title: Growth inhibition of malignant glioblastoma by DING protein.
abstract: Malignant gliomas are a highly aggressive type of brain tumor with extremely poor prognosis. These tumors are highly invasive and are often surgically incurable and resistant to chemotherapeutics and radiotherapy. Thus, novel therapies that target pathways involved in growth and survival of the tumor cells are required for the treatment of this class of brain tumors. Previous studies revealed that epidermal growth factor receptor and extracellular-signal-regulated kinases (ERKs), which are involved in the induction of cell proliferation, are activated in the most aggressive type of glioma, i.e. glioblastoma multiforme (GBM). In fact, GBMs with increased levels of ERK activity exhibit a more aggressive phenotype than the others with moderate ERK activity, pointing to the importance of ERK and its kinase activity in the development and progression of these tumors. In this study, we have evaluated the effect of p38SJ, a novel member of the DING family of proteins, derived from Hypericum perforatum calluses, on the growth of malignant glioma cell lines, T98G and U-87MG by focusing on cell cycle and signaling pathways controlled by phosphorylation of various regulatory proteins including ERK. p38SJ, which exhibits profound phosphatase activity, shows the capacity to affect the phosphorylation status of several important kinases modulating signaling pathways, and cell growth and proliferation. Our results demonstrate that p38SJ reduces glioma cell viability and arrests cell cycle progression at G0/G1. The observed growth inhibitory effect of p38SJ is likely mediated by the downregulation of several cell cycle gatekeeper proteins, including cyclin E, Cdc2, and E2F-1. These results suggest that p38SJ may serve as a potential candidate for development of a therapeutic agent for the direct treatment of malignant gliomas and/or as a potential radiosensitizer.
authors: Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Room 741 MERB, 3500 North Broad St., Philadelphia, PA 19140, USA.
authors: Markus J
authors: MJ
authors: Bookland
authors: Nune
authors: N
authors: Darbinian
authors: Michael
authors: M
authors: Weaver
authors: Shohreh
authors: S
authors: Amini
authors: Kamel
authors: K
authors: Khalili
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D019926:Cyclin B / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D018844:Cyclin-Dependent Kinases; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D050684:E2F Transcription Factors / Q000378:metabolism; D019286:Endopeptidase K / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D005909:Glioblastoma / Q000473:pathology / Q000503:physiopathology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020902:Hypericum / Q000737:chemistry; D051379:Mice; D028321:Plant Preparations / Q000494:pharmacology; D063150:Polycomb Repressive Complex 1; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D014162:Transfection; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D019926:Cyclin B; D019927:Cyclin E; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D028321:Plant Preparations; D013778:Tetrazolium Salts; D013844:Thiazoles; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D063150:Polycomb Repressive Complex 1; C489841:RNF2 protein, human; D044767:Ubiquitin-Protein Ligases; D016203:CDC2 Protein Kinase; C528899:CDK1 protein, human; D018844:Cyclin-Dependent Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D019286:Endopeptidase K; C022616:thiazolyl blue