The Prostaglandin EP3 Receptor Is an Independent Negative Prognostic Factor for Cervical Cancer Patients

The differential expression of AFF3 in cervical cancer and its correlation with clinicopathological features and prognosis

BACKGROUND

Cervical cancer (CC) is the second most common malignancy in women, and identifying biomarkers of CC is crucial for prognosis prediction. Here, we investigated the expression of AF4/FMR2 Family Member 3 (AFF3) in CC and its association with clinicopathological features and prognosis.

METHODS

Tumour and adjacent tissues, along with clinicopathological features and follow-up information, were collected from 78 patients. AFF3 expression was assessed using quantitative real-time polymerase chain reaction and Western blotting. The correlation between AFF3 expression and CC symptoms was using chi-square test. The 5-year overall survival (OS) was analysed using the Kaplan-Meier method. The Univariate analysis of prognostic risk factors was conducted using the COX proportional hazards model, followed by multivariate COX regression analysis including variables with p < 0.01.

RESULTS

AFF3 expression was downregulated in CC, and its levels were correlated with lymph node metastasis (LNM) and International Federation of Gynaecology and Obstetrics (FIGO) stage. Patients with low AFF3 expression had a lower 5-year OS rate (52.78%, 19/36). Postoperative survival was reduced in patients with histological grade 3 (G3), myometrial invasion (depth ≥ 1/2), lymphovascular space invasion, LNM, and advanced FIGO stage. Low expression of AFF3 (HR: 2.848, 95% CI: 1.144-7.090) and histological grade G3 (HR: 4.393, 95% CI: 1.663-11.607) were identified as independent prognostic risk factors in CC patients.

CONCLUSION

Low expression of AFF3 and histological G3 are independent predictors of poor prognosis in CC patients, suggesting that AFF3 could serve as a potential biomarker for prognostic assessment in CC.

Nuclear receptor co-repressor NCOR2 and its relation to GPER with prognostic impact in ovarian cancer

PURPOSE

The significance of the non-classical G-protein-coupled estrogen receptor (GPER) as positive or negative prognostic factor for ovarian cancer patients remains still controversial. Recent results indicate that an imbalance of both co-factors and co-repressors of nuclear receptors regulates ovarian carcinogenesis by altering the transcriptional activity through chromatin remodeling. The present study aims to investigate whether the expression of the nuclear co-repressor NCOR2 plays a role in GPER signaling which thereby could positively impact overall survival rates of ovarian cancer patients.

METHODS

NCOR2 expression was evaluated by immunohistochemistry in a cohort of 156 epithelial ovarian cancer (EOC) tumor samples and correlated with GPER expression. The correlation and differences in clinical and histopathological variables as well as their effect on prognosis were analyzed by Spearman's correlation, Kruskal-Wallis test and Kaplan-Meier estimates.

RESULTS

Histologic subtypes were associated with different NCOR2 expression patterns. More specifically, serous and mucinous EOC demonstrated a higher NCOR2 expression (P = 0.008). In addition, high nuclear NCOR2 expression correlated significantly with high GPER expression (cc = 0.245, P = 0.008). A combined evaluation of both high NCOR2 (IRS > 6) and high GPER (IRS > 8) expression revealed an association of a significantly improved overall survival (median OS 50.9 versus 105.1 months, P = 0.048).

CONCLUSION

Our results support the hypothesis that nuclear co-repressors such as NCOR2 may influence the transcription of target genes in EOC such as GPER. Understanding the role of nuclear co-repressors on signaling pathways will allow a better understanding of the factors involved in prognosis and clinical outcome of EOC patients.

An immune-related prognostic signature associated with immune landscape and therapeutic responses in gastric cancer

Immune-related genes (IRGs) have attracted attention in recent years as therapeutic targets in various tumors. However, the role of IRGs in gastric cancer (GC) has not been clearly elucidated. This study presents a comprehensive analysis exploring the clinical, molecular, immune, and drug response features characterizing the IRGs in GC. Data were acquired from the TCGA and GEO databases. The Cox regression analyses were performed to develop a prognostic risk signature. The genetic variants, immune infiltration, and drug responses associated with the risk signature were explored using bioinformatics methods. Lastly, the expression of the IRS was verified by qRT-PCR in cell lines. In this manner, an immune-related signature (IRS) was established based on 8 IRGs. According to the IRS, patients were divided into the low-risk group (LRG) and high-risk group (HRG). Compared with the HRG, the LRG was characterized by a better prognosis, high genomic instability, more CD8+ T cell infiltration, greater sensitivity to chemotherapeutic drugs, and greater likelihood of benefiting from the immunotherapy. Moreover, the expression result showed good consistency between the qRT-PCR and TCGA cohort. Our findings provide insights into the specific clinical and immune features underlying the IRS, which may be important for patient treatment.

