Identification of highly connected and differentially expressed gene subnetworks in metastasizing endometrial cancer

We have identified nine highly connected and differentially expressed gene subnetworks between aggressive primary tumors and metastatic lesions in endometrial carcinomas. We implemented a novel pipeline combining gene set and network approaches, which here allows integration of protein-protein interactions and gene expression data. The resulting subnetworks are significantly associated with disease progression across tumor stages from complex atypical hyperplasia, primary tumors to metastatic lesions. The nine subnetworks include genes related to metastasizing features such as epithelial-mesenchymal transition (EMT), hypoxia and cell proliferation. TCF4 and TWIST2 were found as central genes in the subnetwork related to EMT. Two of the identified subnetworks display statistically significant association to patient survival, which were further supported by an independent validation in the data from The Cancer Genome Atlas data collection. The first subnetwork contains genes related to cell proliferation and cell cycle, while the second contains genes involved in hypoxia such as HIF1A and EGLN3. Our findings provide a promising context to elucidate the biological mechanisms of metastasis, suggest potential prognostic markers and further identify therapeutic targets. The pipeline R source code is freely available, including permutation tests to assess statistical significance of the identified subnetworks.

Type of vascular invasion in association with progress of endometrial cancer

Vascular invasion (VI) is a well-established marker for lymph node metastasis and outcome in endometrial cancer. Our study explored whether specific types of VI, defined as lymphatic (LVI) or blood vessel invasion (BVI), predict pattern of metastasis. From a prospectively collected cohort, we conducted a case-control study by selecting three groups of endometrial cancer patients (n = 183): 52 with positive lymph nodes at primary surgery, 33 with negative nodes at primary surgery and later recurrence and death from disease, and 98 with negative nodes and no recurrence. All patients underwent hysterectomy with lymphadenectomy. Immunohistochemical staining with D2-40 and CD31 antibodies was used to differentiate between BVI and LVI. By immunohistochemical staining, detection of VI increased from 24.6 to 36.1% of the cases. LVSI was significantly more often seen in patients with positive lymph nodes compared with patients with negative nodes (p = 0.001). BVI was significantly more often seen in node-negative patients with recurrence compared with node-negative patients without recurrence (p = 0.011). In multivariable analysis, BVI, age, and tumor grade were predictors separating patients with and without recurrence. Lymph node-positive patients showed more often LVI compared with lymph node-negative patients, while BVI seems to be a predictor for recurrent disease.

Preoperative imaging markers and PDZ-binding kinase tissue expression predict low-risk disease in endometrial hyperplasias and low grade cancers

PURPOSE

Distinguishing complex atypical hyperplasia (CAH) from grade 1 endometrioid endometrial cancer (EECG1) preoperatively may be valuable in order to prevent surgical overtreatment, particularly in patients wishing preserved fertility or in patients carrying increased risk of perioperative complications.

MATERIAL AND METHODS

Preoperative histological diagnosis and radiological findings were compared to final histological diagnosis in patients diagnosed with CAH and EECG1. Imaging characteristics at preoperative magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography/computer tomography (FDG-PET/CT) were compared with tumor DNA oligonucleotide microarray data, immunohistochemistry findings and clinicopathological annotations.

RESULTS

MRI assessed tumor volume was higher in EECG1 than in CAH (p=0.004) whereas tumor apparent diffusion coefficient value was lower in EECG1 (p=0.005). EECG1 exhibited increased metabolism with higher maximum and mean standard uptake values (SUV) than CAH (p≤0.002). Unsupervised clustering of EECG1 and CAH revealed differentially expressed genes within the clusters, and identified PDZ-binding kinase (PBK) as a potential marker for selecting endometrial lesions with less aggressive biological behavior.

CONCLUSION

Both PBK expression and preoperative imaging yield promising biomarkers that may aid in the differentiation between EECG1 and CAH preoperatively, and these markers should be further explored in larger patient series.

