Expression of basic fibroblast growth factor (bFGF), FGF receptor 1 and FGF receptor 2 in uterine leiomyomas and myometrium during the menstrual cycle, after menopause and GnRHa treatment.

ABSTRACT

BACKGROUND: To investigate whether basic fibroblast growth factor (bFGF) is involved in the growth regulation of human uterine leiomyomas the expression of bFGF and its receptors was measured in leiomyomas and myometrium obtained under different endocrine conditions. METHODS: The expression of bFGF, fibroblast growth factor receptor 1 (FGFR1) and fibroblast growth factor receptor 2 (FGFR2) was analyzed by immunohistochemistry and Western blot. RESULTS: Twenty-seven women with leiomyomas included eight in the proliferative phase, seven in the secretory phase, six after menopause and six after GnRHa treatment. In the proliferative phase, bFGF staining in leiomyomas was significantly stronger than in any other leiomyoma group. After GnRHa treatment, the expression of bFGF in both leiomyomas and myometrium was weaker than in the proliferative phase. The staining of FGFR1 was less intense in proliferative phase myometrium than in myometrium from any other group, significantly weaker than in the secretory phase. The leiomyomas demonstrated homogeneous cytoplasmic FGFR1 staining that was similar in all groups, except in the GnRHa treated patients where a more intense staining was observed, significantly stronger than in proliferative phase leiomyomas. No tissue differences were observed for staining of FGFR2 and no significant differences were observed between the different groups. Slightly less staining of FGFR2 was found in leiomyomas in the secretory phase but it did not reach statistical significance. The specificity of immunostaining was confirmed by Western blot. CONCLUSIONS: We suggest that the regulation of bFGF, and to some extent also its receptors in leiomyomas and in myometrium, is influenced by sex steroid hormones. However, the lack of differences in expression between leiomyomas and myometrium favors the view that bFGF does not necessarily contribute to the differences in growth regulation in these tissues.