2), p38, and extracellular signal-regulated kinase 1/2 (ERK1/2) activity. Flow cytometry revealed that paclitaxel-induced apoptosis of MCF-7 cells and of other paclitaxel-sensitive breast cancer cell lines was maintained in the presence of inhibitors of p38 (SB203580) or mitogen-activated protein/ERK kinase 1 signaling (PD98059) but abrogated when cells were treated with the JNK1/2 inhibitor SP600125. SP600125 reversed Akt inhibition and abolished FOXO3a nuclear accumulation in response to paclitaxel. Moreover, conditional activation of JNK mimicked paclitaxel activity and led to dephosphorylation of Akt and FOXO3a. Furthermore, mouse embryonic fibroblasts (MEF) derived from JNK1/2 knockout mice displayed very high levels of active Akt, and in contrast to wild-type MEFs, paclitaxel treatment did not alter Akt activity or elicit FOXO3a nuclear translocation. Taken together, the data show that cell death of breast cancer cells in response to paclitaxel is dependent upon JNK activation, resulting in Akt inhibition and increased FOXO3a activity.
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Affiliation(s)
- Andrew Sunters
- Cancer Research UK Labs, Department of Cancer Medicine, London
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380
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Gilley J, Ham J. Evidence for increased complexity in the regulation of Bim expression in sympathetic neurons: involvement of novel transcriptional and translational mechanisms. DNA Cell Biol 2006; 24:563-73. [PMID: 16153157 DOI: 10.1089/dna.2005.24.563] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The BH3-only protein Bim is induced following NGF deprivation in developing sympathetic neurons and contributes to their death by apoptosis. The regulation of Bim activity is complex, and involves both transcriptional and posttranslational mechanisms. We have previously shown that both the FOXO subfamily of Forkhead transcription factors and the JNK/c-Jun pathway contribute to the transcriptional induction of Bim expression and subsequent apoptosis of sympathetic neurons following NGF deprivation. Bim activity can also be modulated by JNK-mediated phosphorylation after NGF deprivation in these cells. Here, we provide evidence for additional complexity in the transcriptional and translational control of Bim expression. We show that the first intron of the bim gene contains elements with silencer and enhancer properties that can modulate the basal activity and NGF deprivation-induced activity of the previously characterized bim promoter. Surprisingly, we find that some of the elements responsible for these effects are linked to two novel, alternative promoters located towards the 3' end of the intron that have minimal, or no activity in sympathetic neurons. Finally, we provide evidence that Bim expression is reduced in sympathetic neurons by the presence of an upstream open reading frame in the 5' leader of bim transcripts.
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Affiliation(s)
- Jonathan Gilley
- Molecular Haematology and Cancer Biology Unit, Camelia Botnar Laboratories, Institute of Child Health, University College London, UK
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381
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Tao Y, Wei Q, Xu Z, Bai R, Li Y, Luo C, Dong Y, Gao G, Lu Y. Holistic and network analysis of meningioma pathogenesis and malignancy. Biofactors 2006; 28:203-19. [PMID: 17473381 DOI: 10.1002/biof.5520280307] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Meningiomas, which originate from arachnoid cells and constitute the largest subgroup of all intracranial tumors, are generally benign, yet have the capacity to progress into a higher histological grade of malignancy associated with an increase in biological aggressivity and/or capacity to recur. To elucidate meningioma pathogenesis and malignancy, we applied a holistic and network approach analyzing cDNA and tissue microarray results. A potential pathway leading to meningioma angiogenesis, apoptosis and proliferation was evidenced as well as a regulatory network of the biomarkers including Ki-67, AR, CD34, P53, c-MYC, etc. which might support clinical research. In this potential pathway, ITGB1 could be the most important "superoncogene" playing a vital role in apoptosis and proliferation, while FOXO3A, MDM4 and MT3 are important to the malignancy process. Some genes are first reported that could explain why radiation induces meningioma and why more female than male patients are affected. Further, we present the hypothesis that HIV-Tat protein might have a close relationship with meningioma pathogenesis and malignancy.
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Affiliation(s)
- Yingqun Tao
- Department of Neurosurgery, The General Hospital of Shenyang Military Region, Shenyang, P.R. China.
