Proliferative Effects Of Estrogen Research Articles

ATM suppresses c-Myc overexpression in the mammary epithelium in response to estrogen

ATM gene mutation carriers are predisposed to estrogen-receptor-positive breast cancer (BC). ATM prevents BC oncogenesis by activating p53 in every cell; however, much remains unknown about tissue-specific oncogenesis after ATM loss. Here, we report that ATM controls the early transcriptional response to estrogens. This response depends on topoisomerase II (TOP2), which generates TOP2-DNA double-strand break (DSB) complexes and rejoins the breaks. When TOP2-mediated ligation fails, ATM facilitates DSB repair. After estrogen exposure, TOP2-dependent DSBs arise at the c-MYC enhancer in human BC cells, and their defective repair changes the activation profile of enhancers and induces the overexpression of many genes, including the c-MYC oncogene. CRISPR/Cas9 cleavage at the enhancer also causes c-MYC overexpression, indicating that this DSB causes c-MYC overexpression. Estrogen treatment induced c-Myc protein overexpression in mammary epithelial cells of ATM-deficient mice. In conclusion, ATM suppresses the c-Myc-driven proliferative effects of estrogens, possibly explaining such tissue-specific oncogenesis.

Tumor board presentation of a woman with metastatic, hormone receptor‐positive, mismatch repair‐deficient endometrial cancer

Tumor board presentation of a woman with metastatic, hormone receptor‐positive, mismatch repair‐deficient endometrial cancer

Progesterone and endometrial cancer

It is well established that unopposed estrogen, either endogenous or therapeutic, can induce endometrial hyperplasia and potentially endometrial cancer (EC). Anovulatory cycles, obesity, and insulin resistance are major risk factors for EC. Progestogen (progesterone and progestin), including levonorgestrel intrauterine device, are able to prevent or to treat hyperplasia, atypical hyperplasia, and even well-differentiated EC, as presented in this review. During menopausal hormone therapy, progestogens protect the endometrium against the proliferative effects of estrogens in women with a uterus. Whereas, recent epidemiologic data suggest that micronized progesterone (MP) is apparently safer for the breast, it could be less efficient than synthetic progestin on the endometrium. However, several studies from biopsies during treatment with MP do not show any increased risk of hyperplasia. Lack of compliance could explain the results on EC.

Prevalence of Breast Benign Findings in Women Residing in an Area of Chronic Exposure to HCH, DDT and Dioxin

Organochlorine compounds are known for their hormone-active properties, with emphasis on their performance as environmental estrogens. It is discussed whether its prolonged action in the body could lead to lesions in the breast tissue associated with the proliferative effect of estrogens on the epithelial cells of the breast. This study aimed to estimate the occurrence of benign breast diseases (BBD) in women living in an area with a history of chronic exposure to Hexachloroexan, DDT and Dioxin. A cross - sectional study was carried out in Cidade dos Meninos (CM), a district located in the municipality of Duque de Caxias (MDC), State of Rio de Janeiro - Brazil. Women 35 years of age or older residing on the site were eligible for the study. Mammography and / or ultrasound examinations were performed for investigation and categorization according to the Birads classification. We compared the mammographic findings classified in categories 2, 3 and 4 with the results classified in category 1 (without findings). The results obtained in this study population were compared with the results of the Municipality of Duque de Caxias, which were obtained through the SISMAMA / DATASUS data from July 2014 to July 2015, equivalent to the period of data collection in the exposed population . For this comparison the ratios of ratios and 95% confidence interval (95% CI) were used. A total of 111 women aged 35-79 years (M - 52 years; SD - 10.6) participated in the study. The prevalence of BBD was higher in the study population compared to MDC (OR = 1.49 - 95% CI 1.305 - 1.699). The results of the comparison of the study population with the municipality of Duque de Caxias suggest a higher prevalence of DBM in the studied population, corroborating with the hypothesis of association of the exposure to the occurrence of proliferative DBM.