Expression of Progesterone Receptor A as an Independent Negative Prognosticator for Cervical Cancer

The role of progesterone receptor A (PRA) for the survival outcome of cervical cancer patients is ambiguous. In mouse models, it has been shown that PRA plays a rather protective role in cancer development. The aim of this study was to assess its expression by immunohistochemistry in 250 cervical cancer tissue samples and to correlate the results with clinicopathological parameters including patient survival. PRA expression was positively correlated with the International Federation of Gynecology and Obstetrics (FIGO) classification scores. PRA was significantly overexpressed in adenocarcinomas compared to squamous epithelial carcinoma subtypes. Correlation analyses revealed a trend association with the HPV virus protein E6, a negative correlation with p16 and a positive correlation with EP3. PRA expression was also associated with the expression of RIP140, a transcriptional coregulator that we previously identified as a negative prognostic factor for survival in cervical cancer patients. Univariate survival analyses revealed PRA as a negative prognosticator for survival in patients with cervical adenocarcinoma. Multivariate analyses showed that simultaneous expression of RIP140 and PRA was associated with the worst survival, whereas with negative RIP140, PRA expression alone was associated with the best survival. We can therefore assume that the effect of nuclear PRA on overall survival is dependent upon nuclear RIP140 expression.

Examining SNP-SNP interactions and risk of clinical outcomes in colorectal cancer using multifactor dimensionality reduction based methods

Background: SNP interactions may explain the variable outcome risk among colorectal cancer patients. Examining SNP interactions is challenging, especially with large datasets. Multifactor Dimensionality Reduction (MDR)-based programs may address this problem.

Objectives: 1) To compare two MDR-based programs for their utility; and 2) to apply these programs to sets of MMP and VEGF-family gene SNPs in order to examine their interactions in relation to colorectal cancer survival outcomes.

Methods: This study applied two data reduction methods, Cox-MDR and GMDR 0.9, to study one to three way SNP interactions. Both programs were run using a 5-fold cross validation step and the top models were verified by permutation testing. Prognostic associations of the SNP interactions were verified using multivariable regression methods. Eight datasets, including SNPs from MMP family genes (n = 201) and seven sets of VEGF-family interaction networks (n = 1,517 SNPs) were examined.

Results: ∼90 million potential interactions were examined. Analyses in the MMP and VEGF gene family datasets found several novel 1- to 3-way SNP interactions. These interactions were able to distinguish between the patients with different outcome risks (regression p-values 0.03–2.2E-09). The strongest association was detected for a 3-way interaction including CHRM3.rs665159_EPN1.rs6509955_PTGER3.rs1327460 variants.

Conclusion: Our work demonstrates the utility of data reduction methods while identifying potential prognostic markers in colorectal cancer.

Prostanoid Signaling in Cancers: Expression and Regulation Patterns of Enzymes and Receptors

Cancer-associated disturbance of prostanoid signaling provides an aberrant accumulation of prostanoids. This signaling consists of 19 target genes, encoding metabolic enzymes and G-protein-coupled receptors, and prostanoids (prostacyclin, thromboxane, and prostaglandins E2, F2α, D2, H2). The study addresses the systems biology analysis of target genes in 24 solid tumors using a data mining pipeline. We analyzed differential expression patterns of genes and proteins, promoter methylation status as well as tissue-specific master regulators and microRNAs. Tumor types were clustered into several groups according to gene expression patterns. Target genes were characterized as low mutated in tumors, with the exception of melanoma. We found at least six ubiquitin ligases and eight protein kinases that post-translationally modified the most connected proteins PTGES3 and PTGIS. Models of regulation of PTGIS and PTGIR gene expression in lung and uterine cancers were suggested. For the first time, we found associations between the patient’s overall survival rates with nine multigene transcriptomics signatures in eight tumors. Expression patterns of each of the six target genes have predictive value with respect to cytostatic therapy response. One of the consequences of the study is an assumption of prostanoid-dependent (or independent) tumor phenotypes. Thus, pharmacologic targeting the prostanoid signaling could be a probable additional anticancer strategy.

