Cyclic bcl-2 gene expression in human uterine endometrium during menstrual cycle

Effect of mifepristone on proliferation and apoptosis of Ishikawa endometrial adenocarcinoma cells

OBJECTIVE

To determine the mechanism by which mifepristone improves breakthrough bleeding, the effects of mifepristone on proliferation and apoptosis of Ishikawa endometrial carcinoma cells were evaluated in the presence and absence of progestin.

DESIGN

Prospective basic research study.

SETTING

Research laboratories for reproductive health at a university medical school.

PATIENT(S)

None.

INTERVENTION(S)

Ishikawa cells were cultured in vitro. Mifepristone and/or medroxyprogesterone acetate at various concentrations were added to the cells.

MAIN OUTCOME MEASURE(S)

Determination of cell proliferation and apoptosis.

RESULT(S)

Colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and bromodeoxyuridine (BrdU) labeling analysis demonstrated that mifepristone inhibited the growth of Ishikawa cells and percentage of BrdU-labeled cells in a time- and dose-dependent manner. Flow cytometry analysis demonstrated that mifepristone at 100 micromol/L, which completely inhibited cell proliferation, increased the proportion of cells in the S phase and diminished the cells in the G2/M phase. Apoptosis was identified by annexin-V-fluorescein isothiocyanate binding and caspase-3 activation. Immunofluorescent double labeling of Ishikawa cells in the absence or presence of mifepristone revealed that BAX protein expression increased and translocated from cytosol to mitochondria.

CONCLUSION(S)

Mifepristone inhibited cell growth by arresting cell cycle progression at S phase, induced apoptosis through caspase-3 activation, and modulated apoptosis regulatory genes BCL2/BAX and FAS/FASLG in Ishikawa cells. Together, these data imply that the improvement in breakthrough bleeding observed with mifepristone might be due to diminished volume of endometrial tissue similar to that seen with endometrial atrophy.

Bcl-2, BAX, and apoptosis in endometrial hyperplasia after high dose gestagen therapy

OBJECTIVES

The aim of the study was to investigate apoptosis as a growth regulatory mechanism of gestagen in endometrial precancers and to compare differences in the apoptotic cascade after high and low dose gestagen regimens.

METHOD

Pre- and post-treatment paraffin-embedded endometrial hyperplasia specimens from women treated with levonorgestrel intrauterine device (n = 26) and women treated with 10 mg medroxyprogesterone for 10 days per cycle (n = 31) were examined for changes in the expression of Bcl-2 and BAX and the extent of apoptosis after 3 months of treatment. Immunohistochemical expression in tissue specimens for Bcl-2 and BAX was evaluated by H-score. Average number of apoptotic cells per hundred cells within ten different high power field (40 x) was evaluated for each section after in situ apoptosis detection (TUNEL method). A second group of patients with endometrial hyperplasia was examined after 1 week treatment with levonorgestrel IUD (n = 6) or medroxyprogesterone (n = 5) to determine early effects on expression of Bcl-2 and BAX and the extent of apoptosis.

RESULTS

All the patients in the IUD group (n = 31) but only about half of the patients in per oral group (16 of 26) responded to treatment. The glandular reduction in Bcl-2 expression was markedly greater for the IUD patients than for the patients who received oral gestagen. The decrease in BAX expression after IUD treatment was less than the reduction of Bcl-2. Decrease in glandular Bcl-2 after 3 months of treatment was coincident with a significant increase in the measurable amount of apoptosis. In stromal cells, the increase in expression of Bcl-2 and BAX was found after gestagen treatment, the response being much more marked for the IUD group. The non- responders to per oral gestagen had no Bcl-2 expression in stroma after 3 months of therapy whereas an increase was observed for the responders. After 1 week, glandular Bcl-2 expression was significantly reduced after treatment in the IUD group. As for the rest, no changes were detected in either of the groups.

CONCLUSION

Our results indicate that proteins in the apoptotic cascade are regulated by gestagen therapy in human endometrial precancers. Expression of these proteins is shown to be dependent on administration form and/or type of gestagen. Stromal Bcl-2 expression appears to be a potential biomarker which can separate responders of gestagen treatment from non-responders after oral administration.

Receptorial and mitochondrial apoptotic pathways in normal and neoplastic human endometrium

Under normal conditions, in human endometrium, apoptotic and antiapoptotic factors play an important role in tissue homeostasis. Abnormalities of apoptosis, a process implicated in several events in the reproductive organs, may contribute to neoplastic transformation. The present study aimed to investigate the involvement of both the receptorial and the mitochondrial pathways of apoptosis in normal endometrium and in endometrial carcinoma, by measuring caspase-3 and caspase-8 activities and cytosolic cytochrome c levels. Twelve endometrial carcinomas and nine normal endometrial specimens (four in mild proliferative phase, five in late secretory phase) were included in this study. Cytosolic fractions, obtained by differential centrifugation of tissue homogenates, were analyzed for caspase-3 and caspase-8 activities, as well as for cytochrome c content. Caspase-8 activity in normal secretory phase endometrium was higher than that in the proliferative phase and in the endometrial carcinoma. Moreover, higher cytochrome c levels were detected in endometrial carcinoma with respect to normal secretive endometrium. No significant differences were found in caspase-3 activity between normal and pathologic endometrium. The results obtained suggest that in normal endometrium, apoptosis takes place through the activation of both receptorial and mitochondrial pathways. Defects in both these pathways may contribute to the development of endometrial carcinoma.

Menstrual-like breakdown and apoptosis in human endometrial explants

BACKGROUND

Apoptosis occurs in late secretory and menstrual human endometrium and is thought to play an important role in endometrial physiology. Menstrual-like breakdown has been observed in vitro in endometrial explants. The purpose of this study was to assess the role of apoptosis in menstrual-like breakdown in human endometrial explants.

METHODS

Human endometrial tissue was obtained during the mid-secretory phase and cultured with or without estrogen and progesterone. The occurrence of breakdown was assessed by histology. Apoptosis was determined by gel electrophoresis for the detection of DNA fragmentation and by immunohistochemistry using the M30 CytoDEATH and anti-cleaved caspase-3 (CASP3) antibodies for the detection of caspase activity. Expression of BCL2 and BAX was quantified using real-time PCR analysis.

RESULTS

Apoptosis occurred in human endometrial explants at all time-points studied. Cleaved CASP3 and M30 antigen expression increased in all explants, suggesting the involvement of CASP3 in the apoptosis. Low BCL2:BAX ratios were observed in all samples when compared with pre-culture controls. Estradiol and progesterone supplementation of the culture media reduced or eliminated menstrual-like breakdown but did not affect the degree of apoptosis observed.

CONCLUSIONS

The apoptosis observed in endometrium during the late secretory phase and menstrual phase does not appear to be mechanistically related to the tissue breakdown but rather may be involved in the impending remodelling that occurs in the endometrium in the transition from secretory to proliferative phase following the menses.

Endometriotic cells are resistant to interferon-gamma-induced cell growth inhibition and apoptosis: a possible mechanism involved in the pathogenesis of endometriosis

In order to evaluate the involvement of cell proliferation and apoptosis in the pathogenesis of endometriosis, we investigated the effects of interferon-gamma (IFN-gamma) on cell growth inhibition and apoptosis of cultured ovarian endometriotic cyst stromal cells (ECSC), eutopic endometrial stromal cells with endometriosis (ESCwE) and normal endometrial stromal cells (NESC) by modified methylthiazoletetrazolium assay, 5-bromo-2'-deoxyuridine incorporation assay and internucleosomal DNA fragmentation assay. The expression of apoptosis-related molecules and IFN-gamma receptor 1 was also examined in ECSC, ESCwE and NESC using western blot analysis. IFN-gamma significantly inhibited cell proliferation and DNA synthesis of ESCwE and NESC, and induced apoptosis of these cells. In contrast, IFN-gamma did not show apparent effects on the viable cell number, DNA synthesis, or apoptosis of ECSC. An up-regulated expression of Bcl-2 and Bcl-X(L) proteins was observed in ECSC in comparison with ESCwE and NESC, whereas the levels of Bax, Bad, Fas and Fas ligand proteins in ECSC were similar to those in ESCwE and NESC. IFN-gamma receptor 1 expression was detected in ECSC, ESCwE and NESC. Enhanced expression of anti-apoptotic molecules in the ectopic endometrial cells may contribute to the development of endometriosis by conferring resistance to cytokine-induced apoptosis and increasing the chance that these cells will survive and implant outside the uterus. Further investigations on the regulation of cell proliferation in both the endometriotic and the normal endometrium may be important for the elucidation of the pathogenesis of endometriosis.