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382
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Franco-Molina MA, Mendoza-Gamboa E, Miranda-Hernández D, Zapata-Benavides P, Castillo-León L, Isaza-Brando C, Tamez-Guerra RS, Rodríguez-Padilla C. In vitro effects of bovine dialyzable leukocyte extract (bDLE) in cancer cells. Cytotherapy 2006; 8:408-14. [PMID: 16923617 DOI: 10.1080/14653240600847266] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
BACKGROUND Bovine dialyzable leukocyte extract (bDLE) is a dialyzate of a heterogeneous mixture of low molecular weight substances released from disintegrated blood leukocytes or lymphoid tissue obtained from homogenized bovine spleen. The purpose of this study was to determine if bDLE had cytotoxic effects and modulated apoptosis gene expression in breast cancer cells. METHODS The MCF-7, BT-474, MDA-MB-453, A-427, Calu-1, U937 and L5178Y cancer cell lines and PBMC human cells were treated with bDLE (0-0.66 U/mL) for 72 h. The bDLE effect on cell growth proliferation was evaluated by MTT assay, and the MCF-7 was evaluated by ethidium bromide-acridine orange staining; total DNA was evaluated for DNA fragmentation, and total RNA was isolated for p53, bag-1, c-myc, bim, bax, bcl-2 and bad mRNA expression. RESULTS The bDLE had dose-dependent cytotoxic effects and demonstrated an IC50 at a dosage of 0.06 U/mL (P<0.05). The bDLE did not affect the viability of normal human PBMC. The bDLE induced DNA fragmentation at doses of 0.06 and 0.13 U/mL in MCF-7 breast cancer cells. The bDLE induced cytotoxic effects and suppressed the p53, bag-1, c-myc, bax, bcl-2, and bad mRNA expression that influences apoptosis in MCF-7 breast cancer cells. Bim mRNA expression was not detected. DISCUSSION This may open up interesting prospects for the treatment of human breast cancer.
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Affiliation(s)
- M A Franco-Molina
- Departamento de Inmunología y Virología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León, México
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383
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Qi XJ, Wildey GM, Howe PH. Evidence That Ser87 of BimEL Is Phosphorylated by Akt and Regulates BimEL Apoptotic Function. J Biol Chem 2006; 281:813-23. [PMID: 16282323 DOI: 10.1074/jbc.m505546200] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bim, the Bcl-2 interacting mediator of cell death, is a member of the BH3-only family of pro-apoptotic proteins. Recent studies have demonstrated that the apoptotic activity of Bim can be regulated through a post-translational mechanism whereby ERK phosphorylation serves as a signal for Bim ubiquitination and proteasomal degradation. In this report, we investigated the signaling pathways leading to Bim phosphorylation in Ba/F3 cells, an interleukin-3 (IL-3)-dependent B-cell line. IL-3 stimulation induced phosphorylation of Bim(EL), one of the predominant isoforms of Bim expressed in cells, at multiple sites, as evidenced by the formation of at least three to four bands by Western blotting that were sensitive to phosphatase digestion. The appearance of multiple, phosphorylated species of Bim(EL) correlated with Akt, and not ERK, activation. The PI3K inhibitor, LY294002, blocked IL-3-stimulated Akt activity and partially blocked Bim(EL) phosphorylation. In vitro kinase assays showed that recombinant Akt could directly phosphorylate a GST-Bim(EL) fusion protein and identified the Akt phosphorylation site in the Bim(EL) domain as Ser(87). Further, we demonstrated that cytokine stimulation promotes Bim(EL) binding to 14-3-3 proteins. Finally, we show that mutation of Ser(87) dramatically increases the apoptotic potency of Bim(EL). We propose that Ser(87) of Bim(EL) is an important regulatory site that is targeted by Akt to attenuate the pro-apoptotic function of Bim(EL), thereby promoting cell survival.
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Affiliation(s)
- Xiao-Jun Qi
- Department of Cell Biology, Cleveland Clinic Lerner College of Medicine, Cleveland Clinic Foundation, OH 44195, USA
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384
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Yamamura Y, Lee WL, Inoue KI, Ida H, Ito Y. RUNX3 cooperates with FoxO3a to induce apoptosis in gastric cancer cells. J Biol Chem 2005; 281:5267-76. [PMID: 16373335 DOI: 10.1074/jbc.m512151200] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The transcription factor RUNX3, which mediates apoptosis and cell growth inhibition in gastric epithelial cells, is a candidate tumor suppressor that is frequently lost in gastric cancer cells. Here, we found that restoration of RUNX3 expression in the cell line not expressing RUNX3 induced apoptosis and that it physically interacted with the Forkhead transcription factor FoxO3a/FKHRL1, known to be an important regulator of apoptosis and the cell cycle. Active unphosphorylated FoxO3a/FKHRL1 was expressed in the gastric cancer cell lines. RUNX3-induced apoptosis depended on the expression of Bim, a proapoptotic BH3-only protein, and both RUNX3 and FoxO3a/FKHRL1 were required for induction of Bim expression. Furthermore, we showed that interaction of RUNX3 and FoxO3a/FKHRL1 was also indispensable for Bim expression and apoptosis in mouse embryonic fibroblasts. In the Bim promoter, RUNX3 bound to two conserved RUNX-binding elements (RBE1 and RBE2), with RBE1 being immediately downstream of a FoxO-binding element. The physical interaction of RUNX3 and FoxO3a/FKHRL1 on the Bim promoter activated transcription of Bim. These findings show that RUNX3 cooperates with FoxO3a/FKHRL1 to participate in the induction of apoptosis by activating Bim and may play an important role in tumor suppression in gastric cancer.