Abstract 2243: Elucidating the mechanism of action of molecular iodine on breast cancer cells

Abstract Each year, over 1.7 million women are diagnosed with breast cancer worldwide and about 35% of these diagnosed are expected to die from the disease. A significant barrier to improving treatment of breast cancer lies in our incomplete understanding of breast cancer initiation and metastasis. Regular use of molecular iodine has been shown to reduce the sensitivity of breast cells to the proliferative effects of estrogen, resulting in normalization of breast tissue.The aim of the current study was to evaluate the mechanisms of molecular iodine on two common breast cancer sub-types using well-established breast cancer cell lines. In order to study Luminal A and triple-negative breast cancer in vitro, MCF7 (cells from a luminal A subtype) and MDA-MB231 (cells from a triple-negative subtype), were treated with molecular iodine at various concentrations to measure proliferation and cell death. This was subsequently followed by gene expression analysis of key important molecular markers, which are primarily responsible for cell growth and apoptosis. Primary human mammary epithelial cells derived from healthy female donor were used as an internal control. Data from this study indicated that molecular iodine had potent inhibitory effects on cell growth and showed a dramatic increase in cell death in both breast cancer cell lines. Gene expression analysis using quantitative RT-PCR further confirmed that cell cycle genes controlling G1-S phase transition were largely up-regulated. Changes were not seen in Cyclin B expression levels, which further suggest that cells were arrested before entry into cell division. BCL-2, PPAR-α and PPAR-γ were also up-regulated along with down-regulation of Caspase 3, suggesting molecular iodine induced cell death through activation of a caspase-independent apoptosis pathway. Interestingly, mesenchymal-epithelial transition (MET) occurrence was noticed upon molecular iodine treatment as indicated by sharp increase of GATA3 and E-Cadherin and significant down-regulation of Vimentin in invasive MDA-MB231 cells. Our current study enables us to understand a molecular mechanism controlling tumor cell growth and demonstrates potent cellular effects of molecular iodine on breast cancer cell lines. These results also demonstrate promising effects of molecular iodine for regulation of breast cancer EMT differentiation, which is required for tumor initiation and metastasis. Further studies are underway to determine possible effects of molecular iodine in these breast cancer subtypes using in vitro 3D models. Note: This abstract was not presented at the meeting. Citation Format: Zack Xu, Xin Chen, Noymi Yam, kin Chan, Usha Nagavarapu. Elucidating the mechanism of action of molecular iodine on breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2243. doi:10.1158/1538-7445.AM2017-2243

GPER mediates estrogen-induced signaling and proliferation in human breast epithelial cells and normal and malignant breast.

17β-Estradiol (estrogen), through receptor binding and activation, is required for mammary gland development. Estrogen stimulates epithelial proliferation in the mammary gland, promoting ductal elongation and morphogenesis. In addition to a developmental role, estrogen promotes proliferation in tumorigenic settings, particularly breast cancer. The proliferative effects of estrogen in the normal breast and breast tumors are attributed to estrogen receptor α. Although in vitro studies have demonstrated that the G protein-coupled estrogen receptor (GPER, previously called GPR30) can modulate proliferation in breast cancer cells both positively and negatively depending on cellular context, its role in proliferation in the intact normal or malignant breast remains unclear. Estrogen-induced GPER-dependent proliferation was assessed in the immortalized nontumorigenic human breast epithelial cell line, MCF10A, and an ex vivo organ culture model employing human breast tissue from reduction mammoplasty or tumor resections. Stimulation by estrogen and the GPER-selective agonist G-1 increased the mitotic index in MCF10A cells and proportion of cells in the cell cycle in human breast and breast cancer explants, suggesting increased proliferation. Inhibition of candidate signaling pathways that may link GPER activation to proliferation revealed a dependence on Src, epidermal growth factor receptor transactivation by heparin-bound EGF and subsequent ERK phosphorylation. Proliferation was not dependent on matrix metalloproteinase cleavage of membrane-bound pro-HB-EGF. The contribution of GPER to estrogen-induced proliferation in MCF10A cells and breast tissue was confirmed by the ability of GPER-selective antagonist G36 to abrogate estrogen- and G-1-induced proliferation, and the ability of siRNA knockdown of GPER to reduce estrogen- and G-1-induced proliferation in MCF10A cells. This is the first study to demonstrate GPER-dependent proliferation in primary normal and malignant human tissue, revealing a role for GPER in estrogen-induced breast physiology and pathology.

