title: ERK2 is essential for the growth of human epithelioid malignant mesotheliomas.
abstract: Members of the extracellular signal-regulated kinase (ERK) family may have distinct roles in the development of cell injury and repair, differentiation and carcinogenesis. Here, we show, using a synthetic small-molecule MEK1/2 inhibitor (U0126) and RNA silencing of ERK1 and 2, comparatively, that ERK2 is critical to transformation and homeostasis of human epithelioid malignant mesotheliomas (MMs), asbestos-induced tumors with a poor prognosis. Although MM cell (HMESO) lines stably transfected with shERK1 or shERK2 both exhibited significant decreases in cell proliferation in vitro, injection of shERK2 cells, and not shERK1 cells, into immunocompromised severe combined immunodeficiency (SCID) mice showed significant attenuated tumor growth in comparison to shControl (shCon) cells. Inhibition of migration, invasion and colony formation occurred in shERK2 MM cells in vitro, suggesting multiple roles of ERK2 in neoplasia. Microarray and quantitative real-time PCR analyses revealed gene expression that was significantly increased (CASP1, TRAF1 and FAS) or decreased (SEMA3E, RPS6KA2, EGF and BCL2L1) in shERK2-transfected MM cells in contrast to shCon-transfected MM cells. Most striking decreases were observed in mRNA levels of Semaphorin 3 (SEMA3E), a candidate tumor suppressor gene linked to inhibition of angiogenesis. These studies demonstrate a key role of ERK2 in novel gene expression critical to the development of epithelioid MMs. After injection of sarcomatoid human MM (PPMMill) cells into SCID mice, both shERK1 and shERK2 lines showed significant decreased tumor growth, suggesting heterogeneous effects of ERKs in individual MMs.
authors.affiliation: Department of Pathology, University of Vermont College of Medicine, Burlington, VT 05405-0068, USA. arti.shukla@uvm.edu
authors.forename: Arti
authors.initials: A
authors.lastname: Shukla
authors.forename: Jedd M
authors.initials: JM
authors.lastname: Hillegass
authors.forename: Maximilian B
authors.initials: MB
authors.lastname: MacPherson
authors.forename: Stacie L
authors.initials: SL
authors.lastname: Beuschel
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Vacek
authors.forename: Kelly J
authors.initials: KJ
authors.lastname: Butnor
authors.forename: Harvey I
authors.initials: HI
authors.lastname: Pass
authors.forename: Michele
authors.initials: M
authors.lastname: Carbone
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Testa
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Heintz
authors.forename: Brooke T
authors.initials: BT
authors.lastname: Mossman
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D020869:Gene Expression Profiling; D006801:Humans; D007124:Immunoenzyme Techniques; D008654:Mesothelioma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D016513:Mice, SCID; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D010997:Pleural Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D023041:Xenograft Model Antitumor Assays
chemical_list: D014408:Biomarkers, Tumor; D002070:Butadienes; D009570:Nitriles; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C113580:U 0126; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3