EP4 as a Negative Prognostic Factor in Patients with Vulvar Cancer

New prognostic factors and targeted therapies are urgently needed to improve therapeutic outcomes in vulvar cancer patients and to reduce therapy related morbidity. Previous studies demonstrated the important role of prostaglandin receptors in inflammation and carcinogenesis in a variety of tumor entities. In this study, we aimed to investigate the expression of EP4 in vulvar cancer tissue and its association with clinicopathological data and its prognostic relevance on survival. Immunohistochemistry was performed on tumor specimens of 157 patients with vulvar cancer treated in the Department of Obstetrics and Gynecology, Ludwig-Maximilian-University of Munich, Germany, between 1990 and 2008. The expression of EP4 was analyzed using the well-established semiquantitative immunoreactivity score (IRS) and EP4 expression levels were correlated with clinicopathological data and patients' survival. To specify the tumor-associated immune cells, immunofluorescence double staining was performed on tissue samples. In vitro experiments including 5-Bromo-2'-Deoxyuridine (BrdU) proliferation assay and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid (MTT) viability assay were conducted in order to examine the effect of EP4 antagonist L-161,982 on vulvar carcinoma cells. EP4 expression was a common finding in in the analyzed vulvar cancer tissue. EP4 expression correlated significantly with tumor size and FIGO classification and differed significantly between keratinizing vulvar carcinoma and nonkeratinizing carcinoma. Survival analysis showed a significant correlation of high EP4 expression with poorer overall survival (p = 0.001) and a trending correlation between high EP4 expression and shorter disease-free survival (p = 0.069). Cox regression revealed EP4 as an independent prognostic factor for overall survival when other factors were taken into account. We could show in vitro that EP4 antagonism attenuates both viability and proliferation of vulvar cancer cells. In order to evaluate EP4 as a prognostic marker and possible target for endocrinological therapy, more research is needed on the influence of EP4 in the tumor environment and its impact in vulvar carcinoma.

The underlying molecular mechanism and drugs for treatment in adrenal cortical carcinoma

Purpose: The study aimed to predict and explore the possible clinical value and mechanism of genetic markers in adrenal cortical carcinoma using a bioinformatics analysis method. Methods: The RNA-seqs and miRNAs data were downloaded from TCGA database to identify the differentially expressed genes and differentially expressed miRNAs. The hub-genes were screened by building protein-protein interaction sub-networks with 12 topological analysis methods. We conducted the receiver operating characteristic curve to elevate the diagnostic value of hub-genes in distinguishing the death and alive groups. The survival analysis of hub-genes and key miRNAs were conducted using Kaplan-Meier curves. Furthermore, most significant small molecules were identified as therapeutic candidates for adrenal cortical carcinoma by the CMap analysis. Results: Compared to survival group, we found 475 up-regulated genes and 354 genes and the key pathways leading to the death of different ACC individual patients. Then we used 12 topological analysis methods to found the most possible 22 hub-genes. Among these hub-genes, nine hub-genes (C3, CXCL5, CX3CR1, GRM8, HCAR2, HTR1B, SUCNR1, PTGER3 and SSTR1) could be used to distinguish the death and survival groups for patients. We also revealed that mRNA expressions of 12 genes (C3, CXCL8, CX3CR1, GNAT3, GNGT1, GRM8, HCAR2, HTR1B, HTR1D, PTGER3, SSTR1 and SUCNR1) and four key miRNAs (hsa-mir-330, hsa-mir-489, hsa-mir-508 and hsa-mir-513b) were related to survival. Three most small molecules were identified (H-9, AZ-628 and phensuximide) as potential therapeutic drugs for adrenal cortical carcinoma. Conclusion: The hub-genes expression was significant useful in adrenal cortical carcinoma, provide new diagnostic, prognosis and therapeutic approaches for adrenal cortical carcinoma. Furthermore, we also explore the possible miRNAs involved in regulation of hub-genes.