Fas, FasL, Bcl-2, and Bax in the endometrium of rhesus monkey during the menstrual cycle

To study possible role and regulation of apoptosis occurred in primate endometrium, the expression of apoptosis-related molecules, Fas, FasL, B cell lymphoma/leukaemia-2 (Bcl-2), and Bax were analyzed in relation to occurrence of apoptosis and proliferation in the cycling endometrium of the rhesus monkey using immunohistochemistry and Western blot. The cell apoptosis and proliferation were evaluated by means of in situ 3'-end labeling and Ki67 immunostaining, respectively. The results showed that the expressions of Fas, Fas ligand (FasL), Bcl-2, and Bax were co-localized predominantly in the epithelial cells of the endometrium. Modest Fas staining with no obvious change was detected throughout the menstrual cycle, while the levels of FasL and Bax protein in the epithelial cells increased in the secretory phase when apoptosis was most prevalent. In contrast, epithelial immunostaining for Bcl-2 was maximal during the proliferative phase and decreased in the secretory phase. Bcl-2 immunoreactivity was also detected in some immunocytes. The coordinated expression of Fas, FasL, Bcl-2, and Bax in the cycling endometrium of the rhesus monkey suggests that the cyclic changes in endometrial growth and regression may be regulated by the balance of these factors under the action of ovary steroids.

BAG-1 expression in normal and neoplastic endometrium

OBJECTIVE

BAG-1 has anti-apoptotic actions and is known to bind BCL-2 and steroid receptors. High levels of BAG-1 have been implicated as a prognostic indicator in breast cancer. Whether this observation can be generalized to endometrial cancer remains unknown.

METHODS

IRB permission was obtained for use of human discarded tissue. Immunohistochemical analyses were performed on: proliferative endometrium (PEM, 6), secretory endometrium (SEM, 28), "low-grade" neoplastic lesions (complex atypical hyperplasia and grade 1 endometrial adenocarcinomas) (19), and "high-grade" cancers (grade 2 and 3 endometrial adenocarcinomas) (13). The level of total BAG-1 and its isoforms was evaluated by Western blot in lysates from Ishikawa cells (grade 1), MFE 296 cells (grade 2), and SK-UT(2) cells (grade 3).

RESULTS

The proportion of "high-grade" cancers with positive cytoplasmic staining for BAG-1 was higher than that of secretory endometrium (P = 0.006). Additionally, the proportion of specimens with positive staining for nuclear BAG-1 expression was significantly higher among high-grade carcinoma specimens compared to secretory specimens (P = 0.009). A high proportion (91%) of all specimens were positive for BCL-2, limiting the ability to subcategorize the other variables analyzed. There was no relationship between positive nuclear BAG-1 expression and either estrogen receptor (ER) or progesterone receptor (PR) expression. BAG-1 was expressed in the three cell lines evaluated and total BAG-1 level was not different among the different cell lines.

CONCLUSION

BAG-1 is expressed in the endometrium. High-grade cancers stain more frequently than secretory endometrium for both cytoplasmic and nuclear BAG-1 expression, perhaps indicating an association between expression of BAG-1 and prognosis.

Expression of Apoptosis-Related Proteins in Adenomyotic Uteri Treated with Danazol and GnRH Agonists

The biologic properties of adenomyosis and the effects of therapeutic agents on adenomyosis were evaluated with immunohistochemistry, terminal deoxy-nucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method, transmission electron microscopy, and analysis of genomic abnormality. In the adenomyotic endometrium, estrogen receptor (ER) expression was more intense than in the eutopic endometrium during the secretory phase, and bcl-2 was constantly expressed throughout the menstrual cycle. The expression of ER and bcl-2 was weaker in the adenomyotic endometrium treated with danazol than in that treated with gonadotro-pin-releasing hormone agonist (GnRHa), whereas bcl-2 phosphorylated on serine-87 was more intensely expressed in danazol-treated adenomyotic endometrium than in the GnRHa-treated one. The number of TUNEL-positive cells increased in the adenomyotic endometrium treated with danazol or GnRHa. Ultrastructurally, most of the adenomyotic endometrial cells treated with danazol underwent postapoptotic necrosis and formed a cluster of dead cells. In contrast, cells treated with GnRHa underwent typical apoptosis and were sparsely distributed in the adenomyotic endometrium. Analysis of several cancer-related genes showed no microsatellite instability or loss of heterozygosity in adenomyotic tissues. Therefore, we conclude that the occurrence of adenomyosis is correlated to bcl-2 expression regulated by estrogen and ER rather than genetic mutation.

Endometrial Hyperplasia: A Review

Endometrial hyperplasia is a precursor to the most common gynecologic cancer diagnosed in women: endometrial cancer of endometrioid histology. It is most often diagnosed in postmenopausal women, but women at any age with unopposed estrogen from any source are at an increased risk for developing endometrial hyperplasia. Hyperplasia with cytologic atypia represents the greatest risk for progression to endometrial carcinoma and the presence of concomitant carcinoma in women with endometrial hyperplasia. Abnormal uterine bleeding is the most common presenting symptom of endometrial hyperplasia. Specific Pap smear findings and endometrial thickness per ultrasound could also suggest the diagnosis. Unopposed estrogen in women taking hormone replacement therapy increases the risk of endometrial hyperplasia. Tamoxifen has demonstrated its efficacy in treating women at risk for breast cancer, but it increases the risk of endometrial hyperplasia. The choice of treatment for endometrial hyperplasia is dependent on patient age, the presence of cytologic atypia, the desire for future childbearing, and surgical risk. Endometrial hyperplasia without atypia responds well to progestins. However, women with atypical hyperplasia should be treated with hysterectomy unless other factors preclude surgery.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to describe the definition and classification of endometrial hyperplasia, to outline the clinical features of a patient with endometrial hyperplasia, to point out the natural history of endometrial hyperplasia, and to summarize the diagnostic options for patients with endometrial hyperplasia.

Differential in vitro actions of nitric oxide on human endometrial cell survival

OBJECTIVE

To investigate the presence of caspase-3 and Bcl-2 concentration in human endometrial tissue throughout the menstrual cycle, and study the effect of nitric oxide (NO) on cell proliferation and apoptosis during culture.

DESIGN

Expression of caspase-3 and Bcl-2 concentration in endometrial explants, and examination of L-arginine (L-Arg) effect on epithelial and stromal cell proliferation and apoptosis in vitro.

SETTING

Prospective study.Twenty-seven eumenorrheic women (37 +/- 1.2 years).

INTERVENTION(S)

Endometrial samples were obtained with Pipelle suction curette from the corpus of the uterus.

MAIN OUTCOME MEASURE(S)

Apoptosis (annexin V-FITC binding), Bcl-2 concentration (ELISA), caspase-3 (immunohistochemistry), cell proliferation (spectrophotometric assay), and gene expression (RT-PCR).

RESULT(S)

Caspase-3 was detected by immunoassay in epithelial tissue throughout the menstrual cycle and in stroma during secretory phase. The Bcl-2 concentration was similar in endometrial homogenates obtained throughout the menstrual cycle, but L-Arg decreased Bcl-2 only in endometrium from the proliferative phase. In epithelial cells, NO increased apoptosis by 2.1 +/- 0.2-fold, augmented mRNA expression of Bax, and reduced expression of Bcl-2 compared with basal cultures. In stromal cells, NO increased cell proliferation in a dose-dependent manner, an effect that was blocked by a NO synthase inhibitor.

CONCLUSION(S)

These data indicate that NO has a differential regulatory function on endometrial cell survival, as indicated by the results on stromal cell proliferation and epithelial cell apoptosis during culture, which suggests paracrine interactions between both cell types.

Lifetime expression of stem cell markers in the uterine endometrium

OBJECTIVE

To identify stem cells in uteri from the fetal to the postmenopausal period.

DESIGN

Descriptive, controlled study.

SETTING

Tertiary academic medical center.

PATIENT(S)

Forty archived uterine endometrial samples.

INTERVENTION(S)

Immunohistochemistry with c-kit/CD117, CD34, bcl-2, and Ki67.

MAIN OUTCOME MEASURE(S)

Immunostaining.

RESULT(S)

C-kit/CD117, CD34, bcl-2, and Ki67 were consistently expressed in the stroma of the basalis layer. Bcl-2 was restricted to the fetal uterine endometrium.

