Differential expression of follistatin and FLRG in human breast proliferative disorders.
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.


CONCLUSIONS
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.
Bloise
Enrrico
E
Departments of Obstetrics & Gynecology and Physiology, Federal University of Minas Gerais, Belo Horizonte, Brazil. bloise2@unisi.i
Couto
Henrique L
HL
Massai
Lauretta
L
Ciarmela
Pasquapina
P
Mencarelli
Marzia
M
Borges
Lavinia E
LE
Muscettola
Michela
M
Grasso
Giovanni
G
Amaral
Vania F
VF
Cassali
Geovanni D
GD
Petraglia
Felice
F
Reis
Fernando M
FM
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D005260:Female; D038681:Follistatin / Q000235:genetics* / Q000378:metabolism; D038702:Follistatin-Related Proteins / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008875:Middle Aged; D021381:Protein Transport
D038681:Follistatin; D038702:Follistatin-Related Proteins