G Protein-Coupled Estrogen Receptor Correlates With Dkk2 Expression and Has Prognostic Impact in Ovarian Cancer Patients

PURPOSE

Wnt pathway modulator Dickkopf 2 (Dkk2) and signaling of the G protein-coupled estrogen receptor (GPER) seem to have essential functions in numerous cancer types. For epithelial ovarian cancer (EOC), it has not been proven if either Dkk2 or the GPER on its own have an independent impact on overall survival (OS). So far, the correlation of both factors and their clinical significance has not systematically been investigated before.

METHODS

Expression levels of Dkk2 were immunohistochemically analyzed in 156 patient samples from different histologic subtypes of EOC applying the immune-reactivity score (IRS). Expression analyses were correlated with clinical and pathological parameters to assess for prognostic relevance. Data analysis was performed using Spearman's correlations, Kruskal-Wallis-test and Kaplan-Meier estimates.

RESULTS

Highest Dkk2 expression of all subtypes was observed in clear cell carcinoma. In addition, Dkk2 expression differed significantly (p<0.001) between low and high grade serous ovarian cancer. A significant correlation of Dkk2 with the cytoplasmic GPER expression was noted (p=0.001) but not for the nuclear estrogen receptor alpha (ERα) or beta (ERβ). Patients exhibiting both, high expression Dkk2 (IRS>4) and GPER (IRS>8), had a significantly better overall survival compared to patients with low expression (61 months vs. 33 months; p=0.024).

CONCLUSION

Dkk2 and GPER expression correlates in EOC and combined expression of both is associated with improved OS. These findings underline the clinical significance of both pathways and indicate a possible prognostic impact as well as a potential for treatment strategies addressing interactions between estrogen and Wnt signaling in ovarian cancer.

Interplay Between EGFR and the Platelet-Activating Factor/PAF Receptor Signaling Axis Mediates Aggressive Behavior of Cervical Cancer

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase widely expressed in cervical tumors, being correlated with adverse clinical outcomes. EGFR may be activated by a diversity of mechanisms, including transactivation by G-protein coupled receptors (GPCRs). Studies have also shown that platelet-activating factor (PAF), a pro-inflammatory phospholipid mediator, plays an important role in the cancer progression either by modulating the cancer cells or the tumor microenvironment. Most of the PAF effects seem to be mediated by the interaction with its receptor (PAFR), a member of the GPCRs family. PAFR- and EGFR-evoked signaling pathways contribute to tumor biology; however, the interplay between them remains uninvestigated in cervical cancer. In this study, we employed The Cancer Genome Atlas (TCGA) and cancer cell lines to evaluate possible cooperation between EGFR, PAFR, and lysophosphatidylcholine acyltransferases (LPCATs), enzymes involved in the PAF biosynthesis, in the context of cervical cancer. It was observed a strong positive correlation between the expression of EGFR × PAFR and EGFR × LPCAT2 in 306 cervical cancer samples. The increased expression of LPCAT2 was significantly correlated with poor overall survival. Activation of EGFR upregulated the expression of PAFR and LPCAT2 in a MAPK-dependent fashion. At the same time, PAF showed the ability to transactivate EGFR leading to ERK/MAPK activation, cyclooxygenase-2 (COX-2) induction, and cell migration. The positive crosstalk between the PAF-PAFR axis and EGFR demonstrates a relevant linkage between inflammatory and growth factor signaling in cervical cancer cells. Finally, combined PAFR and EGFR targeting treatment impaired clonogenic capacity and viability of aggressive cervical cancer cells more strongly than each treatment separately. Collectively, we proposed that EGFR, LPCAT2, and PAFR emerge as novel targets for cervical cancer therapy.

