Alterations in steroid hormone receptors in the tamoxifen-treated endometrium

Effects of ‎tamoxifen on the reproductive system of female breast cancer patients: an ultrasound-based cohort study

Background: Tamoxifen (TMX) is regarded as standard treatment for breast cancer (BC) patients‎. In recent years, several studies have reported gynecological side effects and due to TMX's estrogenic effects. Here, we evaluate the side effects of TMX on the ‎endometrium and ovaries of female BC patients. Methods: This was an ultrasound-based cohort study conducted in three oncology centers in Baghdad, Iraq. A total of ‎‎255 female patients were included, 140 premenopausal (PreM) and 115 postmenopausal (PostM), with estrogen receptor (ER)-positive BC using TMX adjuvant hormonal treatment for at least three months after surgery and adjuvant ‎chemo/radiotherapy.‎ Ultrasound (US) on the endometrium and ovaries of the women following ‎BC surgery/chemotherapy (baseline) and at 3, 6, 12, and 24 months following was performed‎. Data collected included age, menopausal status, co-morbid chronic illness and medications, including duration of TMX treatment. Results: Presence of ovarian cyst was significantly higher in the PreM ‎compared to PostM ‎women, while there were no significant differences for other gynecological findings.‎ At ‎baseline, endometrial thickness (ET) was significantly higher in the PreM compared to the PostM women. In both groups, women with increased ET became more frequent from baseline to 3 ‎months, from 3 to 6 ‎months, from 6 to 12 months, and from 12 ‎ to 24 months. At all time periods, ‎women with increased ET was ‎significantly higher in the PostM compared PreM women, resulting ‎in a risk of ET increase by 6 folds (ranging from 3 – ‎‎11 folds) ‎in PostM compared to PreM women. Conclusions: Longer duration of TMX is associated with increased ET. Duration of TMX did not appear to increase the risk of various gynecological outcomes, for example endometrial cancer rate was low. Finally, there was an increase in ET, which appeared to be six-folds higher in PostM compared to PreM women.‎

Endometrial evaluation by ultrasonography, hysteroscopy and histopathology in cases of breast carcinoma on Tamoxifen therapy

Introduction:

Tamoxifen, a nonsteroidal antiestrogenic agent, is used widely as adjunctive therapy for women with breast cancer. Most studies have found that the increased relative risk of developing endometrial cancer for women taking Tamoxifen is two to three times higher than that of an age-matched population. So we designed this study to assess the endometrial status in patients taking Tamoxifen for breast carcinoma.

Material and Methods:

The study was conducted at Govt. Medical College and Rajindra Hospital, Patiala, India. A total of 50 patients of Ca Breast taking Tamoxifen were selected as per study criterion and TVS performed. If endometrial thickness was more than 5 mm hysteroscopy and endometrial HPE was done and data analysed.

Results:

On ultrasonography 35 patients (70%) had an endometrial thickness up to 5 mm. 15 patients (30%) had an endometrial thickness more than 5mm. Out of these, 11 patients, i.e. 22% of total, had an endometrial thickness of 5.1 to 10 mm and 2 patients, i.e. 4% of total had an endometrial thickness of more than 20 mm. Hysteroscopy was done on 11 patients. Out of these 8 patients had a normal hysteroscopic appearance whereas 3 patients had an abnormal hysteroscopic picture. Endometrial HPE of these 11 patients revealed 2 patients had secretory changes, 1 had polyp change, 1 had atrophic endometrium, 3 had simple endometrial hyperplasia, 1 had endometrial adenocarcinoma and 4 patients were reported to have scanty curetting.

Conclusion:

The duration of Tamoxifen therapy turned out to have a relationship with the incidence of endometrial carcinoma (P < 0.0001). Also, a relationship was observed between the duration of Tamoxifen therapy and symptom status of the patients (P < 0.0001). This correlation did not extend to duration of Tamoxifen therapy and endometrial thickness. (P = 0.190). This correlation did not extend to duration of Tamoxifen therapy and endometrial thickness. (P = 0.190).

Differences in estrogen and progesterone receptor expression in endometrial polyps and atrophic endometrium of postmenopausal women with and without exposure to tamoxifen

Postmenopausal women who use tamoxifen present with an increased incidence of endometrial alterations, such as polyps and hyperplasia, in addition to a higher risk of malignant endometrial neoplasms. Among these endometrial changes, polyps are the most common, with a pathogenesis associated with hormonal influence. The objective of this study was to compare the expression of estrogen receptors (ERs) and progesterone receptors (PRs) in endometrial polyps from tamoxifen users with that in endometrial polyps and the atrophic endometrium of postmenopausal tamoxifen non-users. Among women undergoing surgical hysteroscopy, 84 tamoxifen users with benign endometrial polyps were selected. This group was compared to 84 samples of atrophic endometrium and to 252 benign polyps from postmenopausal women who were not treated with tamoxifen. The expression of ER/PR was assessed by immunohistochemical analysis, according to the percentage of stained cells, intensity of nuclear staining and final score. The polyps from tamoxifen users exhibited a higher expression of ER and PR in the glandular epithelium and stroma compared to the atrophic endometrium (P<0.0001). Compared to the polyps from women not treated with tamoxifen, tamoxifen users exhibited a higher PR expression in the epithelium (P=0.0014) and stroma (P=0.0056), with no difference in the expression of ER. In conclusion, endometrial polyps frequently exhibit an increase in ER expression, regardless of tamoxifen use. High levels of PR expression appear to be consistent with the estrogen agonist effects of tamoxifen.

