Effects of Endocrine Interventions Targeting ERα or PR on Breast Cancer Risk in the General Population and Carriers of BRCA1/2 Pathogenic Variants.

There is evidence suggesting that endocrine interventions such as hormone replacement therapy and hormonal contraception can increase breast cancer (BC) risk. Sexual steroid hormones like estrogens have long been known for their adverse effects on BC development and progression via binding to estrogen receptor (ER) α. Thus, in recent years, endocrine interventions that include estrogens have been discussed more and more critically, and their impact on different BC subgroups has increasingly gained interest. Carriers of pathogenic variants in BRCA1/2 genes are known to have a high risk of developing BC and ovarian cancer. However, there remain open questions to what extent endocrine interventions targeting ERα or the progesterone receptor further increase cancer risk in this subgroup. This review article aims to provide an overview and update on the effects of endocrine interventions on breast cancer risk in the general population in comparison to BRCA1/2 mutation carriers. Finally, future directions of research are addressed, to further improve the understanding of the effects of endocrine interventions on high-risk pathogenic variant carriers.

Role of Estrogen Receptor ß, G-Protein Coupled Estrogen Receptor and Estrogen-Related Receptors in Endometrial and Ovarian Cancer.

Ovarian and endometrial cancers are affected by estrogens and their receptors. It has been long known that in different types of cancers, estrogens activate tumor cell proliferation via estrogen receptor α (ERα). In contrast, the role of ERs discovered later, including ERß and G-protein-coupled ER (GPER1), in cancer is less well understood, but the current state of knowledge indicates them to have a considerable impact on both cancer development and progression. Moreover, estrogen related receptors (ERRs) have been reported to affect pathobiology of many tumor types. This article provides a summary and update of the current findings on the role of ERß, GPER1, and ERRs in ovarian and endometrial cancer. For this purpose, original research articles on the role of ERß, GPER1, and ERRs in ovarian and endometrial cancers listed in the PubMed database have been reviewed.

The Complex Roles of Adipokines in Polycystic Ovary Syndrome and Endometriosis.

Polycystic ovary syndrome (PCOS) and endometriosis are frequent diseases of the female reproductive tract causing high morbidity as they can significantly affect fertility and quality of life. Adipokines are pleiotropic signaling molecules secreted by white or brown adipose tissues with a central role in energy metabolism. More recently, their involvement in PCOS and endometriosis has been demonstrated. In this review article, we provide an update on the role of adipokines in both diseases and summarize previous findings. We also address the results of multi-omics approaches in adipokine research to examine the role of single nucleotide polymorphisms (SNPs) in genes coding for adipokines and their receptors, the secretome of adipocytes and to identify epigenetic alterations of adipokine genes that might be conferred from mother to child. Finally, we address novel data on the role of brown adipose tissue (BAT), which seems to have notable effects on PCOS. For this review, original research articles on adipokine actions in PCOS and endometriosis are considered, which are listed in the PubMed database.

Anti-Tumoral Effect of Chemerin on Ovarian Cancer Cell Lines Mediated by Activation of Interferon Alpha Response.

The pleiotropic adipokine chemerin affects tumor growth primarily as anti-tumoral chemoattractant inducing immunocyte recruitment. However, little is known about its effect on ovarian adenocarcinoma. In this study, we examined chemerin actions on ovarian cancer cell lines in vitro and intended to elucidate involved cell signaling mechanisms. Employing three ovarian cancer cell lines, we observed differentially pronounced effects of this adipokine. Treatment with chemerin (huChem-157) significantly reduced OVCAR-3 cell numbers (by 40.8% on day 6) and decreased the colony and spheroid growth of these cells by half. The spheroid size of SK-OV-3 ovarian cancer cells was also significantly reduced upon treatment. Transcriptome analyses of chemerin-treated cells revealed the most notably induced genes to be interferon alpha (IFNα)-response genes like IFI27, OAS1 and IFIT1 and their upstream regulator IRF9 in all cell lines tested. Finally, we found this adipokine to elevate IFNα levels about fourfold in culture medium of the employed cell lines. In conclusion, our data for the first time demonstrate IFNα as a mediator of chemerin action in vitro. The observed anti-tumoral effect of chemerin on ovarian cancer cells in vitro was mediated by the notable activation of IFNα response genes, resulting from the chemerin-triggered increase of secreted levels of this cytokine.