Development and Validation of a Novel 11-Gene Prognostic Model for Serous Ovarian Carcinomas Based on Lipid Metabolism Expression Profile

(1) Background: Biomarkers might play a significant role in predicting the clinical outcomes of patients with ovarian cancer. By analyzing lipid metabolism genes, future perspectives may be uncovered; (2) Methods: RNA-seq data for serous ovarian cancer were downloaded from The Cancer Genome Atlas and Gene Expression Omnibus databases. The non-negative matrix factorization package in programming language R was used to classify molecular subtypes of lipid metabolism genes and the limma package in R was performed for functional enrichment analysis. Through lasso regression, we constructed a multi-gene prognosis model; (3) Results: Two molecular subtypes were obtained and an 11-gene signature was constructed (PI3, RGS, ADORA3, CH25H, CCDC80, PTGER3, MATK, KLRB1, CCL19, CXCL9 and CXCL10). Our prognostic model shows a good independent prognostic ability in ovarian cancer. In a nomogram, the predictive efficiency was notably superior to that of traditional clinical features. Related to known models in ovarian cancer with a comparable amount of genes, ours has the highest concordance index; (4) Conclusions: We propose an 11-gene signature prognosis prediction model based on lipid metabolism genes in serous ovarian cancer.

The role of EP-2 receptor expression in cervical intraepithelial neoplasia

Prostaglandin induced signalling is involved in different cancers. As previously described, the EP3 receptor expression decreases with increasing stage of cervical intraepithelial lesions (CIN). In addition, in cervical cancer EP3 is an independent prognosticator for overall survival and correlates with FIGO stages. Currently the role of Prostaglandin 2 receptor 2 (EP2) in CIN is unknown. The aim of this study was to analyse the expression of EP2 for potential prognostic value for patients with cervical dysplasia. EP2 expression was analysed by immunohistochemistry in 33 patient samples (CIN1–3) using the immune-reactivity scoring system (IRS). Expression levels were correlated with clinical outcome to analyse prognostic relevance in patients with CIN2. Data analysis was performed using non parametric Kruskal–Wallis and Spearman rank sum test. Cytoplasmic expression levels of EP2 correlated significantly (p < 0.001) with different grades of cervical dysplasia. Median EP2-IRS in CIN1 was 2 (n = 8), 3 in CIN2 (n = 9) and 6 in CIN3 (n = 16). Comparing regressive (n = 3, median IRS = 2) to progressive (n = 6, median IRS = 4) CIN2 cases the median IRS differed significantly (p = 0.017). Staining intensity (p = 0.009) and IRS (p = 0.005) of EP2 and EP3 correlate inversely. EP2 expression level significantly increases with higher grade of CIN and could qualify as a potential prognostic marker for the regressive or progressive course in CIN2 lesions. These findings emphasize the significant role of PGE2 signalling in CIN and could help to identify targets for future therapies.

Prostaglandin E2 receptor 3 (EP3) signaling promotes migration of cervical cancer via urokinase-type plasminogen activator receptor (uPAR)

Purpose

Cervical cancer metastasis results in poor prognosis and increased mortality, which is not separated from inflammatory reactions accumulated by prostaglandin E2 (PGE2). As a specific G-protein coupled PGE2 receptor, EP3 is demonstrated as a negative prognosticator of cervical malignancy. Now, we aimed to investigate the pathological mechanism of EP3 in modulating cervical cancer carcinogenesis.

Methods

Bioinformatics analysis was used to identify PAI-1 and uPAR correlations with EP3 expression, as well as the prognosis of cervical cancer patients. In vitro analyses were carried out to investigate the role of EP3 on cervical cancer proliferation and migration.

Results

In vitro studies showed that sulprostone (an EP3 agonist) enhanced the proliferation and migration of cervical cancer cells, whereas silencing of EP3 inhibited their proliferation and migration. Furthermore, EP3 knockdown increased the expression of plasminogen activator inhibitor type 1 (PAI-1), urokinase-type plasminogen activator receptor (uPAR), and phosphorylated extracellular signal-regulated kinases 1/2 (p-ERK1/2), but decreased p53 expression. Bioinformatics analysis showed that both PAI-1 and uPAR were correlated with EP3 expression, as well as the prognosis of cervical cancer patients. The survival analysis further showed that uPAR overexpression (IRS≥2) was correlated with a lower overall survival rate of cervical cancer patients with advanced stages (FIGO III-IV).

Conclusion

These results indicated that EP3 signaling pathway might facilitate the migration of cervical cancer cells through modulating uPAR expression. Therefore, EP3 and uPAR could represent novel therapeutic targets in the treatment of cervical cancer in advantaged stages.

