Association of MiR-1290 and its potential targets with characteristics of estrogen receptor α-positive breast cancer.

Abstract

614 Background: Recent analyses have identified heterogeneity in estrogen receptor (ER) α-positive breast cancer. Subtypes called luminal A and luminal B have been identified, and the tumor characteristics, such as response to endocrine therapy and prognosis are different in these subtypes. However, little is known about how the biological characteristics of ER-positive breast cancer are determined. Methods: In this study, expression profiles of microRNAs (miRNAs) and mRNAs in ER-positive breast cancer tissue were compared between ERhigh Ki67low tumors and ERlow Ki67hightumors by miRNA and mRNA microarrays. Results: Unsupervised hierarchical clustering analyses revealed distinct expression patterns of miRNAs and mRNAs. We identified a down-regulation of miR-1290 and up-regulations of 6 miRNAs in ERhigh Ki67lowtumors. We picked up 11 genes that were potential target genes of the selected miRNAs. Protein expression patterns of the selected target genes were analyzed in ER-positive breast cancer samples by immunohistochemistry: miR-1290 and its 4 putative targets, BCL2, forkhead box A1 (FOXA1), microtubule associated protein tau (MAPT) and N-acetyltransferase-1 (NAT1) were identified. Transfection experiments revealed that introduction of miR-1290 into ER-positive breast cancer cells decreased mRNA and protein expression of NAT1 and FOXA1. Conclusions: Our results suggest that miR-1290 and its potential targets, NAT1 and FOXA1, might be associated with characteristics of ER-positive breast cancer.