DSCAM-AS1 Long Non-Coding RNA Exerts Oncogenic Functions in Endometrial Adenocarcinoma via Activation of a Tumor-Promoting Transcriptome Profile.

Accumulating evidence suggests that lncRNA DSCAM-AS1 acts tumor-promoting in various cancer entities. In breast cancer, DSCAM-AS1 was shown to be the lncRNA being most responsive to induction by estrogen receptor α (ERα). In this study, we examined the function of DSCAM-AS1 in endometrial adenocarcinoma using in silico and different in vitro approaches. Initial analysis of open-source data revealed DSCAM-AS1 overexpression in endometrial cancer (EC) (p < 0.01) and a significant association with shorter overall survival of EC patients (HR = 1.78, p < 0.01). In EC, DSCAM-AS1 was associated with endometrial tumor promotor gene PRL and with expression of ERα and its target genes TFF1 and PGR. Silencing of this lncRNA by RNAi in two EC cell lines was more efficient in ERα-negative HEC-1B cells and reduced their growth and the expression of proliferation activators like NOTCH1, PTK2 and EGR1. DSCAM-AS1 knockdown triggered an anti-tumoral transcriptome response as revealed by Affymetrix microarray analysis, emerging from down-regulation of tumor-promoting genes and induction of tumor-suppressive networks. Finally, several genes regulated upon DSCAM-AS1 silencing in vitro were found to be inversely correlated with this lncRNA in EC tissues. This study clearly suggests an oncogenic function of DSCAM-AS1 in endometrial adenocarcinoma via activation of a tumor-promoting transcriptome profile.

Anthropometric factors and the risk of ovarian cancer: A systematic review and meta-analysis.

BACKGROUND: Excess weight is convincingly associated with several cancers, but the association with ovarian cancer is insufficiently clarified, in particular regarding subgroups defined by menopausal status and ovarian cancer histologic type. AIMS: We carried out a comprehensive systematic review and meta-analysis of overweight and obesity in relation to ovarian cancer with focus on different subgroups. METHODS AND RESULTS: We searched PubMed and Web of Science for relevant cohort and case-control studies published from inception to June 2021 in English language and using a clear definition of overweight and obesity. We combined maximally adjusted risk estimates using a random effects model. We analyzed data from 15 cohort and 26 case-control studies, including 28 471 ovarian cancer cases. The relative risk of ovarian cancer for overweight and obesity was 1.06 (95% confidence interval [CI] = 1.00-1.12) and 1.19 (95% CI = 1.11-1.28), respectively. Among premenopausal women, increased ovarian cancer risk was noted for overweight (RR 1.34; 95% CI = 1.03-1.75) and obesity (RR 1.51; 95% CI = 1.21-1.88). By comparison, among postmenopausal women no statistically significant association was found for overweight (RR 1.00; 95% CI 0.87-1.14) and obesity (RR1.03; 95% CI = 0.82-1.31). Increased risk was found for mucinous (RR 1.44; 95% CI = 1.03-2.01) and clear cell (RR 1.82; 95% CI = 1.11-2.99) ovarian cancer subtypes, but not for serous (RR1.12; 95% CI = 0.84-1.50;) and endometroid subtypes (RR1.24; 95% CI =0.96-1.60). CONCLUSIONS: Obesity is associated with increased ovarian cancer risk. That relation is largely due to a positive association between adiposity and ovarian cancer among premenopausal but not postmenopausal women and among cases with mucinous and clear cell but not serous or endometrioid histology.

Expression of estrogen-related receptors in ovarian cancer and impact on survival.