Acting on Hormone Receptors with Minimal Side Effect on Cell Proliferation: A Timely Challenge Illustrated with GLP-1R and GPER

G protein-coupled receptors (GPCRs) constitute a large family of receptors that sense molecules outside the cell and activate inside signal transduction pathways and cellular responses. GPCR are involved in a wide variety of physiological processes, including in the neuroendocrine system. GPCR are also involved in many diseases and are the target of 30% of marketed medicinal drugs. Whereas the majority of the GPCR-targeting drugs have proved their therapeutic benefit, some of them were associated with undesired effects. We develop two examples of used drugs whose therapeutic benefits are tarnished by carcinogenesis risks. The chronic administration of glucagon-like peptide-1 (GLP-1) analogs widely used to treat type-2 diabetes was associated with an increased risk of pancreatic or thyroid cancers. The long-term treatment with the estrogen antagonist tamoxifen, developed to target breast cancer overexpressing estrogen receptors ER, presents agonist activity on the G protein-coupled estrogen receptor which is associated with an increased incidence of endometrial cancer and breast cancer resistance to hormonotherapy. We point out and discuss the need of pharmacological studies to understand and overcome the undesired effects associated with the chronic administration of GPCR ligands. In fact, biological effects triggered by GPCR often result from the activation of multiple intracellular signaling pathways. Deciphering which signaling networks are engaged following GPCR activation appears to be primordial to unveil their contribution in the physiological and physiopathological processes. The development of biased agonists to elucidate the role of the different signaling mechanisms mediated by GPCR activation will allow the generation of new therapeutic agents with improved efficacy and reduced side effects. In this regard, the identification of GLP-1R biased ligands promoting insulin secretion without inducing pro-tumoral effects would offer therapeutic benefit.

Clinicopathological and molecular analysis of endometrial carcinoma associated with tamoxifen

Use of tamoxifen for treatment and prevention of breast cancer is becoming increasingly common. Tamoxifen has been associated with increased risk of endometrial carcinoma, although the exact mechanism of action is unknown. The aim of our study was to seek a possible correlation between endometrial carcinoma, tamoxifen exposure and MSI, PTEN, beta-catenin and K-ras abnormalities. A group of 18 patients with endometrial carcinoma following treatment with tamoxifen were selected. A control group included 15 patients with endometrial carcinoma and associated ovarian hyperthecosis and one patient with endometrial carcinoma and adult granulosa cell tumor of the ovary, chosen because both conditions are associated with increased production of estrogen and increased risk of endometrial carcinoma development. The second control group included 27 randomly selected consecutive patients with endometrial carcinoma without identifiable associated conditions. Immunostaining for beta-catenin was performed on all cases; DNA was extracted and amplified by PCR with primers for beta-catenin, K-ras and PTEN genes. BAT-25 and BAT-26 were analyzed to assess for MSI. There were 16 endometrioid endometrial carcinomas, one mixed carcinoma and one clear cell carcinoma among patients in the tamoxifen group. All patients with ovarian hyperthecosis and adult granulosa cell tumor had endometrioid endometrial carcinoma. In the random control group, there were 26 endometrioid endometrial carcinomas and one carcinosarcoma. Immunohistochemical and mutational analysis for beta-catenin showed abnormalities in 4/11 (36%) and 3/10 (30%) informative cases in the tamoxifen group; 7/16 (44%) and 4/15 (27%) informative cases, respectively in the ovarian hyperthecosis group and 1/27 random control cases (4%) (P<0.05). Patients with tamoxifen exposure had more K-ras mutations and fewer PTEN mutations and MSI as opposed to controls, but the results were not statistically significant. In conclusion, there was a direct relationship between tamoxifen exposure and overexpression of beta-catenin oncoprotein, which is known to play a major role in the pathogenesis of estrogen-driven, type I endometrial adenocarcinoma.

Effects of tamoxifen and raloxifene on normal human endometrial cells in an organotypic in vitro model

The selective estrogen receptor modulator tamoxifen is widely used in breast cancer therapy though its use is associated with an elevated risk of endometrial carcinoma. An organotypic culture model was employed here to examine the effects of tamoxifen and raloxifene, a related compound with no known adverse uterine effects, on epithelial cells of the premenopausal human endometrium. Changes in the expression levels of the proliferation marker Ki67, and estrogen and progesterone receptors were evaluated. No change in the Ki67 index compared to untreated controls was detected in cultures exposed to tamoxifen or tamoxifen+estradiol. In response to tamoxifen, the level of progesterone receptor-expressing organoids was shown to vary markedly between individual samples, whereas no change in estrogen receptor expression could be demonstrated. A significant decrease in Ki67 expression was observed in raloxifene-exposed cultures. Raloxifene or raloxifene+estradiol had no effect on progesterone receptor expression. The expression of estrogen receptor was markedly inhibited in response to raloxifene or raloxifene+estradiol in all but two samples displaying an intense estrogen receptor labelling. The present observations add to current clinical data on the respective estrogen receptor agonist and antagonist activities of tamoxifen and raloxifene on the human uterus by providing novel insights into the interindividual variation in cellular responses. Our organotypic model may have uses as an alternative to animal experimentation in preclinical screening of the endometrial effects of selective estrogen receptor modulators and may serve as a tool in personalized medicine by identifying patients with an increased risk of developing endometrial pathologies.

Effect of tamoxifen on endometrial histology, hormone receptors, and cervical cytology: a prospective study with follow-up

OBJECTIVES

Our major hypothesis for these studies was that tamoxifen's varied effects on the endometrium might be due in part to differences in effect on estrogen and progesterone receptors [ER, progesterone receptor isoform A (PRA), and progesterone receptor isoform B (PRB)]. We aimed to evaluate the changes in histology in serial endometrial biopsies (Em bx), Papanicolaou smears (Pap smears), and endometrial ultrasounds as well as changes in the expression of ER, PRA, and PRB in response to tamoxifen. We propose that understanding and correlating the dynamics of receptor expression with histologic and cytologic changes will help us better understand the effect of tamoxifen on the endometrium and its role in the development of endometrial carcinoma in some patients.

METHODS

Forty-two patients to be started on tamoxifen underwent a pretreatment Em bx and Pap smear. Follow-up serial Em bxs and Pap smears were obtained at sixth month and then at yearly intervals for up to 6 biopsies per case. Maturation indices (MIs) were determined on the Pap smears, and ER, PRA, and PRB immunostains were performed on the biopsies. Follow-up data is for a maximum of 10 years. Trends in changes in endometrial histology were analyzed and when atrophic or inactive endometrium changed to proliferative endometrium on treatment it was considered to be an increase in estrogen effect and the vice versa changes as a decrease in estrogen effect.