ERβ Selective Agonist Inhibits Angiotensin-Induced Cardiovascular Pathology in Female Mice

Cardiac hypertrophy in humans can progress to cardiac failure if the underlying impetus is poorly controlled. An important direct stimulator of hypertrophy and its progression is the angiotensin II (AngII) peptide. AngII also causes hypertension that indirectly contributes to cardiac hypertrophy. Others and we have shown that estrogens acting through the estrogen receptor (ER)-β can inhibit AngII-induced or other forms of cardiac hypertrophy in mice. However, the proliferative effects of estrogen in breast and uterus that promote the development of malignancy preclude using the steroid to prevent cardiac disease progression. We therefore tested whether an ERβ selective agonist, β-LGND2, can prevent hypertension and cardiac pathology in female mice. AngII infusion over 3 weeks significantly stimulated systolic and diastolic hypertension, cardiac hypertrophy, and cardiac fibrosis, all significantly prevented by β-LGND2 in wild-type but not in ERβ genetically deleted mice. AngII stimulated the Akt kinase to phosphorylate and inhibit the glycogen synthase kinase-3β kinase, leading to GATA4 transcription factor activation and hypertrophic mRNA expression. As a novel mechanism, all these actions were opposed by estradiol and β-LGND2. Our findings provide additional understanding of the antihypertrophic effects of ERβ and serve as an impetus to test specific receptor agonists in humans to prevent the worsening of cardiovascular disease.

Abstract 1307: Enhancing hormone therapy in endometrial cancer by differentially targeting epigenetic repression of progesterone receptor expression.

Abstract Endometrial cancer, the most common gynecological cancer in women worldwide, has a worse relative five year survival rate today than in 1975, signifying the urgent need for innovative new treatment strategies. Endometrial cancer is a hormonally-regulated disease in which progesterone counters the proliferative effect of estrogen. Response to progestin-based therapy strongly correlates with expression of progesterone receptor (PR). However, many endometrial tumors have low levels or loss of PR, which limits the clinical application of progestin-based therapy. Using endometrial cancer cell lines with variable expression of endogenous PR, our objectives are to 1) understand the epigenetic mechanisms by which PR is suppressed in different endometrial tumor types, and 2) apply clinically-relevant strategies to restore functional PR expression and amplify efficacy of progestin therapy. In well-differentiated type I endometrial cancer cells with modest baseline PR expression, we found that a component of the polycomb-repressor complex (PRC) mediated PR transcriptional suppression through binding to the PRB promoter. Treatment with histone deacetylase inhibitors (HDACi) effectively reversed this transcriptional repression as evidenced by a 10-fold increase in PR mRNA levels. On the contrary, PRC did not occupy the PRB promoter in poorly-differentiated type II endometrial cancer cells devoid of PR expression, and HDACi had no impact on PR expression in these cells. Rather, PR expression was permanently repressed by DNA methylation as demonstrated by direct methylation-specific DNA sequencing. In addition, histone H3 in the PRB promoter region was methylated in these PR-negative cell lines, providing further support for PR transcriptional suppression. This “permanent” suppression could be partially overcome with DNA methyltransferase inhibitors (DNMTi). Importantly, the restored PR in both well-differentiated and poorly-differentiated endometrial cancer cells was functional as a progesterone-activated transcription factor as demonstrated by nuclear localization of PR, increased transcription of multiple PR target genes, and cell cycle arrest. Our findings reveal that, depending on the mechanism of PR transcriptional suppression, epigenetic modulation restores endogenous PR expression and progesterone-mediated activation in endometrial cancer cell lines. Ongoing studies are confirming that sensitivity to progestin therapy can be restored with epigenetic modulators in human-in-mouse xenograft models. This preclinical study provides the foundation for future clinical trials in which strategies to re-establish functional PR expression are anticipated to resensitize endometrial tumors to progestin therapy. Citation Format: Shujie Yang, Yichen Jia, Xiaoyue Liu, Xue Xaio, Yuping Zhang, Eric J. Devor, Xiangbing Meng, Kimberly K. Leslie. Enhancing hormone therapy in endometrial cancer by differentially targeting epigenetic repression of progesterone receptor expression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1307. doi:10.1158/1538-7445.AM2013-1307

