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Effect of raloxifene treatment on osteocyte apoptosis in postmenopausal women.

ABSTRACT: Increased osteocyte apoptosis, as the result of estrogen deficiency, could play a role in the decrease of bone mass and bone strength seen in postmenopausal osteoporosis. We investigated whether treatment with raloxifene of postmenopausal women with osteoporosis affects osteocyte apoptosis. Transiliac bone biopsies were obtained from 26 osteoporotic women at baseline and after 2 years of treatment with placebo or raloxifene. Immunohistochemical detection of cleaved caspase-3 was performed on sections from nondecalcified bone biopsies to visualize apoptosis. In the trabecular bone total osteocytes, positively stained osteocytes and empty lacunae were counted and percent positive cells and percent empty lacunae determined. Statistical evaluation was performed by Wilcoxon's paired t-test and Spearman's rank correlations. There was no significant difference in percentage positive osteocytes between baseline and follow-up biopsies in both the placebo and the raloxifene groups. The percentage empty lacunae increased significantly in the placebo group (11.20 +/- 1.43 vs. 9.00 +/- 2.25, P = 0.014) but not in the raloxifene group. At baseline in both groups combined, there was a negative correlation between indices of bone remodeling and the percentage positive osteocytes (bone formation rate/bone volume r = -0.67, P = 0.001). We found no direct evidence for an effect of raloxifene treatment on osteocyte apoptosis, but small effects of raloxifene treatment cannot be excluded. The percent of apoptotic osteocytes was dependent on the level of bone remodeling in an individual.

SUBMITTER: van Essen HW

PROVIDER: S-EPMC2039811 | biostudies-other | 2007 Sep

REPOSITORIES: biostudies-other

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Project description: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 labeled 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

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Effect of raloxifene treatment on osteocyte apoptosis in postmenopausal women.

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