RESULTS

None of the subjects developed hyperplasia or malignancy. Two patients' Em bx demonstrated atypical cells associated with eosinophilic metaplasia, but subsequent biopsies had no atypia. Of the 42 patients, 37 had serial Em bxs in which evaluation for trends could be performed. Twelve of 37 (32.4%) had an overall decrease in estrogen effect on endometrial histology with another 12/37 (32.4%) showing no estrogenic effect on endometrial histology. Six of 37 patients (16.2%) showed an increased estrogen effect on endometrial histology. Seven of 37 (18.9%) had variable endometrial histology with no definable pattern. There was a statistically significant increase in PRA expression compared with baseline as time progressed (P<0.05). The PRB showed a contrasting significant decrease in expression at 2.5 and 3.5 years (P<0.05). There was no significant change in ER expression over the course of the study (P>0.05). Seven of 12 (58.3%) with a decreased estrogenic effect on endometrial histology had a concordant decrease in PRB expression. Seven of 12 (58.3%) with no change in endometrial histology also had a concordant decrease in PRB expression. Comparing the MI of Pap smears with histologic activity of the endometrium revealed minimal correlation between the two. However, in the patients with an increased estrogen effect on endometrial histologic activity, there was no correlation with the MI. Additionally, 57% of patients showed no correlation between endometrial histologic activity and ultrasound findings.

CONCLUSIONS

Tamoxifen had an antiestrogenic or neutral effect on endometrial histology and Pap smears of most subjects, but estrogenic, or variable effects were also observed in a minority of patients. Tamoxifen treatment was accompanied by an uncoupling of the regulation of PRA and PRB expression without effect on ER expression. Overall, expression of PRB decreased whereas that of PRA increased.

Are endometrial polyps from pre-menopausal women similar to post-menopausal women? An immunohistochemical comparison of endometrial polyps from pre- and post-menopausal women

OBJECTIVE

Do endometrial polyps from pre- and post-menopausal women have similar immunohistochemical expression of oestrogen and progesterone receptors (ER, PR) and markers of cellular proliferation/apoptosis (Ki67 and Bcl-2).

DESIGN

Prospective cohort study. Non-parametric statistical analysis was used.

SETTING

Polyps recruited from women attending an out-patient hysteroscopy clinic in a UK district general hospital.

PATIENTS

Fourteen pre-menopausal and 16 post-menopausal women who presented with abnormal bleeding with endometrial polyps.

INTERVENTIONS

Immunohistochemical staining was performed on endometrial polyps.

MAIN OUTCOME MEASURES

Significant differences or correlations between hormone receptor expression (oestrogen and progesterone) and cell growth indices (Ki67 and Bcl-2).

RESULTS

Endometrial polyps from pre- and post-menopausal women had significant differences in their expression of hormone receptors and Ki67. However, polyps from both groups of women had similarly increased levels of Bcl-2, an inhibitor of apoptosis.

CONCLUSIONS

Pre- and post-menopausal polyps exhibit differing hormone receptor and proliferation markers, presumably a result of their hormonal milieu. However, both groups appear to have lost the usual control mechanisms for apoptotic regulation, this appears to be responsible for their growth.

An immunohistochemical comparison of endometrial polyps from postmenopausal women exposed and not exposed to HRT

OBJECTIVE

Our study set out to test the null hypothesis that oestrogen containing continuous combined hormone replacement therapy (HRT) would not affect the hormone receptor expression (oestrogen and progesterone receptors-ER, PR) or markers of cell proliferation/apoptosis (Ki67 and Bcl-2) in endometrial polyps from postmenopausal women exposed and not exposed to HRT.

DESIGN

Immunohistochemical staining for ER, PR, Ki67 and Bcl-2 was performed on polyps obtained from two groups of postmenopausal women.

SETTING

Polyps were obtained from postmenopausal women attending an outpatient hysteroscopy clinic in a district general hospital (Bradford Royal Infirmary, UK).

POPULATION

Twenty-five postmenopausal women presenting with abnormal bleeding subsequently diagnosed with endometrial polyps (16 from women not exposed to HRT, 9 from women exposed to HRT).

METHODS

Semiquantitative immunohistochemistry was performed.

MAIN OUTCOME MEASURES

Significant differences or correlations in either hormone receptor expression or markers of cell proliferation/apoptosis between the two groups of polyps.

RESULTS

There were no significant differences for hormone receptor expression (ER and PR) between endometrial polyps exposed and not exposed to HRT. Bcl-2 expression was higher than Ki67 in both groups, but polyps from HRT users had increased levels reflecting decreased apoptosis in these polyps.

CONCLUSIONS

HRT has no demonstrable effect on polyp ER and PR expression. However, HRT does appear to inhibit apoptosis and cell proliferation in endometrial polyps, which may affect polyp growth.

Does tamoxifen therapy affect the hormone receptor expression and cell proliferation indices of endometrial polyps? An immunohistochemical comparison of endometrial polyps from postmenopausal women exposed and not exposed to tamoxifen

OBJECTIVE

This study set out to test the null hypothesis that tamoxifen therapy would not affect the hormone receptor expression (oestrogen and progesterone receptors-ER and PR) or markers of cell proliferation/apoptosis (Ki67 and Bcl-2) of endometrial polyps from postmenopausal women exposed and not exposed to tamoxifen.

METHODS

Endometrial polyps were prospectively obtained from women presenting with abnormal bleeding attending an out-patient hysteroscopy clinic who subsequently underwent endometrial polypectomy (16 from postmenopausal women not exposed to tamoxifen, 9 from women exposed to tamoxifen). Immunohistochemical staining for ER, PR, Ki67 and Bcl-2 was performed on polyps from both groups of women. Non-parametric statistical analysis was used (Mann-Whitney and Spearmans rank correlation).