Tissue and imaging biomarkers for hypoxia predict poor outcome in endometrial cancer

Hypoxia is frequent in solid tumors and linked to aggressive phenotypes and therapy resistance. We explored expression patterns of the proposed hypoxia marker HIF-1α in endometrial cancer (EC) and investigate whether preoperative functional imaging parameters are associated with tumor hypoxia. Expression of HIF-1α was explored both in the epithelial and the stromal tumor component. We found that low epithelial HIF-1α and high stromal HIF-1α expression were significantly associated with reduced disease specific survival in EC. Only stromal HIF-1α had independent prognostic value in Cox regression analysis. High stromal HIF-1α protein expression was rare in the premalignant lesions of complex atypical hyperplasia but increased significantly to invasive cancer. High stromal HIF-1α expression was correlated with overexpression of important genes downstream from HIF-1α, i.e. VEGFA and SLC2A1 (GLUT1). Detecting hypoxic tumors with preoperative functional imaging might have therapeutic benefits. We found that high stromal HIF-1α expression associated with high total lesion glycolysis (TLG) at PET/CT. High expression of a gene signature linked to hypoxia also correlated with low tumor blood flow at DCE-MRI and increased metabolism measured by FDG-PET. PI3K pathway inhibitors were identified as potential therapeutic compounds in patients with lesions overexpressing this gene signature. In conclusion, we show that high stromal HIF-1α expression predicts reduced survival in EC and is associated with increased tumor metabolism at FDG-PET/CT. Importantly; we demonstrate a correlation between tissue and imaging biomarkers reflecting hypoxia, and also possible treatment targets for selected patients.

The genomic landscape and evolution of endometrial carcinoma progression and abdominopelvic metastasis

Recent studies have detailed the genomic landscape of primary endometrial cancers, but the evolution of these cancers into metastases has not been characterized. We performed whole-exome sequencing of 98 tumor biopsies including complex atypical hyperplasias, primary tumors and paired abdominopelvic metastases to survey the evolutionary landscape of endometrial cancer. We expanded and reanalyzed The Cancer Genome Atlas (TCGA) data, identifying new recurrent alterations in primary tumors, including mutations in the estrogen receptor cofactor gene NRIP1 in 12% of patients. We found that likely driver events were present in both primary and metastatic tissue samples, with notable exceptions such as ARID1A mutations. Phylogenetic analyses indicated that the sampled metastases typically arose from a common ancestral subclone that was not detected in the primary tumor biopsy. These data demonstrate extensive genetic heterogeneity in endometrial cancers and relative homogeneity across metastatic sites.

Abstract 3864: Aneuploidy predicts aggressiveness and poor prognosis in endometrial cancer, and is reflected in a 9-gene signature

Introduction: Ploidy is among the most frequently studied biomarkers in endometrial cancer (EC), but lacks validation in larger studies. Mechanisms leading to tumor aneuploidy are only partly understood, and few studies have examined the molecular distinctions between diploid and aneuploid tumors in EC. Loss of the cohesin subunit STAG2 has been proposed as a driver of aneuploidy in several cancer types, but has not yet been explored for EC.

Aims: In this study, we wanted to investigate ploidy status in primary EC in relation to standard clinicopathologic variables including FIGO stage, grade, histologic type and age, as well as outcome. Further, we wanted to evaluate genes differentially expressed between aneuploid and diploid primary tumor samples, and the proposed aneuploidy marker STAG2 in EC.

Materials and methods: DNA ploidy was determined by flow cytometry in fresh tumor tissue for 794 patients, enrolled from 1980 - 2013. For expression analysis, RNA was extracted from fresh frozen primary tumor tissue from 144 samples, and measured with Agilent DNA microarrays (cat. no G4 112F). Significance Analysis of Microarrays (SAM) was run to identify differentially expressed genes between diploid and aneuploid cases. In order to identify the signature genes reflecting the differences between the two groups with highest accuracy, support vector machine (SVM) with 10-fold cross validation was applied. An aneuploidy score was calculated by subtracting the sum of expression of down-regulated genes from the sum of expression of up-regulated genes in the signature. Immunohistochemistry (IHC) was performed on tissue microarrays from 526 patients, with STAG2 antibody SA-2 (J12): sc-81852 (Santa Cruz Biotechnology). TCGA EC data were explored, and used for external validation.

