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Osteosarcoma Mediates Apoptosis Induced by Chelerythrine in Kinase / Extracellular Signal-Regulated Kinase Pathway Protein / Extracellular Signal-Regulated Kinase Activation of the RAF / Mitogen-Activated
| Content Provider | Semantic Scholar |
|---|---|
| Author | Piperdi, Sajida Gorlick, Richard |
| Copyright Year | 2008 |
| Abstract | Purpose:Chelerythrine, a widely used broad-range protein kinase C inhibitor, induces apoptosis in many cell types. In this study, the mechanism of chelerythrine-induced apoptosis in osteosarcoma was investigated. Experimental Design: Signaling pathways activated by chelerythrine in osteosarcoma were detected byWestern blots. Impacts of RAF/mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK MAPK on apoptosis and cell survival were studied using genetic approaches and pharmacologic pathway ^ specific inhibitors. Results: Osteosarcoma cells underwent apoptosis rapidly after treatment with chelerythrine. Three parallel MAPKs pathways, including the ERKs, c-Jun NH2 kinases, and p38, were activated by chelerythrine in a dose-dependent and time-dependent fashion. For the ERKs, the activation was evident at the earliest time point tested (2 minutes) and sustained for >4 hours. Introduction of a dominant-negative H-RAS mutant (17N) partially attenuated ERK activation and delayed the onset of apoptosis induced by chelerythrine. The ERK activation and apoptotic effects of chelerythrine were greatly abrogatedby the pharmaceutical inhibitors of MEK, but not by those of c-Jun NH2 kinase or p38. Moreover, osteosarcoma cells were sensitized to chelerythrine by transient transfection with wild-type MEK1or constitutively active MEK1and became resistant with dominant-negative MEK1. Other protein kinase C inhibitors, including GF109203X or Go« 6976, did not cause ERK activation or apoptosis in the same timeframe tested. Conclusion: In osteosarcoma, chelerythrine-induced apoptosis is mediated through activation of the RAF/MEK/ERK pathway. These findings suggest that activating the ERK MAPK, as opposed to inhibiting it, may be a therapeutic strategy in osteosarcoma. Chelerythrine chloride (benzophenanthridine alkaloid), a natural extract from Chelidonium majus, is a selective and potent inhibitor of protein kinase C (PKC; ref. 1). Chelerythrine has a variety of biological effects, including antimicrobial, antiplatelet, and antitumor activity, presumably associated with PKC inhibition (2, 3). However, in some studies, chelerythrine seemed to act independent of PKC (4, 5). In addition, it was reported that chelerythrine induced apoptosis in connection with generation of reactive oxidative species and subsequent activation of c-Jun NH2 terminal kinases (JNK) and p38, which are members of the mitogen-activated protein kinase (MAPK) family, also including the extracellular signal-regulated kinases (ERK; refs. 5, 6). MAPK pathways play pivotal roles in cell proliferation, differentiation, and survival (7). The closely related MAPK pathways are regulated through a series of phosphorylation steps in a three-component module: MAPKs are activated by MAPK kinases (MAPKK) on dual residues of threonine and tyrosine, and MAPKKs are in turn phosphorylated by MAPKK kinases (MAPKKK) on dual residues of serine/threonine. This unusual feature ensures the tight control on the signals transduced by MAPK pathways in terms of specificity, intensity, and duration. The ERK1 and ERK2 MAPKs (ERK1/2), often activated by growth factors, are widely considered as prosurvival and oncogenic. The constitutively active form of the MAPK/ERK kinase (MAPKK of ERK, MEK1/2) is sufficient to transform murine fibroblast 3T3 cells (8, 9). Activating mutations are frequently found in BRAF (a MAPKKK), or its upstream activator, RAS, in colorectal cancer and melanoma (10). Accordingly, pharmaceutical inhibitors targeting the RAS/RAF/MEK/ ERK pathways have been developed and are actively being tested for their therapeutic effects in human cancers (11). Human Cancer Biology Authors’Affiliation: Department of Pediatrics and Molecular Pharmacology,The Albert Einstein College of Medicine,The Children’s Hospital at Montefiore, Bronx, NewYork Received12/9/07; revised 4/16/08; accepted 5/21/08. Grant support:National Cancer Institute grant R01CA-83132, Foster Foundation, and Swim Across America Foundation. The costs of publication of this article were defrayed in part by the payment of page charges.This article must therefore be hereby marked advertisement in accordance with18 U.S.C. Section1734 solely to indicate this fact. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). Requests for reprints: Richard Gorlick, Pediatrics and Molecular Pharmacology, Albert Einstein College of Medicine; Department of Pediatrics, The Children’s Hospital at Montefiore, 3415 Bainbridge Avenue, Rosenthal 3rd Floor, Bronx, NY 10467. Phone: 718-741-2333; Fax : 718-920-6506; E-mail: rgorlick@ montefiore.org. F2008 American Association for Cancer Research. doi:10.1158/1078-0432.CCR-07-5113 www.aacrjournals.org Clin Cancer Res 2008;14(20) October15, 2008 6396 American Association for Cancer Research Copyright © 2008 on December 17, 2011 clincancerres.aacrjournals.org Downloaded from DOI:10.1158/1078-0432.CCR-07-5113 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.medicinabiomolecular.com.br/biblioteca/pdfs/Cancer/ca-2032.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