RESULTS

Endometrial polyps from tamoxifen users had significantly lower oestrogen receptor but increased progesterone receptor and Bcl-2 expression. There were no significant differences for proliferation markers (Ki67) between postmenopausal endometrial polyps exposed and not exposed to tamoxifen.

CONCLUSIONS

Tamoxifen has a significant affect on hormone receptor expression and markers of apoptosis in endometrial polyps. The results support the hypothesis that tamoxifen promotes polyp growth by inhibiting apoptosis. The mechanism for this does not appear to be oestrogen receptor mediated.

The G protein-coupled receptor GPR30 mediates the proliferative effects induced by 17beta-estradiol and hydroxytamoxifen in endometrial cancer cells

The growth of both normal and transformed epithelial cells of the female reproductive system is stimulated by estrogens, mainly through the activation of estrogen receptor alpha (ERalpha), which is a ligand-regulated transcription factor. The selective ER modulator tamoxifen (TAM) has been widely used as an ER antagonist in breast tumor; however, long-term treatment is associated with an increased risk of endometrial cancer. To provide new insights into the potential mechanisms involved in the agonistic activity exerted by TAM in the uterus, we evaluated the potential of 4-hydroxytamoxifen (OHT), the active metabolite of TAM, to transactivate wild-type ERalpha and its splice variant expressed in Ishikawa and HEC1A endometrial tumor cells, respectively. OHT was able to antagonize only the activation of ERalpha by 17beta-estradiol (E2) in Ishikawa cells, whereas it up-regulated c-fos expression in a rapid manner similar to E2 and independently of ERalpha in both cell lines. This stimulation occurred through the G protein-coupled receptor named GPR30 and required Src-related and epidermal growth factor receptor tyrosine kinase activities, along with the activation of both ERK1/2 and phosphatidylinositol 3-kinase/AKT pathways. Most importantly, OHT, like E2, stimulated the proliferation of Ishikawa as well as HEC1A cells. Transfecting a GPR30 antisense expression vector in both endometrial cancer cell lines, OHT was no longer able to induce growth effects, whereas the proliferative response to E2 was completely abrogated only in HEC1A cells. Furthermore, in the presence of the inhibitors of MAPK and phosphatidylinositol 3-kinase pathways, PD 98059 and wortmannin, respectively, E2 and OHT did not elicit growth stimulation. Our data demonstrate a new mode of action of E2 and OHT in endometrial cancer cells, contributing to a better understanding of the molecular mechanisms involved in their uterine agonistic activity.

Clinicopathologic study of 56 patients with endometrial cancer during or after adjuvant tamoxifen use for their breast cancers

OBJECTIVES

The aim of this study was to describe the clinicopathologic features and prognosis of endometrial cancer patients diagnosed during or after tamoxifen treatment for breast cancer.

METHODS

Fifty-six tamoxifen-related endometrial cancers were identified from 10 hospitals in Japan. Past users were defined as endometrial cancer patients diagnosed more than 12 months after the cessation of tamoxifen treatment for breast cancer. All other users were classified as recent users.

RESULTS

Age at diagnosis of the endometrial cancer ranged from 29 to 81 years. Sixteen (29%) and 19 (34%) patients were nulliparous and overweight, respectively. When the patients were divided into two groups: 30 recent and 26 past users, the distribution of various clinical characteristics, except for age at the time of diagnosis for endometrial cancer and the interval between the diagnoses of two cancers, was similar for two groups. The daily dose, duration and cumulative dose also showed no significant difference between the two groups. Past users had histopathologically more invasive tumors showing prognostically more unfavorable subtypes than recent users. The background lesions including endometrial polyps and diffuse cystic changes were similar for the two groups. The cumulative 3-year survival was significantly worse for past users than for recent users (74.8% and 96.4%, respectively, P < 0.04). In multivariate analysis including recentness of tamoxifen use and age at diagnosis of endometrial cancer, the significance of past user disappeared.

CONCLUSIONS

Past users had a worse prognosis of endometrial cancer with more invasive histologic features than recent users, probably because they included more elderly patients.

LH-RH agonists offer very good protection against the adverse gynaecological effects induced by tamoxifen

This study was initiated to evaluate the efficacy of luteinizing hormone-releasing hormone (LH-RH) agonists in protecting premenopausal patients against the adverse gynaecological effects induced by tamoxifen. Between January 1998 and January 2000, 85 premenopausal breast cancer patients were included in this prospective study. All were to receive LH-RH agonists and tamoxifen for a minimum of two years. All patients underwent a pretreatment gynaecological evaluation and annual follow-up. Bone density was also measured at the start of treatment and then after 2, 3 and 4 years. Pretreatment evaluation revealed 2 polyps. At one and two years of follow-up, no abnormal symptoms were noted and echographic findings were normal. At three years of follow-up, a polyp associated with adnexal masses was discovered. Histology revealed ovarian and endometrial metastases of infiltrating lobular breast carcinoma. Bone density evaluation after 2, 3 and 4 years of treatment showed no significant bone loss. LH-RH agonists offer safe protection against the gynaecological side-effects of tamoxifen in premenopausal breast cancer patients.

Electrospray ionization-tandem mass spectrometry and 32P-postlabeling analyses of tamoxifen-DNA adducts in humans

BACKGROUND

Although the nonsteroidal antiestrogen tamoxifen is used as an adjuvant chemotherapeutic agent to treat hormone-dependent breast cancer and as a chemopreventive agent in women with elevated risk of breast cancer, it has also been reported to increase the risk of endometrial cancer. Reports of low levels of tamoxifen-DNA adducts in human endometrial tissue have suggested that tamoxifen induces endometrial cancer by a genotoxic mechanism. However, these findings have been controversial. We used electrospray ionization-tandem mass spectrometry (ES-MS/MS) and 32P-postlabeling analyses to investigate the presence of tamoxifen-DNA adducts in human endometrial tissue.