Results: Aneuploidy was significantly associated with predictors of poor outcome including FIGO stage, grade, histologic subtype and age (p<0.001), and worse 5-year disease specific survival (DSS, p<0.001). SVM identified 9 genes (3 up- and 6 down-regulated) yielding a good accuracy for identifying aneuploid tumor status. The aneuploidy score was significantly associated with all standardly applied clinicopathologic surrogate markers for outcome (p<0.01) and DSS (p = 0.001). No association was found between STAG2 expression by IHC and ploidy status, however loss of STAG2 was associated with better DSS than intact STAG2 (p = 0.05). In TCGA data, 8.1% of EC patients had STAG2 mutations, with slightly better DSS compared to patients without mutation (p = 0.05).

Conclusions: DNA ploidy estimated by flow cytometry adds prognostic information in EC. Loss of STAG2 expression is not associated with aneuploidy. A 9-gene signature reflects ploidy status and predicts aggressive tumor behavior. The role of the 9 genes will be further explored to unveil potential involvement in aneuploidy development in EC.

Citation Format: Karen K. Mauland, Kanthida Kusonmano, Elisabeth Wik, Mari K. Halle, Jone Trovik, Hans K. Haugland, Anne M. Oyan, Helga B. Salvesen. Aneuploidy predicts aggressiveness and poor prognosis in endometrial cancer, and is reflected in a 9-gene signature. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3864. doi:10.1158/1538-7445.AM2015-3864

Endometrial Carcinoma Recurrence Score (ECARS) validates to identify aggressive disease and associates with markers of epithelial-mesenchymal transition and PI3K alterations

PURPOSE

Our previously reported 29-gene expression signature identified an aggressive subgroup of endometrial cancer patients with PI3K activation. We here wanted to validate these findings by independent patient series.

PATIENTS AND METHODS

The 29-gene expression signature was assessed in fresh frozen tumor tissue from 280 primary endometrial carcinomas (three independent cohorts), 19 metastatic lesions and in 333 primary endometrial carcinomas using TCGA data, and expression was related to clinico-pathologic features and survival. The 29-gene signature was assessed by real-time quantitative PCR, DNA oligonucleotide microarrays, or RNA sequencing. PI3K alterations were assessed by immunohistochemistry, DNA microarrays, DNA sequencing, SNP arrays or fluorescence in situ hybridization. A panel of markers of epithelial-mesenchymal transition (EMT) was also correlated to the 29-gene signature score.

RESULTS

High 29-gene Endometrial Carcinoma Recurrence Score (ECARS) values consistently validated to identify patients with aggressive clinico-pathologic phenotype and reduced survival. Within the presumed favorable subgroups of low grade, endometrioid tumors confined to the uterus, high ECARS still predicted a poor prognosis. The score was higher in metastatic compared to primary lesions (P<0.001) and was significantly associated with potential measures of PI3K activation, markers of EMT and vascular invasion as an indicator of metastatic spread (all P<0.001).

CONCLUSIONS

ECARS validates to identify aggressive endometrial carcinomas in multiple, independent patients cohorts. The higher signature score in metastatic compared to primary lesions, and the potential link to PI3K activation and EMT, support further studies of ECARS in relation to response to PI3K and EMT inhibitors in clinical trials of metastatic endometrial carcinoma.

Abstract 4502: DNA ploidy in tumor correlates with age, and explains some of the poor prognostic impact of age in endometrial carcinomas

Background: Endometrial cancer incidence is increasing in industrialized countries, and the demand for better prognostic markers in order to individualize treatment is emerging. DNA ploidy has previously shown independent prognostic impact in smaller studies. In this study, we wanted to investigate the prognostic impact of ploidy in primary endometrial tumors, and the link between DNA ploidy and patient age at diagnosis in relation to traditional clinicopathologic prognostic variables. Study design: 663 patients treated for endometrial carcinoma at Haukeland University Hospital, Norway, from 1981 through 2010 were included. DNA ploidy in fresh tumor specimens was measured by flow-cytometry. Comprehensive clinical and histopathologic data, treatment and complete follow-up were collected. The software PASWStatistics18 was used for statistical analysis. Results: DNA aneuploidy was significantly correlated to high patient age at diagnosis (p&lt;0.001). It was also correlated to non-endometrioid histology and high-grade tumors (p&lt;0.001) and high FIGO stage (p=0.012). In univariate survival analysis (Kaplan Meier), the 5-year disease specific survival of patients with diploid tumors was 89%, versus 65% for aneuploid tumors (p&lt;0.001). In Cox regression analysis, aneuploidy was significantly associated with poor survival (HR=2.4, 95%CI 1.6 - 3.8, p&lt;0.001), adjusted for FIGO stage, age, grade, and histologic subtype. Interestingly, the prognostic impact of patient age diminished when ploidy status was included in the Cox analysis. Conclusion: DNA ploidy estimation in endometrial carcinoma tumor tissue is highly associated with patient age at diagnosis, as well as prognosis. The prognostic impact of age decreases when adjusting for ploidy status in tumor.