Abstract 2253: New targets of mTORC1 pathway in ER-positive cells

Abstract mTOR complex 1 (mTORC1) regulates protein translation, autophagy, and cell growth. These cellular functions are often dysregulated in cancer, therefore identification of mTORC1 targets in control of these processes is of great interest for development of targeted cancer therapies. While rapamycin shown an effect in early clinical trials, the effectiveness of rapamycin in treatment of breast cancer has been variable. Estrogen receptor (ER) ≤ mediates the proliferative effects of estrogen and represents an important clinical target in treatment of ER-positive cancers. Tamoxifen is an anti-estrogen that has become the standard agent for the treatment of ER-positive breast cancer, where it acts as an antagonist. However, resistance to tamoxifen, and other endocrine or anti-estrogen therapies develops in many cases. One mechanism by which resistance develops is through phosphorylation of ERα, allowing it to act in estrogen-independent manner. Phosphorylation of Ser118 and Ser167 is important for transcriptional activity of ERα. The regulation of these sites is complex, involving inputs from the mTOR and MAPK signaling pathways. Importantly, ERα phosphorylation correlates with resistance to tamoxifen, and is a prognostic marker for disease progression and survival. Therefore, the goal of our study is to identify new targets of mTORC1 pathway important for growth and proliferation of ER-positive cells. Thus, inhibition of downstream components of the mTORC1 pathway together in combination with anti-estrogen therapy may prove to be an effective strategy in treatment of ER-positive cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2253. doi:1538-7445.AM2012-2253

Expression pattern of GPR30 in endometriosis

Introduction: G-protein coupled receptor 30 (GPR30) is a seven-transmembrane receptor suggested to be part of non-genomic estrogen responses that can, in contrast to the classic or genomic mode of ER action, occur rapidly within minutes. GPR30 mediated estrogen action is involved in multiple physiological processes, as well as pathological processes, as for example the proliferative effects of estrogen and tamoxifen in endometrial cancer cells. Since Estrogen action plays a key role in endometriosis and is partly mediated by GPR30 in a various number of physiological and pathological processes, the investigation of its expression in endometriosis could be of particular interest.

Abstract 271: Rapid regulation of ion channel KCNK5 by ERα in breast cancer cell lines MCF-7 and T47D promotes cell proliferation

Abstract Many human breast tumors rely on the proliferative effect of estrogen to propagate. Estrogenic compounds, such as the endogenous ligand 17β-estradiol, signals in various manners, most prominently through the estrogen receptors (ERs). The ERs – alpha and beta, respectively – are transcription factors belonging to the superfamily of nuclear receptors. They act by genomical and non-genomical mechanisms in a ligand-dependent as well as -independent manner, exerting ligand-, promoter- and tissue-specific transcriptional programs. Due to the proliferative effect of ERα in breast it is an important factor in tumor progression. ERα is used clinically as a biomarker and is therapeutically targeted by treatment with antagonistic compounds, for instance tamoxifen. Although extensively studied, the mechanism by which ERα promotes proliferation remains to be fully established. Here we present the finding that ERα rapidly upregulates the potassium ion channel KCNK5 (TASK-2, K2P5.1) in human breast cancer cell lines MCF-7 and T47D. ERα binds at the enhancer of the KCNK5 gene upon estrogen stimulation, subsequently inducing increases in transcript and protein levels of KCNK5. The observed upregulation was strikingly quick, with a sharp peak within one to two hours, before leveling off. Protein levels, however, did not increase until after 12 hours. Treatment with compounds antagonizing ERα transactivation efficiently suppressed this upregulation, further supporting the notion of direct ERα regulation, as compared to non-genomic signaling. Estrogen treatment also increased KCNK5 currents in both cell lines. Various roles for potassium channels in cancer cells have previously been suggested, as for example proliferative, metastatic and anti-apoptotic factors. Knockdown of KCNK5 by siRNA in MCF-7 and T47D cells decreased their proliferation. Additionally, in T47D cells, the estrogen-induced proliferation was repressed when KCNK5 was silenced. This prompts further studies to understand the role of KCNK5 in the proliferation of breast cancer cells and clinical relevance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 271. doi:10.1158/1538-7445.AM2011-271

