Apoptosis, cellular proliferation and expression of p53 in human uterine leiomyomas and myometrium during the menstrual cycle and after menopause.

ABSTRACT

BACKGROUND: Cell proliferation, apoptosis and expression of p53 proteins were studied in human uterine leiomyomas and myometrium during the menstrual cycle and after menopause. METHODS: Expression of ki-67 and p53 was analyzed by immunohistochemistry and by immunoblotting. Apoptosis was detected by in situ 3' end labelling of cells with DNA fragmentation. RESULTS: In both the proliferative and the secretory phases, ki-67 expression was higher in leiomyomas than in myometrium and both tissues showed higher expression in the secretory than in the proliferative phase. No difference in apoptotic index was observed between leiomyomas and myometrium or between the proliferative and secretory phases. After menopause, the expression of ki-67 as well as the apoptotic index was lower than in the proliferative and secretory phases and no significant difference between tissues was seen. Both leiomyomas and myometrium showed negative staining for p53. Immunohistochemical results regarding p53 were confirmed by Western blot. CONCLUSIONS: Our findings indicate that sex steroids influence the growth of leiomyomas by stimulating cell proliferation rather than by affecting apoptosis. The rate of cell proliferation is higher in fertile age than after menopause and appears to be enhanced under the influence of progesterone.