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 4502. doi:1538-7445.AM2012-4502

Abstract 330: Gene expression signature characterized by PI3Kinase activation and Stathmin overexpression validates to identify aggressive disease and a potential for PI3Kinase-inhibitors in endometrial carcinomas

Background: We have recently reported a gene expression signature defining an aggressive subgroup of endometrial cancer patients characterized by PI3Kinase activation and Stathmin overexpression, suggesting the potential for PI3Kinase inhibitors against this disease (Salvesen et al, PNAS 2009). In the present study we wanted to validate the value of these measures for PI3Kinase activation prospectively in an independent patient series.

Methods: A prospectively collected, independent patient series of 158 cases of endometrial carcinoma was assessed. Real-time quantitative PCR was performed for the 29 genes in the previously defined gene signature. Stathmin expression in formalin fixed tumor specimens was assessed by immunohistochemistry (IHC).

Results: A high signature score predicted shorter recurrence free (p=0.001) and disease-specific survival (p=0.002). A high score was also significantly associated with high age (p=0.04), high FIGO stage (p=0.03), non-endometrioid histology (p&lt;0.001), high grade (p&lt;0.001) and lymph node metastases (p=0.02). High signature score was also correlated with overexpression of Stathmin in tumor tissue (p≪0.002).

Conclusion: The finding validates that previously identified markers for PI3Kinase activation identify aggressive phenotype in endometrial cancer. This further supports a potential for PI3Kinase-inhibitors in the treatment of metastatic endometrial carcinoma. We suggest that clinical trials with drugs targeting the PI3Kinase pathway involve stratification related to biomarkers, including the expression levels for this gene signature and Stathmin.

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 330. doi:10.1158/1538-7445.AM2011-330

High BMI is significantly associated with positive progesterone receptor status and clinico-pathological markers for non-aggressive disease in endometrial cancer

BACKGROUND

Endometrial cancer incidence is increasing in industrialised countries. High body mass index (BMI, kg  m(-2)) is associated with higher risk for disease. We wanted to investigate if BMI is related to clinico-pathological characteristics, hormone receptor status in primary tumour, and disease outcome in endometrial cancer.

PATIENTS AND METHODS

In total, 1129 women primarily treated for endometrial carcinoma at Haukeland University Hospital during 1981-2009 were studied. Body mass index was available for 949 patients and related to comprehensive clinical and histopathological data, hormone receptor status in tumour, treatment, and follow-up.

RESULTS

High BMI was significantly associated with low International Federation of Gynaecology and Obstetrics (FIGO) stage, endometrioid histology, low/intermediate grade, and high level of progesterone receptor (PR) mRNA by qPCR (n=150; P=0.02) and protein expression by immunohistochemistry (n=433; P=0.003). In contrast, oestrogen receptor (ERα) status was not associated with BMI. Overweight/obese women had significantly better disease-specific survival (DSS) than normal/underweight women in univariate analysis (P=0.035). In multivariate analysis of DSS adjusting for age, FIGO stage, histological subtype, and grade, BMI showed no independent prognostic impact.

CONCLUSION

High BMI was significantly associated with markers of non-aggressive disease and positive PR status in a large population-based study of endometrial carcinoma. Women with high BMI had significantly better prognosis in univariate analysis of DSS, an effect that disappeared in multivariate analysis adjusting for established prognostic markers. The role of PR in endometrial carcinogenesis needs to be further studied.