METHODS

Endometrial DNA from eight tamoxifen-treated women and eight untreated women was hydrolyzed to nucleosides and assayed for (E)-alpha-(deoxyguanosin-N2-yl)-tamoxifen (dG-Tam) and (E)-alpha-(deoxyguanosin-N2-yl)-N-desmethyltamoxifen (dG-desMeTam), the two major tamoxifen-DNA adducts that have been reported to be present in humans and/or experimental animals treated with tamoxifen, using on-line sample preparation coupled with high-performance liquid chromatography (HPLC) and ES-MS/MS. The same DNA samples were assayed for the presence of dG-Tam and dG-desMeTam by (32)P-postlabeling methodology, using two different DNA digestion and labeling protocols, followed by both thin-layer chromatography and HPLC.

RESULTS

We did not detect either tamoxifen-DNA adduct by HPLC-ES-MS/MS analyses (limits of detection for dG-Tam and dG-desMeTam were two adducts per 10(9) nucleotides and two adducts per 10(8) nucleotides, respectively) or by 32P-postlabeling analyses (limit of detection for both adducts was one adduct per 10(9) nucleotides) in any of the endometrial DNA samples.

CONCLUSION

The initiation of endometrial cancer by tamoxifen is probably not due to a genotoxic mechanism involving the formation of dG-Tam or dG-desMeTam.

Inhibition of tumor-associated fatty acid synthase activity antagonizes estradiol- and tamoxifen-induced agonist transactivation of estrogen receptor (ER) in human endometrial adenocarcinoma cells

Overexpression of the lipogenic enzyme fatty acid synthase (FAS) is a common molecular feature in subsets of sex-steroid-related tumors including endometrium and breast carcinomas that are associated with poor prognosis. Pharmacological inhibition of tumor-associated FAS hyperactivity is under investigation as a chemotherapeutic target. We examined the effects of the mycotoxin cerulenin (a covalent FAS inactivator), and the novel small compound C75 (a slow-binding FAS inhibitor) on estradiol (E2)- and tamoxifen (TAM)-stimulated ER-driven molecular responses in Ishikawa cells, an in vitro model of well-differentiated human endometrial carcinoma. We evaluated the effects of FAS inhibition on E2- and TAM-induced estrogen receptor (ER) transcriptional activity by using transient cotransfection assays with an estrogen-response element reporter construct (ERE-Luciferase). Antiestrogenic effects of cerulenin and C75 were observed by dose-dependent inhibition of E2-stimulated ERE-dependent transcription, whereas FAS inhibitors did not significantly increase the levels of ERE transcriptional activity in the absence of E2. Moreover, pharmacological blockade of FAS activity completely abolished TAM-stimulated ERE activity. To address the reliability of transient transfection assays, the effects of FAS inhibitors on E2-inducible gene products were evaluated. FAS blockade induced a dose-dependent decrease in E2-inducible alkaline phosphatase activity. E2-stimulated accumulation of progesterone receptor (PR) and HER-2/neu oncogene was abolished in the presence of FAS blockers. FAS inhibition also resulted in a marked downregulation of E2-stimulated ERalpha expression, and noticeably impaired E2-induced ERalpha nuclear accumulation. A dose-dependent decrease in cell proliferation and cell viability was observed after FAS blockade. A Cell Death ELISA, detecting DNA fragmentation, demonstrated that FAS inhibitors stimulated apoptosis of Ishikawa cells. The analysis of critical E2- and TAM-related cell cycle proteins revealed an increase of both the expression and the nuclear accumulation of cyclin-dependent kinase inhibitors p21WAF1/CIP1 and p27Kip1 following FAS inhibition. To rule out non-FAS cerulenin- and C75-related effects, we finally monitored ER signaling after silencing of FAS gene expression using the highly sequence-specific mechanism of RNA interference (RNAi). The concentrations of E2 and TAM inducing half-maximal ERE activity (EC50) dramatically increased (>100 times) in FAS RNAi-transfected Ishikawa cells. Moreover, depletion of FAS by RNAi also caused loss of ERalpha expression, downregulation of PR, and accumulation of p21WAF1/CIP1 and p27Kip1 in E2-stimulated Ishikawa cells. If chemically stable FAS inhibitors or cell-selective vector systems able to deliver RNAi targeting FAS gene demonstrate systemic anticancer effects in vivo, our results render FAS as a novel target for the prevention and treatment of endometrial carcinoma.

Hysteroscopically Targeted Biopsies Compared with Blind Samplings in Endometrial Assessment of Menopausal Women Taking Tamoxifen for Breast Cancer

STUDY OBJECTIVE

To determine the validity of tissue sampling accomplished by hysteroscopically targeted or blind biopsies in the assessment of endometrial morbidity associated with tamoxifen treatment.

DESIGN

Retrospective, unrandomized study (Canadian Task Force classification II-2).

SETTING

Public hospital.

PATIENTS

One hundred seventy-six menopausal women who had an endometrial stripe of more than 4 mm on transvaginal ultrasonography.

INTERVENTION

Review of histopathologic reports of patients undergoing hysteroscopy followed by targeted (94 samplings) or blind (82 samplings) endometrial biopsies.

MEASUREMENTS AND MAIN RESULTS

Histopathology was considered the reference test to assess endometrial morbidity, and correlates with hysteroscopic findings were made to evaluate the validity of the two sampling procedures. Overall, in 23 women (13.0%) tissue samples were insufficient for pathologic evaluation. Functional or atrophic endometrium and cystic atrophy were found in 51 (28.8%) and 37 patients (21.0%), respectively. Polyps, hyperplasias, and carcinomas were found in 38 (21.5%), 19 (10.7%), and 6 (3.3%), respectively. Blind biopsies failed to detect 5 of 5 polyps and 33 of 37 cystic atrophies, and in 34.1% of cases provided insufficient tissue for diagnosis; however, no hyperplasias or carcinomas were undetected. All specimens collected under vision were pathologically evaluable; 34 of 38 hysteroscopic reports of cystic atrophy were confirmed, and neither endometrial polyps nor hyperplasias and carcinomas were undetected. In distinguishing between normal and abnormal endometrium, hysteroscopy showed sensitivity and negative predictive value of 100% regardless of sampling modality. We found better specificity (80.0% vs 68.9%) and positive predictive value (68.9% vs 43.7%) for hysteroscopic diagnosis when tissue was collected under vision compared with blind sampling.