Electronic supplementary material

The online version of this article (10.1007/s00432-020-03272-0) contains supplementary material, which is available to authorized users.

COX-2-PGE2-EPs in gynecological cancers

PURPOSE

Nonsteroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors (COXibs) inhibit the progression of endometrial cancer, ovarian cancer and cervical cancer. However, concerning the adverse effects of NSAIDs and COXibs, it is still urgent and necessary to explore novel and specific anti-inflammation targets for potential chemoprevention. The signaling of cyclooxygenase 2-prostaglandin E₂-prostaglandin E₂ receptors (COX-2-PGE₂-EPs) is the central inflammatory pathway involved in the gynecological carcinogenesis.

METHODS

Literature searches were performed to the function of COX-2-PGE₂-EPs in gynecological malignancies.

RESULTS

This review provides an overview of the current knowledge of COX-2-PGE₂-EPs signaling in endometrial cancer, ovarian cancer and cervical cancer. Many studies demonstrated the upregulated expression of the whole signaling pathway in gynecological malignancies and some focused on the function of COX-2 and cAMP-linked EP2/EP4 and EP3 signaling pathway in gynecological cancer. By contrast, roles of EP1 and the exact pathological mechanisms have not been completely clarified. The studies concerning EP receptors in gynecological cancers highlight the potential advantage of combining COX enzyme inhibitors with EP receptor antagonists as therapeutic agents in gynecological cancers.

CONCLUSION

EPs represent promising anti-inflammation biomarkers for gynecological cancer and may be novel treatment targets in the near future.

The prostaglandin receptor EP2 determines prognosis in EP3-negative and galectin-3-high cervical cancer cases

Recently our study identified EP3 receptor and galectin-3 as prognosticators of cervical cancer. The aim of the present study was the analysis of EP2 as a novel marker and its association to EP3, galectin-3, clinical pathological parameters and the overall survival rate of cervical cancer patients. Cervical cancer tissues (n = 250), as also used in our previous study, were stained with anti-EP2 antibodies employing a standardized immunohistochemistry protocol. Staining results were analyzed by the IRS scores and evaluated for its association with clinical-pathological parameters. H-test of EP2 percent-score showed significantly different expression in FIGO I-IV stages and tumor stages. Kaplan-Meier survival analyses indicated that EP3-negative/EP2-high staining patients (EP2 IRS score ≥2) had a significantly higher survival rate than the EP3-negative/EP2-low staining cases (p = 0.049). In the subgroup of high galectin-3 expressing patients, the group with high EP2 levels (IRS ≥2) had significantly better survival rates compared to EP2-low expressing group (IRS <2, p = 0.044). We demonstrated that the EP2 receptor is a prognostic factor for the overall survival in the subgroup of negative EP3 and high galectin-3 expressed cervical cancer patients. EP2 in combination with EP3 or galectin-3 might act as prognostic indicators of cervical cancer. EP2, EP3, and galectin-3 could be targeted for clinical diagnosis or endocrine treatment in cervical cancer patients, which demands future investigations.

EP3 receptor is a prognostic factor in TA-MUC1-negative ovarian cancer

PURPOSE

Prostaglandin-mediated inflammatory reactions play a major role in different cancers. Recently, it has been observed that prostaglandin E2-receptor 3 (EP3) might be an independent prognostic factor for overall survival in cervical and endometrial cancer. The role of EP3 expression in ovarian cancer is currently unknown.

METHODS

EP3 expression was analyzed by immunohistochemistry in 156 patient samples using the IR-scoring system. Expression levels were correlated with clinical and pathological parameters and with overall survival (OS) to assess for prognostic relevance. Data analysis was performed using Spearman's correlations, Kruskal-Wallis test and Kaplan-Meier estimates.

RESULTS

EP3 expression was significantly higher in clear-cell carcinoma (p < 0.001) compared to the other histological subtypes. No further correlations with clinical parameters could be found. EP3 expression correlated significantly with FSH-receptor expression (p < 0.001), galectin-1 expression in the tumor (p = 0.012) and with cytoplasmatic TA-MUC1 expression (p = 0.001). None of these parameters showed significant correlation with OS. In the TA-MUC1 negative subgroup, EP3 negative patients showed significantly longer OS (median OS: 102 months vs. 34 months in EP3 positive patients, p = 0.035), while EP3 did not appear to have prognostic relevance in the TA-MUC1-positive subgroup.