CONCLUSION(S)

By studying the immunolocalization of stem cell markers (i.e., c-kit, CD34, and bcl-2), we found that stem cells are present continuously in the uterine endometrium from the fetal period. The cells seem to be located mainly in the stroma of the basalis and to be independent of hormonal regulation to avoid cyclic shedding. A small number of latent stem cells dormant in the stroma of the basalis were found to have the potential for mesenchymal differentiation.

Differential expression of Akt/protein kinase B, Bcl-2 and Bax proteins in human leiomyoma and myometrium

The expression and activation of serine/threonine protein kinase, Akt, in leiomyoma and in adjacent myometrium of human uteri was studied parallel with the changes of Bcl-2, Bax proteins, estrogen and progesterone receptors during menstrual cycle and early stage of the menopause. Abundant expression of Akt protein was detected in the studied tissues during menstrual cycle, the rate of increase was higher in leiomyoma than in corresponding myometrium. The expression of estrogen receptor alpha, progesterone receptor and of Bcl-2 protein changed parallel with that of Akt protein. The level of phosphorylated Akt (pAkt(473)) was seen only in leiomyoma samples from the growing period of tumors. At early stage of menopause levels of all studied proteins were lower than that in the menstrual cycle with the exception of Bax protein expression, which was high in leiomyoma. Our data suggest the involvement of phosphatidylinositol 3-kinase/Akt signaling in the pathomechanism of leiomyoma.

Expression of steroid receptors and proteins related to apoptosis in endometria of women with polycystic ovary syndrome

OBJECTIVE

To evaluate the expression of steroid hormone receptors, proteins related to apoptosis, and cell proliferation in endometria from women with polycystic ovary syndrome (PCOS).

DESIGN

Case-control study.

SETTING

Hospital research unit.

PATIENT(S)

Eight women with PCOS and 12 fertile healthy women of similar age to those with PCOS.

INTERVENTION(S)

Endometrial samples were obtained from women with PCOS (PCOSE) and normal (NE) women during the proliferative phase of the menstrual cycle.

MAIN OUTCOME MEASURE(S)

Expression studies (immunohistochemistry and reverse transcription-polymerase chain reaction) and DNA fragmentation [TdT-mediated dUTP nick end labeling (TUNEL)].

RESULT(S)

In stroma, protein expression of estrogen receptor alpha, Bcl-2, and Bax was higher in PCOSE than in NE; epithelial cells had a greater expression of androgen receptor in the nucleus and a lower expression in the cytoplasm of PCOSE. Cell proliferation was higher in the epithelia of NE, while the expression of caspase-3 and DNA fragmentation was similar in both groups. The bax mRNA expression was higher in PCOSE, and bcl-2 mRNA expression was similar between groups. A higher bcl-2/bax relative ratio in PCOSE was observed.

CONCLUSION(S)

An alternating expression of proteins related to cell survival in endometria from PCOSE may potentially be associated with the disruption of their endometrial cell cycle.

Angiogenesis, p53, and bcl-2 expression as prognostic indicators in endometrial cancer: comparison with traditional clinicopathologic variables

We investigated the relation of expression of tumor-suppressor gene product p53, apoptosis-regulator gene product bcl-2, and CD34 (as a measure of microvessel density [MVD]) with traditional clinicopathologic prognostic variables in endometrial carcinoma (histologic type, grade, depth of myometrial invasion, angiolymphatic invasion, lymph node involvement). In specimens from 63 patients with endometrial carcinoma, the mean MVD (64.38+/-28.71 microvessels per 200x field) was not related to any clinicopathologic variables. Nuclear p53 expression was detected in 15 (23.8%) patients and was higher in nonendometrioid carcinomas (p<0.05) and in tumors with increasing histologic grade (p<0.001). Cytoplasmic bcl-2 staining was seen in 79.3% of the tumors. There was a negative correlation between bcl-2 expression and histologic type and tumor grade (p<0.05). In survival analysis, patient age, FIGO stage, high expression of p53, low expression of bcl-2, and high and intermediate MVD values were found to be the most significant prognostic indicators of survival (p<0.05). In multivariate regression analysis, FIGO stage and low bcl-2 expression were found to be the only independent indicators of prognosis (p<0.05).

Multiple mechanisms are involved in apoptotic cell death in the mouse uterus and vagina after ovariectomy

Withdrawal of sex hormones by gonadectomy results in rapid involution of mouse reproductive organs. To study the regression mechanism in the uterus and vagina after ovariectomy, histologic and biochemical changes were examined. Apoptotic cells were detected by in situ 3'-DNA nick end labeling method and electron microscopy, while the number of cells showing incorporation of bromo-deoxyuridine (BrdU) decreased in the uterus and vagina after ovariectomy. DNA fragmentation in the uterus was observed even at estrus and the degree of fragmentation increased after ovariectomy. DNA fragmentation in the vagina occurred 1-5 days after ovariectomy. Semi-quantitative RT-PCR revealed that expression of Fas-ligand and tumor necrosis factor-alpha (TNF-alpha) mRNA in the uterus and vagina was increased by ovariectomy. These results suggest that apoptotic cell death is induced by ovariectomy through the mediation of both Fas and TNF-alpha in the mouse uterus and vagina; however, uterine and vaginal cells in CBA lpr(cg)/lpr(cg) mice lacking functional Fas showed apoptosis, indicating that Fas is not the sole regulator of apoptosis in female reproductive organs in mice.

Expression and cyclic variability of CYP3A4 and CYP3A7 isoforms in human endometrium and cervix during the menstrual cycle

CYP3A4, a cytochrome p450 (p450) isoform metabolizes estrogens, whereas CYP3A7, a fetal liver p450 isoform, is involved in estriol biosynthesis. The goal of this study was to evaluate expression of these enzymes in human uterine tissue during the proliferative and secretory phases of the menstrual cycle. Endometrium and cervix specimens were collected from women undergoing hysterectomy (n = 36). Total mRNA was extracted, quantified, and reverse-transcription polymerase chain reaction (RT-PCR) was carried out using consensus primers for CYP3A. The 453 base pairs PCR product was hybridized with specific internal oligonucleotide probes for CYP3A4 or CYP3A7 end labeled with (32)P gamma-ATP. The relative intensity of hybridization was determined by autoradiography. Expression of CYP3A7 in endometrium was significantly greater (approximately 10-fold) in the proliferative phase compared with the secretory phase (p < 0.05). CYP3A4 expression was comparable between the two phases. Expression of both enzymes was minimal in the cervix. Fluorescence in situ hybridization of paraffinized sections indicated localized expression of CYP3A enzymes in the glandular epithelium as well as the stroma. Comparison of relative fluorescence intensity indicated differential expression of CYP3A7 in various phases of the menstrual cycle. These results suggest that CYP3A expression in the endometrium of premenopausal women may vary depending on the menstrual cycle phase.

Elevated soluble Fas ligand levels may suggest a role for apoptosis in women with endometriosis

OBJECTIVE

To evaluate soluble Fas ligand concentrations in serum and peritoneal fluid from women with endometriosis and from fertile controls without endometriosis, and to study levels of soluble Fas ligand in conditioned media of cultured endometrial stromal cells.

DESIGN

Prospective, experimental trial.

SETTING

Two academic IVF centers.

PATIENT(S)

Twenty-nine fertile women without endometriosis and 57 infertile women with endometriosis (32 with stage I or II disease and 25 with stage III or IV disease).

MAIN OUTCOME MEASURE(S)

Enzyme-linked immunosorbent assay was used to measure soluble Fas ligand concentrations in paired samples of serum and peritoneal fluid from women with and without endometriosis. Concentrations were also measured in conditioned media of cultured endometrial stromal cells at basal conditions and after stimulation with interleukin-8 (0.001-10 ng/mL) and tumor necrosis factor-alpha (1-10 ng/mL).

RESULT(S)

Compared with fertile controls and women with early-stage of endometriosis, women with moderate to severe endometriosis had elevated serum (87.2 +/- 6.4, 88.2 +/- 6.9, and 162.3 +/- 7.8 pg/mL, respectively) and peritoneal fluid (81.0 +/- 6.0, 80.5 +/- 6.8, and 166.2 +/- 10.3 pg/mL, respectively) concentrations of soluble Fas ligand. Serum levels of soluble Fas ligand positively correlated with levels in peritoneal fluid. Comparison of patients in the same menstrual cycle in each group revealed that increased levels of soluble Fas ligand in patients with advanced endometriosis were not attributable to the difference in cycle phases. Soluble Fas ligand was not detected in conditioned media of endometrial stromal cells under baseline conditions or after stimulation.