CONCLUSION

In women taking tamoxifen, endometrial evaluation performed by blind sampling is safe in excluding hyperplasias or carcinomas. For complete understanding of tamoxifen-associated morbidity, hysteroscopy with sampling under vision has better diagnostic compliance.

K-ras mutation in tamoxifen-related endometrial polyps

BACKGROUND

K-ras mutation is thought to occur at an early stage of neoplastic progression in the endometrium. The authors investigated mutations in codon 12 of K-ras in tamoxifen (TAM)-related endometrial polyps.

METHODS

DNA was extracted from 11 frozen endometrial polyps from TAM-treated patients with breast carcinoma. Mutations were detected using the mutant allele-specific amplification method. The results subsequently were analyzed for correlations with immunohistochemical data that were obtained using antibodies against estrogen receptors (ERs; alpha and beta forms), progesterone receptors (PRs; A and B forms), and Ki-67.

RESULTS

Mutations in codon 12 of K-ras were observed in 7 of 11 TAM-related endometrial polyps. Expression levels of ER-alpha and PR-B were high in the glandular epithelium and low in the stroma. PR-A expression was high in both the glandular epithelium and the stroma. In the glandular epithelium, expression of ER-beta appeared to be lower than expression of ER-alpha. The Ki-67 index in the glandular epithelium ranged from 2 to 38, whereas the index ranged from 0 to 4 in the stroma (P < 0.01).

CONCLUSIONS

The incidence of mutations in codon 12 of K-ras in TAM-related endometrial polyps (64%) was greater than the incidence of these same mutations in sporadic endometrial hyperplasias (4.5-23%). High expression levels of ER-alpha, PR-A, and PR-B in the glandular epithelium were observed in all polyps, regardless of K-ras codon 12 mutation status and Ki-67 index. The authors' findings may support the hypothesis that the polyp-carcinoma sequence partly indicates the development of endometrial carcinoma in postmenopausal women who have been treated with TAM.

Para/autocrine regulation of estrogen receptors in hippocampal neurons

Previous studies have shown that estrogens, originating from ovaries, have a wide variety of estrogen receptor (ER)-mediated effects in the hippocampus. In the present study, we have investigated whether estrogens, which are synthesized in the hippocampus, could induce these effects as well. As a parameter, we used ER expression in response to estrogen synthesis, because estrogen receptors are ligand-inducible transcription factors. The experiments were carried out with cultures of isolated adult rat hippocampal cells, which contained about 95% neurons and about 5% oligodendrocytes in serum-free and steroid-free medium. Hippocampal neurons express both estrogen receptor isoforms (ERalpha and ERbeta), as shown by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. The release of estrogens by hippocampal neurons was quantified by radioimmunoassay (RIA). The ER isoforms (alpha and beta) were studied by semiquantitative immunocytochemical image analysis. Hippocampal cells precultured for 4 days were found to synthesize 17beta-estradiol for the next 8 days. This synthesis was completely inhibited by letrozol, an aromatase inhibitor. Inhibition of estrogen synthesis by letrozol induced a significant decrease in ERalpha expression, but an increase in ERbeta. As a control, supplementation of the medium with 17beta-estradiol resulted in a significant increase of ERalpha expression, whereas ERbeta was downregulated. Our findings provide evidence for a de novo synthesis of estrogens in the hippocampus, differential regulation of estrogen receptor isoforms by estrogen and consequently for a para/autocrine loop of estrogen action in the hippocampus.

The early response of the postmenopausal endometrium to tamoxifen: expression of estrogen receptors, progesterone receptors, and Ki-67 antigen

OBJECTIVE

To enlighten the early response of endometrium to tamoxifen by assessing the expression of estrogen receptors, progesterone receptors, Ki-67, and the histological response in endometria from normal postmenopausal women treated for 21 days with tamoxifen.

DESIGN

A total of 40 women, scheduled to undergo vaginal hysterectomy because of uterine prolapse, were randomly assigned to the tamoxifen group (20 mg/day; 20 women) or the control group (20 women). Samples were obtained from the upper and the lower thirds of the uterine cavity. Standard immunohistochemical staining of estrogen and progesterone receptors and of Ki-67 was performed on frozen sections. Staining was assessed using semiquantitative immunoreactivity scores.

RESULTS

Simple endometrial hyperplasia was diagnosed in 18 of the 20 samples exposed to tamoxifen compared with only 2 of the 20 controls ( P< 0.0005). Staining was increased in both the epithelium and stroma in the tamoxifen samples, a difference that was significant for estrogen receptors in glandular epithelium (180 +/- 80 v 110 +/- 110; P< 0.05). Also, Ki-67 antigen was expressed more frequently in both glandular epithelium ( P< 0.05) and stroma ( P< 0.05) in the tamoxifen samples.

CONCLUSIONS

Tamoxifen rapidly up-regulated the cell proliferation markers, an effect that was associated with enhanced growth as confirmed by increased expression of estrogen receptors and Ki-67, in addition to a high incidence of glandular hyperplasia.