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Affiliation(s)
- Yasuko Yamamura
- Oncology Research Institute, National University Medical Institutes, Institute of Molecular and Cell Biology, Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117592, Singapore
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385
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Abstract
Cancer Research UK has recently sponsored a meeting, organized by the UK Medical Research Council, on cancer drug resistance. Several of the molecular mechanisms responsible for this clinical outcome, such as DNA interstrand crosslink repair, apoptosis evasion, cytochrome P450 and P-glycoprotein, were discussed. There was a special focus on leukaemia, breast and ovarian cancer, and the potential use of positron-emission tomography to study anticancer-drug resistance. The progress made in translating these findings to the clinic, like Gefitinib, P-glycoprotein phenotyping, or genome-wide analysis technology, was also discussed.
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Affiliation(s)
- E Yagüe
- MRC Clinical Sciences Centre, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
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386
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Real PJ, Benito A, Cuevas J, Berciano MT, de Juan A, Coffer P, Gomez-Roman J, Lafarga M, Lopez-Vega JM, Fernandez-Luna JL. Blockade of epidermal growth factor receptors chemosensitizes breast cancer cells through up-regulation of Bnip3L. Cancer Res 2005; 65:8151-7. [PMID: 16166289 DOI: 10.1158/0008-5472.can-05-1134] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Epidermal growth factor receptor-1 (EGFR) and EGFR-2 (HER2) have become major targets for cancer treatment. Blocking antibodies and small-molecule inhibitors are being used to silence the activity of these receptors in different tumors with varying efficacy. Thus, a better knowledge on the signaling pathways activated by EGFR and HER2 may help unravel novel therapeutic targets and molecular markers of response. Here, we show that treatment of breast cancer cell lines with blocking antibodies against EGFR (cetuximab) or HER2 (trastuzumab) promotes the specific induction of proapoptotic Bnip3L and chemosensitization. Moreover, we found that the Bnip3L gene is transcriptionally activated by FoxO3a. Trastuzumab-mediated induction of Bnip3L and nuclear translocation of FoxO3a was also shown in pleural effusion cells from a breast cancer patient. Transfection of breast cancer cells with constitutively active FoxO3a or with Bnip3L promotes sensitization to chemotherapy-induced apoptosis. On the contrary, blockade of Bnip3L expression by a small interfering RNA strategy significantly diminished the chemosensitizing effect of cetuximab. We found also an inverse correlation between EGFR and Bnip3L expression in surgical specimens from patients with breast cancer. Therefore, blockading EGFR or HER2 specifically up-regulates Bnip3L, which is required for chemosensitization of breast cancer cells. This novel pathway provides also the rationale for therapeutic strategies aimed to induce the expression of Bnip3L.
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Affiliation(s)
- Pedro J Real
- Unidad de Genetica Molecular, Hospital Universitario Marques de Valdecilla, Servicio Cantabro de Salud, Santander, Spain
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387
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Pastorino JG, Hoek JB, Shulga N. Activation of glycogen synthase kinase 3beta disrupts the binding of hexokinase II to mitochondria by phosphorylating voltage-dependent anion channel and potentiates chemotherapy-induced cytotoxicity. Cancer Res 2005; 65:10545-54. [PMID: 16288047 DOI: 10.1158/0008-5472.can-05-1925] [Citation(s) in RCA: 309] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Transformed cells are highly glycolytic and overexpress hexokinase II (HXK II). HXK II is capable of binding to the mitochondria through an interaction with the voltage-dependent anion channel (VDAC), an abundant outer mitochondrial membrane protein. The binding of HXK II to mitochondria has been shown to protect against loss of cell viability. Akt activation inhibits apoptosis partly by promoting the binding of HXK II to the mitochondria, but the mechanism through which Akt accomplishes this has not been characterized. The present report shows that Akt mediates the binding of HXK II to the mitochondria by negatively regulating the activity of glycogen synthase kinase 3beta (GSK3beta). On inhibition of Akt, GSK3beta is activated and phosphorylates VDAC. HXK II is unable to bind VDAC phosphorylated by GSK3beta and dissociates from the mitochondria. Inhibition of Akt potentiates chemotherapy-induced cytotoxicity, an effect that is dependent on GSK3beta activation and its attendant ability to disrupt the binding of HXK II to the mitochondria. Moreover, agents that can force the detachment of HXK II from mitochondria in the absence of Akt inhibition or GSK3beta activation promoted a synergistic increase in cell killing when used in conjunction with chemotherapeutic drugs. Such findings indicate that interference with the binding of HXK II to mitochondria may be a practicable modality by which to potentiate the efficacy of conventional chemotherapeutic agents.
