Metronomic dosing of ovarian cancer cells with the ATR inhibitor AZD6738 leads to loss of CDC25A expression and resistance to ATRi treatment

OBJECTIVE

ATR kinase inhibitors promote cell killing by inducing replication stress and through potentiation of genotoxic agents in gynecologic cancer cells. To explore mechanisms of acquired resistance to ATRi in ovarian cancer, we characterized ATRi-resistant ovarian cancer cells generated by metronomic dosing with the clinical ATR inhibitor AZD6738.

METHODS

ATRi-resistant ovarian cancer cells (OVCAR3 and OV90) were generated by dosing with AZD6738 and assessed for sensitivity to Chk1i (LY2603618), PARPi (Olaparib) and combination with cisplatin or a CDK4/6 inhibitor (Palbociclib). Models were characterized by diverse methods including silencing CDC25A in OV90 cells and assessing impact on ATRi response. Serum proteomic analysis of ATRi-resistant OV90 xenografts was performed to identify circulating biomarker candidates of ATRi-resistance.

RESULTS

AZD6738-resistant cell lines are refractory to LY2603618, but not to Olaparib or combinations with cisplatin. Cell cycle analyses showed ATRi-resistant cells exhibit G1/S arrest following AZD6738 treatment. Accordingly, combination with Palbociclib confers resistance to AZD6738. AZD6738-resistant cells exhibit altered abundances of G1/S phase regulatory proteins, including loss of CDC25A in AZD6738-resistant OV90 cells. Silencing of CDC25A in OV90 cells confers resistance to AZD6738. Serum proteomics from AZD6738-resistant OV90 xenografts identified Vitamin D-Binding Protein (GC), Apolipoprotein E (APOE) and A1 (APOA1) as significantly elevated in AZD6738-resistant backgrounds.

CONCLUSIONS

We show that metronomic dosing of ovarian cancer cells with AZD6738 results in resistance to ATR/ Chk1 inhibitors, that loss of CDC25A expression represents a mechanism of resistance to ATRi treatment in ovarian cancer cells and identify several circulating biomarker candidates of CDC25A low, AZD6738-resistant ovarian cancer cells.

Improving Risk Assessment for Metastatic Disease in Endometrioid Endometrial Cancer Patients Using Molecular and Clinical Features: An NRG Oncology/Gynecologic Oncology Group Study

Objectives: A risk assessment model for metastasis in endometrioid endometrial cancer (EEC) was developed using molecular and clinical features, and prognostic association was examined. Methods: Patients had stage I, IIIC, or IV EEC with tumor-derived RNA-sequencing or microarray-based data. Metastasis-associated transcripts and platform-centric diagnostic algorithms were selected and evaluated using regression modeling and receiver operating characteristic curves. Results: Seven metastasis-associated transcripts were selected from analysis in the training cohorts using 10-fold cross validation and incorporated into an MS7 classifier using platform-specific coefficients. The predictive accuracy of the MS7 classifier in Training-1 was superior to that of other clinical and molecular features, with an area under the curve (95% confidence interval) of 0.89 (0.80-0.98) for MS7 compared with 0.69 (0.59-0.80) and 0.71 (0.58-0.83) for the top evaluated clinical and molecular features, respectively. The performance of MS7 was independently validated in 245 patients using RNA sequencing and in 81 patients using microarray-based data. MS7 + MI (myometrial invasion) was preferrable to individual features and exhibited 100% sensitivity and negative predictive value. The MS7 classifier was associated with lower progression-free and overall survival (p ≤ 0.003). Conclusion: A risk assessment classifier for metastasis and prognosis in EEC patients with primary tumor derived MS7 + MI is available for further development and optimization as a companion clinical support tool.

Evaluation of a Patient With Non-Myoinvasive Uterine Serous Carcinoma Confined to a Polyp and Positive Peritoneal Washings With Somatic ARHGAP35 and KRAS Mutations

Currently, the application of peritoneal washings as a diagnostic tool for endometrial cancer staging is not well defined. The case described aims to highlight the current ambiguity surrounding the use of peritoneal washings in clinical practice. 

A 69-year-old G3P3003 presented to her gynecologist with complaints of new-onset heavy vaginal bleeding. The patient sought an endometrial biopsy, which suggested serous endometrial intraepithelial carcinoma (EIC) focally suspicious for invasive carcinoma, with the involvement of polyps. Based on these results, a robotic-assisted total laparoscopic hysterectomy, bilateral salpingo-oophorectomy, bilateral sentinel lymph node dissection, and omentectomy were performed. Results from her final pathology exhibited a stage IA uterine serous carcinoma (USC) involving a polyp (4.2 cm in greatest dimension) with no myometrial or lymphovascular invasion, but washings were positive for adenocarcinoma. Based on her family history of malignancy, the patient underwent germline panel testing. The patient’s somatic tumor testing demonstrated proficient DNA mismatch repair status, microsatellite stability, low tumor mutational burden (4 mut/Mb), low loss of heterozygosity (9%), amplification of the ERBB2 (HER2/neu) gene by both immunohistochemistry (3+, 20% positive) and fluorescence in-situ hybridization. Her tumor also had weakly positive estrogen receptor expression (1+, 10% positive); furthermore, some pathogenic variants in KRAS (c.37G>T), PIK3CA (c.263G>A), and TP53 (c.743G>A) were identified. Given the incongruent findings found with the positive peritoneal washing and negative lymph node involvement in addition to molecular testing, management for this patient was unclear.

Ultimately, this case highlights a number of advances within the field of gynecological oncology but also emphasizes the persistent ambiguity and incongruency in the management of patients with early-stage high-risk histologies. Moving forward it will become increasingly important to be able to develop a more standardized process to assess how these diagnostic tools should inform prognosis and treatment plans.

Pharmacological targeting of polyamine and hypusine biosynthesis reduces tumor activity of endometrial cancer

Endometrial cancer (EC) is a common and deadly cancer in women and novel therapeutic approaches are urgently needed. Polyamines (putrescine, spermidine, spermine) are critical for mammalian cell proliferation and MYC coordinately regulates polyamine metabolism through ornithine decarboxylase (ODC). ODC is a MYC target gene and rate-limiting enzyme of polyamine biosynthesis and the FDA-approved anti-protozoan drug α-difluoromethylornithine (DFMO) inhibits ODC activity and induces polyamine depletion that leads to tumor growth arrest. Spermidine is required for the hypusine-dependent activation of eukaryotic translation initiation factors 5A1 (eIF5A1) and 5A2 (eIF5A2) and connects the MYC/ODC-induced deregulation of spermidine to eIF5A1/2 protein translation, which is increased during cancer cell proliferation. We show that the eIF5A1 is significantly upregulated in EC cells compared to control cells (p = 0.000038) and that combined pharmacological targeting of ODC and eIF5A hypusination with cytostatic drugs DFMO and N1-guanyl-1,7-diaminoheptane (GC7), respectively, reduces eIF5A1 activation and synergistically induces apoptosis in EC cells. In vivo, DFMO/GC7 suppressed xenografted EC tumor growth in mice more potently than each drug alone compared to control (p = 0.002) and decreased putrescine (p = 0.045) and spermidine levels in tumor tissues. Our data suggest DFMO and GC7 combination therapy may be useful in the treatment or prevention of EC.

Peptide ancestry informative markers in uterine neoplasms from women of European, African, and Asian ancestry

Characterization of ancestry-linked peptide variants in disease-relevant patient tissues represents a foundational step to connect patient ancestry with disease pathogenesis. Nonsynonymous single-nucleotide polymorphisms encoding missense substitutions within tryptic peptides exhibiting high allele frequencies in European, African, and East Asian populations, termed peptide ancestry informative markers (pAIMs), were prioritized from 1000 genomes. In silico analysis identified that as few as 20 pAIMs can determine ancestry proportions similarly to >260K SNPs (R² = 0.99). Multiplexed proteomic analysis of >100 human endometrial cancer cell lines and uterine leiomyoma tissues combined resulted in the quantitation of 62 pAIMs that correlate with patient race and genotype-confirmed ancestry. Candidates include a D451E substitution in GC vitamin D-binding protein previously associated with altered vitamin D levels in African and European populations. pAIMs will support generalized proteoancestry assessment as well as efforts investigating the impact of ancestry on the human proteome and how this relates to the pathogenesis of uterine neoplasms.

Abstract 2502: Co-existing P53 and ARID1A mutations promote metastatic endometrial tumorigenesis

P53 and ARID1A are frequently mutated across cancer but rarely in the same tumor. Uterine endometrial cancer displays the highest P53-ARID1A mutual exclusivity rate. The genetic basis underlying P53-ARID1A mutual exclusivity and the relationship between molecular programs imposed by either mutation have not been elucidated in vivo mouse models. Here, genetically engineered mice were used to discern both unique and overlapping roles of P53 and ARID1A in the endometrium. Endometrial epithelial hyperplasia is driven by P53 loss with oncogenic PIK3CAH1047R in the endometrial epithelium. Sorted hyperplastic endometrial epithelial cells were transcriptome profiled and compared to control cells and ARID1A-PIK3CA mutant endometrium. Both P53 and ARID1A mutations lead to activation of inflammatory pathways but differ on other gene expression programs, such as epithelial-to-mesenchymal transition. Gene expression patterns observed in the genetic mouse models are reflective of human tumors with respective genetic alterations. ARID1A co-regulates P53 transcriptional gene targets, and the P53 pathway is activated in ARID1A mutant endometrial tumors. Finally, TP53 and ARID1A mutations co-occur more frequently in metastatic lesions, and co-existing TP53-ARID1A mutations are viable in the endometrium and lead to invasive endometrial cancer. These data suggest P53 and ARID1A mutations stimulate shared and distinct tumorigenic programs in the endometrium and promote metastasis when existing simultaneously. We propose that ARID1A loss in P53 mutant endometrial cancer promotes metastasis.