PURPOSE: This study further approaches the role of estrogen-related receptors (ERRs) in ovarian cancer. Protein expression of ERRα, ERRß and ERRγ in ovarian cancer was assessed and was correlated with ovarian cancer markers, steroid hormone receptors and cancer-associated genes. Additionally, we examined to what extent expression of ERRs affects survival of ovarian cancer patients. METHODS: For this purpose, we established a tissue microarray from 208 ovarian cancer patients and performed immunohistochemical analyses of the mentioned proteins. RESULTS: ERRα and ERRγ protein could be detected at different levels in more than 90% of all ovarian cancer tissues, whereas expression of ERRß was observed in 82.2% of the cases. ERRα was found to positively correlate with ovarian cancer marker CEA (p < 0.005) and ERRγ correlated with ERα (p < 0.001). Univariate survival analyses revealed that ERRα expression did not affect overall (OS) or progression-free survival (PFS) of ovarian cancer patients. In contrast, higher expression of ERRß in serous ovarian cancers was found to lead to a significantly decreased OS (p < 0.05). The strongest impact on survival was exhibited by ERRγ. Lower expression of this receptor in women with serous ovarian cancers indicated significantly increased OS compared to those with higher levels of ERRγ (p < 0.05). Multivariate survival analyses revealed ERRγ as an independent prognostic marker regarding OS of patients with serous ovarian cancer. CONCLUSION: Our data demonstrating that ERR proteins are frequently expressed in ovarian cancer and high levels of ERRß and ERRγ significantly decreased OS of serous ovarian cancer patients suggest that these proteins might be interesting therapy targets in this cancer entity.

Icb-1 expression inhibits growth and fulvestrant response of breast cancer cells and affects survival of breast cancer patients.

PURPOSE: Human gene icb-1 recently has been reported to be part of a gene expression score predicting response to antiestrogen fulvestrant in breast cancer patients. In the present study, we examined to what extent icb-1 expression would affect the response of breast cancer cells to this antiestrogen in vitro and investigated underlying molecular mechanisms. Using open access mRNA data, we elucidated the significance of icb-1 expression for survival of breast cancer patients. METHODS: Icb-1 gene expression was knocked down by RNAi. Breast cancer cell growth after treatment with fulvestrant was assessed using the Cell Titer Blue assay. Gene expression was analyzed by Western blot analysis or RT-qPCR. Survival analyses were performed using bioinformatical online tools and data. RESULTS: Knockdown of icb-1 in T-47D breast cancer cells significantly increased growth of this cell line and also elevated the growth-stimulatory effect of E2 (p < 0.001). After treatment with different concentrations of fulvestrant, icb-1 knockdown cells exhibited a significantly enhanced response to this drug (p < 0.01). On the molecular level, icb-1 knockdown led to elevated expression of ESR1 and its target gene TFF1 (pS2) and enhanced E2-triggered up-regulation of proliferation genes. Finally, bioinformatical meta-analysis of gene expression data of 3951 breast cancer patients revealed that high icb-1 expression increases their relapse-free survival (HR = 0.87, p < 0.05). CONCLUSION: The presented data further support a tumor-suppressive role of icb-1 in breast cancer and suggest an inhibitory effect of this gene on fulvestrant action, which both are suggested to be mediated by suppression of cellular E2 response.

Estrogen Actions in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) lacks estrogen receptor (ER) α, but the expression of estrogen receptors ERß and G protein-coupled estrogen receptor 1 (GPER-1) is able to trigger estrogen-responsivity in TNBC. Estrogen signaling in TNBC can also be activated and modulated by the constitutively active estrogen-related receptors (ERRs). In this review article, we discuss the role of ERß and GPER-1 as mediators of E2 action in TNBC as well as the function of ERRs as activators and modulators of estrogen signaling in this cancer entity. For this purpose, original research articles on estrogen actions in TNBC were considered, which are listed in the PubMed database. Additionally, we performed meta-analyses of publicly accessible integrated gene expression and survival data to elucidate the association of ERß, GPER-1, and ERR expression levels in TNBC with survival. Finally, options for endocrine therapy strategies for TNBC were discussed.