CONCLUSION(S)

Serum and peritoneal fluid of women with moderate to severe endometriosis contain elevated concentrations of soluble Fas ligand compared to women with minimal or mild endometriosis and women without endometriosis. These findings suggest a role for apoptotic dysregulation in the pathophysiology of endometriosis.

Apoptosis-related proteins and steroid hormone receptors in normal, hyperplastic, and neoplastic endometrium

The purpose of this study was to evaluate the distribution and frequency of apoptosis-related proteins and their correlation with estrogen, progesterone, and androgen receptors in endometrial tissues. Immunohistochemical analyses of bcl-2, bax, bcl-x, and steroid receptors were performed in 22 endometrial carcinomas, 26 endometrial hyperplasias, and 19 cases of normal cyclical endometrium. Bcl-2 was expressed in 45.4% of carcinomas and 92.3% of hyperplasias. Bax immunostaining was found in 90.9% of carcinomas and 76.9% of hyperplasias. Bcl-x positivity was similar in carcinomas (68.1%) and endometrial hyperplasias (76.9%). In normal cyclical endometria, bcl-2 staining was intense and diffuse in the proliferative phase, but decreased dramatically in the early and mid-secretory phase to reappear in the late secretory phase. Bax was expressed throughout the menstrual cycle but more strongly in the secretory phase. Bcl-x displayed a similar degree of expression in proliferative and secretory endometria. Nineteen carcinomas (86.3%), 25 hyperplasias (96.1%), and 18 normal cyclical endometria (94.7%) were positive for estrogen receptor (ER). Progesterone receptor (PR) was observed in 20 carcinomas (90.9%), all hyperplasias (100%), and 18 normal cyclical endometria (94.7%). Androgen receptor (AR) positivity was seen in 7 carcinomas (31.8%), 6 hyperplasias (23.0%), and 3 normal cyclical endometria (15.7%). There was a statistically positive correlation between bcl-x and ER and a tendency toward significant correlation between bcl-x and PR and between ER and PR in carcinomas. In hyperplasias, there was a significant positive correlation between bcl-2 and PR and between bcl-2 and bax and a negative correlation between ER and bax. There was a statistically significant difference for bcl-2 (p = 0.001) and bax (p = 0.001) between the hyperplasia and carcinoma groups. There was increased expression of bax, decreased expression of bcl-2, and persistence of bcl-x protein in advanced endometrial carcinomas. Our findings show that ovarian hormones have a regulatory role on bcl-2 protein and that there is a correlation between other members of the bcl-2 family (bcl-x and bax) and steroid hormone receptors. Bax/bcl-x may be the major control mechanisms of apoptosis in advanced carcinomas; other members of the bcl-2 family may also be under hormonal control.

Role of nitric oxide and bcl-2 family genes in the regulation of human endometrial apoptosis

OBJECTIVE

To investigate the role of nitric oxide (NO) and death regulatory genes, bcl-2 and bax, in human endometria apoptosis.

DESIGN

Expression of bcl-2, bax, NO synthases (NOS), and the apoptotic effect of L-arginine on endometrial explants in vitro.

SETTING

Prospective study.

PATIENT(S)

Thirty-seven eumenorrheic women.

INTERVENTION(S)

Endometrial samples were obtained with Pipelle suction curette after women signed institutional informed consent forms.

MAIN OUTCOME MEASURE(S)

DNA fragmentation (TUNEL), immunohistochemistry, and reverse transcription polymerase chain reaction.

RESULT(S)

Apoptosis was detected in mid and late secretory endometria. L-arginine induced an increase in apoptosis in stroma (threefold), glands (eightfold), and surface epithelia (fourfold) in proliferative but not secretory endometria explants. Immunostaining of Bcl-2 was almost absent in the secretory endometria, whereas Bax increased in the stroma at the end of the menstrual cycle, coincident to the decrease in the bcl-2/bax mRNA relative ratio (P<.05) observed in secretory endometria.

CONCLUSION(S)

The induction of DNA fragmentation by L-arginine on proliferative endometria suggests that NO may be involved in the endometrial apoptotic process, whose control may be related predominantly to the changes of Bcl-2 expression.

Bax, Bcl-2, and p53 expression in endometrial cancer

BACKGROUND

It has not been fully clarified whether alteration of Bax and other apoptosis-relating proteins of Bcl-2 and p53 is involved in endometrial carcinogenesis.

METHODS

A total of 56 frozen tissues, which included 14 normal endometria, 13 endometrial hyperplasias (10 without atypia and 3 with atypia), and 29 endometrial carcinomas, were examined for the expression of Bax, Bcl-2, and p53 using immunohistochemistry. For Bax-negative cases, PCR-direct sequencing was performed for the bax gene. For cases with p53 overexpression, mutational analysis was performed for the p53 gene using a yeast functional assay and sequencing.

RESULTS

Both Bax and Bcl-2 were distinctly expressed in the normal proliferative phase endometrium. A decreased Bcl-2/Bax ratio in the secretory phase endometrial gland cells due to suppressed Bcl-2 expression was observed. Bax expression was positive in all 13 endometrial hyperplasias, while it was absent in 6 of 29 endometrial carcinomas (20.7%). Negative Bax expression in endometrial carcinoma was not related to tumor stage, histologic subtype, or other histopathologic prognostic factors. Bax expression showed no relationship to either p53 overexpression or Bcl-2 expression. In the DNA of 6 Bax-negative cases, we found a frameshift insertion mutation at codon 58 (AAG to CAAG) in the BH3 domain despite the absence of mutation in the (G)8 tract, suggesting that this codon may be another preferred target for bax mutation other than the (G)8 tract. Mutational analysis was available for 7 of 10 cases with p53 overexpression, in which 5 cases were found to have a missense mutation and 2 cases had no mutation of the p53 gene. At least 10 of 29 (34.5%) cases of endometrial carcinoma were associated with sequence-verified mutation in the bax gene and/or p53 gene.

CONCLUSIONS

The bax gene frameshift mutation appears to cause a loss of Bax expression in endometrial carcinoma. Codon 58 may be a preferred target of bax gene mutation in endometrial carcinomas. The bax gene mutation seems to occur in the early stage of the genesis of a subset of endometrial carcinomas.

Expression of Bcl-2, Bcl-x, Mcl-1, Bax and Bak in human uterine leiomyomas and myometrium during the menstrual cycle and after menopause

To investigate the expression of Bcl-2, Bcl-x, Mcl-1, Bax and Bak proteins in human uterine leiomyomas and homologous myometrium during the menstrual cycle and after menopause. The expression of Bcl-2, Bcl-x, Mcl-1, Bax and Bak in leiomyomas (n=24) and myometrial samples (n=22) from women with leiomyomas was measured by immunohistochemistry and Western blot. Measured by immunohistochemistry, a significant difference between leiomyomas and myometrium was observed only for the Bax protein, in tissues obtained from women in the secretory phase of the menstrual cycle. The Bcl-2 staining was more abundant in leiomyomas than in myometrium only in tissues obtained in the proliferative phase of the cycle. Bcl-2 was more abundant in leiomyomas from women of fertile age than in leiomyomas from menopausal women. No significant differences were observed for the Bcl-x or Bak proteins, whereas the Mcl-1 protein was significantly less abundant in secretory phase leiomyomas than in leiomyomas from menopausal women. Western blot analysis based on pools of tissue extracts from the different groups essentially confirmed the data obtained by immunohistochemistry. Bcl-2 family proteins are expressed in leiomyomas and myometrium in different phases related to and influenced by gonadal steroids. These proteins are suggested to interact with each other in the regulation of programmed cell death, apoptosis, but their specific role in growth control of uterine leiomyomas remains to be investigated.

Effects of the levonorgestrel-releasing intrauterine system on proliferation and apoptosis in the endometrium

BACKGROUND

The levonorgestrel-releasing intrauterine system (LNg-IUS) has been shown to be effective in the management of menorrhagia. In order to evaluate the effects of LNg-IUS on endometrial proliferation and apoptosis, proliferating cell nuclear antigen (PCNA) expression, apoptosis, Fas and Bcl-2 protein expression in the endometrium were determined at the early proliferative phase of the menstrual cycle before and 3 months after LNg-IUS insertion.