Citation Format: Jake J. Reske, Mike R. Wilson, Jeanne Holladay, John I. Risinger, Ronald L. Chandler. Co-existing P53 and ARID1A mutations promote metastatic endometrial tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2502.

Abstract 566: Therapeutic targeting of the polyamine pathway and EIF5A1 hypusination in endometrial cancer with DFMO and GC7

The polyamines putrescine, spermidine, and spermine are well-characterized oncometabolites upregulated in cancers and drive their proliferation and spread. Endometrial cancers (ECs) express high levels of ornithine decarboxylase (ODC), a rate-limiting enzyme of polyamine biosynthesis and decreased levels of spermidine/spermine N1-acetyltransferase (SAT1), a key negative regulator of polyamines. In addition, the deoxyhypusine synthase (DHPS) enzyme necessary for spermidine-dependent hypusination of eIF5A1 is highly expressed in ECs. Hypusinated EIF5A1 is needed by cancer cells to support their increased protein translation needs. Collectively, these findings suggest that the polyamine pathway is particularly active and necessary in EC. Here we evaluated the effect of ODC inhibitor difluoromethylornithine (DFMO) and DHPS inhibitor N1-Guanyl-1,7-Diaminoheptane (GC7) alone or in combination on the growth of ECs. GC7 and DFMO were effective in suppressing growth in EC cell lines in vitro as measured by MTS viability and proliferation assays. These effects were accompanied by decreased hypusinated EIF5A1 in treated cells. However, neither compound induced apoptotic cell death when applied singly. We did note that when non-apoptotic inducing doses of DFMO and GC7 were combined, EC cells showed a marked combinatorial decrease in viability, proliferation, and hypusinated EIF5A1 levels. Importantly we found that combined DFMO/GC7 treatment caused apoptotic cell death of EC cells as measured by cleaved PARP. Furthermore, levels of cleaved caspases 3 and 7 were increased in these cells while caspases 5 or 9 were not cleaved. In summary we found for the first time that pharmacologically increased depression of the polyamine pathway as measured by decreased hypusinated EIFA1 can lead to apoptotic cell death in ECs. These data suggest that targeting the polyamine pathway and particularly its role in protein translation through EIF5A1 hypusination may be an effective treatment strategy.

Citation Format: HongIm Kim, Chad Schultz, Andre Bachmann, John I. Risinger. Therapeutic targeting of the polyamine pathway and EIF5A1 hypusination in endometrial cancer with DFMO and GC7 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 566.

An immune competent orthotopic model of endometrial cancer with metastasis

Endometrial cancer is the most common gynecologic malignancy in the U.S. with metastatic disease remaining the major cause of patient death. Therapeutic strategies have remained essentially unchanged for decades. A significant barrier to progression in treatment modalities stems from a lack of clinically applicable in vivo models to accurately mimic endometrial cancer; specifically, ones that form distant metastases and maintain an intact immune system. To address this problem, we have established the first immune competent murine orthotopic tumor model for metastatic endometrial cancer by creating a green fluorescent protein labeled cell line from an endometrial cancer that developed in a Pgr ^cre/+ Pten ^f/f Kras ^G12D genetically engineered mouse. These cancer cells were grafted into the abraded uterine lumen of ovariectomized recipient mice treated with estrogen and subsequently developed local and metastatic endometrial tumors. We noted primary tumor formation in 59% mixed background and 86% of C57BL/6 animals at 4 weeks and distant lung metastases in 78% of mice after 2 months. This immunocompetent orthotopic tumor model closely resembles some human metastatic endometrial cancer, modeling both local metastasis and hematogenous spread to lung and has significant potential to advance the study of endometrial cancer and its metastasis.

Ubiquitin Carboxyl-Terminal Hydrolase L1 (UCHL1) Promotes Uterine Serous Cancer Cell Proliferation and Cell Cycle Progression

Uterine serous carcinoma (USC) is the most aggressive form of endometrial cancer, with poor survival rates and high recurrence risk. Therefore, the purpose of this study was to identify therapeutic targets that could aid in the management of USC. By analyzing endometrial cancer samples from The Cancer Genome Atlas (TCGA), we found Ubiquitin Carboxyl-Terminal Hydrolase L1 (UCHL1) to be highly expressed in USC and to correlate with poorer overall survival. UCHL1 silencing reduced cell proliferation in vitro and in vivo, cyclin B1 protein levels and cell cycle progression. Further studies showed that UCHL1 interacts with cyclin B1 and increases cyclin B1 protein stability by deubiquitination. Treatment of USC-bearing mice with the UCHL1-specific inhibitor reduced tumor growth and improved overall survival. Our findings suggest that cyclin B1 is a novel target of UCHL1 and targeting UCHL1 is a potential therapeutic strategy for USC.

Human Ovarian Cancer Tumor Formation in Severe Combined Immunodeficient (SCID) Pigs

Ovarian cancer (OvCa) is the most lethal gynecologic malignancy, with two-thirds of patients having late-stage disease (II-IV) at diagnosis. Improved diagnosis and therapies are needed, yet preclinical animal models for ovarian cancer research have primarily been restricted to rodents, for data on which can fail to translate to the clinic. Thus, there is currently a need for a large animal OvCa model. Therefore, we sought to determine if pigs, being more similar to humans in terms of anatomy and physiology, would be a viable preclinical animal model for OvCa. We injected human OSPC-ARK1 cells, a chemotherapy-resistant primary ovarian serous papillary carcinoma cell line, into the neck muscle and ear tissue of four severe combined immune deficient (SCID) and two non-SCID pigs housed in novel biocontainment facilities to study the ability of human OvCa cells to form tumors in a xenotransplantation model. Tumors developed in ear tissue of three SCID pigs, while two SCID pigs developed tumors in neck tissue; no tumors were detected in non-SCID control pigs. All tumor masses were confirmed microscopically as ovarian carcinomas. The carcinomas in SCID pigs were morphologically similar to the original ovarian carcinoma and had the same immunohistochemical phenotype based on expression of Claudin 3, Claudin 4, Cytokeratin 7, p16, and EMA. Confirmation that OSPC-ARK1 cells form carcinomas in SCID pigs substantiates further development of orthotopic models of OvCa in pigs.

MIG-6 suppresses endometrial epithelial cell proliferation by inhibiting phospho-AKT

Background

Aberrant hyperactivation of epithelial proliferation, AKT signaling, and association with unopposed estrogen (E2) exposure is the most common endometrial cancer dysfunction. In the normal uterus, progesterone (P4) inhibits proliferation by coordinating stromal-epithelial cross-talk, which we previously showed is mediated by the function of Mitogen-inducible gene 6 (Mig-6). Despite their attractive characteristics, non-surgical conservative therapies based on progesterone alone have not been universally successful. One barrier to this success has been the lack of understanding of the P4 effect on endometrial cells.

Method

To further understand the role of Mig-6 and P4 in controlling uterine proliferation, we developed a Sprr2f-cre driven mouse model where Mig-6 is specifically ablated only in the epithelial cells of the uterus (Sprr2f^cre+Mig-6^f/f). We examined P4 effect and regulation of AKT signaling in the endometrium of mutant mice.

Results

Sprr2f^cre+Mig-6^f/f mice developed endometrial hyperplasia. P4 treatment abated the development of endometrial hyperplasia and restored morphological and histological characteristics of the uterus. P4 treatment reduced cell proliferation which was accompanied by decreased AKT signaling and the restoration of stromal PGR and ESR1 expression. Furthermore, our in vitro studies revealed an inhibitory effect of MIG-6 on AKT phosphorylation as well as MIG-6 and AKT protein interactions.

Conclusions

These data suggest that endometrial epithelial cell proliferation is regulated by P4 mediated Mig-6 inhibition of AKT phosphorylation, uncovering new mechanisms of P4 action. This information may help guide more effective non-surgical interventions in the future.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4502-7) contains supplementary material, which is available to authorized users.

Ornithine decarboxylase as a therapeutic target for endometrial cancer

Ornithine Decarboxylase (ODC) a key enzyme in polyamine biosynthesis is often overexpressed in cancers and contributes to polyamine-induced cell proliferation. We noted ubiquitous expression of ODC1 in our published endometrial cancer gene array data and confirmed this in the cancer genome atlas (TCGA) with highest expression in non-endometrioid, high grade, and copy number high cancers, which have the worst clinical outcomes. ODC1 expression was associated with worse overall survival and increased recurrence in three endometrial cancer gene expression datasets. Importantly, we confirmed these findings using quantitative real-time polymerase chain reaction (qRT-PCR) in a validation cohort of 60 endometrial cancers and found that endometrial cancers with elevated ODC1 had significantly shorter recurrence-free intervals (KM log-rank p = 0.0312, Wald test p = 5.59e-05). Difluoromethylornithine (DFMO) a specific inhibitor of ODC significantly reduced cell proliferation, cell viability, and colony formation in cell line models derived from undifferentiated, endometrioid, serous, carcinosarcoma (mixed mesodermal tumor; MMT) and clear cell endometrial cancers. DFMO also significantly reduced human endometrial cancer ACI-98 tumor burden in mice compared to controls (p = 0.0023). ODC-regulated polyamines (putrescine [Put] and/or spermidine [Spd]) known activators of cell proliferation were strongly decreased in response to DFMO, in both tumor tissue ([Put] (p = 0.0006), [Spd] (p<0.0001)) and blood plasma ([Put] (p<0.0001), [Spd] (p = 0.0049)) of treated mice. Our study indicates that some endometrial cancers appear particularly sensitive to DFMO and that the polyamine pathway in endometrial cancers in general and specifically those most likely to suffer adverse clinical outcomes could be targeted for effective treatment, chemoprevention or chemoprevention of recurrence.