Abstract 1201: Role of the chemokine CXCL12 in the estrogen response of breast cancer cells

Abstract The purpose of this study was to investigate the extent to which CXCL12 mediates the effects of estrogen in estrogen-responsive breast cancer cells. Expression microarray studies have identified CXCL12 as a gene regulated consistently by estrogen in estrogen-responsive breast cancer cells in our own and other laboratories and it has been reported that CXCL12 mediates the proliferative effects of estrogen. CXCL12 activates two seven transmembrane G protein-coupled receptors, CXCR4 and CXCR7, that transducer signals via heterotrimeric G-proteins. CXCR4 has long been accepted, whereas CXCR7 was identified more recently as a potential CXCL12 receptor. Methods: Expression of CXCL12, CXCR4 and CXCR7 was measured in five estrogen-responsive and five estrogen-nonresponsive breast cancer cell lines by qRT-PCR and western transfer analysis. The effects of CXCL12 on proliferation of the cells were assessed by DNA quantification and on migration in a modified Boyden chamber assay. The ability of CXCL12 to activate the downstream signalling molecules, MAPK and Akt, was measured by western transfer analysis with a phospho-specific antibodies. The motogenic responses of different breast cancer cell lines to CXCL12 were measured in modified Boyden chamber and in vitro wounding assays. The relative importance of CXCR4 in the CXCL12 response was probed with a specific inhibitor of CXCR4 receptor. Results: The expression of CXCL12, CXCR4 and CXCR7 varied greatly between the ten breast cancer cell lines analyzed. CXCL12 expression was highest in estrogen-responsive T-47D cells whereas CXCR4 and CXCR7 expression was highest in estrogen-nonresponsive MDA-MB-231 cells. CXCL12 was detected after secretion into medium conditioned by T-47D and MCF-7 breast cancer cells. CXCL12 did not stimulate the proliferation of MCF-7 or T-47D cells in the absence or presence of estrogen. CXCL12 did stimulate breast cancer cell migration in a concentration-dependent manner and cells that express high concentrations of the CXCL12 receptor were more responsive to CXCL12. CXCL12 stimulated Phosphorylation of both MAPK and Akt in estrogen-responsive and non-responsive breast cancer cells. Conclusion: This study shows that CXCL12 does not mediate the proliferative effects of estrogen on breast cancer cells. CXCL12 does however stimulate the migration of both estrogen-responsive and estrogen non-responsive breast cancer cells. CXCL12 mediates it effects in breast cancer cells by activation on both the MAPK and Akt signal transduction pathways. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1201. doi:10.1158/1538-7445.AM2011-1201

Abstract 2894: Co-regulatory relationship between estrogen receptor alpha and the mTOR/S6K1 signaling pathways

Abstract ERα mediates the proliferative effects of estrogen and represents an important clinical target in treatment of breast cancer. Tamoxifen is an anti-estrogen that has become the standard agent for the treatment of ER-positive breast cancer, where it acts as an antagonist. However, resistance to tamoxifen, and other endocrine or anti-estrogen therapies develops in many cases. One mechanism by which resistance develops is through phosphorylation of ERα, allowing it to act in estrogen-independent manner. Phosphorylation of Ser118 and Ser167 is important for transcriptional activity of ERα. The regulation of these sites is complex, involving inputs from the mTOR and MAPK signaling pathways. Importantly, ERα phosphorylation correlates with resistance to tamoxifen, and is a prognostic marker for disease progression and survival. Thus, the mechanism of these phosphorylation events, as well as the identity of the kinases responsible may have important clinical consequences. In this study we demonstrate that the mTOR/S6K1 pathway controls activation of ERα by phopshorylating it on these two critical residues. Chromosomal region 17q23 containing the RPS6KB1 gene is frequently amplified in breast cancer cells, and S6K1 is overexpressed in about 30% of cases. Overexpression of S6K1 correlates with increased rapamycin sensitivity. The role of S6K1 in disease development and progression is supported by the observation that S6K1 overexpression is associated with poor prognosis in breast cancer patients. However, the reason for high-level amplification of the RPS6KB1 gene specifically in breast cancer, and not other cancer types is not well understood. In this study, we demonstrate that in response to estrogen activation, ERα activates expression of S6K1 by upregulating transcription of the RPS6KB1 gene. Increased levels of S6K1 promote further phosphorylation and activation of ERα, creating a positive feed-forward loop. We hypothesize that this relationship promotes breast cancer cell growth, thus providing a selective advantage to S6K1- and ERα-overexpressing cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2894. doi:10.1158/1538-7445.AM2011-2894

