The role of microRNA-27a/b and microRNA-494 in estrogen-mediated downregulation of tissue factor pathway inhibitor α

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.

[Contribution of closed mitral commissurotomy in the surgery of rheumatic mitral stenosis]

The objective of this work was to study the indications, techniques and results of closed heart mitral commissurotomy in patients with rheumatic mitral stenosis in Morocco.

METHODS

All patients who had undergone closed heart mitral commissurotomy for rheumatic mitral stenosis, operated between 1999 and 2008 were collected in this study. Mitral stenosis was diagnosed and evaluated using Doppler echocardiography. Patients with commissural calcification, severe mitral regurgitation, and surgical tricuspid or aortic valvular disease were excluded from this study.

RESULTS

Six hundred and twenty-five patients have been collected. 62.2% were young with an age between 18 and 35 years and 491 (78.8%) were female. Seventy-nine percent of patients had stage III or IV NYHA and were in sinus regular rhythm. The closed heart mitral commissurotomy was performed for all patients through a left thoracotomy using either digital or dual dilatation. The mitral area was significantly increased postoperatively to 2.11 ± 0.32 with 100% opening of the anterior commissure, while the posterior commissure was opened only for 93.7% of patients. There were nine perioperative deaths (4.9%) and all patients who died had severe mitral stenosis (<0.8 cm(2)) with an elevated systolic pulmonary artery pressure (>60 mmHg).

CONCLUSION

The closed heart mitral commissurotomy provides excellent results in young patients with rheumatic mitral stenosis.