METHODS

PCNA, Fas and Bcl-2 protein expression were analysed using an avidin-biotin immunoperoxidase method. Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick-end labelling (TUNEL) method.

RESULTS

PCNA, immunolocalized both in the nuclei of endometrial glands and stroma was less abundant 3 months after insertion (P < 0.05). Bcl-2 protein, immunolocalized in the cytoplasm of endometrial glands but not in the stroma, became scanty 3 months after insertion. Fas antigen, immunolocalized only in endometrial glands before insertion, became prominent in both endometrial glands and stroma 3 months after insertion. The apoptosis-positive rate of the nuclei in both endometrial glands and stroma was significantly higher 3 months after insertion relative to that before insertion (P < 0.05).

CONCLUSIONS

LNg-IUS resulted in a decrease in endometrial proliferation and an increase in apoptosis in endometrial glands and stroma. The increase in apoptosis associated with increased Fas antigen expression and decreased Bcl-2 protein expression in the endometrium may be one of the underlying molecular mechanisms by which LNg-IUS insertion causes the atrophic change of the endometrium.

Apoptosis in the normal human amnion at term, independent of Bcl-2 regulation and onset of labour

This study was designed to detect apoptosis in the human amnion and to elucidate the signalling pathway involved in its regulation. Samples of human amnion were obtained from 34 women (weeks 11-42 of gestation) and studied using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) method with light microscopy (LM) and transmission electron microscopy (TEM). Apoptotic regulators in the samples were studied by immunohistochemistry and caspase activity assay. The TUNEL method with LM demonstrated that the percentage of TUNEL-positive cells in the amniotic epithelium was the highest in weeks 40-41 of gestation (P < 0.05) independent of the onset of labour, and the cells were often detached from the epithelium into the amniotic cavity at term. The TUNEL method with TEM clearly showed the characteristic features of apoptosis such as the nuclear condensed chromatin with abundant free 3'-OH DNA ends, cell shrinkage and a decrease in the number of desmosomes, except for the presence of apoptotic bodies. Fas and Fas ligand (FasL) were constantly expressed on apical membranes of amniotic epithelial cells from weeks 16-27 through to 40-41 of gestation, while no Bcl-2 expression was observed throughout the gestational periods. Activities of caspase-3 and caspase-8, but not of caspase-9, were higher in weeks 40-41 than those from weeks 16-27 of gestation (P < 0.01). We conclude that apoptosis in term amniotic epithelium is independent of Bcl-2 regulation and onset of labour, and may play an important role in the fragility and rupture of human fetal membranes at term.

Differential mechanisms of neuroprotection by 17 beta-estradiol in apoptotic versus necrotic neurodegeneration

The major goal of this study was to compare mechanisms of the neuroprotective potential of 17 beta-estradiol in two models for oxidative stress-independent apoptotic neuronal cell death with that in necrotic neuronal cell death in primary neuronal cultures derived from rat hippocampus, septum, or cortex. Neuronal apoptosis was induced either by staurosporine or ethylcholine aziridinium (AF64A), as models for necrotic cell death glutamate exposure or oxygen-glucose deprivation (OGD) were applied. Long-term (20 hr) pretreatment (0.1 microm 17 beta-estradiol) was neuroprotective in apoptotic neuronal cell death induced by AF64A (40 microm) only in hippocampal and septal neuronal cultures and not in cortical cultures. The neuroprotective effect was blocked by the estrogen antagonists ICI 182,780 and tamoxifen and the phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002. In glutamate and OGD-induced neuronal damage, long-term pretreatment was not effective. In contrast, short-term (1 hr) pretreatment with 17 beta-estradiol in the dose range of 0.5-1.0 microm significantly reduced the release of lactate dehydrogenase and improved morphology of cortical cultures exposed to glutamate or OGD but was not effective in the AF64A model. Staurosporine-induced apoptosis was not prevented by either long- or short-term pretreatment. The strong expression of the estrogen receptor-alpha and the modulation of Bcl proteins by 17 beta-estradiol in hippocampal and septal but not in cortical cultures indicates that the prevention of apoptotic, but not of necrotic, neuronal cell death by 17 beta-estradiol possibly depends on the induction of Bcl proteins and the density of estrogen receptor-alpha.

Apoptosis in adriamycin cardiomyopathy and its modulation by probucol

The dose-dependent cardiomyopathy and heart failure due to adriamycin have been shown to be due to increased oxidative stress and loss of myocytes. We examined the incidence of myocardial apoptosis as well as changes in the expression of apoptotic regulatory gene products in an established animal model of adriamycin cardiomyopathy. Rats were treated with adriamycin (cumulative dose, 15 mg/kg), and the hearts were examined for apoptosis as well as expression of Bax, caspase 3, and Bcl-2 at 0, 4, 10, 16, and 21 days after the treatment. A significant increase in the incidence of apoptosis was seen at 4 days, followed by a decline at 10 and 16 days of posttreatment. At 21 days, the number of apoptotic cells increased again and included cells of the conducting system. Expression of Bax corresponded to these biphasic changes, whereas the converse was true for the expression of Bcl-2. The latter peaked at 10 days followed by a decline at 16 and 21 days. The Bax/Bcl-2 ratio also correlated with the incidence of apoptosis. Expression of caspase 3 correlated with increased apoptosis, but only at early time points. Probucol (cumulative dose, 120 mg/kg), a known antioxidant as well as promoter of endogenous antioxidants, significantly reduced the incidence of apoptosis as well as expression of Bax. Adriamycin-induced hemodynamic changes were also prevented by probucol. These data suggest that adriamycin-induced apoptosis is mediated by oxidative stress and may play a role in the development of heart failure.

Apoptosis may be an early event of progestin therapy for endometrial hyperplasia

OBJECTIVE

The aim of this study was to investigate the role of apoptosis during progestin therapy for the treatment of endometrial hyperplasia.

METHODS

Pre- and posttreatment paraffin-embedded endometrial tissue samples from 19 women with endometrial hyperplasia were examined for changes in glandular cellularity and apoptotic activity related to the administration of progestins. Twelve patients were successfully treated with progestin therapy and 7 patients failed treatment. Glandular cellularity was assessed based on calculating the average number of cells per gland obtained on histologic examination of hematoxylin and eosin stained tissue sections. Apoptotic activity was assessed on the same tissue sections by counting the average number of apoptotic cells per 10 high power fields (hpf) using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) assay. The effects of progesterone on apoptotic activity in a low-grade endometrial adenocarcinoma cell line (Ishikawa cells) was also examined using an ELISA cell death detection kit.

RESULTS

Glandular cellularity significantly decreased with progestin therapy in both treatment outcome groups. The reduction in cells per gland was significantly greater in the group of successfully treated cases compared to the treatment failures (P = 0.005). However, within the successfully treated group, in situ detection of apoptotic cells using the TUNEL assay showed no statistical difference between pre- and posttreatment endometrial samples. Interestingly, a significant decrease in apoptosis was found in posttreatment samples of the group with persistent hyperplasia. The average number of apoptotic cells detected in 10 hpf was reduced from 7.9 prior to treatment to 3.1 after progestin therapy (P = 0.03). In the progesterone-treated Ishikawa cell line, an increase in apoptotic activity started at 24 h, reached a peak at 48 h, and continued up to 72 h of hormone treatment. At 48 h, apoptotic activity was 42.6% greater than in the untreated control (P = 0.04). By 72 h of progesterone treatment, apoptosis was 37.2% greater in the treated cells compared to the noninoculated cells (P = 0.04).

CONCLUSIONS

Progestin-induced apoptosis may occur during the early period of treatment for endometrial hyperplasia. Compared to the fully responsive group, persistent endometrial hyperplasia may have intrinsically different molecular mechanisms in response to progestin therapy.

Mitotic arrest of endometrial epithelium after paclitaxel therapy for breast cancer

We report the histopathologic findings in endometrial curettings from a 31-year-old woman with dysfunctional uterine bleeding who had received paclitaxel therapy for breast carcinoma. Paclitaxel, a member of the taxane family of antineoplastic agents that is used in the treatment of breast carcinoma, ovarian carcinoma, and non-small cell lung carcinoma, acts by the simultaneous promotion of tubulin assembly into microtubules and inhibition of microtubule disassembly. The curettings in this case showed fragmented menstrual phase endometrium with striking numbers of mitotic figures. Cell divisions were arrested in metaphase. Glandular epithelial cells showed strong immunoreactivity for bcl-2 and MIB-1. We attribute this marked morphologic effect to paclitaxel-induced mitotic arrest of the endometrium.