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Affiliation(s)
- John G Pastorino
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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388
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Bali P, Pranpat M, Swaby R, Fiskus W, Yamaguchi H, Balasis M, Rocha K, Wang HG, Richon V, Bhalla K. Activity of suberoylanilide hydroxamic Acid against human breast cancer cells with amplification of her-2. Clin Cancer Res 2005; 11:6382-9. [PMID: 16144943 DOI: 10.1158/1078-0432.ccr-05-0344] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE We determined the effects of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, on hsp90 and its client proteins Her-2, AKT, and c-Raf, as well as evaluated the cytotoxic effects of co-treatment of SAHA with trastuzumab or docetaxel in human breast cancer BT-474 and SKBR-3 cells containing amplification of Her-2. EXPERIMENTAL DESIGN The cells were treated with SAHA (1.0-5.0 micromol/L) and/or trastuzumab (5-40 microg/mL) or docetaxel (5-20 nmol/L). Following this, apoptosis and the levels of p21(WAF1), p27(KIP1), AKT, c-Raf, and Her-2, as well as of the key regulators of apoptosis were determined. Synergistic interaction between drugs was evaluated by median dose-effect analysis. RESULTS Treatment with SAHA up-regulated p21(WAF1) and p27(KIP1) levels, increased the percentage of cells in G2-M phase of the cell cycle, as well as induced apoptosis in a dose-dependent manner. This was associated with up-regulation of the pro-death Bak and Bim, as well as with attenuation of the levels of Her-2 and XIAP, survivin, Bcl-2, and Bcl-x(L) proteins. SAHA treatment induced acetylation of hsp90. This reduced the chaperone association of Her-2 with hsp90, promoting polyubiquitylation and degradation of Her-2. SAHA also attenuated the levels of c-Raf and AKT. Co-treatment with SAHA significantly increased trastuzumab or docetaxel-induced apoptosis of BT-474 and SKBR-3 cells. Additionally, median dose-effect analysis revealed that co-treatment with SAHA and trastuzumab or docetaxel induced synergistic cytotoxic effects against the breast cancer cells. CONCLUSIONS These preclinical findings support the development of SAHA in combination with docetaxel and/or trastuzumab against Her-2-amplified breast cancer.
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Affiliation(s)
- Purva Bali
- Department of Interdisciplinary Oncology, Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, Florida 33612, USA
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389
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Morris JB, Kenney B, Huynh H, Woodcock EA. Regulation of the proapoptotic factor FOXO1 (FKHR) in cardiomyocytes by growth factors and alpha1-adrenergic agonists. Endocrinology 2005; 146:4370-6. [PMID: 16020479 DOI: 10.1210/en.2005-0162] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Apoptotic responses in cardiomyocytes are opposed by the protein kinase Akt (protein kinase B) and thus can be suppressed by a number of growth factors and cytokines. In some cell types, Akt phosphorylates and inactivates members of the forkhead box (FOXO) family of transcription factors that are active in regulating the expression of proapoptotic cytokines and signaling intermediates. In the current study, we investigated the possibility that FOXO1 (FKHR) was expressed, regulated, and functional in cardiomyocytes. Addition of epidermal growth factor (EGF) (10 nM) to neonatal rat cardiomyocytes caused rapid phosphorylation of Akt and slower FOXO1 phosphorylation. In contrast, the alpha1-adrenergic receptor agonist phenylephrine (50 microM) did not phosphorylate Akt and caused dephosphorylation of FOXO1 acutely and increased FOXO1 expression with chronic exposure. Phenylephrine, but not EGF, caused nuclear translocation of FOXO1, a response that is associated with dephosphorylation. Overexpression of FOXO1 activated transcription of the proapoptotic cytokine, TNFalpha-related apoptosis-inducing ligand, as indicated by reporter gene activity. This response was enhanced by phenylephrine and inhibited by EGF. FOXO1 is expressed, regulated, and functionally active in cardiomyocytes and thus may contribute to apoptotic responses in heart.
