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Open Access Highly Accessed Research article

Differential expression of follistatin and FLRG in human breast proliferative disorders

Enrrico Bloise12, Henrique L Couto1, Lauretta Massai3, Pasquapina Ciarmela4, Marzia Mencarelli5, Lavinia E Borges2, Michela Muscettola5, Giovanni Grasso3, Vania F Amaral6, Geovanni D Cassali6, Felice Petraglia2 and Fernando M Reis1*

Author Affiliations

1 Departments of Obstetrics & Gynecology and Physiology, Federal University of Minas Gerais, Belo Horizonte, Brazil

2 Department of Obstetrics and Gynecology, University of Siena, Siena, Italy

3 Department of Biomedical Sciences, University of Siena, Siena, Italy

4 Department of Molecular Pathology and Innovative Therapies, Polytechnic University of Marche, Ancona, Italy

5 Department of Physiology, University of Siena, Siena, Italy

6 Department of Pathology, Federal University of Minas Gerais, Belo Horizonte, Brazil

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BMC Cancer 2009, 9:320  doi:10.1186/1471-2407-9-320

Published: 9 September 2009

Abstract

Background

Activins are growth factors acting on cell growth and differentiation. Activins are expressed in high grade breast tumors and they display an antiproliferative effect inducing G0/G1 cell cycle arrest in breast cancer cell lines. Follistatin and follistatin- related gene (FLRG) bind and neutralize activins. In order to establish if these activin binding proteins are involved in breast tumor progression, the present study evaluated follistatin and FLRG pattern of mRNA and protein expression in normal human breast tissue and in different breast proliferative diseases.

Methods

Paraffin embedded specimens of normal breast (NB - n = 8); florid hyperplasia without atypia (FH - n = 17); fibroadenoma (FIB - n = 17); ductal carcinoma in situ (DCIS - n = 10) and infiltrating ductal carcinoma (IDC - n = 15) were processed for follistatin and FLRG immunohistochemistry and in situ hybridization. The area and intensity of chromogen epithelial and stromal staining were analyzed semi-quantitatively.

Results

Follistatin and FLRG were expressed both in normal tissue and in all the breast diseases investigated. Follistatin staining was detected in the epithelial cytoplasm and nucleus in normal, benign and malignant breast tissue, with a stronger staining intensity in the peri-alveolar stromal cells of FIB at both mRNA and protein levels. Conversely, FLRG area and intensity of mRNA and protein staining were higher both in the cytoplasm and in the nucleus of IDC epithelial cells when compared to NB, while no significant changes in the stromal intensity were observed in all the proliferative diseases analyzed.

Conclusion

The present findings suggest a role for follistatin in breast benign disease, particularly in FIB, where its expression was increased in stromal cells. The up regulation of FLRG in IDC suggests a role for this protein in the progression of breast malignancy. As activin displays an anti-proliferative effect in human mammary cells, the present findings indicate that an increased FST and FLRG expression in breast proliferative diseases might counteract the anti-proliferative effects of activin in human breast cancer.