Apoptosis and expression of Bcl-2 and Bax in eutopic endometrium from women with endometriosis

OBJECTIVE

To evaluate and compare spontaneous apoptosis and Bcl-2 and Bax expression in eutopic endometrium from women with and without endometriosis.

DESIGN

Apoptosis and Bcl-2 and Bax expression were examined in eutopic endometrium from women with and without endometriosis.

SETTING

Instituto de Biología y Medicina Experimental-CONICET, Department of Gynecology and Department of Gynecological Pathology, Clínicas University Hospital, Buenos Aires, Argentina.

PATIENT(S)

Women with untreated endometriosis (n = 14) and controls (n = 16).

INTERVENTION(S)

Collection of endometrial samples during diagnostic or therapeutic laparoscopy.

MAIN OUTCOME MEASURE(S)

Apoptotic cells were detected with use of the dUTP nick-end labeling (TUNEL) assay; Bcl-2 and Bax expressions were assessed with use of immunohistochemical techniques.

RESULT(S)

Spontaneous apoptosis was significantly lower in eutopic endometrium from patients with endometriosis, compared with healthy controls (2.26 +/- 0.53 and 9.37 +/- 1.69 apoptotic cells/field, respectively) and was independent of cycle phase. An increased expression of Bcl-2 protein was found in proliferative eutopic endometrium from patients with endometriosis. Bax expression was absent in proliferative endometrium, whereas there was an increase in its expression in secretory endometrium from both patients and controls.

CONCLUSION(S)

Women with endometriosis show decreased number of apoptotic cells in eutopic endometrium. The abnormal survival of endometrial cells may result in their continuing growth into ectopic locations.

Is endometriosis an endometrial disease?

Endometriosis is characterised by the presence of abnormally located tissue resembling the endometrium with glands and stroma. Several hypotheses have attempted to explain the development of such tissue. The most often cited theory, that of implantation, proposes that the physiological phenomenon of endometrial reflux in the fallopian tubes during menstruation may, in certain conditions, overcome local defense mechanisms, implant, and proliferate. The implantation theory does not explain why endometriosis will develop only in approximately 10-15% of women, while the reflux of endometrial tissue via the fallopian tubes during menstruation is a quasi-universal phenomenon. The endometrium of women affected by endometriosis could be abnormal compared with endometrium of healthy women. The abnormal endometrium could be able to protect itself from harmful effects of immune cells by expressing specific antigens, by harbouring a different immune cell population and by synthetizing and secreting immunosuppressive factors. Several others characteristic features of endometrium have been described in women with endometriosis: (1) production of its own estrogens in too heavy amount; (2) aptitude for setting up on peritoneum; (3) tendencies to proliferate and to invade tissue; (4) aggressiveness for the peritoneum; (5) auto-protection from physiological apoptosis; (6) abnormal expression of heat shock proteins; and (7) excessive angiogenesis.

Cytokine regulation of apoptotic susceptibility in a human endometrial epithelial cell line

The effects of four endometrial cytokines, transforming growth factor beta1 (TGF-beta1), interleukin-1beta (IL-1beta), epidermal growth factor (EGF), and hepatocyte growth factor (HGF), on Fas-mediated apoptosis in the human endometrial epithelial cell line, HHUA, were investigated. Although the cell growth of HHUA was not directly affected by TGF-beta1, IL-1beta, or EGF, pretreatment of HHUA with TGF-beta1, IL-1beta, or EGF enhanced Fas-mediated growth suppression and Fas-mediated DNA fragmentation in the cells. Flow cytometric analyses demonstrated that TGF-beta1, IL-1beta, and EGF did not induce Fas expression on the cell surface. These results suggest that TGF-beta1, IL-1beta, and EGF enhances apoptotic susceptibility of the cells. However, HGF inhibited Fas-mediated growth suppression and DNA fragmentation in the cells without any increase in Fas antigen expression on the cells. This finding suggests that HGF suppresses apoptotic susceptibility of the cells. From these results, we conclude that the endometrial cytokines may play a role in reshaping the endometrium after menstruation or in regulating apoptotic susceptibility in endometrial epithelium in the mid- to late-secretory period.

Hormonal regulation of physiological cell turnover and apoptosis

Physiological cell turnover plays an important role in maintaining normal tissue function and architecture. This is achieved by the dynamic balance of cellular regeneration and elimination, occurring periodically in tissues such as the uterus and mammary gland, or at constant rates in tissues such as the gastrointestinal tract and adipose tissue. Apoptosis has been identified as the prevalent mode of physiological cell loss in most tissues. Cell turnover is precisely regulated by the interplay of various endocrine and paracrine factors, which modulate tissue and cell-specific responses on proliferation and apoptosis, either directly, or by altering expression and function of key cell proliferative and/or death genes. Although recent studies have provided significant information on specific tissue systems, a clearly defined pathway that mediates cell turnover has not yet emerged for any tissue. Several similarities exist among the various tissues with regard to the intermediates that regulate tissue homeostatis, enabling a better understanding of the general mechanisms involved in the process. Here we review the mechanisms by which hormonal and cytokine factors mediate cell turnover in various tissues, emphasizing common themes and tissue-specific differences.

Apoptosis, bcl-2 expression, and proliferation in benign and malignant endometrial epithelium: An approach using multiparameter flow cytometry

OBJECTIVE

Disturbances in the regulation of cell proliferation and differentiation play an important role in the formation of neoplastic lesions. Consequently, abnormalities in apoptosis regulation may contribute to this process. Expression of a neoepitope on cytokeratin 18, unmasked by an early caspase cleavage event and recognized by the novel monoclonal antibody M30, is an indicator of early epithelial cell apoptosis. The purpose of this study was to evaluate the quantitative relation among apoptosis (M30), cell persistence (bcl-2), and proliferation (S-phase fraction; SPF) in malignant and benign endometrium.

METHODS

Using multiparameter DNA flow cytometry on 54 formalin-fixed paraffin-embedded samples from benign (proliferative, secretory, inactive, and hyperplastic endometrium) and malignant (grades 1-3 endometrial adenocarcinoma) endometrial tissue, bcl-2 expression and M30 reactivity were assessed together with the SPF in the cytokeratin-positive epithelial cells.

RESULTS

Benign cyclic endometrium showed a relatively high bcl-2 expression and low M30 reactivity in the proliferative phase whereas in the secretory phase this relation was inverse. In endometrial hyperplasia the expression of bcl-2 was increased compared to that in secretory and postmenopausal endometrium, but still below the level of proliferative samples. The expression of M30 also increased compared to normal proliferative endometrium but did not reach the level of endometrium in the secretory phase of the menstrual cycle. In cancer the expression of bcl-2 decreased with the progression of differentiation grade. For M30 expression this relation was inverse. Overall there was a significant increase of M30 reactivity in cancerous compared to hyperplasia and normal cyclic endometrium.

CONCLUSION

Transition of endometrial epithelium from hyperplasia to cancer seems to involve both increased apoptosis and decreased bcl-2 expression. Flow cytometric evaluation of M30 and bcl-2 expression levels, with the SPF, in currettage specimens from postmenopausal patients complaining of bleeding provides a quantitative assessment of endometrial apoptosis, anti-apoptosis, and proliferation. Further studies are needed to determine the relationship among these three processes as indicators of the biological behavior of gynecological tumors.

The patterns of expression of an apoptosis-related CK18 neoepitope, the bcl-2 proto-oncogene, and the Ki67 proliferation marker in normal, hyperplastic, and malignant endometrium

Expression of a neoepitope on cytokeratin 18, recognized by the monoclonal antibody M30, is an early indicator of apoptosis in epithelial cells. The aim of this study was to determine the equilibrium between apoptosis (M30), anti-apoptosis (bcl-2), and proliferation (Ki-67) in different endometrial conditions. Paraffin-embedded samples (n = 107), representing proliferative endometrium (18), secretory endometrium (19), postmenopausal endometrium (15), disordered proliferative endometrium (6), simple hyperplasia (12), complex hyperplasia (8), and endometrial adenocarcinoma (29), were evaluated immunohistochemically. The indirect streptavidin-biotin-horseradish peroxidase technique, with 3-amino-9-ethylcarbazole as the chromogen, was used to visualize the reactions. Proliferative endometrium showed high bcl-2 and Ki-67 expression levels with no M30. In the secretory phase, the balance was tipped in favor of M30 with a decrease of bcl-2 and Ki-67. Postmenopausal endometrium revealed high Ki-67 and bcl-2 expression levels and no M30. In complex hyperplasia, M30, bcl-2, and Ki-67 showed increased expression. In endometrial carcinoma, an increasing reactivity for M30 and Ki-67 was seen as the grade progressed. bcl-2 reacted weakly and only in grade 1 cancer. Immunohistochemistry facilitates the study of the expression of proteins related to cyclic endometrial activity. Interruption of these cyclic events is associated with specific disturbances in the expression patterns of these proteins.

