title: PEA-15 inhibits tumor cell invasion by binding to extracellular signal-regulated kinase 1/2.
abstract: Phosphoprotein enriched in astrocytes of 15 kDa (PEA-15) binds to extracellular signal-regulated kinase 1 and 2 (ERK1/2) mitogen-activated protein (MAP) kinases to alter ERK1/2 cellular localization and target preferences and binds to adaptors in the extrinsic cell death pathway to block apoptosis. Here, we report that PEA-15 protein expression is inversely correlated with the invasive behavior of breast cancer in an immunohistochemical analysis of a breast cancer progression tissue microarray. Short hairpin RNA-mediated inhibition of PEA-15 expression increased the invasion of PEA-15-expressing tumor cells in vitro, suggesting a causative role for PEA-15 in the inhibition of invasion. This causative role was confirmed by the finding that the enforced expression of PEA-15 in invasive tumor cells reduced invasion. The effect of PEA-15 on tumor invasion is mediated by its interaction with ERK1/2 as shown by the following: (a) PEA-15 mutants that fail to bind ERK1/2 did not inhibit invasion; (b) overexpression of ERK1 or activated MAP/ERK kinase (MEK) reversed the inhibitory effect of PEA-15; (c) when an inhibitor of ERK1/2 activation reduced invasion, PEA-15 expression did not significantly reduce invasion further. Furthermore, we find that the effect of PEA-15 on invasion seems to relate to the nuclear localization of activated ERK1/2. PEA-15 inhibits invasion by keeping ERK out of the nucleus, as a PEA-15 mutant that cannot prevent ERK nuclear localization was not able to inhibit invasion. In addition, membrane-localized ERK1, which sequesters endogenous ERK1 to prevent its nuclear localization, also inhibited invasion. These results reveal that PEA-15 regulates cancer cell invasion via its ability to bind ERK1/2 and indicate that nuclear entry of ERK1/2 is important in tumor behavior.
authors.affiliation: Department of Medicine, University of California-San Diego, The Scripps Research Institute, 9500 Gilman Drive, La Jolla, CA 92093, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Glading
authors.forename: James A
authors.initials: JA
authors.lastname: Koziol
authors.forename: Joseph
authors.initials: J
authors.lastname: Krueger
authors.forename: Mark H
authors.initials: MH
authors.lastname: Ginsberg
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001943:Breast Neoplasms / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D016466:CHO Cells; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000201:enzymology; D006224:Cricetinae; D003412:Cricetulus; D005909:Glioblastoma / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D009369:Neoplasms / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014162:Transfection
chemical_list: D051017:Apoptosis Regulatory Proteins; D047908:Intracellular Signaling Peptides and Proteins; C092039:PEA15 protein, human; D010750:Phosphoproteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3