CONCLUSION

The potential prognostic relevance of EP3 expression for OS in TA-MUC1 negative patients might reflect an interplay between the COX and the MUC1 pathway, as it has been shown that MUC1 could induce COX2 expression. Our findings support the importance of the prostanoid signaling in TA-MUC1 negative ovarian cancer; however, future studies are necessary to characterize specific pathways and possible interactions.

EP3 receptor antagonist L798,106 reduces proliferation and migration of SK-BR-3 breast cancer cells

Purpose: COX-2 overexpression and elevated levels of prostaglandin E2 (PGE2) play an important role in breast cancer carcinogenesis. Recently, expression of the PGE2 receptor EP3 has been shown to be a positive prognostic factor in breast cancer. This study analyzes the functional aspects of targeting EP3 in breast cancer cell lines. Material and methods: EP3 and EP1 expressions were determined in five breast cancer cell lines on the mRNA- and the protein-level. The selected cell lines were subsequently stimulated for 24-72 hrs with 10-1,000 nM of PGE2, the EP1/EP3 agonist sulprostone and the EP3 antagonist L798,106. Cell proliferation was determined via BrdU-assay, migration via scratch assay, EP3, Gi-protein and p-ERK1/2 expressions via Western blot and cAMP concentrations via ELISA. The Mann-Whitney-U-test was used to test for statistical significance. Results: The cell lines T-47D (EP3 expression 77.7%) and SK-BR-3 (EP3 expression 48.7%) were chosen. EP3 antagonism reduced its expression on SK-BR-3 significantly, while no effect was observed on T-47D. The proliferation and migration of SK-BR-3 cells were significantly reduced due to treatment with the EP1/3 agonist, the EP3 antagonist or a combination of both. Neither agonism nor antagonism influenced cell proliferation or migration in T-47D. In SK-BR-3, EP3 antagonism showed a significant decrease in Gi-protein levels, an increase in cAMP levels, and no significant change in p-ERK1/2 expression. Conclusion: Antagonism of the EP3 receptor results in a reduced proliferation and migration of SK-BR-3 breast cancer cells, potentially mediated via a Gi-protein-cAMP pathway. The results suggest that EP3 plays a role in tumorigenesis. This is in accordance with the cell culture data of other gynecological tumors, but it is conflicting in so far, as positive EP3 expression is clinically a positive prognostic marker in breast cancer. Therefore, other factors may be important in explaining this contradiction.

The role of EP3-receptor expression in cervical dysplasia

PURPOSE

Prostaglandin-mediated inflammatory reactions play a major role in different cancers. Prostaglandin E2-receptor 3 (EP3) expression correlates with FIGO stages in cervical cancer and has been shown to be an independent prognostic factor for overall survival. EP3 expression levels in cervical intraepithelial neoplasia (CIN) as the precursor lesion of cervical cancer are currently unknown.

METHODS

EP3 expression was analyzed by immunohistochemistry in 124 patient samples (CIN 1-3 and healthy controls) using the IR-scoring system. Expression levels were correlated with clinical outcome to assess for prognostic relevance in patients with CIN 2. Data analysis was performed using Kruskal-Wallis and Mann-Whitney U test.

RESULTS

EP3 expression levels significantly correlated with different grades of cervical dysplasia. Median EP3-IRS in healthy cervical tissue was 12 (n = 13) compared to 9 in CIN 1 (n = 38; p = 0.031 vs. healthy control), 6 in CIN 2 (n = 45; p < 0.001 vs. CIN 1) and 4 in CIN 3 (n = 28, p = 0.008 vs. CIN 2). The percentage of EP3 expressing cells in CIN 2 lesions was significantly lower in progressive than in regressive cases (mean percentage of EP3 positive cells in progress: 3.8%, n = 18; in regress: 9.3%, n = 20; p = 0.040).

CONCLUSION

EP3 expression significantly decreases with higher grades of cervical intraepithelial neoplasia-which is in line with published IR scores in cervical cancer patients-and seems to be a prognostic marker for regression or progression of CIN 2 lesions. Our findings support the importance of the prostanoid pathway in cervical cancer and could help to identify targets for future therapies.