Abstract LB-281: Meta analysis of gene transcripts from fatty livers and liver cancers of C57BL6 mice identifies potential drivers of HCC

Rates of obesity are increasing and 640 million adults were considered obese in 2014 an increase of 27.5% over the past three decades. Obesity is strongly linked with increased cancer risk and particularly so for liver cancer in men. Although virus infection had been the leading cause of hepatocellular carcinoma (HCC) in the past, the incidence of obesity induced Non-Alcoholic Fatty Liver Disease (NAFLD) a precursor to HCC is increasing and the number of new HCC cases increased 38% and HCC deaths 56% in the last decade. In this study, we conducted meta-analysis of gene expression profiles obtained from livers of high fat diet fed and chemically induced liver cancers of male C57BL/6 mice in order to elucidate the characteristics of fatty liver and HCC. Three separate studies fed mice high fat diets with 60% kcal% fat (from lard and soy bean oil) diet starting at 7 or 8 week old, and continued for 7-10 weeks (7 weeks, GSE40638; 10 weeks, GSE52333; and 8 weeks, GSE79434). We compared these three studies with a liver cancer study (GSE51188) which induced cancers following a single dose of 25 mg/kg diethyl nitrosamine. Affymetrix Mouse Gene 1.0 ST Array was used for high fat diet studies, and Illumina MouseRef-8 x2.0 BeadChips was used for cancer study. We analyzed each study data with GEO2R (comparison against respective normal liver) and performed meta-analysis of the four data sets by Advaita Pathway Guide software. The analysis identified 118 genes ≥0.2 log2 fold-change (Log2FC) and &lt;0.05 p-value (Allowed &gt;0.05 for 1/3 high fat diet studies to increase the candidate genes, but the direction of changes is the same with other two studies). Among these 118 genes, 22 genes were up-regulated and another 17 genes were down-regulated in all four data sets. 29 genes were elevated in tumor, but lowered in high fat diet. On the other hand, 50 genes were lowered in tumor and elevated in high fat diet. We identified Annexin A2 (Anxa2) among the 22 genes which were up-regulated in all data sets, Anxa2 has consistently been reported to be increased in liver tumors and is associated with poor prognosis. The Anxa2 finding suggests our methodology is robust. Besides Anxa2, Nucleoporin 62 (Nup62), Lactate Dehydrogenase A (Ldha), Oxysterol Binding Protein-Like 3 (Osbpl3) were also up-regulated in all studies (Log2FC of liver tumor: Anxa2=2.75, Nup62=0.35, Ldha=0.53, Osbpl3=1.82). Osbpl3 had higher Log2FC value following Anxa2, and its expression was found to be upregulated in some cancers. Importantly, all these were significantly associated with lower overall survival rates in male HCC patients of The Cancer Genome Atlas (TCGA Genes; ANXA2, p=0.00032; NUP62, p=0.000003; LDHA, p=0.0154; OSBPL3, p=0.0255). This data analysis identified several new genes that may be involved in developing cancer from fatty liver, and they might be useful cancer biomarkers based on their association with poor survival.

Citation Format: Kumiko Kato-Shoji, Noriyuki Miyoshi, Miki Igarashi, John I. Risinger, Yutaka Shoji. Meta analysis of gene transcripts from fatty livers and liver cancers of C57BL6 mice identifies potential drivers of HCC [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 LB-281. doi:10.1158/1538-7445.AM2017-LB-281

Abstract 1242: Ornithine decarboxylase as a therapeutic target in endometrial cancer

Endometrial cancer is the 4th most common cancer and the 6th deadliest cancer in US women. The American Cancer Society estimates there will be 60,050 new endometrial cancers in 2016, an increase of more than 10% from the previous year highlighting the need for more effective treatments and prevention. Ornithine Decarboxylase (ODC) a key enzyme in polyamine synthesis is often overexpressed in cancers and contributes to cell proliferation and tumor growth. Therefore, ODC and the polyamine pathway are considered rational targets for cancer treatment or prevention. We noted ubiquitous expression of ODC1 in our previously published endometrial cancer gene array data and confirmed this in the cancer genome atlas (TCGA), finding expression in all four molecular sub-types with highest expression in copy number high cancers which have the worst clinical outcomes. Therefore, we explored the association of ODC1 gene expression with clinical outcomes of overall survival (OS) and recurrence in the TCGA cohort and noted that elevated ODC1 was significantly related to OS (Wald test p=0.001) and recurrence (p=0.01). Importantly, we confirmed these observations using QRT-PCR in a validation cohort of 60 endometrial cancers and found that endometrial cancers with elevated ODC1 had significantly shorter recurrence-free intervals (p=5.59x10-5) and elevated hazard ratio=3.72. Similar to TCGA data we also noted a strong trend to worse OS ( p=0.00014) with elevated hazard ratio 3.81. Numerous studies including clinical trials have examined the chemopreventive and anti-tumor effects of difluoromethylornithine (DFMO), a specific inhibitor of ODC. We found that DFMO treatment significantly reduced cell proliferation, cell viability, and colony formation in human cell line models derived from undifferentiated, endometrioid, serous, MMT and clear cell endometrial cancers. In contrast, immortalized uterine endometrial epithelial cells (EM E6/E7 TERT1) were less sensitive to DFMO. To confirm the significant effects of DFMO in vitro we performed an in vivo study with human endometrial cancer (ACI-98) tumor-bearing athymic nude mice. Xenografted mice were either treated with 2% (w/v) DFMO supplied in drinking water or water only (n=10/group). DFMO significantly reduced the tumor burden in mice compared to controls (p=0.0023). ODC-regulated polyamines (putrescine [Put] and spermidine [Spd]) known activators of cell proliferation were strongly decreased in response to DFMO, in both tumor tissue ([Put] (p=0.0006), [Spd] (p&lt;0.0001)) and blood plasma ([Put] (p&lt;0.0001), [Spd] (p=0.0049)) of treated mice. Results of these studies indicate that some endometrial cancers appear particularly sensitive to DFMO. Our findings indicate that the polyamine pathway in endometrial cancers in general and specifically those most clinically relevant endometrial cancers could be targeted for effective treatment, chemoprevention or chemoprevention of recurrence.

Citation Format: Hong Im Kim, Chad R. Schultz, Andrea L. Buras, Elizabeth Friedman, Alyssa M. Fedorko, Leigh G. Seamon, Gadisetti Chandramouli, André S. Bachmann, John I. Risinger. Ornithine decarboxylase as a therapeutic target in endometrial cancer [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 1242. doi:10.1158/1538-7445.AM2017-1242

Abstract A19: Cytoplasmic ARID1A and poor outcome in ovarian cancer patients

Objective: Frequent loss of function mutations in the chromatin remodeling protein and tumor suppressor, AT-rich interactive domain-containing protein 1A (ARID1A), have been noted in ovarian cancers, particularly clear-cell and mucinous histotypes. We initially investigated the relationship between differential ARID1A protein levels and patient survival in a well-annotated ovarian cancer tissue microarray. Our analyses revealed distinct cellular localization patterns for ARID1A using moderately stringent assay conditions and we observed a relationship between cytoplasmic staining of ARID1A and poor disease outcome. We further investigated the relevance of cytoplasmic ARID1A in vitro in a cell line model of ARID1A-mutated, clear-cell ovarian cancer and found that ectopic expression of a cytoplasm-localized variant of ARID1A enhances cellular proliferation relative to wild type ARID1A restored cells.

Methods: Tissue microarrays representing a natural distribution of ovarian cancer histotypes (N=259) were stained for ARID1A and scored. Four patient subgroups were further defined based on the absence or presence of distinct ARID1A staining in nuclear and/or cytoplasmic tumor cell compartments. Relationships between ARID1A staining pattern and patient outcome were investigated using univariate and multivariate Cox regression modeling with Wald testing and Kaplan-Meier method with log-rank testing. Nuclear localization sequence variants of ARID1A were generated and phenotypic assessments of cellular proliferation were performed following ectopic expression of cytoplasm-localized versus wild type, i.e. nuclear-localized, ARID1A in a cell line model of ARID1A-mutated, clear cell ovarian cancer cells (TOV21G).

Results: Using a moderately stringent IHC assay for ARID1A, loss of nuclear ARID1A was observed in 7% of ovarian cancer patients, and women with versus without loss of nuclear ARID1A had similar survival. Prevalent cytoplasmic staining was observed in 14% of cases overall and was more common in mucinous (50%), clear cell (42%) and serous (11%) adenocarcinomas than other histotypes (p=0.002). Prevalent cytoplasmic ARID1A was not only associated with an increased risk of death in the entire cohort (HR=1.67, 95% CI=1.137-2.454, p=0.009), but was also an independent predictor of worse survival (adjusted HR=1.530, 95% CI=1.017-2.301, p=0.041) after adjusting for patient age at diagnosis, site of disease, stage, cell type and grade. Comparative in vitro analyses of cytoplasmic and wild type ARID1A variants, ectopically-expressed in clear-cell ovarian cancer cells revealed that cytoplasmic ARID1A confers an increased proliferative phenotype relative to wild type ARID1A restored cells.