G protein-coupled estrogen receptor 1 (GPER-1) and agonist G-1 inhibit growth of ovarian cancer cells by activation of anti-tumoral transcriptome responses: impact of GPER-1 mRNA on survival.

PURPOSE: The present study intended to further elucidate the role of G protein-coupled estrogen receptor 1 (GPER-1) in ovarian cancer by comparing the effects of a GPER-1 knockdown and treatment with its agonist G-1 on cell growth, apoptosis, and the transcriptome of two ovarian cancer cell lines. Furthermore, the role of GPER-1 in ovarian cancer survival was examined. METHODS: GPER-1 expression in OVCAR-3 and OAW-42 ovarian cancer cells was knocked down by RNAi. The effects on cell growth were measured by means of the fluorimetric cell titer blue assay and on the transcriptome by Affymetrix GeneChip analysis. The effect of GPER-1 on patient's survival was examined using open source mRNA and clinical data of 1657 ovarian cancer patients. RESULTS: GPER-1 knockdown resulted in a significant growth stimulation of both cell lines, whereas treatment with agonist G-1 decreased growth of both cell lines in a dose-dependent manner. Transcriptome analyses revealed a set of 18 genes being conversely regulated after GPER-1 knockdown and G-1 treatment. Generally, treatment with G-1 led to a transcriptome response associated with growth inhibition. In contrast, knockdown of GPER-1 exerted opposite effects, stimulating pathways activating mitosis, but inhibiting pathways associated with apoptosis or interferon signaling. Further analyses using open-access mRNA and clinical data by bioinformatical online tools revealed a longer OS (HR = 0.86, p = 0.057) and PFS (HR = 0.81, p = 0.0035) of ovarian cancer patients with high GPER-1 mRNA expression. CONCLUSIONS: The results of this study clearly support the hypothesis that GPER-1 acts as a tumor suppressor in ovarian cancer.

Long non-coding RNA CCAT1 is overexpressed in endometrial cancer and regulates growth and transcriptome of endometrial adenocarcinoma cells.

BACKGROUND: Long non-coding RNAs (lncRNAs) play important roles in regulation of gene expression and are involved in pathogenesis of different diseases including cancer. Recent studies suggested the lncRNA Colon cancer associated transcript-1 (CCAT1) to act as putative oncogene. In this study, to elucidate the role of this lncRNA in endometrial cancer, we examined its expression in normal endometrium and type 1 endometrial cancer and knocked down its expression in endometrial cancer cell lines followed by transcriptome and pathway analyses. METHODS: CCAT1 expression was examined in 100 tissue samples of normal endometrium and type 1 endometrial cancer tissues by means of RT-qPCR. Knockdown of CCAT1 expression in HEC-1B and RL95/2 endometrial cancer cells was performed by siRNA transfection. Affymetrix GeneChip arrays were used to elucidate the effect of both lncRNAs on the transcriptome of these cell lines. RESULTS: Median CCAT1 expression was found to be 9.3-fold higher in endometrial cancer when compared to normal endometrium (p < 0.05). In contrast to premenopausal endometrium and G1, G2 and G3 graded endometrial cancer, CCAT1 expression was nearly absent in postmenopausal tissue. Knockdown of CCAT1 by transient siRNA transfection significantly reduced proliferation of HEC-1B cancer cells in vitro by 35.5 % 6 days after transfection and notably reduced their colony formation ability. Affymetrix microarray and Ingenuity pathway analyses revealed a set of up- or down-regulated genes in transfected ERα-negative HEC-1B cells forming a network controlled by the key regulators TNF and TP53, including genes known to be involved in growth control, providing putative molecular mechanisms underlying the observed growth inhibition of HEC-1B cells. In contrast, CCAT1 knockdown in ERα-positive RL95/2 cells did not significantly affect proliferation, but resulted in down-regulation of a network of ERα target genes. CONCLUSIONS: Given that the lncRNA CCAT1 was found to be overexpressed in endometrial cancer, affected the growth of HEC-1B cells and the expression of growth regulatory genes, our data suggest CCAT1 to exert oncogenic functions in endometrial cancer and encourage further studies to examine to what extent this lncRNA might be a potential therapy target in this cancer entity.

