IN-VIVO ESTROGEN REGULATION OF EPIDERMAL GROWTH-FACTOR RECEPTOR IN HUMAN ENDOMETRIUM

The effects of estrogen and progesterone on the expression of epiderma l growth factor receptor (EGFR) in human endometrium were studied in h ypogonadal women under conditions that simulated a normal menstrual cy cle. All women received the same regimen of estrogen and progesterone and underwent serial biopsies. In one group of women (group I), a biop sy was obtained before receiving estrogen (CD0) and after 11 days (CD1 1) of estrogen replacement. A second group of women was biopsied on CD 11 and CD21 to assess the combined effects of progesterone and estroge n (group II). Immunohistochemistry was used to test for the presence o f EGFR, and a ribonuclease protection assay was used to assess the amo unts of EGFR messenger ribonucleic acid (RNA) relative to ribosomal RN A in the tissue. In group I, a significant increase in EGFR messenger RNA from CD0 to CD11 was observed. A similar increase was observed to occur between CD11 and CD21 in group II. Immunostaining for EGFR was a bsent in all CD0 biopsies, but was present in all estrogen-exposed end ometrium. No difference in immunostaining was noted between CD11 and C D21. We conclude that estrogen stimulates the synthesis of EGFR in hum an endometrium and that progesterone does not appear to modulate this effect. The examination of other parameters in hormone-replaced hypogo nadal subjects will be valuable in understanding the complex physiolog ical regulation of the human endometrium.