Conclusions: ARID1A cellular localization and abundance varied across ovarian cancer histotypes and cytoplasmic localization was indicative of worse outcome. Our in vitro studies suggest cytoplasmic ARID1A increases the proliferative potential of clear-cell ovarian tumor cells and provides phenotypic evidence supporting the poor disease outcomes we observe in patients exhibiting cytoplasmic ARID1A. These findings support further investigations combining assessments of ARID1A cellular localization and abundance patterns towards the identification of ovarian cancer patients with an elevated risk to experience poor disease outcome.

Citation Format: Nicholas W. Bateman, Kevin A. Byrd, Kelly A. Conrads, John I. Risinger, Carl Morrison, Kunle Odunsi, Chad A. Hamilton, G. Larry Maxwell, Kathleen M. Darcy, Thomas P. Conrads. Cytoplasmic ARID1A and poor outcome in ovarian cancer patients. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A19.

Abstract LB-127: Enrichment of chromosome 1 and 6p21 genes associated with worse progression-free and overall survival in endometrial cancer patients

Endometrial cancers are generally considered to have favorable outcomes. However, recurrent, and/or non-endometrioid types and some high-grade endometrioid lesions often have very poor survival with limited treatment options. The genes specifically associated with these poor outcomes are not well described. The integrated genomic characterization of endometrial cancers was published in 2013 and the associated RNA-Seq data of these uterine corpus cancers are publicly available at The Cancer Genome Atlas [Nature 497 (7447):67-73]. However, studies on the association of gene expression with the overall survival and recurrence of these endometrial cancers are not yet reported. In this work, we identify those genes associated with survival and recurrence endpoints. RSEM Normalized RNA-Seq (UNC Illumina HiSeq RNASeq V2, level 3) data was downloaded from the TCGA website and survival data extracted from this resource. Cox regression analysis was performed using the survival package in R-environment. The cohort of the patients used in this study cover a large proportion of endometrioid type, while the remaining are serous and mixed histologic types. The proportion of grades 1 to 3 is 84:101:168 and stages I & II (low) to III & IV (high) is 263:87. The ratio of microsatellite unstable to stable cases is about 1:2 approximately both in living and diseased. The tissues were not micro-dissected leaving tumor infiltrates, stroma and other debris. This analysis identified 160 genes significant at p ≤ 0.001 for either overall survival and recurrence free survival or both. In the overall survival analysis, 82 genes were at hazard ratio (HR) ≥ 1 and 48 were at HR ≤ 1. We noted that chromosome 1 was over-represented among gene locations from these gene transcripts. In addition to enrichment of chromosome 1 genes we noted a cluster of genes located on 6p21 with elevated hazard ratios associated with poor clinical outcome. Ontology analysis of the survival associated genes was assessed by EASE software which pointed out the immune response genes have hazard ratios under 1 suggesting that it is a predominant mechanism associated with positive clinical outcome. The finding of immune response genes association with positive clinical outcome (HR ≤ 1) is provocative that prompts further investigation in the assessment and therapy of endometrial cancer. The enrichment of genes on chromosomes 1 and 6 offer further clues to the mechanisms underlying those endometrial cancers with poor clinical outcome.

Citation Format: Rusheeswar Challa, GVR Chandramouli, Alyssa Fedorko, Thomas P. Conrads, John I. Risinger. Enrichment of chromosome 1 and 6p21 genes associated with worse progression-free and overall survival in endometrial cancer patients. [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 LB-127. doi:10.1158/1538-7445.AM2015-LB-127

MicroRNAs in endometrial cancers from black and white patients

OBJECTIVE

Previous studies have identified differences in gene mutations among endometrial cancers from whites and blacks suggesting that differences in tumor biology may explain racial disparities in patient outcome. Micro RNAs (miRNAs) have emerged as regulators of transcript expression and their aberrant expression has been discovered in many diseases, including endometrial cancer. We performed quantitative polymerase chain reaction-based analysis in a set of endometrial cancers to identify whether there are racial differences in miRNA expression.

STUDY DESIGN

Tumor cells from 50 stage-I endometrioid endometrial cancer specimens from 41 white and 9 black patients were prepared by laser microdissection and miRNA extracts were analyzed using TaqMan (Life Technologies, Carlsbad, CA) low-density arrays. Statistically significant, differentially expressed miRNAs between blacks and whites were identified using multidimensional scaling, Wilcoxon testing, and analysis of variance.

RESULTS

There were no global differences in miRNA expression between endometrial cancers from 41 white and 9 black patients. To minimize potential bias introduced by unbalanced sample size, we performed a subset analysis with stage- and histology-matched specimens from 9 whites and 9 blacks that identified 18 differentially abundant miRNAs (>2-fold at P < .005). Quantitative polymerase chain reaction validated miRNA-337-3p in an independent set of endometrial cancer specimens from 23 white and 24 black women. There were no racial differences in hsa-miR-337-3p expression in normal endometrium.

CONCLUSION

These data indicate that hsa-mir-337-3p is more frequently down-regulated in endometrial cancers from whites compared to blacks. Future studies are focused on determining the phenotypic impact of miR-337-3p and whether its differential expression is associated with clinical outcome.

Abstract 1570: ARID1A regulation of ATAD2 in gynecologic cancer

ARID1A the DNA binding component of the SWI/SNF nucleosome and chromatin remodeling complex has recently been identified as a tumor suppressor and inactivating mutations have been reported in several tumor types including uterine and ovarian cancer. Approximately 30% of ovarian endometrioid cancers (OEC), 50% of clear cell ovarian cancers (OCCC) and 40% of uterine endometrial cancers harbor ARID1A inactivating mutations. Little is known regarding the subunit composition of SWI/SNF complexes that contain ARID1A in ovarian and uterine cells and less is known regarding the transcriptional and functional consequences of ARID1A loss. In order to further explore the function of ARID1A in gynecologic cancers we restored ARID1A in ACI-98 (undifferentiated uterine cancer) an ARID1A negative and TP53 positive cell line using an inducible Tet-on system. Restoration of ARID1A induced apoptosis in ACI-98 cells after 48h doxycycline (Dox) treatment. We examined the proteome of these cells and catalogued the protein changes following ARID1A complementation using LC MS/MS. Specifically we identified 523 highly significantly differentially expressed proteins (z-score &lt;0.01) from this analysis. Among these was the AAA domain containing 2 (ATAD2) that was dramatically down-regulated in ARID1A restored cells. ATAD2 is a highly conserved protein normally expressed in germ cells but is also over-expressed in some cancers. Affymetrix gene expression results also showed that ATAD2 is over-expressed in some ovarian and uterine cancers compared to normal controls. We further examined the clinical consequence of ATAD2 expression in ovarian cancers using the Kaplan-Meier plots website (http://kmplot.com) and found that the high-expression group has a worse overall survival than those in the low-expression group. ATAD2 associates via its bromodomain with histone H3 and it is known to act as a co-factor for E2Fs, MYC, androgen and estrogen receptors and whose over-expression drives the expression of target genes that induce cell proliferation and resistance to apoptosis. qRT-PCR results indicated that transcription of ATAD2 was not changed by restoration of ARID1A, moreover, anti-ARID1A ChIP-sequence revealed that SWI/SNF-ARID1A is not binding to the promoter of ATAD2. From these results, we suspect that the down regulation of ATAD2 is through a non-transcriptional mechanism. In addition, ARID1A-IP-MS result suggested that ARID1A is itself making complexes with ATAD2. We performed ATAD2 and ARID1A immunohistochemistry on a set of OCCC and OEC primary cancers and found that all cases with ARID1A negative staining preferentially over-express ATAD2. In summary our data indicate that ARID1A decreases levels of ATAD2, that ARID1A-negative OCCC and OEC are a subset of ovary cancer that preferentially overexpress ATAD2, and that ATAD2 over-expressing cancers have worse survival than weak expressers.

Citation Format: Yutaka Shoji, Kelly A. Conrads, Rusheeswar Challa, Brian L. Hood, Guisong Wang, Kathleen M. Darcy, Chad A. Hamilton, George Larry Maxwell, Thomas P. Conrads, John I. Risinger. ARID1A regulation of ATAD2 in gynecologic cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1570. doi:10.1158/1538-7445.AM2014-1570

Human ovarian cancer stroma contains luteinized theca cells harboring tumor suppressor gene GT198 mutations

Ovarian cancer is a highly lethal gynecological cancer, and its causes remain to be understood. Using a recently identified tumor suppressor gene, GT198 (PSMC3IP), as a unique marker, we searched for the identity of GT198 mutant cells in ovarian cancer. GT198 has germ line mutations in familial and early onset breast and ovarian cancers and recurrent somatic mutations in sporadic fallopian tube cancers. GT198 protein has been shown as a steroid hormone receptor coregulator and also as a crucial factor in DNA repair. In this study, using GT198 as a marker for microdissection, we find that ovarian tumor stromal cells harboring GT198 mutations are present in various types of ovarian cancer including high and low grade serous, endometrioid, mucinous, clear cell, and granulosa cell carcinomas and in precursor lesions such as inclusion cysts. The mutant stromal cells consist of a luteinized theca cell lineage at various differentiation stages including CD133(+), CD44(+), and CD34(+) cells, although the vast majority of them are differentiated overexpressing steroidogenic enzyme CYP17, a theca cell-specific marker. In addition, wild type GT198 suppresses whereas mutant GT198 protein stimulates CYP17 expression. The chromatin-bound GT198 on the human CYP17 promoter is decreased by overexpressing mutant GT198 protein, implicating the loss of wild type suppression in mutant cells. Together, our results suggest that GT198 mutant luteinized theca cells overexpressing CYP17 are common in ovarian cancer stroma. Because first hit cancer gene mutations would specifically mark cancer-inducing cells, the identification of mutant luteinized theca cells may add crucial evidence in understanding the cause of human ovarian cancer.