Abstract 1829: Measures of body size and the risk of microsatellite stable and unstable molecular subtypes of sporadic endometrial cancer

Abstract Introduction: Obesity is an established risk factor for endometrial cancer, but its association with microsatellite stable (MSS) and microsatellite instable (MSI) endometrial cancer is not well understood. Therefore, we evaluated the risk for sporadic MSI and MSS endometrial cancers associated with various measures of body size in a population-based case control study. Methods: The study included 126 MSI and 311 MSS incident invasive endometrial cancer cases and 1030 frequency age-matched controls in Alberta, Canada (2002-2006). Risk factor information was ascertained with an in-person interview and microsatellite status of cases was determined using five microsatellite markers (Bat25, Bat26, D5S346, D2S123 and D17S250). Tumors that exhibited instability in ≥2 markers were classified as MSI and tumors that exhibited instability in <2 markers were classified as MSS. Associations were estimated with odds ratios (OR) and 95% confidence intervals (95% CI) using multivariable polytomous logistic regression, which estimated ORs for MSS or MSI cases versus controls as well as for MSI cases versus MSS cases. Results: There was a consistent pattern of increasing risks for both MSS and MSI cancer with increasing waist circumference (WC), waist-to-hip ratio and body mass index (BMI) (all Ptrend < 0.005). Nonetheless, the magnitude of risk with the increasing measures of body size was generally greater for MSI cancer than for MSS cancer. Overweight women (BMI=25-30 kg/m2) had an increased risk for MSI cancer (OR=1.8, 95%CI=1.0-3.4), but not for MSS cancer (OR=1.0, 95%CI=0.7-1.4), with a suggested elevation in risk for MSI compared to MSS cancer (OR=1.9 95%CI=1.0-3.8). Obese women (≥30 kg/m2) had an increased risk for both MSS (OR=2.3, 95%CI=1.6-3.2) and MSI (OR=4.5, 95%CI=2.5-8.0) cancer, but again, there was a suggested elevation in risk for MSI cancer compared to MSS cancer (OR=1.9 95%CI=1.0-3.7). After adjusting for waist circumference, the risk for MSS cancer among obese women was completely attenuated (OR=1.1, 95%CI=0.6-1.9), while the risk for MSI cancer (OR=3.2, 95%CI=1.4-7.2) was only slightly attenuated. Further, in the case-case comparisons the risks for MSI compared to MSS cancer for overweight (OR=2.5, 95%CI=1.1-5) and obese women (OR=2.9, 95%CI=1.2-7.3) were strengthened after adjusting for WC. Conclusion: Our findings indicate that greater body size increases the risk for both MSS and MSI cancer and imply that maintaining a healthy body weight will reduce endometrial cancer risk. Since bioavailable estrogen is elevated in overweight and obese women, the relatively greater risks for MSI compared to MSS cancer observed for these women suggest that the proliferative effects of estrogen in the endometrium are more pronounced when DNA mismatch repair has been compromised as occurs in MSI cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1829.