Knockdown of PTEN decreases expression of estrogen receptor ß and tamoxifen sensitivity of human breast cancer cells.

Estrogen receptors (ERs) and the PTEN-Akt-mTor pathway are important growth regulators in human breast cancer cells, which both are known to affect response to tamoxifen therapy. Recently it was reported that ERß activates PTEN expression and tamoxifen sensitivity of human breast cancer cells. In this study we examined whether expression of ERß in turn might be affected by tumor suppressor PTEN, analyzed the effect of this interaction on tamoxifen response and the co-expression of both genes in human breast cancer samples. After siRNA-mediated PTEN knockdown, Western blot analysis revealed a reduction of ERß protein expression by 67.2% in MCF-7 cells and by 73.6% in T-47D cells (both p < 0.01), results which could be verified on the mRNA level. In cells with normal PTEN and ERß status, after 6 days of treatment with 1 µM 4-OH tamoxifen, E2-driven proliferation was decreased by 64.5% in MCF-7 and by 57.7% in T-47D cells (both p < 0.01). After knockdown of PTEN expression, the same concentration of 4-OH TAM reduced E2-triggered growth only by 34.9% (MCF-7) and by 41.8% (T-47D) (both p < 0.01 vs control siRNA). Importantly, treatment with ERß agonist DPN (5 nM) significantly decreased the inhibitory effect of a PTEN knockdown on tamoxifen response of both cell lines (p < 0.05). Additionally, Spearmans rank association analysis of PTEN and ERß 1 mRNA levels in 115 normal and malignant breast tissue samples revealed a strong positive correlation of both genes (rho = 0.6085, p < 0.0001). The data of previous studies reporting an important role of ERß in tamoxifen sensitivity and our findings suggest down-regulation of ERß triggered by PTEN knockdown contributed to the decreased response of breast cancer cells to tamoxifen observed in this study. Our data also suggest expression of ERß might be maintained by tumor suppressor PTEN in human breast cancer cells.

Knockdown of estrogen receptor ß increases proliferation and affects the transcriptome of endometrial adenocarcinoma cells.

BACKGROUND: Estrogen receptor ß (ERß) has been repeatedly suggested to play important roles in hormone-dependent cancer like in tumors of the breast, ovary or prostate. In this study, we intended to further elucidate its role in endometrial cancer. METHODS: For this purpose, we knocked down ERß expression in two endometrial cancer cell lines, the ERα-negative/ERß-positive line HEC-1A and the ERα/ß-positive cell line RL95/2, by means of siRNA transfection. Cell proliferation after transfection was assessed using the fluorescent CTB Assay (Promega). In order to elucidate possible molecular mechanisms which might underlie the effect on proliferation, we performed transcriptome analyses by means of human Affymetrix Human Gene Chip 2.0. Additionally, we treated the employed cell lines with different ERß modulators to examine their effect on proliferation. RESULTS: siRNA-mediated knockdown of ERß significantly increased proliferation of both endometrial cancer cell lines. In HEC-1A cells, proliferation was significantly increased 4, 5 and 6 days after transfection, with a maximum of about 1.7-fold (p < 0.05) on day 6. Endometrial RL95/2 cells with an ERß knockdown exhibited a clearly enhanced proliferation on day 3 and days 4 to 8, when even 2.4-fold higher numbers of viable cells were detected (p < 0.01). Transcriptome analysis revealed that this was accompanied by increased expression of several genes being known to be upregulated in cancer, including proliferation-associated genes and oncogenes, and by repression of genes associated with differentiation, apoptosis or growth inhibition. Corroborating the observed knockdown effects, treatment with the ERß antagonists PHTTP and (R, R) THC was also able to induce proliferation of both cell lines. CONCLUSIONS: Our data clearly support the putative role of ERß as tumor suppressor in endometrium as previously suggested in studies on other tissues and encourage further studies to find out to what extent this molecule might be a potential therapy target in this cancer entity.