Gene expression analysis of early stage endometrial cancers reveals unique transcripts associated with grade and histology but not depth of invasion

Endometrial cancer is the most common gynecologic malignancy in the United States but it remains poorly understood at the molecular level. This investigation was conducted to specifically assess whether gene expression changes underlie the clinical and pathologic factors traditionally used for determining treatment regimens in women with stage I endometrial cancer. These include the effect of tumor grade, depth of myometrial invasion and histotype. We utilized oligonucleotide microarrays to assess the transcript expression profile in epithelial glandular cells laser microdissected from 79 endometrioid and 12 serous stage I endometrial cancers with a heterogeneous distribution of grade and depth of myometrial invasion, along with 12 normal post-menopausal endometrial samples. Unsupervised multidimensional scaling analyses revealed that serous and endometrioid stage I cancers have similar transcript expression patterns when compared to normal controls where 900 transcripts were identified to be differentially expressed by at least fourfold (univariate t-test, p < 0.001) between the cancers and normal endometrium. This analysis also identified transcript expression differences between serous and endometrioid cancers and tumor grade, but no apparent differences were identified as a function of depth of myometrial invasion. Four genes were validated by quantitative PCR on an independent set of cancer and normal endometrium samples. These findings indicate that unique gene expression profiles are associated with histologic type and grade, but not myometrial invasion among early stage endometrial cancers. These data provide a comprehensive perspective on the molecular alterations associated with stage I endometrial cancer, particularly those subtypes that have the worst prognosis.

Gene expression in uterine leiomyoma from tumors likely to be growing (from black women over 35) and tumors likely to be non-growing (from white women over 35)

The study of uterine leiomyomata (fibroids) provides a unique opportunity to investigate the physiological and molecular determinants of hormone dependent tumor growth and spontaneous tumor regression. We conducted a longitudinal clinical study of premenopausal women with leiomyoma that showed significantly different growth rates between white and black women depending on their age. Growth rates for leiomyoma were on average much higher from older black women than for older white women, and we now report gene expression pattern differences in tumors from these two groups of study participants. Total RNA from 52 leiomyoma and 8 myometrial samples were analyzed using Affymetrix Gene Chip expression arrays. Gene expression data was first compared between all leiomyoma and normal myometrium and then between leiomyoma from older black women (age 35 or older) and from older white women. Genes that were found significant in pairwise comparisons were further analyzed for canonical pathways, networks and biological functions using the Ingenuity Pathway Analysis (IPA) software. Whereas our comparison of leiomyoma to myometrium produced a very large list of genes highly similar to numerous previous studies, distinct sets of genes and signaling pathways were identified in comparisons of older black and white women whose tumors were likely to be growing and non-growing, respectively. Key among these were genes associated with regulation of apoptosis. To our knowledge, this is the first study to compare two groups of tumors that are likely to have different growth rates in order to reveal molecular signals likely to be influential in tumor growth.

Transcript expression in endometrial cancers from Black and White patients

OBJECTIVE

Previous studies suggest that differences in molecular features of endometrial cancers between racial groups may contribute to the poorer survival in Blacks. The objective of this investigation was to determine whether gene expression among endometrial cancers is different between Blacks and Whites.

METHODS

Fresh frozen tumors from 25 Black patients were matched by stage, grade, and histology to endometrial cancer specimens from 25 White patients. Each case was macrodissected to produce specimens possessing a minimum of 75% cancer cellularity. A subset of 10 matched pairs was also prepared using laser microdissection (LMD) to produce specimens possessing a minimum of 95% cancer cells. Total RNA isolated from each sample was analyzed using the Affymetrix Human Genome U133 Plus 2.0 arrays. Data were analyzed using principal component analysis and binary class comparison analyses.

RESULTS

Unsupervised analysis of the 50 endometrial cancers failed to identify global gene expression profiles unique to Black or White patients. In a subset analysis of 10 matched pairs from Blacks and Whites prepared using LMD and macrodissection, unsupervised analysis did not reveal a unique gene expression profile associated with race in either set, but associations were identified that relate to sample preparation technique, histology and stage.

CONCLUSIONS

Our microarray data revealed no global gene expression differences and identified few individual gene differences between endometrial cancers from Blacks and Whites. More comprehensive methods of transcriptome analysis could uncover RNAs that may underpin the disparity of outcome or prevalence of endometrial cancers in Blacks and Whites.

Abstract 1966: Analysis of micro RNAs in the racial disparity of endometrial cancer

In the United States endometrial cancer is recognized for having a distinct racial disparity. This disparity by race occurs for both the prevalence of disease and for survival outcome. Caucasians are about two times more likely to develop endometrial cancer than are African Americans. However, African American women are more likely to die from this disease than are Caucasians. The basis for this disparity remains unknown. Previous studies have identified differences in the types and frequencies of gene mutations among endometrial cancers from Caucasians and African-Americans suggesting that the tumors from these two groups might have differing underlying genetic defects. In addition previous studies have utilized gene expression microarray studies in an effort to identify differentially expressed transcripts between African-American and Caucasian women's endometrial cancers. MicroRNAs (miRNA) have emerged as additional regulators of cell function and their aberrant expression and function is noted in many diseases including endometrial cancers. We performed an analysis in a set of early stage endometrial cancers to identify whether differences in miRNA expression may underlie some biologic aspect of this racial disparity. We assayed 50 laser microdissected endometrial cancers using TaqMan Low Density arrays and compared the expression of miRNAs between African-American (9 patients) and Caucasian (41 patients) cancers. Similarly to previous mRNA comparisons by our group, no global differences in miRNA expression were evident between African American and Caucasian endometrial cancers. We further refined our analyses using Partial Least Squares Regression (PLSR) where race-, stage-, and grade-dependent variances were examined which indicated that the depth of invasion affects global associations. An analysis of variance (ANOVA) that considered race and stage as factors and a Wilcoxon signed rank test of these groups revealed a small number of differentially expressed miRNAs. Since the unbalanced sample sizes (41 Caucasian versus 9 African-American cases) may introduce bias, we performed a paired analysis (9 AA cancers v. 9 C cancers). Of several differentially identified miRNAs, hsa-miR-337-3p was consistently identified in class comparisons. We validated the differential expression of hsa-miR-337-3p in an independent set of endometrial cancers from African Americans (n=24) and Caucasians (n=23). Analysis of normal endometrial epithelial expression indicated that hsa-miR-337-3p expression is down-regulated in cancers as compared to normal expression and that there is no difference in expression of hsa-miR-337-3p in the normal endometrium according to race. These data indicate that hsa-mir-337-3p is specifically down-regulated in Caucasian women's endometrial cancers and may play a role in the more frequent development of uterine cancers in Caucasians.

Citation Format: G. Larry Maxwell, GVR Chandramouli, Tracy Litzi, Andrew Berchuck, Thomas P. Conrads, John I. Risinger. Analysis of micro RNAs in the racial disparity of endometrial cancer . [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 1966. doi:10.1158/1538-7445.AM2013-1966

Normal viability of Kai1/Cd82 deficient mice

The KAI1/CD82 tetraspanin is a widely expressed cell surface molecule thought to organize diverse cellular signaling processes. KAI1/CD82 suppresses metastasis but not tumorigenicity, establishing it as one of a class of metastasis suppressor genes. In order to further assess its functions, we have characterized the phenotypic properties of Kai1/Cd82 deleted mice, including viability, fertility, lymphocyte composition, blood chemistry and tissue histopathology, and of their wild-type and heterozygote littermates. Interestingly, Kai1/Cd82(-/-) showed no obvious genotype associated defects in any of these processes and displayed no genotype associated histopathologic abnormalities after 12 or 18 months of life. Expression profiles of non-immortal, wild-type and Kai1/Cd82(-/-) mouse embryo fibroblast (MEFs) indicated distinct sex-specific and genotype-specific profiles. These data identify 191 and 1,271 differentially expressed transcripts (by twofold at P < 0.01) based on Kai1/CD82 genotype status in female and male MEFs, respectively. Differentially expressed genes in male MEFs were surprisingly enriched for cell division related processes, suggesting that Kai1/Cd82 may functionally affect these processes. This suggests that Kai/Cd82 has an unappreciated role in the early establishment of proliferation and division when challenged with a new environment that might play a role in adaptability to new metastatic sites.

Analysis of PSPHL as a Candidate Gene Influencing the Racial Disparity in Endometrial Cancer

Endometrial cancer is the most commonly diagnosed gynecologic malignancy in the United States. A well recognized disparity by race in both incidence and survival outcome exists for this cancer. Specifically Caucasians are about two times more likely to develop endometrial cancer than are African-Americans. However, African-American women are more likely to die from this disease than are Caucasians. The basis for this disparity remains unknown. Previous studies have identified differences in the types and frequencies of gene mutations among endometrial cancers from Caucasians and African-Americans suggesting that the tumors from these two groups might have differing underlying genetic defects. We performed a gene expression microarray study in an effort to identify differentially expressed transcripts between African-American and Caucasian women's endometrial cancers. Our gene expression screen identified a list of potential biomarkers that are differentially expressed between these two groups of cancers. Of these we identified a poorly characterized transcript with a region of homology to phospho serine phosphatase (PSPH) and designated phospho serine phosphatase like (PSPHL) as the most differentially over-expressed gene in cancers from African-Americans. We further clarified the nature of expressed transcripts. Northern blot analysis confirmed the message was limited to a transcript of under 1 kB. Sequence analysis of transcripts confirmed two alternate open reading frame (ORF) isoforms due to alternative splicing events. Splice specific primer sets confirmed both isoforms were differentially expressed in tissues from Caucasians and African-Americans. We further examined the expression in other tissues from women to include normal endometrium, normal and malignant ovary. In all cases PSPHL expression was more often present in tissues from African-Americans than Caucasians. Our data confirm the African-American based expression of the PSPHL transcript in endometrial cancer and also identify its expression in other tissues from African-Americans including ovary and ovarian cancer. PSPHL represents a candidate gene that might influence the observed racial disparity in endometrial and other cancers.