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Affiliation(s)
- James B Morris
- Cellular Biochemistry Laboratory, Baker Heart Research Institute, PO Box 6492, St. Kilda Road Central, Melbourne 8009, Victoria, Australia
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390
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Labied S, Kajihara T, Madureira PA, Fusi L, Jones MC, Higham JM, Varshochi R, Francis JM, Zoumpoulidou G, Essafi A, Fernandez de Mattos S, Lam EWF, Brosens JJ. Progestins regulate the expression and activity of the forkhead transcription factor FOXO1 in differentiating human endometrium. Mol Endocrinol 2005; 20:35-44. [PMID: 16123151 DOI: 10.1210/me.2005-0275] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Menstruation, or cyclic shedding of nonpregnant endometrial tissue with associated bleeding, occurs only in humans and a few other species. This breakdown of the endometrium in response to falling ovarian progesterone levels is a complex process, characterized by local leukocyte infiltration, expression and activation of matrix metalloproteinases, and apoptosis. Spontaneous decidualization (differentiation) of the stromal compartment precedes the cyclic shedding of the endometrium in various menstruating species but the mechanisms that link these processes are not understood. In this study, we identified FOXO1 as a key transcription factor responsible for mediating apoptosis of decidualized human endometrial stromal cells (HESCs) in response to progesterone withdrawal. We demonstrate that medroxyprogesterone acetate (MPA, a synthetic progestin) enhances the expression of FOXO1 in differentiating HESCs while simultaneously inducing cytoplasmic retention and inactivation of FOXO1. Withdrawal of MPA from decidualized HESCs results in rapid nuclear accumulation of FOXO1, increased BIM expression, a proapoptotic FOXO1 target gene, and cell death. Conversely, silencing of FOXO1 expression completely abolishes cell death induced by MPA withdrawal. In summary, the observation that differentiating HESCs become dependent on progesterone signaling for survival through induction and reversible inactivation of FOXO1 suggests a novel mechanism that links decidualization of the endometrium to menstruation.
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Affiliation(s)
- Soraya Labied
- Institute of Reproductive and Developmental Biology, Wolfson & Weston Research Centre for Family Health, Imperial College London, Faculty of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom
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391
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Li R, Moudgil T, Ross HJ, Hu HM. Apoptosis of non-small-cell lung cancer cell lines after paclitaxel treatment involves the BH3-only proapoptotic protein Bim. Cell Death Differ 2005; 12:292-303. [PMID: 15711598 DOI: 10.1038/sj.cdd.4401554] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A significant variation in susceptibility to paclitaxel-mediated killing was observed among a panel of short-term cultured non-small-cell lung cancer (NSCLC) cell lines. Susceptibility to killing by paclitaxel correlated with expression of the BH3-only protein, Bim, but not with other members of Bcl-2 family. NSCLC cell lines with the highest level of Bim expression are most susceptible to apoptosis induction after paclitaxel treatment. Forced expression of Bim increased paclitaxel-mediated killing of cells expressing an undetectable level of Bim. Conversely, knock down of Bim, but not Bcl-2 expression, decreased the susceptibility of tumor cells to paclitaxel-mediated killing. Similar observations were made using a panel of breast and prostate cancer cell lines. Paclitaxel impairs microtubule function, causes G2/M cell cycle blockade, mitochondria damage, and p53-independent apoptosis. These results established Bim as a critical molecular link between the microtubule poison, paclitaxel, and apoptosis.
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Affiliation(s)
- R Li
- Laboratory of Cancer Immunobiology, Robert W Franz Cancer Research Center, Earle A Chiles Research Institute, Providence Portland Medical Center, Portland, OR 97213, USA
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392
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Essafi A, Fernández de Mattos S, Hassen YAM, Soeiro I, Mufti GJ, Thomas NSB, Medema RH, Lam EWF. Direct transcriptional regulation of Bim by FoxO3a mediates STI571-induced apoptosis in Bcr-Abl-expressing cells. Oncogene 2005; 24:2317-29. [PMID: 15688014 DOI: 10.1038/sj.onc.1208421] [Citation(s) in RCA: 238] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this study, we have used the human BV173 and the mouse BaF3/Bcr-Abl-expressing cell lines as model systems to investigate the molecular mechanisms whereby STI571 and FoxO3a regulate Bim expression and apoptosis. FoxO3a lies downstream of Bcr-Abl signalling and is constitutively phosphorylated in the Bcr-Abl-positive BV173 and BaF3/Bcr-Abl cells. Inhibition of Bcr-Abl kinase by STI571 results in FoxO3a activation, induction of Bim expression and apoptosis. Using reporter gene assays, we demonstrate that STI571 and FoxO3a activate Bim transcription through a FoxO-binding site (FHRE) located within the promoter. This was verified by DNA pull-down and chromatin immunoprecipitation analyses. We find that conditional activation of FoxO3a leads to induction of Bim expression and apoptosis. Conversely, silencing of FoxO3a in Bcr-Abl-expressing cells abolishes STI571-mediated Bim induction and apoptosis. Together, the results presented clearly confirm FoxO3a as a key regulator of apoptosis induced by STI571, and show that Bim is a direct transcriptional target of FoxO3a that mediates the STI571-induced apoptosis. Thus, STI571 induces an accumulation of FoxO3a activity which in turn binds directly to an FHRE in the promoter to activate Bim expression and apoptosis.