Estrogen receptor ß is associated with expression of cancer associated genes and survival in ovarian cancer.

BACKGROUND: In ovarian cancer, the role of estrogen receptors (ERs), particularly of ERß, being suggested as tumor suppressor in breast and prostate cancer, remains unclear. We examined the expression of nuclear and cytoplasmic ERß in ovarian cancer and correlated it with expression of ovarian cancer markers CA125, CEA and CA72-4, steroid hormone receptors ERα and PR, cancer-associated genes EGFR, p53, HER2 and proliferation marker Ki-67. Additionally we examined to what extent expression of ERß and the other proteins affects survival of ovarian cancer patients. METHODS: We established a tissue microarray from 171 ovarian cancer patients and performed immunohistochemical analyses of the mentioned proteins. RESULTS: Nuclear ERß was detected in 47.31% of the ovarian cancer tissues and cytoplasmic expression of this receptor was observed in 23.08%. Nuclear expression of ERß was significantly decreased in the G3 subgroup compared to better differentiated cancers (p <  0.01) and correlated with ovarian cancer markers CEA (95% CI 0.1598-0.4465; p <  0.0001) and CA72-4 (95% CI 0.05953-0.3616; p <  0.01). Cytoplasmic ERß expression correlated with EGFR levels (95% CI 0.1059-0.4049; p <  0.001). ERα expression was associated with expression of CA125 and PR. Overall survival of patients with tumors expressing cytoplasmic ERß was significant longer compared to those with ERß-negative ovarian cancer (chi-square statistic of the log-rank, p < 0.05). Progression-free survival was dependent on expression of PR (chi-square statistic of the log-rank, p < 0.05) and Ki-67 (p = 0.05). CONCLUSIONS: Our data suggest an important, but distinct role of nuclear and cytoplasmic ERß expression in ovarian cancer and encourage further studies on its role in this cancer entity.

Human Chorionic Gonadotropin and Breast Cancer.

Breast cancer is well known as a malignancy being strongly influenced by female steroids. Pregnancy is a protective factor against breast cancer. Human chorionic gonadotropin (HCG) is a candidate hormone which could mediate this antitumoral effect of pregnancy. For this review article, all original research articles on the role of HCG in breast cancer were considered, which are listed in PubMed database and were written in English. The role of HCG in breast cancer seems to be a paradox. Placental heterodimeric HCG acts as a protective agent by imprinting a permanent genomic signature of the mammary gland determining a refractory condition to malignant transformation which is characterized by cellular differentiation, apoptosis and growth inhibition. On the other hand, ectopic expression of ß-HCG in various cancer entities is associated with poor prognosis due to its tumor-promoting function. Placental HCG and ectopically expressed ß-HCG exert opposite effects on breast tumorigenesis. Therefore, mimicking pregnancy by treatment with HCG is suggested as a strategy for breast cancer prevention, whereas targeting ß-HCG expressing tumor cells seems to be an option for breast cancer therapy.

Effect of estrogen receptor ß agonists on proliferation and gene expression of ovarian cancer cells.

