Induction of miR-21 by retinoic acid in estrogen receptor-positive breast carcinoma cells: biological correlates and molecular targets.
Retinoids are promising agents for the treatment/prevention of breast carcinoma. We examined the role of microRNAs in mediating the effects of all-trans-retinoic acid (ATRA), which suppresses the proliferation of estrogen receptor-positive (ERα(+)) breast carcinoma cells, such as MCF-7, but not estrogen receptor-negative cells, such as MDA-MB-231. We found that pro-oncogenic miR-21 is selectively induced by ATRA in ERα(+) cells. Induction of miR-21 counteracts the anti-proliferative action of ATRA but has the potentially beneficial effect of reducing cell motility. In ERα(+) cells, retinoid-dependent induction of miR-21 is due to increased transcription of the MIR21 gene via ligand-dependent activation of the nuclear retinoid receptor, RARα. RARα is part of the transcription complex present in the 5'-flanking region of the MIR21 gene. The receptor binds to two functional retinoic acid-responsive elements mapping upstream of the transcription initiation site. Silencing of miR-21 enhances ATRA-dependent growth inhibition and senescence while reverting suppression of cell motility afforded by the retinoid. Up-regulation of miR-21 results in retinoid-dependent inhibition of the established target, maspin. Knockdown and overexpression of maspin in MCF-7 cells indicates that the protein is involved in ATRA-induced growth inhibition and contributes to the ATRA-dependent anti-motility responses. Integration between whole genome analysis of genes differentially regulated by ATRA in MCF-7 and MDA-MB-231 cells, prediction of miR-21 regulated genes, and functional studies led to the identification of three novel direct miR-21 targets: the pro-inflammatory cytokine IL1B, the adhesion molecule ICAM-1 and PLAT, the tissue-type plasminogen activator. Evidence for ICAM-1 involvement in retinoid-dependent inhibition of MCF-7 cell motility is provided.
Laboratory of Molecular Biology, Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, Italy.
Mineko
M
Terao
Maddalena
M
Fratelli
Mami
M
Kurosaki
Adriana
A
Zanetti
Valeria
V
Guarnaccia
Gabriela
G
Paroni
Anna
A
Tsykin
Monica
M
Lupi
Maurizio
M
Gianni
Gregory J
GJ
Goodall
Enrico
E
Garattini
D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D055106:Genome-Wide Association Study; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics; D007375:Interleukin-1 / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics*; D011960:Receptors, Estrogen; D010959:Tissue Plasminogen Activator / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*
D007375:Interleukin-1; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D011960:Receptors, Estrogen; D018799:Intercellular Adhesion Molecule-1; D014212:Tretinoin; C067262:PLAT protein, human; D010959:Tissue Plasminogen Activator