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Affiliation(s)
- Abdelkader Essafi
- Cancer Research-UK labs, Department of Cancer Medicine, MRC Cyclotron Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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393
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Walgren RA, McLeod HL. Small inhibitory RNA – a tool for credentialing candidate genes. Pharmacogenomics 2005; 6:281-92. [PMID: 16013959 DOI: 10.1517/14622416.6.3.281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The effect of a drug is related to the interaction of the numerous gene products that participate in a drug pathway. The clinical importance of genetic variability on the overall outcome of most drug pathways remains to be determined. As a result, there is a need to efficiently identify the genes that not only participate in the pathway but also play a significant role in regulating the effects of a drug. The emerging technique of specific gene silencing through RNA interference initiated by small inhibitory RNA may prove to be a useful and powerful tool in the credentialing of candidate genes in drug pathways.
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394
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Tan TT, Degenhardt K, Nelson DA, Beaudoin B, Nieves-Neira W, Bouillet P, Villunger A, Adams JM, White E. Key roles of BIM-driven apoptosis in epithelial tumors and rational chemotherapy. Cancer Cell 2005; 7:227-38. [PMID: 15766661 DOI: 10.1016/j.ccr.2005.02.008] [Citation(s) in RCA: 237] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 01/19/2005] [Accepted: 02/18/2005] [Indexed: 12/30/2022]
Abstract
Defective apoptosis not only promotes tumorigenesis, but also can confound chemotherapeutic response. Here we demonstrate that the proapoptotic BH3-only protein BIM is a tumor suppressor in epithelial solid tumors and also is a determinant in paclitaxel sensitivity in vivo. Furthermore, the H-ras/mitogen-activated protein kinase (MAPK) pathway conferred resistance to paclitaxel that was dependent on functional inactivation of BIM. Whereas paclitaxel induced BIM accumulation and BIM-dependent apoptosis in vitro and in tumors in vivo, the H-ras/MAPK pathway suppressed this BIM induction by phosphorylating BIM and targeting BIM for degradation in proteasomes. The proteasome inhibitor Velcade (P-341, Bortezomib) restored BIM induction, abrogated H-ras-dependent paclitaxel resistance, and promoted BIM-dependent tumor regression, suggesting the potential benefits of combinatorial chemotherapy of Velcade and paclitaxel.
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Affiliation(s)
- Ting-Ting Tan
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey 08854, USA
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395
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Rosas M, Birkenkamp KU, Lammers JWJ, Koenderman L, Coffer PJ. Cytokine mediated suppression of TF-1 apoptosis requires PI3K activation and inhibition of Bim expression. FEBS Lett 2004; 579:191-8. [PMID: 15620712 DOI: 10.1016/j.febslet.2004.11.074] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 11/15/2004] [Accepted: 11/15/2004] [Indexed: 10/26/2022]
Abstract
Phosphatidylinositol 3-kinase (PI3K) and its effector protein kinase B (PKB/c-akt) have been implicated as critical mediators of cytokine-induced survival signals. In this study, we have utilized an IL-5 dependent hematopoietic cell line (TF-1) to investigate the signaling events involved in cytokine-dependent erythroblast survival. We demonstrate that IL-5 rescues TF-1 cells from apoptosis through a PI3K/PKB-dependent signaling pathway. Cytokine-withdrawal leads to activation of the Forkhead transcription factor FOXO3a and subsequent expression of the pro-apoptotic Bcl-2 family member Bim. Bim is itself sufficient to induce apoptosis in these cells. Importantly, activation of an inducible active FOXO3a mutant is alone sufficient for upregulation of Bim expression and induction of apoptosis. These data define a mechanism by which survival factors inhibit the default apoptotic pathway and can regulate TF-1 erythroblast survival.
