title: MicroRNAs 221 and 222 inhibit normal erythropoiesis and erythroleukemic cell growth via kit receptor down-modulation.
abstract: MicroRNAs (miRs) are small noncoding RNAs that regulate gene expression primarily through translational repression. In erythropoietic (E) culture of cord blood CD34+ progenitor cells, the level of miR 221 and 222 is gradually and sharply down-modulated. Hypothetically, this decline could promote erythropoiesis by unblocking expression of key functional proteins. Indeed, (i) bioinformatic analysis suggested that miR 221 and 222 target the 3' UTR of kit mRNA; (ii) the luciferase assay confirmed that both miRs directly interact with the kit mRNA target site; and (iii) in E culture undergoing exponential cell growth, miR down-modulation is inversely related to increasing kit protein expression, whereas the kit mRNA level is relatively stable. Functional studies show that treatment of CD34+ progenitors with miR 221 and 222, via oligonucleotide transfection or lentiviral vector infection, causes impaired proliferation and accelerated differentiation of E cells, coupled with down-modulation of kit protein: this phenomenon, observed in E culture releasing endogenous kit ligand, is magnified in E culture supplemented with kit ligand. Furthermore, transplantation experiments in NOD-SCID mice reveal that miR 221 and 222 treatment of CD34+ cells impairs their engraftment capacity and stem cell activity. Finally, miR 221 and 222 gene transfer impairs proliferation of the kit+ TF-1 erythroleukemic cell line. Altogether, our studies indicate that the decline of miR 221 and 222 during exponential E growth unblocks kit protein production at mRNA level, thus leading to expansion of early erythroblasts. Furthermore, the results on kit+ erythroleukemic cells suggest a potential role of these miRs in cancer therapy.
authors.affiliation: Department of Hematology, Oncology, and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Felli
authors.forename: Laura
authors.initials: L
authors.lastname: Fontana
authors.forename: Elvira
authors.initials: E
authors.lastname: Pelosi
authors.forename: Rosanna
authors.initials: R
authors.lastname: Botta
authors.forename: Desirée
authors.initials: D
authors.lastname: Bonci
authors.forename: Francesco
authors.initials: F
authors.lastname: Facchiano
authors.forename: Francesca
authors.initials: F
authors.lastname: Liuzzi
authors.forename: Valentina
authors.initials: V
authors.lastname: Lulli
authors.forename: Ornella
authors.initials: O
authors.lastname: Morsilli
authors.forename: Simona
authors.initials: S
authors.lastname: Santoro
authors.forename: Mauro
authors.initials: M
authors.lastname: Valtieri
authors.forename: George Adrian
authors.initials: GA
authors.lastname: Calin
authors.forename: Chang-Gong
authors.initials: CG
authors.lastname: Liu
authors.forename: Antonio
authors.initials: A
authors.lastname: Sorrentino
authors.forename: Carlo M
authors.initials: CM
authors.lastname: Croce
authors.forename: Cesare
authors.initials: C
authors.lastname: Peschle
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D049109:Cell Proliferation; D019295:Computational Biology; D004920:Erythropoiesis / Q000235:genetics / Q000502:physiology*; D005312:Fetal Blood / Q000166:cytology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D008156:Luciferases; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism*; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*
chemical_list: D018952:Antigens, CD34; D035683:MicroRNAs; D008156:Luciferases; D019009:Proto-Oncogene Proteins c-kit