BACKGROUND: Estrogen receptor (ER) ß has been suggested to affect ovarian carcinogenesis. We examined the effects of four ERß agonists on proliferation and gene expression of two ovarian cancer cell lines. METHODS: OVCAR-3 and OAW-42 ovarian cancer cells were treated with the ERß agonists ERB-041, WAY200070, Liquiritigenin and 3ß-Adiol and cell growth was measured by means of the Cell Titer Blue Assay (Promega). ERß expression was knocked down by transfection with specific siRNA. Additionally, transcriptome analyses were performed by means of Affymetrix GeneChip arrays. To confirm the results of DNA microarray analysis, Western blot experiments were performed. RESULTS: All ERß agonists tested significantly decreased proliferation of OVCAR-3 and OAW-42 cells at a concentration of 10 nM. Maximum antiproliferative effects were induced by flavonoid Liquiritigenin, which inhibited growth of OVCAR-3 cells by 31.2% after 5 days of treatment, and ERB-041 suppressing proliferation of the same cell line by 29.1%. In OAW-42 cells, maximum effects were observed after treatment with the ERß agonist WAY200070, inhibiting cell growth by 26.8%, whereas ERB-041 decreased proliferation by 24.4%. In turn, knockdown of ERß with specific siRNA increased cell growth of OAW-42 cells about 1.9-fold. Transcriptome analyses revealed a set of genes regulated by ERß agonists including ND6, LCN1 and PTCH2, providing possible molecular mechanisms underlying the observed antiproliferative effects. CONCLUSION: In conclusion, the observed growth-inhibitory effects of all ERß agonists on ovarian cancer cell lines in vitro encourage further studies to test their possible use in the clinical setting.

Agonists and knockdown of estrogen receptor ß differentially affect invasion of triple-negative breast cancer cells in vitro.

BACKGROUND: Estrogen receptor ß (ERß) is expressed in the majority of invasive breast cancer cases, irrespective of their subtype, including triple-negative breast cancer (TNBC). Thus, ERß might be a potential target for therapy of this challenging cancer type. In this in vitro study, we examined the role of ERß in invasion of two triple-negative breast cancer cell lines. METHODS: MDA-MB-231 and HS578T breast cancer cells were treated with the specific ERß agonists ERB-041, WAY200070, Liquiritigenin and 3ß-Adiol. Knockdown of ERß expression was performed by means of siRNA transfection. Effects on cellular invasion were assessed in vitro by means of a modified Boyden chamber assay. Transcriptome analyses were performed using Affymetrix Human Gene 1.0 ST microarrays. Pathway and gene network analyses were performed by means of Genomatix and Ingenuity Pathway Analysis software. RESULTS: Invasiveness of MBA-MB-231 and HS578T breast cancer cells decreased after treatment with ERß agonists ERB-041 and WAY200070. Agonists Liquiritigenin and 3ß-Adiol only reduced invasion of MDA-MB-231 cells. Knockdown of ERß expression increased invasiveness of MDA-MB-231 cells about 3-fold. Transcriptome and pathway analyses revealed that ERß knockdown led to activation of TGFß signalling and induced expression of a network of genes with functions in extracellular matrix, tumor cell invasion and vitamin D3 metabolism. CONCLUSIONS: Our data suggest that ERß suppresses invasiveness of triple-negative breast cancer cells in vitro. Whether ERß agonists might be useful drugs in the treatment of triple-negative breast cancer, has to be evaluated in further animal and clinical studies.

Molecular profiling of estrogen receptor α and progesterone receptor transcript variants in endometrial cancer.

The human genes coding for estrogen receptor alpha (ERα) and progesterone receptor (PR) express multiple receptor splice variants. Some of these receptor variants previously have been shown to exert distinct functions in cancer cells and might therefore differentially affect individual prognosis or therapy response. To examine the role of ERα- and PR-isoforms in endometrial cancer, we compared the expression of 19 ERα transcripts and 15 PR mRNA isoforms in human endometrium and in endometrioid endometrial cancer. Expression of seven ERα splice variants, total PR and of five PR transcript isoforms was found to be significantly decreased in endometrial cancer. In endometrioid G3 tumors, expression of 17 ERα and 10 PR splice variants was reduced when compared to normal tissue. Notably, only 13% of G3 tumors did not express any ERα variant and only in 25% of G3 samples no PR transcripts were expressed. Seven splice variants were preferentially expressed in G1 and G2 tumors. In G1 tumors, a higher number of different ERα and PR splice variants was expressed than in normal endometrium, G2 or G3 tumors. Expression of total PR and of single PR splice variants was found to be positively associated with PTEN. Our results encourage further studies to elucidate to what extent the heterogeneous co-expression profiles we found in endometrial cancer patients differentially affect both individual prognosis and therapy response.