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Affiliation(s)
- Marcela Rosas
- Department of Pulmonary Diseases H02.128, University Medical Center, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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396
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Park SJ, Wu CH, Gordon JD, Zhong X, Emami A, Safa AR. Taxol Induces Caspase-10-dependent Apoptosis. J Biol Chem 2004; 279:51057-67. [PMID: 15452117 DOI: 10.1074/jbc.m406543200] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Taxol (paclitaxel) is known to inhibit cell growth and trigger significant apoptosis in various cancer cells. Although taxol induces apoptosis of cancer cells, its exact mechanism of action is not yet known. In this study we investigated death receptors, FAS-associated death domain protein (FADD), the activation of caspases-10 and -8 as well as the downstream caspases, and reactive oxygen species (ROS) in taxol-induced apoptosis in the CCRF-HSB-2 human lymphoblastic leukemia cell line. Pretreating the cells with neutralizing antibodies to Fas, tumor necrosis factor (TNF)-alpha receptor 1, or TNF-related apoptosis-inducing ligand receptors (DR4 and DR5) did not affect taxol-induced apoptosis, but transfection of the cells with a dominant negative FADD plasmid resulted in inhibition of taxol-induced apoptosis, revealing that taxol induces apoptosis independently of these death receptors but dependently on FADD. Furthermore, the drug induced activation of caspases-10, -8, -6, and -3, cleaved Bcl-2, Bid, poly(ADP-ribose) polymerase, and lamin B, and down-regulated cellular levels of FLICE-like inhibitory protein (FLIP) and X-chromosome-linked inhibitor of apoptosis protein (XIAP). However, despite the release of cytochrome c from the mitochondria in taxol-treated cells, caspase-9 was not activated. Inhibitors of caspases-8, -6, or -3 partially inhibited taxol-induced apoptosis, whereas the caspase-10 inhibitor totally abrogated this process. Taxol-induced apoptosis was also associated with decreased mitochondrial membrane potential (Deltapsim) and a significant increase in ROS generation. However, increased ROS production was not directly involved in taxol-triggered apoptosis. Therefore, these results demonstrate for the first time that taxol induces FADD-dependent apoptosis primarily through activation of caspase-10 but independently of death receptors.
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MESH Headings
- Adaptor Proteins, Signal Transducing/biosynthesis
- Adaptor Proteins, Signal Transducing/chemistry
- Annexin A5/pharmacology
- Antineoplastic Agents, Phytogenic/pharmacology
- Apoptosis
- Apoptosis Regulatory Proteins
- Blotting, Western
- Carrier Proteins/metabolism
- Caspase 10
- Caspase 3
- Caspase 6
- Caspase 8
- Caspase 9
- Caspases/biosynthesis
- Caspases/metabolism
- Cell Culture Techniques
- Cell Line
- Cell Line, Tumor
- Cell Survival
- Coloring Agents/pharmacology
- Cytochromes c/metabolism
- Cytosol/metabolism
- Dose-Response Relationship, Drug
- Down-Regulation
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- Fas-Associated Death Domain Protein
- Flow Cytometry
- Genes, Dominant
- Humans
- Intracellular Signaling Peptides and Proteins
- Membrane Potentials
- Mitochondria/metabolism
- Mitochondrial Proteins/metabolism
- Models, Biological
- Paclitaxel/pharmacology
- Plasmids/metabolism
- Poly(ADP-ribose) Polymerases/metabolism
- Proto-Oncogene Proteins c-bcl-2/metabolism
- Reactive Oxygen Species
- Receptors, Tumor Necrosis Factor, Type I/metabolism
- Tetrazolium Salts/pharmacology
- Thiazoles/pharmacology
- Transfection
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Affiliation(s)
- Soo-Jung Park
- Department of Pharmacology and Toxicology and Indiana University Cancer Center, Indianapolis, Indiana 46202, USA
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397
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Abrams MT, Robertson NM, Yoon K, Wickstrom E. Inhibition of glucocorticoid-induced apoptosis by targeting the major splice variants of BIM mRNA with small interfering RNA and short hairpin RNA. J Biol Chem 2004; 279:55809-17. [PMID: 15509554 DOI: 10.1074/jbc.m411767200] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glucocorticoids (GCs) induce apoptosis in lymphocytes and are effective agents for the treatment of leukemia. The activated glucocorticoid receptor initiates a transcriptional program leading to caspase activation and cell death, but the critical signaling intermediates in GC-induced apoptosis remain largely undefined. We have observed that GC induction of the three major protein products of the Bcl-2 relative Bim (BimEL, BimS, and BimL) correlates with GC sensitivity in a panel of human precursor B-cell (pre-B) acute lymphoblastic leukemia (ALL) cell lines. To test the hypothesis that Bim facilitates GC-induced apoptosis, we reduced BIM mRNA levels and Bim protein levels by RNA interference in highly GC-sensitive pre-B ALL cells. Reducing Bim proteins by either electroporation of synthetic small interfering RNA (siRNA) duplexes or lentivirus-mediated stable expression of short hairpin RNA inhibited the activation of caspase-3 and increased cell viability following GC exposure. We also observed that the extent of GC resistance correlated with siRNA silencing potency. siRNA duplexes that reduced only BimEL or BimEL and BimL (but not BimS) exhibited less GC resistance than a potent siRNA that silenced all three major isoforms, implying that induction of all three Bim proteins contributes to cell death. Finally, the modulation of GC-induced apoptosis caused by Bim silencing was independent of Bcl-2 expression levels, negating the hypothesis that the ratio of Bim to Bcl-2 regulates apoptosis. These results offer evidence that the induction of Bim by GC is a required event for the complete apoptotic response in pre-B ALL cells.
