Abstract
Select changes in microRNA (miRNA) expression correlate with estrogen receptor alpha (ER alpha) expression in breast tumors. miR-21 is higher in ER alpha positive than negative tumors, but no one has examined how estradiol (E(2)) regulates miR-21 in breast cancer cells. Here we report that E(2) inhibits miR-21 expression in MCF-7 human breast cancer cells. The E(2)-induced reduction in miR-21 was inhibited by 4-hydroxytamoxifen (4-OHT), ICI 182 780 (Faslodex), and siRNA ER alpha indicating that the suppression is ER alpha-mediated. ER alpha and ER beta agonists PPT and DPN inhibited and 4-OHT increased miR-21 expression. E(2) increased luciferase activity from reporters containing the miR-21 recognition elements from the 3'-UTRs of miR-21 target genes, corroborating that E(2) represses miR-21 expression resulting in a loss of target gene suppression. The E(2)-mediated decrease in miR-21 correlated with increased protein expression of endogenous miR-21-targets Pdcd4, PTEN and Bcl-2. siRNA knockdown of ER alpha blocked the E(2)-induced increase in Pdcd4, PTEN and Bcl-2. Transfection of MCF-7 cells with antisense (AS) to miR-21 mimicked the E(2)-induced increase in Pdcd4, PTEN and Bcl-2. These results are the first to demonstrate that E(2) represses the expression of an oncogenic miRNA, miR-21, by activating estrogen receptor in MCF-7 cells.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, N.I.H., Intramural
MeSH terms
-
3' Untranslated Regions / chemistry
-
Apoptosis Regulatory Proteins / genetics
-
Breast Neoplasms / genetics*
-
Breast Neoplasms / metabolism
-
Cell Line, Tumor
-
Cycloheximide / pharmacology
-
Dactinomycin / pharmacology
-
Down-Regulation
-
Estradiol / analogs & derivatives
-
Estradiol / pharmacology*
-
Estrogen Antagonists / pharmacology
-
Estrogen Receptor alpha / agonists
-
Estrogen Receptor alpha / antagonists & inhibitors
-
Estrogen Receptor alpha / genetics
-
Estrogen Receptor beta / agonists
-
Estrogen Receptor beta / antagonists & inhibitors
-
Estrogen Receptor beta / genetics
-
Female
-
Fulvestrant
-
Gene Expression Regulation, Neoplastic*
-
Genes, Reporter
-
Humans
-
MicroRNAs / antagonists & inhibitors
-
MicroRNAs / genetics
-
MicroRNAs / metabolism*
-
Nucleic Acid Synthesis Inhibitors / pharmacology
-
Promoter Regions, Genetic
-
Protein Synthesis Inhibitors / pharmacology
-
RNA, Antisense / metabolism
-
RNA-Binding Proteins / genetics
-
Tamoxifen / analogs & derivatives
-
Tamoxifen / pharmacology
-
ras GTPase-Activating Proteins / genetics
Substances
-
3' Untranslated Regions
-
Apoptosis Regulatory Proteins
-
Estrogen Antagonists
-
Estrogen Receptor alpha
-
Estrogen Receptor beta
-
MIRN21 microRNA, human
-
MicroRNAs
-
Nucleic Acid Synthesis Inhibitors
-
PDCD4 protein, human
-
Protein Synthesis Inhibitors
-
RNA, Antisense
-
RNA-Binding Proteins
-
ras GTPase-Activating Proteins
-
Tamoxifen
-
afimoxifene
-
Dactinomycin
-
Fulvestrant
-
Estradiol
-
Cycloheximide