PPP2R1A mutations are common in the serous type of endometrial cancer

Recently unbiased sequencing efforts identified PPP2R1A mutations in clear cell ovarian cancers (OCC). Similar mutations were also noted with high frequency in uterine serous carcinoma. Because the endometrium develops from the same developmental precursors we further examined the hypothesis that PPP2R1A mutations might also occur in diverse histologic subtypes of uterine cancer. We sequenced the PPP2R1A in 22 cell line models of uterine cancer and 10 primary cancers. We found no mutations in the cell lines originally derived from endometrioid (n = 13), undifferentiated (n = 3), clear cell (n = 1), and carcinosarcoma (n = 3) cancers. However, we found a CCC (Pro) to CGC (Arg) codon 179 mutation in the ACI-158 serous carcinoma cell line, a CCC (Pro) to CTC (Leu) in a primary serous carcinoma as well as a CGC (Arg) to CAC (His) codon 258 mutation in a poorly differentiated endometrioid cancer. We sequenced a large panel of endometrial malignancies (n = 181) and found 12 mutants. Importantly, we confirmed a high frequency of mutation in 8 of 25 (32%) serous carcinomas a subtype with well-recognized poor prognosis. Mutations were infrequent in endometrioid cancer and absent in clear cell and carcinosarcoma subtypes. The PPP2R1A mutation regions are conserved among species and known to interact with the regulatory subunits of the PP2A enzyme. PPP2R1A mutant endometrial cancers may represent good candidates for personalized drug therapies particularly for women with the lethal serous histologic variant of uterine cancer.

Abstract 3037: Role of KCNN4 in ovarian cancer and its pharmacologic activation increases sensitivity to cisplatin

Ovarian cancer is the second most common and most lethal gynecologic cancer in the United States with an estimated 15520 deaths expected from 21,650 cases. Patients with stage I disease have a relatively favorable survival approaching 80%, however most patients are first diagnosed with stage III and IV metastatic disease and have very poor prognosis. Expression of potassium channel genes has been shown to affect chemosensitivity and cell proliferation in several tumor types. We examined the expression of the known potassium channel genes in ovarian cancer and the presumptive cells of ovarian cancer origin. Affymetrix U133 Plus2.0 array data identified that the KCNN4 gene was up-regulated in 15 of 20 stage IIIC or IV serous ovarian cancers compared to eight cases of normal ovarian surface epithelium. This result was confirmed by quantitative real-time polymerase chain reactions (qRT-PCR) using an independent set of 25 ovarian cancers compared to 10 normals. Also, we assessed expression of KCNN4 in a large set (101 ovarian cases) of publically available microarray data (Berchuck, et al. Clin Cancer Res, 2009) and normal fallopian tube. These data confirmed that KCNN4 was highly-expressed in ovarian cancer and also showed expression in normal fallopian tube epithelial cells -the other suspected candidate for the cell of origin of ovarian cancers. KCNN4 forms the intermediate conductance Ca2+ – activated K+ channel (IKCa channel), which serves as a highly sensitive environmental sensor of intracellular calcium. Studies in other tumor types suggest that potassium channels are integral components of cellular proliferation. siRNA and shRNA mediated knockdown of KCNN4 resulted in decreased cell proliferation in cell culture models of ovarian cancer suggesting an essential role for KCNN4 in ovarian cancer cell growth and viability. Furthermore we hypothesized that by pharmacologically activating these channels we could further increase the killing of ovarian cancer cells by cis-platinum. We found that 9 of 11 ovarian cancer cell lines demonstrated functionally active IKCa channels and we were able to increase the sensitivity of these cells to cis-platinum following IKCa channel activation with 1-EBIO -a specific activator of IKCa channels. The chemo-sensitizing effect of treating these cells with the activator was reversed by adding clotrimazole -a specific inhibitor of the IKCa channels, further suggesting this effect was mediated through KCNN4. Furthermore, co-treatment of 1-EBIO and a non-lethal dose of cis-platinum to OVCAR5 cells resulted in apoptotic cell death suggesting a chemo-sensitizing role for IKCa channels. Preliminary data in vivo mimic some of the in vitro results. Our data shows that KCNN4 is integral to ovarian cancer cell growth and that sensitization with pharmacologic activators such as 1-EBIO may have future therapeutic benefit for increasing cancer cell sensitivity to chemotherapeutics.

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 3037. doi:10.1158/1538-7445.AM2011-3037

Proteomic analysis of stage I endometrial cancer tissue: identification of proteins associated with oxidative processes and inflammation

OBJECTIVE

The present study aimed to identify differentially expressed proteins employing a high resolution mass spectrometry (MS)-based proteomic analysis of endometrial cancer cells harvested using laser microdissection.

METHODS

A differential MS-based proteomic analysis was conducted from discrete epithelial cell populations gathered by laser microdissection from 91 pathologically reviewed stage I endometrial cancer tissue samples (79 endometrioid and 12 serous) and 10 samples of normal endometrium from postmenopausal women. Hierarchical cluster analysis of protein abundance levels derived from a spectral count analysis revealed a number of proteins whose expression levels were common as well as unique to both histologic types. An independent set of endometrial cancer specimens from 394 patients were used to externally validate the differential expression of select proteins.

RESULTS

209 differentially expressed proteins were identified in a comparison of stage I endometrial cancers and normal post-menopausal endometrium controls (Q<0.005). A number of differentially abundant proteins in stage I endometrial cancer were identified and independently validated by western blot and tissue microarray analyses. Multiple proteins identified with elevated abundance in stage I endometrial cancer are functionally associated with inflammation (annexins) and oxidative processes (peroxiredoxins). PRDX1 and ANXA2 were both confirmed as being overexpressed in stage I cancer compared to normal endometrium by independent TMA (Q=0.008 and Q=0.00002 respectively).

CONCLUSIONS

These data provide the basis for further investigation of previously unrecognized novel pathways involved in early stage endometrial carcinogenesis and provide possible targets for prevention strategies that are inclusive of both endometrioid and serous histologic subtypes.

The role of miR-31 and its target gene SATB2 in cancer-associated fibroblasts

It is well established that there is a dynamic relationship between the expanding tumor and the host surrounding tissue. Cancer-associated fibroblasts (CAFs), the most common cellular population found in the tumor microenvironment, supporting tumor growth and dissemination. Here, we set out to determine the factors that may be involved in dramatic alteration of gene expression pattern in CAFs, focusing on microRNA and transcriptional regulators. We established matched pairs of human CAFs isolated from endometrial cancer and normal endometrial fibroblasts. MicroRNA and mRNA analyses identified differential expression of 11 microRNAs, with miR-31 being the most downregulated microRNA in CAFs (p = 0.007). We examined several putative miR-31 target genes identified by microarray analysis and demonstrated that miR-31 directly targets the homeobox gene SATB2, which is responsible for chromatin remodeling and regulation of gene expression, and was significantly elevated in CAFs. The functional relevance of miR-31 and SATB2 were tested in in vitro models of endometrial cancer. Overexpression of miR-31 significantly impaired the ability of CAFs to stimulate tumor cell migration and invasion, without affecting tumor cell proliferation. Genetic manipulation of SATB2 levels in normal fibroblasts or CAFs showed that, reciprocally to miR-31, SATB2 increased tumor cell migration and invasion, while knockdown of endogenous SATB2 in CAFs reversed this phenotype. Introduction of SATB2 into normal fibroblasts stimulated expression of a number of genes involved in cell invasion, migration and scattering. These findings provide new insights into tumor-stroma interaction and document that miR-31 and its target gene SATB2, are involved in regulation of tumor cell motility.

Abstract 4050: Normalization of TaqMan human microRNA array data using average expression of controls

The growing interest on microRNA (miRNA) expression in cancer motivates the need for improvement of technical aspects. TaqMan Human MicroRNA Arrays with comprehensive coverage of 667 unique miRNAs from Sanger miRBase are now available (Applied Biosystems, Foster city, CA) to quantitatively assay miRNA expression. A recent study reported that these qRT-PCR arrays perform better than miRNA microarrays which utilizes U6 RNA as an endogenous control for normalization. However, the choice of control for normalization varies depending on the tissue under examination. The TaqMan Low Density Arrays (TLDA) arrays A and B include six different controls with at least quadruplet assays for each. A recent study indicated that the average expression normalization including all miRNAs on array performed better than other normalization methods indicating a further need to examine normalization of TaqMan miRNA array data. The choice of a suitable control other than an average expression over the entire array is a more general approach for qRT-PCR data since constant average expression may not be valid for these arrays. Hence, we combined both concepts to determine a normalization constant. We examined miRNA expressions of 5 endometrial cancer cell lines assayed by these TaqMan Low Density Arrays for miRNA. Each cell line was assayed in triplicate. The cycle threshold (Ct) values of positive controls U6 (MammU6), RNU48, RNU44, RNU24, RNU6B, RNU43 in these were found to be in the range of 15 to 39 where RNU6B and RNU43 had low expressions. In some cases, we observed failures in endogenous control U6 and differences between arrays A and B. Therefore multiple controls were included for normalization but with appropriate weighting for highly expressed controls. This was done by calculating the average of 2−Ct values for controls that had Ct-values below a threshold level (Ct &lt; 25) and transforming this average back to logarithmic scale to the base 2. We then compared the normalized Ct-values by this method with the normalization using geometric average method. This weighted average normalization method resulted in smaller replicate variances of controls than the geometric average method.

