Augmented cell survival in eutopic endometrium from women with endometriosis: expression of c-myc, TGF-beta1 and bax genes - PubMed (original) (raw)

Augmented cell survival in eutopic endometrium from women with endometriosis: expression of c-myc, TGF-beta1 and bax genes

M Cecilia Johnson et al. Reprod Biol Endocrinol. 2005.

Abstract

Background: Endometriosis is a common gynaecological disorder characterized by the presence of endometrial tissue outside of the uterus. The fragments in normal menstruation are composed of necrotic and living cells, which do not survive in ectopic locations because of programmed cell death. The aim of this study was to evaluate if the balance between cell proliferation and apoptosis is changed in eutopic endometrium from women with endometriosis throughout the menstrual cycle by studying bax (pro-apoptotic), c-myc (regulator of cell cycle) and TGF-beta1 (involved in cell differentiation) genes.

Methods: Eutopic endometrium was obtained from: 30 women with endometriosis (32.8 +/- 5 years) and 34 fertile eumenorrheic women (36 +/- 5.3 years). We analyzed apoptosis (TUNEL: DNA fragmentation); cell proliferation (immunohistochemistry (IHC) for Ki67); c-myc, bax and TGF-beta1 mRNA abundance (RT-PCR) and TGF-beta1 protein (IHC) in endometrial explants.

Results: Cell proliferation strongly decreased from proliferative to late secretory phases in glands, but not in stroma, in both endometria. Positive staining in glands and stroma from proliferative endometrium with endometriosis was 1.9- and 2.2-fold higher than control endometrium, respectively (p < 0.05). Abundance of c-myc mRNA was 65% higher in proliferative endometrium from endometriosis than normal tissue (p < 0.05). TGF-beta1 (mRNA and protein) augmented during mid secretory phase in normal endometrium, effect not observed in endometrium with endometriosis. In normal endometrium, the percentage of apoptotic epithelial and stromal cells increased more than 30-fold during late secretory phase. In contrast, in endometrium from endometriosis, not only this increase was not observed, besides bax mRNA decreased 63% versus normal endometrium (p < 0.05). At once, in early secretory phase, apoptotic stromal cells increased 10-fold with a concomitant augment of bax mRNA abundance (42%) in endometria from endometriosis (p < 0.05).

Conclusion: An altered expression of c-myc, TGF-beta1 and bax was observed in eutopic endometrium from endometriosis, suggesting its participation in the regulation of cell survival in this disease. The augmented cell viability in eutopic endometrium from these patients as a consequence of a reduction in cell death by apoptosis, and also an increase in cell proliferation indicates that this condition may facilitate the invasive feature of the endometrium.

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Figures

Figure 1

Figure 1

Immunohistochemical staining for Ki67, TGF-β1 and apoptosis by TUNEL in explants of human endometrium throughout the menstrual cycle obtained from normal (A, C, E, G, I, J and K) and endometriosis (B, D, F, H and L) women. Representative human endometrium explants from (A, B, E, F and I) proliferative phase and (C, D, G, H, J, K and L) secretory phase of the menstrual cycle with positive immuno-staining for (A-D) Ki67 and (E-H) TGF-β1 or positive DNA fragmentation by TUNEL (K and L). Immunohistochemitry (I) and TUNEL (J) negative controls. Cell nuclei are stained with haematoxylin (immunohistochemitry) or propidium iodine (TUNEL). g: glandular, s: stroma, rc: red blood cell. Magnification, 400×.

Figure 2

Figure 2

PCR amplification from endometrium cDNA of women without (Normal) and with endometriosis using primers for c-myc (330-bp) and 18S rRNA (192-bp). Representative gel is shown. Graph illustrates the corresponding amplification relative to 18S rRNA and the results are given as mean ± SEM from: 6 and 6 proliferative (P); 6 and 5 early secretory (ES); 5 and 4 mid secretory (MS) and 5 and 4 late secretory (LS) eutopic endometria obtained from women without and with endometriosis, respectively. (-) PCR amplification without template. *p < 0.05 vs. normal endometria.

Figure 3

Figure 3

Percentage of apoptotic cells in epithelial (A) and stromal cell (B) compartments in human endometrium explants obtained from normal women and women with endometriosis. Histological sections were evaluated by TUNEL technique (see text). The results are given as mean ± SEM from: 5 and 6 proliferative; 5 and 6 early secretory; 4 and 5 mid secretory; 7 and 6 late secretory eutopic endometria obtained from women without (normal) and with endometriosis, respectively. *p < 0.05 vs. normal endometria. °p < 0.05 vs. early secretory phase. #p < 0.05 vs. late secretory phase.

Figure 4

Figure 4

PCR amplification from endometrium cDNA of women without (Normal) and with endometriosis using primers for bax (334-bp) and 18S rRNA (192-bp). Representative gel is shown. Graph illustrates the corresponding amplification relative to 18S rRNA (192-bp) and the results are given as mean ± SEM from 5 and 5 proliferative (P); 6 and 5 early secretory (ES); 5 and 6 mid secretory (MS) and 4 late secretory (LS) eutopic endometria obtained from women without (normal) and with endometriosis, respectively. (-) PCR amplification without template. *p < 0.05 vs. normal endometria. #p < 0.05 vs. proliferative phase.

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