Estrogen-regulated developmental neuronal apoptosis is determined by estrogen receptor subtype and the Fas/Fas ligand system

Adult sexual dimorphism in neuronal cell number is controlled by estrogen exposure during a tightly defined period of rat brain development. The mechanisms of estrogen's effect are unknown; one possibility is regulation of programmed cell death (apoptosis). In this study we have shown that estradiol can function as a neuroprotective agent or an inducer of apoptosis, depending on the estrogen receptor-subtype present in the cell. Thus, ERalpha has a neuroprotective effect, while ERbeta mediates the induction of apoptosis in neuronal cells. Moreover, we show that estrogen-induced apoptosis through ER-beta requires the expression of Fas- and Fas ligand (FasL) proteins, since the absence of FasL in neurons prevents this effect. Furthermore, we demonstrate that microglia-secreted products induce the expression of FasL necessary to mediate estradiol-ERbeta apoptotic effect. These findings may explain the dichotomous effect of fetal estradiol on the adult neuronal number.

B cell leukaemia/lymphoma-2 protein concentrations during normal pregnancy

We evaluated bcl-2 protein levels in whole blood, and intraerythrocytic products of lipoperoxidation, in 65 healthy pregnant primiparous women at the end of the first, second and third trimesters of pregnancy. During pregnancy we found a progressive increase in concentrations of bcl-2 and intraerythrocytic products of lipoperoxidation. Moreover, a positive correlation was found between bcl-2 concentrations and lipoperoxidation products, and between bcl-2 protein, E2 and progesterone. The results show that modifications occurring during pregnancy are accompanied by variations of bcl-2 protein.

Enhanced Fas/CD95-mediated apoptosis by epidermal growth factor in human endometrial epithelial cells

Epidermal growth factor (EGF) has been reported to regulate apoptosis in various cell lineages. Throughout the menstrual cycle overexpression of the EGF receptor in the secretory epithelium and constitutive expression of EGF in all types of endometrial cells were identified by immunohistochemical study of normal human endometrial tissues. However, it is not known whether EGF also regulates endometrial apoptosis. This study examined the regulatory functions of EGF in endometrial apoptosis by using a human endometrial epithelial cell line HHUA which is susceptible to Fas-mediated apoptosis. Although EGF alone did not affect the cell growth of HHUA, EGF pretreatment of HHUA enhanced Fas-mediated growth suppression and Fas-mediated DNA fragmentation in the cells. Flowcytometric analyses demonstrated that EGF did not induce Fas expression on the cell surface while expressions of the EGF receptor were down-regulated. These results suggest that EGF may enhance apoptotic susceptibility of the endometrial epithelium, especially in the secretory epithelium.

Expression of macrophage inflammatory protein-1alpha (MIP-1alpha) in human endometrium throughout the menstrual cycle

OBJECTIVE

To investigate the distribution and the role of macrophage inflammatory protein-1alpha (MIP-1alpha) in human endometrium during cyclic changes.

SETTING

Department of Obstetrics and Gynaecology, Shiga University of Medical Science and University Hospital.

MATERIALS

Eighteen endometrial tissue specimens surgically resected or biopsied from women with normal menstrual cycles, without hormonal disorder or endometrial diseases.

METHODS

By immunohistochemistry, using monoclonal antibodies (lambda delta 78 for MIP-1alpha and CR3/43 for human leukocyte antigen-DR (HLA-DR)).

RESULTS

Immunoreactivity for anti-MIP-1alpha was distributed diffusely in epithelial cells throughout the proliferative and secretory phases but was absent during menstruation due to degenerative or necrotic changes. HLA-DR was expressed in epithelial cells only in the late secretory phase and was not expressed in stromal cells.

CONCLUSION

Immunohistochemical analysis showed the presence of MIP-1alpha in the endometrial epithelium. Expression of HLA-DR in epithelial cells was observed only in the late secretory phase, suggesting that accumulation of MIP-1alpha in epithelium occurred by self production and not via a receptor mediated pathway. MIP-1alpha was released from the denuded epithelium during menstruation and appeared to contribute to the accumulation of monocytes/macrophages into the endometrial cavity. MIP-1alpha has a number of biological effects other than monocytic chemotaxis, and some of these effects may be exerted in the endometrial tissue.

Apoptosis, proliferation, and sex hormone receptors in superficial parts of human endometrium at the end of the secretory phase

Apoptosis with one regulator, Bcl-2, and proliferation with the marker Ki-67 were studied in 75 endometrial biopsies representing superficial parts of endometrium from 35 regularly menstruating women premenstrually and menstrually. Hormonal withdrawal was studied in serum samples and potentiated in epithelium by the decreasing 17beta-estradiol and progesterone receptor scores 4 days premenstrually. The apoptotic index increased 2 days before the onset of menstruation and peaked on the second menstrual day. The high apoptotic index together with low proliferation in endometrial epithelium at the end of the menstrual cycle are similar to the involution process seen in other hormone-dependent organs. In stroma, the apoptotic index increased later, at the onset of menstruation, and the increase was lower than that in epithelium. The Ki-67 index increased during the last 3 days of the secretory phase, parallel with an increasing progesterone receptor score and decreasing Bcl-2 staining, and peaked at the onset of menstruation. The findings in stroma concur with high proliferation at the end of the menstrual cycle and high cell turnover during menstruation, suggesting the participation of stroma in the renewal process of endometrium.

Down-regulation of bcl-2 is a potential marker of the efficacy of progestin therapy in the treatment of endometrial hyperplasia

OBJECTIVE

The objective of this study was to evaluate the expression of bcl-2, a regulatory protein in programmed cell death, in endometrial hyperplasia before and after progestational therapy.

METHODS

Pre- and posttreatment paraffin-embedded endometrial tissue samples from 20 women with an initial diagnosis of endometrial hyperplasia were obtained from archived files. Cases were evaluated and classified as either complete resolution of hyperplasia or persistent hyperplasia in response to progestin treatment. Sections were examined for bcl-2, estrogen receptor, and progesterone receptor expression using immunohistochemistry and compared within the treatment response groups.

RESULTS

Among the 20 women studied, 13 had complete regression of their hyperplasia with progestin treatment and 7 had evidence of persistent disease after therapy. Bcl-2 expression was significantly decreased after treatment from a mean reactivity score of 2.08 to 0.31 (P = 0.0005) in the group of patients whose hyperplasia completely regressed with progestin administration. Among the women who had persistent hyperplasia after therapy, no significant change was observed between pre- and posttreatment bcl-2 expression, with a mean reactivity of 1.86 to 1. 29, respectively (P = 0.075). Progestational therapy significantly decreased the status of estrogen receptors from a mean score of 2.08 to 0.46 (P = 0.0005) in completely resolved cases of hyperplasia and from 2.00 to 0.43 (P = 0.0025) in persistent hyperplasias. Treatment also significantly decreased the status of progesterone receptors from a mean reactivity score of 1.92 to 0.31 (P = 0.0005) in cases of regressed hyperplasia and from a mean reactivity of 1.86 to 0.29 (P = 0.005) in persistent cases of hyperplasia.

CONCLUSIONS

Bcl-2 expression decreases following successful progestin treatment of endometrial hyperplasias, whereas it remains expressed in hyperplasias which persist despite progestational therapy. This suggests that bcl-2 expression may represent a component of the therapeutic effects exerted in the endometium during progestational therapy in the treatment of hyperplasia. The activity of the oncoprotein may be a potential measure of the progress of treatment.

