RESUMO
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.
Assuntos
Leiomioma/patologia , Menopausa/fisiologia , Ciclo Menstrual/fisiologia , Miométrio/patologia , Proteína Supressora de Tumor p53/genética , Neoplasias Uterinas/patologia , Adulto , Apoptose/genética , Apoptose/fisiologia , Western Blotting , Divisão Celular/genética , Divisão Celular/fisiologia , Feminino , Regulação Neoplásica da Expressão Gênica , Genes p53/genética , Genes p53/fisiologia , Humanos , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Antígeno Ki-67/biossíntese , Antígeno Ki-67/química , Antígeno Ki-67/genética , Leiomioma/genética , Pessoa de Meia-Idade , Proteína Supressora de Tumor p53/biossíntese , Neoplasias Uterinas/genéticaRESUMO
OBJECTIVE: We sought to examine the change of cytosolic calcium concentration caused by prostaglandin F(2)(alpha) and RU 486 in cultured human myometrial cells. STUDY DESIGN: Human myometrial cells obtained from 16 nonpregnant women were loaded with fura 2, and the intracellular cytosolic calcium concentrations were measured by the use of wavelength spectrophotofluorometry. RESULTS: Application of prostaglandin F(2)(alpha) (2.8 micromol/L) caused an initial rapid rise in cytosolic calcium concentration followed by sustained cytosolic calcium oscillations at an average frequency of 0.43 +/- 0.04 min(-1) and an amplitude in the range of 296.82 +/- 27. 16 nmol/L. The oscillatory activity was not affected by increasing the concentration of prostaglandin F(2)(alpha) but varied by changing the concentration of extracellular cytosolic calcium concentration. The cytosolic calcium oscillations were suppressed by caffeine, 2,5-di-tert-butylhydroquinone, and lanthanum but not affected by ryanodine. Verapamil decreased the amplitude but not the frequency of oscillations. The progesterone antagonist RU 486 at a concentration of 10(-8) to 10(-5) mol/L had no significant effect on the basal intracellular cytosolic calcium. However, RU 486 (10(-5) mol/L) significantly increased the frequency but not the amplitude of intracellular cytosolic calcium oscillations induced by prostaglandin F(2)(alpha). CONCLUSION: The results indicate that prostaglandin F(2)(alpha)-stimulated cytosolic calcium oscillations are mediated by an increase in both cytosolic calcium release from inositol 1,4,5-trisphosphate-sensitive cytosolic calcium stores and a cytosolic calcium influx from the extracellular space. Moreover, RU 486 seems to directly regulate prostaglandin F(2)(alpha)-induced intracellular cytosolic calcium in human myometrial cells.
