ERRα is an
orphan nuclear receptor emerging as a novel
biomarker of
breast cancer. Over-expression of ERRα in
breast tumor is considered as a prognostic factor of poor clinical outcome. The mechanisms underlying the dysexpression of this
nuclear receptor, however, are poorly understood.
MicroRNAs (
miRNAs) regulate gene expression at the post-transcriptional level and play important roles in
tumor initiation and progression. In the present study, we have identified that the expression of ERRα is regulated by miR-137, a potential
tumor suppressor
microRNA. The bioinformatics search revealed two putative and highly conserved target-sites for miR-137 located within the ERRα
3'UTR at nt 480-486 and nt 596-602 respectively.
Luciferase-reporter assay demonstrated that the two predicted target sites were authentically functional. They mediated the repression of reporter gene expression induced by miR-137 in an additive manner. Moreover, ectopic expression of miR-137 down-regulated ERRα expression at both
protein level and
mRNA level, and the miR-137 induced ERRα-knockdown contributed to the impaired proliferative and migratory capacity of
breast cancer cells. Furthermore, transfection with miR-137 mimics suppressed at least two downstream target genes of ERRα-CCNE1 and WNT11, which are important effectors of ERRα implicated in
tumor proliferation and migration. Taken together, our results establish a role of miR-137 in negatively regulating ERRα expression and
breast cancer cell proliferation and migration. They suggest that manipulating the expression level of ERRα by
microRNAs has the potential to influence
breast cancer progression.