Effect of long-term treatment with steroid hormones or tamoxifen on the progesterone receptor and androgen receptor in the endometrium of ovariectomized cynomolgus macaques

The progesterone receptor (PR) and androgen receptor (AR) belong to the nuclear receptor superfamily. Two isoforms of PR (A and B) have been identified with different functions. The expression of AR, each isoform of PR and their involvement in long-term effects on the endometrium after hormonal replacement therapy (HRT) or tamoxifen (TAM) treatment is not known. The aims of this study were to determine PR(A+B), PRB and AR distribution by immunohistochemistry in the macaque (Macaca fascicularis) endometrium. Ovariectomized (OVX) animals were orally treated continuously for 35 months with either conjugated equine estrogens (CEE); medroxyprogesterone acetate (MPA); the combination of CEE/MPA; or TAM. Treatment with CEE/MPA tended to down-regulate PR in the superficial glands, but increased it in the stroma. TAM treatment increased both the PR and PRB levels in the stroma. Overall, less than 20% of the cells were positive for the PRB isoform and less variation was observed after steroid treatment. AR was found in the stroma, mainly distributed in the basal layer of the endometrium in the OVX and steroid treated groups, but was absent in the TAM treated group. No AR was found in the glandular epithelium. The present data show that long-term hormone treatment affects the PR level, and also the ratio between PRA and PRB in the endometrium.

The effects of tamoxifen on proliferation and steroid receptor expression in postmenopausal endometrium

AIM

To study the effects of tamoxifen on the proliferation index and oestrogen receptor (ER) and progesterone receptor (PR) expression in postmenopausal endometrium.

METHODS

A total of 125 endometrial specimens of postmenopausal women, comprising benign endometria from tamoxifen users (n = 35) and non-users (n = 24), and endometrial cancer from tamoxifen users (n = 15) and non-users (n = 51), were immunohistochemically examined using MIB-1, anti-ER, and anti-PR antibodies in endometrial epithelium and stroma.

RESULTS

In benign endometrium the mean MIB-1 index in the epithelium was higher in tamoxifen users than in non-users (mean, 13% (SD, 13%) v mean, 2% (SD, 2%); p < 0.05), whereas in endometrial cancer the MIB-1 index was higher, but similar in tamoxifen users and non-users (mean, 32% (SD, 24%) and mean, 35% (SD, 18%)). The expression of ER was comparably high in benign epithelium from tamoxifen users and non-users (97% and 92%, respectively), but in endometrial cancer it was lower in tamoxifen users (60% and 88%; p < 0.05). The expression of PR in stromal cells was higher in tamoxifen users, both in benign (84% v 54%) and in malignant endometrium (33% v 10%; p < 0.05).

CONCLUSION

The proliferation index (as measured by MIB-1) in benign endometrial epithelium is higher in tamoxifen users than in non-users, and this might play a role in the reported higher incidence of endometrial cancer in postmenopausal tamoxifen users. The increased expression of PR in stroma from tamoxifen users with both benign and malignant endometrium demonstrates an additional oestrogenic effect of tamoxifen on the endometrial stroma.

Tamoxifen regulates human telomerase reverse transcriptase (hTERT) gene expression differently in breast and endometrial cancer cells

Tamoxifen is widely applied as an antiestrogenic agent for adjuvant therapy in the treatment of breast cancer, while its estrogen-agonistic activity occasionally causes proliferative disorders or carcinogenesis at other sites, such as the uterus. We reported that estrogen activates telomerase in breast and endometrial cancer cells. The present study examines the effects of tamoxifen on the gene expression of human telomerase reverse transcriptase (hTERT) in breast and endometrial cancer cells. Tamoxifen inhibited the cell growth of MCF-7 cells, as well as hTERT mRNA expression in the presence of estrogen (E2), antagonizing the E2 effects. In contrast, tamoxifen stimulated the growth of Ishikawa cells and activated hTERT mRNA expression in the absence or presence of E2, exhibiting estrogen-agonistic action. Transient expression assays revealed that these actions of tamoxifen are achieved by transcriptional regulation of the hTERT promoter. An estrogen responsive element (ERE) in the hTERT 5' regulatory region was partly responsible for both the E2-antagonistic and -agonistic actions of tamoxifen. Tamoxifen activated the MAP kinase cascade in Ishikawa cells, but not in MCF-7 cells, and the activation of hTERT mRNA expression was effectively blocked by MEK inhibitor, suggesting that the MAP kinase pathway is involved in the tamoxifen-induced activation of hTERT. These findings indicate that tamoxifen regulates hTERT expression in a cell-type specific manner. Tamoxifen-induced activation of hTERT may be one component of estrogen agonistic function of tamoxifen that is involved in endometrial carcinogenesis induced by this agent.

Estrogen replacement therapy induces telomerase RNA expression in the macaque endometrium

OBJECTIVE

To evaluate the effects of hormonal therapies on the expression of telomerase RNA (TRNA) in the endometrium of ovariectomized female cynomolgus macaques (Macaca fascicularis).

DESIGN

Randomized long-term experimental trial.

SETTING

Animal study at an academic research institution.

PATIENT(S)

Surgically postmenopausal cynomolgus macaques.

INTERVENTION(S)

Treatments were given in the diet for three years and included conjugated equine estrogens (CEE), CEE + medroxyprogesterone acetate (MPA), and tamoxifen, at clinically relevant doses.

MAIN OUTCOME MEASURE(S)

Expression of TRNA within the basal glands, basal stroma, superficial glands, and superficial stroma of the endometrium by radiolabeled in situ hybridization.

RESULT(S)

Conjugated equine estrogens increased glandular TRNA expression, and the addition of MPA decreased this effect. Tamoxifen induced glandular TRNA expression to a lesser degree. Both CEE + MPA and tamoxifen increased stromal TRNA expression. The expression of TRNA in the endometrial glands was always greater than TRNA expression in the stroma. Treatment groups with greater proliferation and progesterone receptor expression also had elevated TRNA; within-group correlations were not significant. No statistically significant difference occurred between the basal and superficial endometrial layers.

CONCLUSION(S)

These results show for the first time a cell-specific hormonal regulation of TRNA in the primate endometrium, with up-regulation of TRNA by treatments associated with increased risk of endometrial cancer in women.

