The role of microRNA‐27a/b and microRNA‐494 in estrogen‐mediated downregulation of tissue factor pathway inhibitor α. (6th May 2016)

• Record Type: Journal Article
• Authors: Ali, H. O.; Arroyo, A. B.; González‐Conejero, R.; Stavik, B.; Iversen, N.; Sandset, P. M.; Martínez, C.; Skretting, G.
• Is Part Of: Journal of thrombosis and haemostasis. Volume 14:Number 6(2016:Jun.)
• Page Start: 1226
• Page End: 1237
• Publication Date: 2016-05-06
• Subjects: estrogens -- hsa‐mir‐27a -- microRNA -- microRNA‐27b, human -- hsa‐mir‐494 -- TFPI; Thrombosis -- Periodicals; Hemostasis -- Periodicals; Blood coagulation disorders -- Periodicals; 616.1
• DOI: 10.1111/jth.13321
• Languages: English
• ISSNs: 1538-7933

Abstract

Abstract : Essentials Estrogens are known to influence the expression of microRNAs in breast cancer cells. We looked at microRNAs in estrogenic regulation of tissue factor pathway inhibitor α (TFPIα). Estrogen upregulated microRNA‐27a/b and microRNA‐494 through the estrogen receptor α. MicroRNA‐27a/b and microRNA‐494 are partly involved in estrogenic downregulation of TFPIα. Summary: Background: Tissue factor pathway inhibitor (TFPI) has been linked to breast cancer pathogenesis. We have recently reported TFPI mRNA levels to be downregulated by estrogens in a breast cancer cell line (MCF7) through the estrogen receptor α (ERα). Accumulating evidence also indicates that activation of ERα signaling by estrogens may modulate the expression of target genes indirectly through microRNAs (miRNAs). Objectives: To examine if miRNAs are involved in the estrogenic downregulation of TFPIα. Methods: Computational analysis of the TFPI 3′‐untranslated region (UTR) identified potential binding sites for miR‐19a/b, miR‐27a/b, miR‐494, and miR‐24. Transient overexpression or inhibition of the respective miRNAs was achieved by transfection of miRNA mimics or inhibitors. Direct targeting of TFPI 3′‐UTR by miR‐27a/b and miR‐494 was determined by luciferase reporter assay in HEK293T cells. Effects of 17α‐ethinylestradiol (EE2) and fulvestrant on relative miR‐27a/b, miR‐494, and TFPI mRNA levels in MCF7 cells were determined by qRT‐PCR and secreted TFPIα protein by ELISA. Transient knockdown of ERα was achieved by siRNA transfection. Results: EE2 treatment lead to a significant increase in miR‐19a, miR‐27a/b, miR‐494, and miR‐24 mRNA levels in MCF7 cells through ERα. miR‐27a/b and miR‐494 mimics lead to reduced TFPI mRNA and protein levels. Luciferase assay showed direct targeting of miR‐27a/b and miR‐494 on TFPI mRNA. Impaired estrogen‐mediated downregulation of TFPI mRNA was detected in anti–miR‐27a/b and anti–miR‐494 transfected cells. Conclusions: Our results provide evidence that miR‐27a/b and miR‐494 regulate TFPIα expression and suggest a possible role of these miRNAs in the estrogen‐mediated downregulation of TFPIα.