Proteomic differential display analysis identified upregulated astrocytic phosphoprotein PEA-15 in human malignant pleural mesothelioma cell lines

Department of Biochemistry and Functional Proteomics, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi, Japan.
Proteomics (Impact Factor: 3.81). 11/2009; 9(22):5078-89. DOI: 10.1002/pmic.200800284
Source: PubMed


We performed proteomic differential display analysis of human malignant pleural mesothelioma (MPM) cell lines and a human pleural mesothelial cell line by using 2-DE and LC-MS/MS. The human MPM cell lines were NCI-H28, NCI-H2052 and NCI-H2452, and the human pleural mesothelial cell line was MeT-5A. Between MeT-5A and NCI-H2052, we found 38 protein spots whose expression levels were different, from the results of 2-DE; 28 protein spots appeared higher, and 10 other protein spots lower in NCI-H2052 than in MeT-5A. These spots were analyzed by LC-MS/MS analysis and identified by a peptide sequence tag. However, from the results of 2-DE of the other cell lines, there was only one consistently upregulated protein, astrocytic phosphoprotein PEA-15, in all three MPM cell lines. Western blotting using specific antibodies against PEA-15 confirmed the elevated expression level of PEA-15 in all three MPM cell lines compared with MeT-5A cells and normal pleura tissues from patients. PEA-15 was knocked down in NCI-H2052 cells, and the proliferation of PEA-15-silenced NCI-H2052 cells was suppressed 7-15% compared with negative control cells. These results suggest that PEA-15 expression is likely to be associated with the tumorigenesis of MPM.

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Available from: Xiulian Zhang, Dec 10, 2015
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    • "PEA-15 is known to be upregulated in a variety of cancer subsets including immortal cancer cell lines (e.g. MCF-7 and HeLa cells) (Condorelli et al., 1999), malignant pleural mesothelioma cells (Kuramitsu et al., 2009), breast cancer cells (Stassi et al., 2005), non-small cell lung cancer (NSCLC) cells (Zanca et al., 2008), glioblastoma (Eramo et al., 2005) and renal cell carcinomas (Heikaus et al., 2008). Mice overexpressing PEA-15 also displayed an increase in skin tumourigenesis with a four-fold increase in papilloma number compared to their wild type littermates (Formisano et al., 2005), suggesting a potential role for PEA-15 in tumour formation and cancer progression. "
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    ABSTRACT: Phosphoprotein enriched in astrocytes-15 (PEA-15) is a cytoplasmic protein that sits at an important junction in intracellular signalling and can regulate diverse cellular processes, such as proliferation and apoptosis, dependent upon stimulation. Regulation of these processes occurs by virtue of the unique interaction of PEA-15 with other signalling proteins. PEA-15 acts as a cytoplasmic tether for the mitogen-activated protein kinases, extracellular signal-regulated kinase 1/2 (ERK1/2) preventing nuclear localisation. In order to release ERK1/2, PEA-15 requires to be phosphorylated via several potential pathways. PEA-15 (and its phosphorylation state) therefore regulates many ERK1/2-dependent processes, including proliferation, via regulating ERK1/2 nuclear translocation. In addition, PEA-15 contains a death effector domain (DED) which allows interaction with other DED-containing proteins. PEA-15 can bind the DED-containing apoptotic adaptor molecule, Fas-associated death domain protein (FADD) which is also dependent on the phosphorylation status of PEA-15. PEA-15 binding of FADD can inhibit apoptosis as bound FADD cannot participate in the assembly of apoptotic signalling complexes. Through these protein-protein interactions, PEA-15-regulated cellular effects have now been investigated in a number of disease-related studies. Changes in PEA-15 expression and regulation have been observed in diabetes mellitus, cancer, neurological disorders and the cardiovascular system. These changes have been suggested to contribute to the pathology related to each of these disease states. As such, new therapeutic targets based around PEA-15 and its associated interactions are now being uncovered and could provide novel avenues for treatment strategies in multiple diseases.
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    • "These findings were supported by a previous report that single-agent erlotinib therapy had no efficacy in a phase II clinical trial involving patients with MPM [89]. Kuramitsu et al. also investigated therapeutic targets using a proteomic approach [90]. Overexpression of the astrocytic phosphoprotein PEA-15 was identified in MPM cell lines in a comparative study of normal pleural and MPM cell lines by 2D-PAGE. "
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    • "Although these immunohistochemical biomarkers may help in the differential diagnosis of MPM to some degree, novel biomarkers with higher sensitivity and specificity have also been long required. Proteomic studies on MPM conducted to date have used tissue microarray samples [13], plasma samples, pleural effusions [14] and cell lines [15] [16] [17] [18] [19], none however, has used direct protein extracts from surgical specimens of MPM, probably because MPM has a complex histology and clinical materials are difficult to obtain. "
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