C-fos and c-jun expression in human endometrium and myometrium

Area of Science:

• Reproductive Endocrinology
• Molecular Biology
• Oncogenes

Background:

• Estrogen acts as a mitogen in the human endometrium and myometrium.
• Estrogen signaling pathways in these tissues are not fully understood.
• Estrogen induces c-fos and c-jun mRNA expression in other estrogen-responsive cells.

Purpose of the Study:

• To investigate the expression of c-fos and c-jun mRNA in human endometrium, myometrium, and leiomyoma tissues.
• To determine the role of these proto-oncogenes in estrogen-induced signaling.
• To compare proto-oncogene expression in nonpregnant, pregnant, and leiomyomatous tissues.

Main Methods:

• Northern blotting was used to analyze c-fos and c-jun mRNA expression.
• Tissues were obtained from women in various hormonal states, including different menstrual cycle phases and term pregnancy.
• Paired samples of endometrium, myometrium, and leiomyoma were analyzed.

Main Results:

• Strong c-fos and c-jun mRNA expression was detected in nonpregnant endometria during both follicular and luteal phases.
• c-fos expression was significantly higher in proliferative endometrium compared to adjacent myometrium.
• Weak expression of both proto-oncogenes was observed in most myometrial and leiomyoma samples, with no significant differences between normal myometrium and leiomyoma.
• c-fos and c-jun mRNA expression was nearly undetectable in pregnant endometrium and myometrium, with significantly lower levels compared to nonpregnant tissues.

Conclusions:

• c-fos and c-jun activation may be part of estrogen-induced signal transduction in the endometrium.
• This signaling pathway appears to be inhibited during term pregnancy.
• The distinct expression patterns suggest different steroid hormone signaling mechanisms in endometrium versus myometrium.
• The strong expression in proliferative and secretory endometrium suggests roles beyond epithelial cell proliferation.