title: Activin type II receptor restoration in ACVR2-deficient colon cancer cells induces transforming growth factor-beta response pathway genes.
abstract: The activin type II receptor (ACVR2) gene is a putative tumor suppressor gene that is frequently mutated in microsatellite-unstable colon cancers (MSI-H colon cancers). ACVR2 is a member of the transforming growth factor (TGF)-beta type II receptor (TGFBR2) family and controls cell growth and differentiation. SMAD proteins are major intracellular effectors shared by ACVR2 and TGFBR2 signaling; however, additional shared effector mechanisms remain to be explored. To discover novel mechanisms transmitting the ACVR2 signal, we restored ACVR2 function by transfecting wild-type ACVR2 (wt-ACVR2) into a MSI-H colon cancer cell line carrying an ACVR2 frameshift mutation. The effect of ACVR2 restoration on cell growth, SMAD phosphorylation, and global molecular phenotype was then evaluated. Decreased cell growth was observed in wt-ACVR2 transfectants relative to ACVR2-deficient vector-transfected controls. Western blotting revealed higher expression of phosphorylated SMAD2 in wt-ACVR2 transfectants versus controls, suggesting cells deficient in ACVR2 had impaired SMAD signaling. Microarray-based differential expression analysis revealed substantial ACVR2-induced overexpression of genes implicated in the control of cell growth and tumorigenesis, including the activator protein (AP)-1 complex genes JUND, JUN, and FOSB, as well as the small GTPase signal transduction family members, RHOB, ARHE, and ARHGDIA. Overexpression of these genes is shared with TGFBR2 activation. This observed similarity between the activin and TGF-beta signaling systems suggests that activin may serve as an alternative activator of TGF-beta effectors, including SMADs, and that frameshift mutation of ACVR2 may contribute to MSI-H colon tumorigenesis via disruption of alternate TGF-beta effector pathways.
authors.affiliation: Department of Medicine, Division of Gastroenterology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Elena
authors.initials: E
authors.lastname: Deacu
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Mori
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Sato
authors.forename: Jing
authors.initials: J
authors.lastname: Yin
authors.forename: Andreea
authors.initials: A
authors.lastname: Olaru
authors.forename: Anca
authors.initials: A
authors.lastname: Sterian
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.forename: Suna
authors.initials: S
authors.lastname: Wang
authors.forename: Karsten
authors.initials: K
authors.lastname: Schulmann
authors.forename: Agnes
authors.initials: A
authors.lastname: Berki
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Kan
authors.forename: John M
authors.initials: JM
authors.lastname: Abraham
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Meltzer
mesh_terms: D030301:Activin Receptors, Type II / Q000502:physiology*; D002455:Cell Division; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000502:physiology; D015398:Signal Transduction; D051899:Smad2 Protein; D015534:Trans-Activators / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D004268:DNA-Binding Proteins; D018125:Receptors, Transforming Growth Factor beta; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D030301:Activin Receptors, Type II; D000077294:Receptor, Transforming Growth Factor-beta Type II