Estrogen modulates neuronal Bcl-xL expression and beta-amyloid-induced apoptosis: relevance to Alzheimer's disease

Recent findings indicate that estrogen is neuroprotective, a cellular effect that may contribute to its clinical benefits in delaying the development of Alzheimer's disease. In this report, we identify a novel neuronal action of estrogen that may contribute to its neuroprotective mechanism(s). Specifically, we report that estrogen significantly increases the expression of the antiapoptotic protein Bcl-xL in cultured hippocampal neurons. This effect presumably reflects classic estrogen transcriptional regulation, as we identified a putative estrogen response element in the bcl-x gene. Estrogen-induced enhancement of Bcl-xL is associated with a reduction in measures of beta-amyloid-induced apoptosis, including inhibition of both caspase-mediated proteolysis and neurotoxicity. A similar relationship between estrogen, Bcl-xL expression, and resistance to degeneration was also observed in human hippocampus. We report neuronal colocalization of estrogen receptor and Bcl-xL immunoreactivities that is most prominent in hippocampal subfield CA3, a region that shows relatively little immunoreactivity to paired helical filament-1, a marker of Alzheimer's disease neurodegeneration. These data suggest a novel mechanism of estrogen neuroprotection that may be relevant to estrogen's suggested ability to modulate neuronal viability across the life span, from neural sexual differentiation and development through age-related neurodegenerative conditions.

Cell death and proliferation and its relation to collagen degradation in uterine involution of rat

Collagen concentration, procollagenase localization, and their association with cell proliferation and apoptosis during postpartum involution, were investigated biochemically and histochemically in postpartum day 1, 3, 5, and 7 rat uterine tissues. In control animals, uterine wet weight, soluble protein, and collagen decreased rapidly during days 1 to 3 postpartum, and the DNA concentration in the uterine horn rapidly decreased, as noted by others. Simultaneously, both apoptosis and cell proliferation were observed in these tissues. These processes were highest in smooth muscle cells on day 3 postpartum. Procollagenase was found in the cell cytoplasm through days 1 to 3 postpartum, was highest on the third day postpartum, and appeared to gradually diminish by day 5 postpartum. Disorganization of collagen fibers was observed, under polarized microscopy by a strong birefringence of collagen fibers of the circular smooth muscle cell layers. However, this disorganization of the uterine collagen diminished progressively from day 3 to day 7. Treatment with estradiol or a combination of estradiol and progesterone suppressed cellular turnover and attenuated the changes in DNA, total amino acids, and collagen on day 3 postpartum. In this study, cellular turnover and biochemical and morphological changes appeared to be closely associated. Gonadal steroid hormones appear to influence these changes and retard uterine involution. This study suggests that a dynamic turnover of the cellular population takes place during uterine involution. It is possible that other factors, in addition to steroid hormones, contribute to uterine involution. It is to be postulated that these factors either are themselves decreased or, alternatively, may increase the inhibition of other unknown factors by an indirect mechanism.

bcl-2 protein expression in endometrial carcinoma: the lack of correlation with p53

bcl-2 expression was examined on paraffin-embedded specimens in proliferative, hyperplastic, and neoplastic human endometrium by immunohistochemistry. The results of bcl-2 immunostaining in endometrial carcinomas were compared with clinicopathological indicators as well as with p53 accumulation. The streptavidin-peroxidase detection system was used and the intensity and the distribution of immunostaining was evaluated semiquantitatively by counting H-score values. Expression of the bcl-2 protein was found in 2 out of 5 cases of proliferative endometrium (mean H-score 0.4, range 0.35-0.45), 4 out of 5 cases of simple hyperplasia (mean H-score 1.23; range 1.0-1.4), 4 out of 5 cases of complex hyperplasia (mean H-score 1.1; range 0.7-1.2) and in 7 out of 25 cases of endometrial carcinoma (mean H-score 0.48; range 0.35-0.65). All bcl-2 positive slides were obtained from patients who had endometrial cancer and who were in the early (stage I due to FIGO) clinical stage of the disease. bcl-2 expression was not related to age, surgical stage or histopathological features, and neither was there an inverse correlation between bcl-2 immunostaining and p53 expression reported in the study of neoplastic endometrium. Our data indicate that mechanisms other than p53 may play a role in the regulation of bcl-2 expression in endometrial carcinomas.

Correlation of proliferation indices, apoptosis, and related oncogene expression (bcl-2 and c-erbB-2) and p53 in proliferative, hyperplastic, and malignant endometrium

BACKGROUND

The various morphological groupings of endometrial pathology are often difficult to distinguish from each other. The endometrium is an actively proliferating tissue and there is an overlap in cell proliferation fraction (CPF) between benign proliferative endometrium (BPE) and endometrial carcinoma (EC). Apoptosis in benign cycling endometrium is related to the menstrual cycle. In this study we evaluated CPF, apoptosis, and oncogenes that relate to cell turnover (bcl-2, p53, and c-erbB-2) in the spectrum of endometrial pathology.

METHODS

We examined a total of 64 cases consisting of 10 cases of BPE, 18 cases of simple endometrial hyperplasia (SEH), 18 cases of complex hyperplasia (CEH; including eight cases with atypical hyperplasia), and 18 cases of EC, FIGO grade 1. CPF was measured by the mitotic index (MI) and by the percentage of Ki-67 positive nuclei (Ki-67 index). Apoptotic index (AI) was determined on hematoxylin and eosin sections.

RESULTS

MI was 2.48% in BPE, 0.65% in SEH, 0.6% in CEH, and 0.91% in EC (P < .00001). Ki-67 index was 38.44%, 16.4%, 23.25%, and 31.7% respectively (P < .00001). AI was 1.17%, 2.2%, 2.57%, and 3.31% respectively (P = .02). The AI/MI and AI/Ki-67 ratios were lowest in BPE and highest in SEH (P = .007). All cases of BPE, 84% of SEH cases, 77% of CEH cases, and 88% of EC cases displayed cytoplasmic and/or nuclear bcl-2 expression. Cytoplasmic bcl-2 expression increased from BPE to SEH, whereas it decreased in CEH and EC with emergence of only nuclear expression. Of the EC cases, 38.8% showed intense nuclear bcl-2 reactivity and a significantly higher Ki-67 index than cases with cytoplasmic expression (P = .01). No p53 or c-erbB-2 expression was seen in either BPE or EH. Of the EC cases, 50% were positive for p53 whereas 30% were positive for c-erbB-2. C-erbB-2-positive cases had a significantly higher Ki-67 index and AI than negative cases (P = .02). Cases of EC with p53 expression also had significantly higher AI (P = .01).

CONCLUSIONS

In actively proliferating tissues like endometrium, CPF does not correlate with progression to malignancy. In contrast, AI and derived AI/CPF ratios are better indicators of progression. The expression of p53, c-erbB-2, and nuclear bcl-2 in EC correlate with higher cell turnover indices (CPF and AI).

Enhancement of apoptotic susceptibility by interleukin-1 beta in human endometrial epithelial cells

Interleukin-1 (IL-1) is considered to be an essential cytokine for embryonic implantation. Expression of the IL-1 receptor in endometrial luminal epithelium increases maximally in the peri-implantation period, and embryonic implantation in mice is blocked by the IL-1 receptor antagonist. However, the function of IL-1 alone in implantation is still unclear. It has been reported that endometrial epithelial cells undergo apoptosis at the implantation site. In this study we have investigated the regulatory function of IL-1 in endometrial epithelial apoptosis, using the human endometrial epithelial cell line HHUA, which is susceptible to Fas-mediated apoptosis. The enhancement of endometrial apoptosis by IL-1 beta was not accompanied by any increase in cell-surface expression of Fas, which suggested that IL-1 beta enhanced the postreceptor apoptotic signals in the activated cells. IL-1 may be a regulator of apoptotic susceptibility in endometrial epithelium in the peri-implantation period.

Platelet-derived growth factor induces apoptosis in vascular smooth muscle cells: roles of the Bcl-2 family

Apoptosis (programmed cell death) is observed in vascular smooth muscle cells (VSMC) in atherosclerotic lesions and stenotic lesions after injury, and modulates the cellularity of these lesions. It is recognized that cell growth and apoptosis are two linked processes. Platelet-derived growth factor (PDGF) induces VSMC proliferation and migration in vitro. We studied the effect of PDGF on apoptosis in VSMC. Cultured rat VSMC were treated with PDGF-AA or PDGF-BB. PDGF-BB induced cell death in cultured VSMC in a time- and dose-dependent manner, but PDGF-AA did not. Gel electrophoresis of genomic DNA and in situ DNA labeling confirmed that the cell death induced by PDGF-BB is apoptosis. PDGF-BB treatment reduced bcl-2 mRNA and bcl-xl mRNA expression, in contrast, induced bcl-xs mRNA expression, linked with the induction of apoptosis in cultured VSMC.