PROBLEM: To investigate the quantitative changes in expression of EGFR mRNA in the myometrium throughout the menstrual cycle.
METHOD: Myometrium was collected at hysterectomy from 27 women with a history of regular cycles. Total RNA (20 μg) was isolated and analyzed by Northern blot using a human EGF-R specific 32P-labeled cDNA probe. The hybridization signals were quantified by densitometry, standardized, and reported in densitometry signal units (DSU). Endometrial specimens from the same uteri were simultaneously evaluated for histologic dating of menstrual cycle day. EGFR gene expression in endometrium was previously reported. Statistical significance of the differences in myometrial gene expression between menstrual phases was evaluated by student's t test.
RESULTS: EGFR mRNA was expressed in all myometrial tissues tested. Levels were higher in the late proliferative phase than in all other phases (P < .05). Women over 40 years old had lower proliferative phase expression than younger women.
CONCLUSION: This data suggests that myometrial EGFR mRNA expression varies in association with the histologic phases of the normal menstrual cycle, and may be affected by aging, even when cycles occur at regular intervals.