ABSTRACT: Title: Transcriptome analysis of human endometrial tissues from healthy post-menoupausal women reflecting the endometrial response to 3-weeks treatment with tibolone, E2 and E2+MPA. In an observational, open, non-randomized, controlled study uterine tissues were collected in order to generate endometrial gene expression profiles. healthy postmenopausal women were enrolled into the following treatment groups: Control-group; Tibolone-group, 2,5 mg of tibolone (administered orally) every day, starting 21 days prior to surgery; Estradiol-group, 2 mg of estradiol (administered orally) every day, starting 21 days prior to surgery; Estradiol+progestagen-group, 2 mg of estradiol (administered orally) and 5 mg of MPA (Medroxy Progesteroneacetate, administered orally) every day, starting 21 days prior to surgery. Pure (100%) endometrium was isolated from the snap-frozen uterine tissues and used for RNA isolation. RNA was labbeled and hybridized to whole genome Affymetrix U133plus2 GeneChips containing 54,614 probe sets, representing approximately 47,000 transcripts. Relative to the control group, 940 genes are regulated in the endometrium of E2 treated patients, whereas only 198 genes are significantly regulated in endometria from tibolone or E2+MPA treated patients. Furthermore, only 9% of E2 regulated genes are also regulated by tibolone (85 out of 940), only 5% are also regulated by E2+MPA treatment and the overlap between tibolone and E2+MPA treatment is about 10%. This indicated that tibolone-treatment results in a weak endometrial profile similarity to E2 treatment and no profile similarity to E2+MPA treatment. A more detailed analysis showed that down stream processes, such as regulation of the cell cycle, angiogenesis and cell proliferation are almost not affected by tibolone treatment but, in contrast, are significantly affected by E2. For example, upon staining with Ki67, a marker for mitotic activity, significantly increased stromal as well as glandular cell proliferation was observed in the endometria from the E2-only treated group, while tibolone treatment resulted only in a slight increase in stromal cell proliferation (and no increase in glandular cell proliferation). These results indicate that in contrast to long-term tibolone use, short-term (21-days) use results in some estrogenic stimulation of the endometrium, which is clearly far less and rather different from what is observed during E2 treatment. References:; Klaassens et al., 2006; Hanifi-Moghaddam et al., 2007; Verheul et al., 2007 Experiment Overall Design: This study was designed as a controlled clinical trial. Patients who visited our clinics to undergo vaginal hysterectomy for treatment of prolapse, were eligible to participate in this study. The trial was performed in the period before the scheduled surgery. After informed consent, the patients were sequentially assigned to one of the following treatment groups: Experiment Overall Design: - Control-group (no hormonal treatment); Experiment Overall Design: - Tibolone-group (2.5 mg tibolone (Livial, N.V. Organon, Oss, The Netherlands) administered orally every day, starting 21 days prior to surgery); Experiment Overall Design: - E2 group (2 mg of estradiol administered orally every day, starting 21 days prior to surgery); Experiment Overall Design: - E2+MPA-group (2 mg estradiol + 5 mg MPA administered orally every day, starting 21 days prior to surgery). Experiment Overall Design: Pure endometrium was isolated and used for profiling. 31 samples, 3 of which were duplicates, were analyzed.
