Expression of acidic fibroblast growth factor (aFGF) and fibroblast growthfactor receptor 4 (FGFR4) in breast fibroadenomas

Background/Aim-Fibroadenomas are benign tumours composed of both glandular and fibrous tissue. The mechanisms regulating the growth of these tumours a nd the relation between the stromal and epithelial cells are poorly underst ood. Acidic fibroblast growth factor (aFGF) is a well known fibroblast acti vator, which acts through four specific cell surface receptors, among which , fibroblast growth factor receptor 4 (FGFR4) is highly specific. The aim o f this study was to evaluate the distribution of aFGF and FGFR4 in specific cell types of fibroadenomas to understand their possible role in the growt h of these breast lesions. Methods-Formalin fixed and paraffin wax embedded tissues from 15 fibroadeno mas and peritumoral normal breasts were investigated for the expression of aFGF and FGFR4 using immunohistochemistry. The presence of aFGF mRNA was al so investigated using in situ hybridisation. Results- Immunoreactivity for aFGF and FGFR4 was seen in epithelial cells, but it was lacking in myoepithelial cells of both normal tissues and fibroa denomas. Strong FGFR4 immunoreactivity was found in stromal fibroblasts, wh ich were also weakly positive for aFGF. aFGF mRNA was detected in epithelia l cells and in some stromal fibroblasts. Conclusions-These results suggest a paracrine/autocrine modulation of epith elial and stromal cells of fibroadenomas through an aFGF-FGFR4 interaction. This interaction might regulate various cell functions and the growth of f ibroadenomas.