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 4050.

Abstract 3375: Normal viability of Kai1/CD82 deficient mice

The KAI1 tetraspanin also known as CD82 is a widely expressed cell surface molecule involved in organizing many diverse cellular signaling processes. Importantly KAI1/CD82 was shown to suppress metastasis but not tumorigenicity in animal models of metastasis, establishing KAI1/CD82 as one of a class of metastasis suppressor genes. The function of KAI1/CD82 regarding its role in controlling metastasis is under scrutiny and many questions remain as to its function in regulating this and other cellular processes. In order to further assess the functions of KAI1/CD82 we examined the effect of germline deletion on viability, fertility, lymphocyte composition, blood chemistry and performed a detailed pathologic analysis of tissues in Kai1/CD82 deficient mice and their wild-type and heterozygote littermates. Interestingly mice deficient in KAI1/CD82 showed no obvious genotype associated defects in any of these processes as compared to their wild-type littermates and displayed no genotype associated abnormalities after 12 or 18 months of life. To further explore the lack of noticeable phenotypes in these mice we employed expression profiling of non-immortal MEF cultures to assess the effect of KAI1/CD82 on global gene expression. Gene expression of MEFs indicated distinct sex specific and genotype specific profiles suggesting some genes as compensatory candidates which might explain the lack of appreciable phenotypes in KAI1/CD82 deficient mice.

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 3375.

Abstract 1181: Expression of epithelial splicing regulatory protein 1 and 2 in ovarian cancer

Epithelial Splicing Regulatory Proteins (ESRP1 and ESRP2) have recently been reported as RNA binding proteins that regulate epithelial specific splicing. We identified over-expression of ESRP1 and ESRP2 in ovarian cancer. The aim of this study was to determine the extent of expression of ESRP1 and ESRP2 in ovarian cancers and to examine whether its expression affects the abundance of the epithelial isoform of the Fibroblast Growth Factor receptor 2 (FGFR2) in ovarian cancer. Furthermore, we studied the regulation of FGFR2 splicing following knock-down of ESRPs in ovarian cancer cells. Affymetrix U133 Plus2.0 Array and quantitative real-time polymerase chain reactions (qRT-PCR) were used to measure gene expression levels in ovarian cancers and normal ovaries. ESRP1, ESRP2, epithelial specific FGFR2 IIIb and mesenchymal isoform FGFR2 IIIc mRNA levels were determined via qRT-PCR. RNA interference (RNAi) was used to knock-down ESRP1 and/or ESRP2 to examine its function on determining FGFR2 isoform expression in ovarian cancer cell line OVCAR3. Affymetrix GeneChip expression array analysis of 20 Stage IIIC serous ovarian cancers and 8 normal ovary surface epithelium brushings identified over-expression of ESRP1 (235 fold) and ESRP2 (33 fold). qRT-PCR confirmed that ESRP1 (7586 fold, p &lt; 0.00001) and ESRP2 (21 fold, p &lt;0.00001) were over-expressed in an independent set of 27 ovarian cancers compared to 11 normals. Since ESRP1 and ESRP2 function to drive the epithelial specific splicing of FGFR2, we examined the relative expression of FGFR2 IIIb and FGFR2 IIIc via qRT-PCR. The epithelial specific FGFR2 IIIb was over-expressed (313 fold; p &lt; 0.00001), whereas the mesenchymal isoform FGFR2 IIIc was down-regulated (75 fold). RNAi knock-down of ESRP1 in OVCAR3 cells resulted in increased levels of mesenchymal specific FGFR2 IIIc (6 fold), but had a minimal effect on FGFR2 IIIb expression (−1 fold). ESRP2 knock-down had no detectable effect on FGFR2 IIIc and IIIb expression. However, ESRP1 and ESRP2 double knock-down results in the predominant expression of FGFR2 IIIc (25 fold) and down-regulation of FGFR2 IIIb (−3 fold) when standardized to a scramble control. Our results confirmed that ESRP1, ESRP2 and FGFR2 IIIb are over-expressed and FGFR2 IIIc is down-regulated in ovarian cancers. Also, results of RNAi double knock-down of ESRP1 and ESRP2 indicate that ESRPs drive the expression of the epithelial isoform FGFR2 IIIb in ovarian cancer cells. These data have implications on the ligand specificity of the FGFR2 receptor and for potential individualized therapies targeting FGF signaling in ovarian 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 1181.

Abstract 1423: SatB2, targeted by miR31, is a modulator in cancer microenvironment

Cancer growth and metastasis involve an active interaction between primary tumor cells and the tumor's microenvironment, which consists of fibroblasts, vascular cells and inflammatory cells. Such interactions between the cancer and the cells within the microenvironment induce differential expression of genes that act to foster the growth, invasion and spread of tumor cells. This study utilizes pair-wise primary cultures of fibroblasts from normal and cancerous human endometrial tissues of the same patients to investigate the potential factors in the tumor microenvironment and their role in carcinogenesis. Both microRNA and mRNA profiling were performed on paired normal and cancer fibroblasts. SatB2 emerged as a promising candidate when its expression was shown to be significantly increased in fibroblasts surrounding the tumor tissues in all but one patients tested (n=8). Further investigation documented that SatB2 is a target for miR31, via 2 binding sites located within the SATB2 3’ UTR region. In concordance, miR31 is down-regulated in tumor fibroblasts, which further implicates the potential role of SatB2 in promoting a favorable environment for tumors. Ectopic expression of SATB2 in normal fibroblasts does not affect the growth rate of an endometrial cancer cell line (EC-1) in co-culture experiments; however, it did increase the motility of EC-1 cells towards these fibroblasts by multiple folds in both in vitro migration and invasion assays. A reduction of SATB2 expression in cancer activated fibroblasts (CAFs) by shRNA attenuated the migratory ability of EC-1 cells, further supporting the role of SatB2 in tumor aggression. Our observations also indicated that the conditioned media from CAFs were sufficient to induce the motility changes in the EC-1 cells. We believe the elucidation of SatB2 pathway(s) will assist in uncovering the intricate connections between tumors and their microenvironments, leading to new targets for treating tumor progression.

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 1423.

Abstract 3035: MicroRNA expression in early stage endometrial cancers

The molecular signatures of endometrial cancers from whole genome gene expression studies are now available setting a stage to explore the key regulators involved in these cancers. Non-coding micro-RNAs (miRNAs) are functionally important regulators of numerous cellular processes affecting growth and dissemination and possibly possess prognostic significance for several cancer types. In a first step toward understanding the miRNA biology of endometrial cancers, we performed an unbiased characterization of about 667 unique human miRNAs in stage-1 endometrial cancers including 51 endometrioid (16 grade-1, 23 grade-2 and 12 grade-3) and 7 serous (grade-3) cancer types and 17 endometrial epithelial samples from healthy individuals. In total, there were 8 stage IA, 32 stage IB and 18 stage IC cancers. RNA was extracted from samples prepared by laser capture micro-dissection which contained minimal non-epithelial cells. TaqMan Low Density Arrays (TLDA) were used to quantitatively determine the expression levels of miRNAs (TaqMan® MicroRNA Arrays A and B from Applied Biosystems). Isolated RNA was transcribed into cDNA and used to quantitatively assess the expression of 768 miRNAs arrayed within the TLDA. The Ct-values were initially normalized by subtracting a reference Ct-value derived from multiple positive controls on the array. These ΔCt values were filtered to exclude the miRNAs that were not expressed in any of the arrays. Statistical calculations were performed on -ΔCt values. In summary, about 158 miRNAs were up or down regulated in cancers at least by four-fold (p&lt;0.001) including many novel candidates for this cancer type. Notably, miR-183* was on average the most differentially over-expressed in both endometrioid and serous cancers compared to normal endometrium. The numbers of miRNAs and their statistical significance to distinguish the histological type, grade, and stage among cancers were found to be in decreasing order respectively. The putative mRNA targets of miRNAs were predicted using Targetscan v. 5.1. These predicted targets were further examined using gene expression data (Affymetrix Human Genome Plus 2.0) of the same RNAs. In conclusion, we identified numerous miRNAs that are disregulated in endometrial cancer. The potential of these miRNAs to define the biology of endometrial cancer is further discussed.

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 3035.

Chemotherapy intensity and toxicity among black and white women with advanced and recurrent endometrial cancer: a Gynecologic Oncology Group Study

BACKGROUND

The purpose of this study was to confirm whether black and white women with endometrial cancer are equally tolerant of chemotherapy and identify factors that impact survival.

METHODS

A retrospective review of 169 black women and 982 white women with the International Federation of Gynecologists and Obstetricians stage III, stage IV, or recurrent endometrial carcinoma was performed. All patients received doxorubicin combined with cisplatin. Chemotherapy parameters that were reviewed included relative dose, relative time, and relative dose intensity. Treatment cycles > or =7 were defined as treatment completion.

RESULTS

Although black patients were more likely to experience grades 3-4 anemia (20% vs 14%) and genitourinary (5% vs 1%) toxicity, and less likely to experience severe gastrointestinal toxicity (10% vs 17%), the overall incidence of grades 3-4 treatment-related chemotoxicity was the same between the 2 groups (82% vs 82%). There were no differences in the number of cycles received, relative dose (0.57 vs 0.58), relative time (0.77 vs 0.78), or relative dose intensity (0.76 vs 0.76) for black and white patients.