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Affiliation(s)
- Marc T Abrams
- Department of Biochemistry and Molecular Pharmacology, Thomas Jefferson University, 233 S. 10th Street, Philadelphia, PA 19107, USA
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398
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Van Der Heide LP, Hoekman MFM, Smidt MP. The ins and outs of FoxO shuttling: mechanisms of FoxO translocation and transcriptional regulation. Biochem J 2004; 380:297-309. [PMID: 15005655 PMCID: PMC1224192 DOI: 10.1042/bj20040167] [Citation(s) in RCA: 531] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Revised: 03/03/2004] [Accepted: 03/09/2004] [Indexed: 12/15/2022]
Abstract
FoxO (forkhead box O; forkhead members of the O class) are transcription factors that function under the control of insulin/insulin-like signalling. FoxO factors have been associated with a multitude of biological processes, including cell-cycle, cell death, DNA repair, metabolism and protection from oxidative stress. Central to the regulation of FoxO factors is a shuttling system, which confines FoxO factors to either the nucleus or the cytosol. Shuttling of FoxO requires protein phosphorylation within several domains, and association with 14-3-3 proteins and the nuclear transport machinery. Description of the FoxO-shuttling mechanism contributes to the understanding of FoxO function in relation to signalling and gene regulation.
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Affiliation(s)
- Lars P Van Der Heide
- Department of Pharmacology and Anatomy, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
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399
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Fukazawa H, Noguchi K, Masumi A, Murakami Y, Uehara Y. BimEL is an important determinant for induction of anoikis sensitivity by mitogen-activated protein/extracellular signal-regulated kinase kinase inhibitors. Mol Cancer Ther 2004. [DOI: 10.1158/1535-7163.1281.3.10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Loss of contact with substratum triggers apoptosis in many normal cell types, a phenomenon termed anoikis. We reported previously that mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) inhibitors induced apoptosis in nonanchored MDA-MB231 and HBC4 human breast cancer cells, whereas anchored cells remained viable. Here, we report that activation of the BH3-only protein BimEL is the major mechanism for induction of anoikis sensitivity by MEK inhibitors in MDA-MB231 and HBC4 cells. On treatment with MEK inhibitors, BimEL in MDA-MB231 and HBC4 cells rapidly increased, irrespective of the state of anchorage. However, it translocated to mitochondria only in nonanchored cells, explaining why attached cells remain viable. MDA-MB231 and HBC4 cells had exceedingly low basal levels of BimEL compared with other breast cancer cells, suggesting that maintenance of low BimEL amount is important for survival of these cells. MEK inhibitors also induced the electrophoretic mobility shift of BimEL, indicative of reduced phosphorylation. In vitro, BimEL was phosphorylated by extracellular signal-regulated kinase on Ser69, which resides in the BimEL-specific insert region. Using phosphospecific antibody against this site, we show that this residue is actually phosphorylated in cells. We also show that phosphorylation of Ser69 promotes ubiquitination of BimEL. We conclude that MEK inhibitors sensitize MDA-MB231 and HBC4 cells to anoikis by blocking phosphorylation and hence degradation of BimEL, a mechanism that these cells depend on to escape anoikis.
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Affiliation(s)
| | | | - Atsuko Masumi
- 2Safety Research on Blood and Biologics, National Institute of Infectious Diseases, Tokyo, Japan
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400
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Wang P, Gilmore AP, Streuli CH. Bim is an apoptosis sensor that responds to loss of survival signals delivered by epidermal growth factor but not those provided by integrins. J Biol Chem 2004; 279:41280-5. [PMID: 15292207 DOI: 10.1074/jbc.c400248200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Anoikis is a rapid apoptosis response that is initiated within a few minutes after inhibition of integrin signaling. In mammary epithelia, anoikis is mediated by subcellular translocation of Bax from the cytosol to mitochondria where it activates the intrinsic apoptosis pathway. The Bcl-2 homology 3 domain-only protein, Bim, has been proposed to have a key role in the apoptosis response of an epithelial cell line with reduced sensitivity to loss of integrin signaling, which undergoes apoptosis over a period of several days in suspension culture. Here we tested the involvement of Bim in the rapid anoikis response of mouse mammary epithelial cells and discovered that Bim does not have a role in detecting integrin-mediated signals. Instead Bim senses the loss of survival cues mediated by epidermal growth factor. Cell lines selected over many passages in culture have lost much of their sensitivity to anoikis signals arising from an altered cellular microenvironment and may undergo apoptosis through acquired mechanisms.
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Affiliation(s)
- Pengbo Wang
- School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
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