Finally! A Model for Progesterone Receptor Action in Normal Human Breast

Substantial clinical and experimental data over the years have supported the conclusion that estradiol-17β is the ovarian hormone primarily responsible for growth and progression of breast cancer (1). Progesterone was assumed to have negligible effects on breast tumorigenesis, in part because of its well established role to inhibit the proliferative effect of estrogen in the epithelial compartments of the endometrium and promote differentiation of the uterine glands (2). However, much publicized observational and clinical studies have more recently implicated progesterone as a proliferative hormone in the normal human breast and as a life-long risk factor for breast cancer, suggesting progesterone also contributes to early stages of breast tumorigenesis (3,4,5,6,7,8,9). Paradoxically, in established breast cancers, the presence of progesterone receptor (PR) in the primary tumor is an independent marker of favorable prognosis and is associated with a more differentiated tumor phenotype, suggesting progesterone has a protective role against progression and invasion once a tumor has developed (10,11,12). Indeed, in most PR-positive breast cancer cell lines, progestins induce a transient proliferation followed by cell cycle arrest such that the long-term effect is growth inhibition (13). This apparent dichotomy suggests that progesterone signaling is altered during disease progression. Uncertainties concerning the role of progesterone in the normal human breast and tumorigenesis have been due in part to the absence of a suitable PR-positive progesterone-responsive experimental system for the normal human breast.

Cholangiocarcinoma: Estrogen-induced autocrine effects of VEGF on cell proliferation

Cholangiocarcinoma: Estrogen-induced autocrine effects of VEGF on cell proliferation

Estrogen Receptor β Functions through Nongenomic Mechanisms in Lung Cancer Cells

Recent studies have shown that estrogens promote the growth of lung cancer cells and may potentially be responsible for increased susceptibility to lung cancer in women. These observations raise the possibility of using antiestrogens in treating and preventing lung cancer. However, it is not clear how estrogen receptors (ERs) modulate the growth of non-small cell lung cancer (NSCLC) cells. Our Western blotting and real-time PCR analysis showed that NSCLC cells expressed ERbeta, but not ERalpha. In addition, ERbeta-specific ligands, but not ERalpha-specific ligands, promoted the growth of lung cancer cells. Furthermore, knockdown of ERbeta by short hairpin RNA constructs resulted in loss of estrogen-dependent growth of lung cancer cells. Interestingly, endogenous ERbeta failed to transcriptionally activate estrogen response element (ERE)-luciferase constructs in NSCLC cells, suggesting a lack of genomic function. Upon further investigation, ERbeta was found to be in the cytoplasm in all lung cancer cells and failed to translocate to the nucleus in the presence of estrogen, as observed by biochemical, ArrayScan, and confocal microscopy experiments. Nonetheless, estrogen caused rapid activation of cAMP, Akt, and MAPK signaling pathways in lung cancer cells. Immunohistochemical analysis of lung tumor biopsies showed strong ERbeta staining in the cytoplasm, whereas no staining was observed for ERalpha. In conclusion, our results suggest that that proliferative effects of estrogen in lung cancer cells is mediated primarily, if not exclusively, by the nongenomic action of ERbeta.

T04-O-05 High dose Testosterone (T) treatment has no adverse effects on the endometrium of Female to Male transsexuals (FtM)

Objects T patches have been approved in Europe for replacement therapy in surgical menopausal women with hypoactive sexual desire. Long-term safety of T administration in women is still unknown. No data exists on the effects of T on the endometrium. The aim of this study is to evaluate the effects of high T doses administered for at least one year on the endometrium. Methods Endometrial biopsies from 30 FtM treated with T (i.m. injection of 100 mg Testoviron Depot /10 days), 30 postmenopausal women (M) undergoing vaginal hysterectomy and 5 premenopausal women (PrM) undergoing hysteroscopy for infertility problems were collected. Endometrial proliferation was evaluated on the basis of histopathology and expression of the Ki-67. Both M and PrM women had not received hormonal treatment for at least one year. Results In FtM T and estradiol (E) levels were increased to above normal female levels (T= 4.2+3.4 ng/mL; E=57.5+39.4 pg/mL). At histological analysis, FTM and M had atrophic endometrium and PrM women had proliferative endometrium. The mean Ki-67 expression in the endometrium was similar in FtM and M (1.1+1.1% and 0.6+0.9%) while it was higher in PrM (42.6 + 17.1; vs. FtM and M p= Conclusions Our data suggests that long term, high dose T treatment does not stimulate endometrial proliferation in FtM subjects. Exogenous T administration appears to contrast proliferative effects of estrogens on endometrium.

