MicroRNAs 221 and 222 inhibit normal erythropoiesis and erythroleukemic cell growth via kit receptor down-modulation.
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.
Felli
Nadia
N
Department of Hematology, Oncology, and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy.
Fontana
Laura
L
Pelosi
Elvira
E
Botta
Rosanna
R
Bonci
Desirée
D
Facchiano
Francesco
F
Liuzzi
Francesca
F
Lulli
Valentina
V
Morsilli
Ornella
O
Santoro
Simona
S
Valtieri
Mauro
M
Calin
George Adrian
GA
Liu
Chang-Gong
CG
Sorrentino
Antonio
A
Croce
Carlo M
CM
Peschle
Cesare
C
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*
D018952:Antigens, CD34; D035683:MicroRNAs; D008156:Luciferases; D019009:Proto-Oncogene Proteins c-kit