ESTROGEN REGULATION OF LACTOFERRIN EXPRESSION IN HUMAN ENDOMETRIUM

PROBLEM: Lactoferrin is an iron-binding glycoprotein that has been sho wn to be overexpressed in human endometrial carcinomas. The purpose of our present study is to investigate the possible role of estradiol in the expression of lactoferrin. METHOD OF STUDY: We investigated 1) se rum levels of lactoferrin in five women during normal ovulatory cycles , 2) serum levels of lactoferrin during ten human menopausal gonadotro pin induced cycles when estradiol levels are high, and 3) lactoferrin expression in five proliferative and five secretory phase endometrium by immunohistochemical studies. The serum concentrations of lactoferri n were measured by a peroxidase-based enzyme-linked immunosorbent assa y. RESULTS: In normal ovulatory cycles, the mean serum lactoferrin con centration during the proliferative phase (0.4013 +/- 0.0242 mu g/mL) was significantly higher (P<0.02) than in the secretory phase (0.3468 +/- 0.0209 mu g/mL). Ln induced cycles, there was gradual increase in lactoferrin levels with increasing estradiol concentrations. Peak lact oferrin levels in induced cycles (0.7495 +/- 0.1148 mu g/mL) were sign ificantly higher (P<0.003) than the midcycle levels (0.423 +/- 0.0424 mu g/mL) in normal cycles. Immunohistochemical analysis of the endomet rium revealed greater expression of lactoferrin in proliferative endom etrium (50.7 +/- 13%, range 28-72%) than in secretory endometrium (19. 2 +/- 4%, range 7-31%). CONCLUSION: These results indicate that estrad iol may play a role in the regulation of lactoferrin expression in hum an endometrium.