In utero exposure to diethylstilbestrol (DES) does not increase genomic instability in normal or neoplastic breast epithelium

In 1992, the National Cancer Institute (NCI) established the Continuation of Follow-Up of DES-Exposed Cohorts to study the long-term health effects of exposure to diethylstilbestrol (DES). Genetic effects on human breast tissue have not been examined. The authors investigated whether breast tissue of women exposed in utero to DES might exhibit the genetic abnormalities that characterize other DES-associated tumors. Subjects enrolled in the NCI Cohort were queried about breast biopsies or breast cancer diagnoses. Available tissue blocks were obtained for invasive cancers (IC), in situ cancers (CIS), or atypical hyperplasia (AH). Exposure status was blinded, lesions were microdissected, and their DNA was analyzed for microsatellite instability (MI) and loss of heterozygosity (LOH), or allele imbalance (AI), at 20 markers on 9 chromosome arms. From 31 subjects (22 exposed, 9 unexposed), 273 samples were analyzed (167 normal epithelium, 16 AH, 30 CIS, 60 IC). Exposed and unexposed subjects exhibited no differences in breast cancer risk factors or demographic characteristics, except for age at diagnosis (exposed vs. unexposed: 43.2 vs. 48.8 years of age, P = .02). The authors found that MI was rare and that AI was common, with frequencies consistent with previous reports. The global age-adjusted relative rate (RR) of AI was 1.3, 95% CI = 0.8-2.4. No statistically significant associations were observed after adjustment for risk factors or after stratification by histology or by chromosome arm. In utero DES exposure does not appear to significantly increase genomic instability in breast epithelium, as measured by MI and AI. Breast tissue may respond differently from that of the reproductive tract to in utero DES exposure. Consequences of in utero DES exposure on the breast may be mediated by proliferative effects of estrogen.

Estrogen receptor β represses breast tumor growth and angiogenesis in vivo

10101 Background: Estrogens are well known stimulators of breast cancer cell growth in vitro as well as in vivo. Two different estrogen receptors exist, namely estrogen receptor (ER) α and β. ERα mediates the proliferative effect of estrogen in breast cancer cells and we have earlier shown that ERβ inhibits cell-cycle progression in vitro. Estrogens are well known stimulators of in vivo breast cancer cell growth as well as angiogenesis, and the effect is mediated through ERα. The function of ERβ in this context is not well understood. Methods: We have used ERα-positive T47D breast cancer cells stably transfected with a Tet/Off regulated ERβ expression vector system. The ERβ-inducible tumor cells are studied in vitro as well as in vivo. Results: By transplanting ERβ-inducible breast cancer cells into SCID-mice, we show that ERβ inhibits tumor growth and reduces the volume of established tumors. Furthermore, we show by immunohistochemistry, that the number of blood microvessels in the tumor periphery is decreased by ERβ expression, counteracting the well-known pro-angiogenic effect of ERα. By Western blot analysis on tumor extracts, we show that the concentration of the important pro-angiogenic growth factors VEGF and bFGF, normally expressed by breast tumor cells, is decreased in the ERβ-expressing tumors compared to the normal tumors. To exclude that the observed anti-angiogenic effect is just a result of reduced tumor growth, we incubated Tet/Off regulated ERβ expressing cells in vitro, during non-hypoxic conditions. We found that the expression of ERβ leads to decreased expression of VEGF and PDGFβ at the mRNA and protein-levels. In transient transfection assays, we found estrogen-ERα mediated up regulation of VEGF, PDGFβ and bFGF-promoter activities in T47D cells, and these activities were all suppressed following co-transfection with an ERβ-expression vector. Conclusions: We conclude that ERβ inhibits growth factor expression at transcriptional level in breast cancer cells; taken together, our data indicates that ERβ inhibits growth and angiogenesis of tumors formed by T47D breast cancer cells. This makes ERβ an interesting therapeutic target in breast cancer and perhaps treatment with the newly designed ERβ-selective ligands might work as a new anti-proliferative and anti-angiogenic therapy. No significant financial relationships to disclose.