Tissue differences but limited sex steroid responsiveness of c-fos and c-jun in human fibroids and myometrium

Sex steroids influence the growth of mammalian uterine tissues and the prot o-oncogenes c-fos and c-jun have been implicated in the cascade of cellular events induced by the cyclic influence of oestrogen and progesterone. To i nvestigate the role of these proto-oncogenes for fibroid growth their mRNA expression was measured in myometrium and fibroids under different hormonal conditions, using a solution hybridization method. Fibroids and myometrium were collected at surgery from premenopausal, postmenopausal and pregnant women as well as women treated with a gonadotrophin releasing hormone agoni st (GnRHa; Goserelin). The phase of the menstrual cycle was determined in a ll the untreated, premenopausal, nonpregnant women. The mRNA expression df c-fos and c-jun in fibroids was significantly lower than in homologous myom etrium. No significant differences in c-fos expression were observed In myo metrium, or fibroids, due to menstrual cycle phase, GnRHa treatment, pregna ncy or the menopause. The c-jun expression in myometrium from pregnant wome n without fibroid disease was significantly higher than the corresponding c ontrol myometrium from premenopausal, non-pregnant women. These results dem onstrate a tissue difference in the expression of c-fos and c-jun between m yometrium and fibroids.