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

Background Cell proliferation, apoptosis and expression of p53 proteins wer e studied in human uterine leiomyomas and myometrium during the menstrual c ycle and after menopause. Methods. Expression of ki-67 and p53 was analyzed by immunohistochemistry a nd 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 expressio n was higher in leiomyomas than in myometrium and both tissues showed highe r expression in the secretory than in the proliferative phase. No differenc e in apoptotic index was observed between leiomyomas and myometrium or betw een the proliferative and secretory phases. After menopause, the expression of ki-67 as well as the apoptotic index was lower than in the proliferativ e and secretory phases and no significant difference between tissues was se en. Both leiomyomas and myometrium showed negative staining for p53, Immuno histochemical results regarding p53 were confirmed by Western blot. Conclusions. Our findings indicate that sex steroids influence the growth o f leiomyomas by stimulating cell proliferation rather than by affecting apo ptosis. The rate of cell proliferation is higher in fertile age than after menopause and appears to be enhanced under the influence of progesterone.