Assessment of hormonally active agents in the reproductive tract of female nonhuman primates

Using the ovariectomized macaque model of postmenopausal women's health, we investigated the effects of long-term treatments (5 weeks-3 years) with estradiol, conjugated equine estrogens (CEE), esterified estrogens, progestins such as medroxyprogesterone acetate (MPA) and nomegestrol acetate, CEE + MPA, tamoxifen, soybean phytoestrogens (SPEs), a variety of putative selective estrogen receptor modulators (SERMs), and androgens. Agents tested were selected on the basis of beneficial effects on arteries and/or bone. Doses were scaled on a caloric or serum-concentration basis to approximate human clinical doses. We evaluated endometrial and mammary gland histopathology and morphometry and used immunohistochemistry to evaluate cell proliferation and expression of estrogen receptor alpha and progesterone receptor (PR). Both estradiol and CEE induced endometrial hyperplasia. MPA antagonized epithelial proliferation induced by CEE in endometrium and induced pseudodecidual stromal hyperplasia in some animals. Tamoxifen induced endometrial polyps, cystic hyperplasia, stromal fibrosis, and PR expression but not Ki-67 expression. SPEs were not estrogenic at dietary doses and antagonized estrogen-induced proliferation in the endometrium and breast. Nandrolone induced mucometra and an adenomyosis-like change. The potential SERM 17 alpha dihydroequilenin did not have uterotrophic or mammotrophic effects. In general, experimental findings in macaques have been predictive of outcomes in human clinical trials of the same agents.

Does tamoxifen change oestrogen and progesterone receptor expression in the endometrium and breast?

We studied the expression of oestrogen and progesterone receptors (ER, PR) in postmenopausal women receiving tamoxifen for breast cancer. In addition the literature addressing the question of ER and PR expression in breast tissue during treatment with tamoxifen was reviewed. We demonstrated consistent expression of ER and PR in endometria from patients receiving tamoxifen, with a trend towards a higher proportion of receptor positive specimens during tamoxifen. In breast cancer tissue, the ER content seemed to be reduced following tamoxifen treatment. After short time exposure to tamoxifen, the PR appeared to be increased, longer treatment caused the PR to go down to pretreatment levels or below.

Surveillance for endometrial cancer in women receiving tamoxifen

Recent studies showing a protective effect of tamoxifen in women at high risk for breast cancer have expanded the indications of the drug. While acting as an estrogen antagonist in the breast, tamoxifen can have estrogenic effects on the endometrium; consensus opinion is that tamoxifen increases the risk for endometrial cancer. Because an increasing number of women are taking tamoxifen, a strategy for gynecologic surveillance is needed. Studies examining the relation between risk for endometrial cancer and tamoxifen use have conflicting results. However, because of an overall interpretation that tamoxifen use slightly increases risk for endometrial cancer, some researchers advocate routine ultrasonography and endometrial biopsy for screening asymptomatic women receiving tamoxifen. This paper reviews the literature on endometrial cancer in women taking tamoxifen and the usefulness of various screening methods in this setting. Risk factors and screening criteria for endometrial cancer in the general population are discussed, and a strategy for surveillance of women taking tamoxifen is proposed. Patients should be screened for signs or symptoms of endometrial abnormality before taking tamoxifen. This evaluation, which should include a careful history, pelvic examination, and Papanicolaou smear, should be repeated annually while the patient is receiving tamoxifen. Although transvaginal ultrasonography is not recommended for routine screening, it is indicated if an adequate pelvic examination cannot be performed or if additional risk factors are present. The likelihood of abnormality is greater for patients who have abnormal bleeding, discharge, abnormal glandular cells on Papanicolaou smear, or an endometrial measurement on ultrasonography of more than 8 mm; these findings should prompt an aggressive evaluation of the endometrium.

Hormonal treatment of endometrial cancer

This article summarizes the endocrine background of women with endometrial cancer at both peripheral and tissue levels, and the current status of clinical trials of hormonal, cytotoxic, and combination regimens. Because significant advances in systemic therapy are required to improve the prognosis of endometrial cancer, recommendations for future clinical investigations will be based on these recent biologic observations.

Estrogen response elements can mediate agonist activity of anti-estrogens in human endometrial Ishikawa cells

Anti-estrogens like hydroxytamoxifen (OHT) have mixed agonist/antagonist activities, leading to tissue-specific stimulation of cellular proliferation. Partial agonist activity of OHT can be observed in vitro in endometrial carcinoma cells like Ishikawa. Here, we have compared several anti-estrogens (including extensively characterized OHT and pure anti-estrogens such as ICI164, 384 and RU58,668, which are devoid of uterotrophic activity) for their capacity to stimulate promoters containing estrogen response elements (EREs) or AP1-binding sites (12-O-tetradecanoylphorbol-13-acetate response elements, TREs), the two types of DNA motifs known to mediate transcriptional stimulation by estrogen receptors. Assays were performed in Ishikawa cells either by transient transfection or by using cell lines with stably propagated reporter vectors. In transient transfection experiments, none of the anti-estrogens displayed agonist activity on the promoters tested. In contrast, significant transcriptional stimulation was observed with low concentrations of OHT and RU39,411 in Ishikawa cells stably propagating reporter constructs containing a minimal ERE3-TATA promoter. In addition, micromolar concentrations of OHT, but not of RU39,411, stimulated stably propagated AP1-responsive reporter constructs. No transcriptional stimulation of ERE- or TRE-containing promoters was observed with the pure anti-estrogens ICI164,384 and RU58,668. These results indicate that the presence of estrogen response elements in promoters is sufficient to mediate cell-specific agonism of anti-estrogens at the transcriptional level, and that stimulation of AP1 activity may be restricted to a subset of anti-estrogens possessing agonist activity on EREs. In addition, our results suggest that transient transfections do not fully recapitulate in vivo conditions required to observe agonist activity of anti-estrogens.

Controversies regarding tamoxifen and uterine carcinoma

An increasing number of cases of endometrial cancer in women receiving tamoxifen have been reported but most are from non-randomized studies and case reports. In the last year, there have been no further results either confirming or disproving an association between tamoxifen and endometrial cancer from randomized controlled studies in breast cancer patients and those participating in chemopreventative trials with tamoxifen. Several papers have examined the possible mechanisms behind tamoxifen's endometrial effects.