CONCLUSIONS

Black patients with advanced stage or recurrent endometrial cancer, treated on 4 Gynecologic Oncology Group (GOG) protocols, had similar dose intensity and severe chemotherapy-related toxicity compared with white patients, suggesting that previously described racial disparities in survival among patients in GOG trials may have an novel etiology.

Serum S100A6 concentration predicts peritoneal tumor burden in mice with epithelial ovarian cancer and is associated with advanced stage in patients

BACKGROUND

Ovarian cancer is the 5th leading cause of cancer related deaths in women. Five-year survival rates for early stage disease are greater than 94%, however most women are diagnosed in advanced stage with 5 year survival less than 28%. Improved means for early detection and reliable patient monitoring are needed to increase survival.

METHODOLOGY AND PRINCIPAL FINDINGS

Applying mass spectrometry-based proteomics, we sought to elucidate an unanswered biomarker research question regarding ability to determine tumor burden detectable by an ovarian cancer biomarker protein emanating directly from the tumor cells. Since aggressive serous epithelial ovarian cancers account for most mortality, a xenograft model using human SKOV-3 serous ovarian cancer cells was established to model progression to disseminated carcinomatosis. Using a method for low molecular weight protein enrichment, followed by liquid chromatography and mass spectrometry analysis, a human-specific peptide sequence of S100A6 was identified in sera from mice with advanced-stage experimental ovarian carcinoma. S100A6 expression was documented in cancer xenografts as well as from ovarian cancer patient tissues. Longitudinal study revealed that serum S100A6 concentration is directly related to tumor burden predictions from an inverse regression calibration analysis of data obtained from a detergent-supplemented antigen capture immunoassay and whole-animal bioluminescent optical imaging. The result from the animal model was confirmed in human clinical material as S100A6 was found to be significantly elevated in the sera from women with advanced stage ovarian cancer compared to those with early stage disease.

CONCLUSIONS

S100A6 is expressed in ovarian and other cancer tissues, but has not been documented previously in ovarian cancer disease sera. S100A6 is found in serum in concentrations that correlate with experimental tumor burden and with clinical disease stage. The data signify that S100A6 may prove useful in detecting and/or monitoring ovarian cancer, when used in concert with other biomarkers.

Melanoma antigen-11 inhibits the hypoxia-inducible factor prolyl hydroxylase 2 and activates hypoxic response

Activation of hypoxia-inducible factors (HIF), responsible for tumor angiogenesis and glycolytic switch, is regulated by reduced oxygen availability. Normally, HIF-alpha proteins are maintained at low levels, controlled by site-specific hydroxylation carried out by HIF prolyl hydroxylases (PHD) and subsequent proteasomal degradation via the von Hippel-Lindau ubiquitin ligase. Using a yeast two-hybrid screen, we identified an interaction between melanoma antigen-11 (MAGE-11) cancer-testis antigen and the major HIF-alpha hydroxylating enzyme PHD2. The interaction was confirmed by a pull-down assay, coimmunoprecipitation, and colocalization in both normoxic and hypoxic conditions. Furthermore, MAGE-9, the closest homologue of MAGE-11, was also found to interact with PHD2. MAGE-11 inhibited PHD activity without affecting protein levels. This inhibition was accompanied by stabilization of ectopic or endogenous HIF-1alpha protein. Knockdown of MAGE-11 by small interfering RNA results in decreased hypoxic induction of HIF-1alpha and its target genes. Inhibition of PHD by MAGE-11, and following activation of HIFs, is a novel tumor-associated HIF regulatory mechanism. This finding provides new insights into the significance of MAGE expression in tumors and may provide valuable tools for therapeutic intervention because of the restricted expression of the MAGE gene family in cancers, but not in normal tissues.

Racial disparities in recurrence among patients with early-stage endometrial cancer: is recurrence increased in black patients who receive estrogen replacement therapy?

BACKGROUND

Population-based studies suggest that, because of inequalities in treatment, black women with localized endometrial cancer have shorter survival compared with white women. The objective of the current investigation was to determine whether there is a racial disparity in outcome between black patients and white patients with early-stage endometrial cancer treated similarly in a clinical trial setting.

METHODS

A retrospective review of 110 black patients and 1,049 white patients with stage I and II endometrial cancer (graded according to the International Federation of Gynecology and Obstetrics grading system) was performed using data from a randomized, placebo-controlled trial performed by the Gynecologic Oncology Group that evaluated postoperative estrogen replacement therapy (ERT) and the risk of cancer recurrence. Demographic, pathologic, treatment, and outcome-related data were collected and analyzed using regression and survival analysis.

RESULTS

Estimates of recurrence-free survival suggested that black patients may be more likely to have disease recurrence, particularly those receiving ERT. Within a median follow-up of 3 years, 5 of 56 black patients with endometrial cancer in the ERT group were identified with recurrent disease compared with only 8 of 521 white patients. Adjusted for age, body mass index, and tumor grade, the relative risk of recurrence among blacks in the ERT group was 11.2 (95% confidence interval, 2.86-43.59; P = .0005).

CONCLUSIONS

The findings of the current study suggested that recurrence-free survival may be shorter among black women with stage I endometrial cancer, even in a clinical trials setting in which patients receive similar treatment and follow-up. This increased risk of recurrence appeared to be most evident in black women with endometrial cancer who maintained ERT after primary treatment.

Overexpression of folate binding protein is associated with shortened progression-free survival in uterine adenocarcinomas

OBJECTIVES

Oligonucleotide array and tissue microarray analysis (TMA) by our group has revealed that folate binding protein (FOLR1) is overexpressed in some types of uterine cancer, particularly tumors with serous histology. Since FOLR1 overexpression is a frequent event in some types of endometrial carcinoma, we examined the relationship between FOLR1 overexpression and clinical and pathologic features to determine its prognostic relevance.

METHODS

A tissue microarray (TMA) comprised of primary tumor specimens from 485 patients diagnosed with endometrial adenocarcinoma was used to identify cases characterized by FOLR1 overexpression. A proportional hazards model was used to evaluate the association of FOLR1 overexpression with progression-free survival while accounting for confounding influences.

RESULTS

Overexpression of FOLR1 was observed in 50/292 (17%) cases and was seen more often in poorly differentiated cancers (22/90 [24%], p=0.051) and tumors with serous histology (16/32 [50%], p<0.001). A shorter progression-free survival was noted in patients with FOLR1 overexpression (log-rank p=0.016) that persisted when the data were limited to patients with stage III/IV disease (log-rank p=0.021) or serous tumors (log-rank p=0.020). Multivariate Cox regression analysis revealed that patients with FOLR1 overexpression had a shorter progression-free survival (H.R. 2.14; 95% CI 1.07-4.28) even when controlling for stage, grade, myometrial invasion and adjuvant chemotherapy.

CONCLUSIONS

Our data show that FOLR1 overexpression is not only a biomarker associated with endometrial cancer, but it also appears to be a prognostic factor associated with adverse outcome. These findings suggest that FOLR1 may be an appealing target for biological therapies in some types of endometrial carcinomas.

Evolutionary diversification of SPANX-N sperm protein gene structure and expression

The sperm protein associated with nucleus in the X chromosome (SPANX) genes cluster at Xq27 in two subfamilies, SPANX-A/D and SPANX-N. SPANX-A/D is specific for hominoids and is fairly well characterized. The SPANX-N gave rise to SPANX-A/D in the hominoid lineage ∼7 MYA. Given the proposed role of SPANX genes in spermatogenesis, we have extended studies to SPANX-N gene evolution, variation, regulation of expression, and intra-sperm localization. By immunofluorescence analysis, SPANX-N proteins are localized in post-meiotic spermatids exclusively, like SPANX-A/D. But in contrast to SPANX-A/D, SPANX-N are found in all ejaculated spermatozoa rather than only in a subpopulation, are localized in the acrosome rather than in the nuclear envelope, and are expressed at a low level in several nongametogenic adult tissues as well as many cancers. Presence of a binding site for CTCF and its testis-specific paralogue BORIS in the SPANX promoters suggests, by analogy to MAGE-A1 and NY-ESO-1, that their activation in spermatogenesis is mediated by the programmed replacement of CTCF by BORIS. Based on the relative density of CpG, the more extended expression of SPANX-N compared to SPANX-A/D in nongametogenic tissues is likely attributed to differences in promoter methylation. Our findings suggest that the recent duplication of SPANX genes in hominoids was accompanied by different localization of SPANX-N proteins in post-meiotic sperm and additional expression in several nongonadal tissues. This suggests a corresponding functional diversification of SPANX gene families in hominoids. SPANX proteins thus provide unique targets to investigate their roles in the function of spermatozoa, selected malignancies, and for SPANX-N, in other tissues as well.

Overexpression of folate binding protein and mesothelin are associated with uterine serous carcinoma

PURPOSE

Folate receptor alpha (FOLR1) is a membrane bound receptor involved in the transport of folate as well as other regulatory cellular processes. The purpose of this study was to examine the expression of FOLR1 in uterine cancers and to identify changes in gene expression that are associated with overexpression of FOLR1.

EXPERIMENTAL DESIGN

Fifty-eight frozen uterine cancer specimens were stained for FOLR1 using immunohistochemistry and results were correlated with transcript expression noted on quantitative PCR. Total RNA from 16 cases of uterine serous carcinoma (USC) was analyzed for gene expression using the Affymetrix HG-U133A and HG-U133B GeneChip set. USCs overexpressing FOLR1 were compared to cancers with an absence of FOLR1 using binary comparison and template matching of data was used to identify genes that correlate with FOLR1 expression. Selected targets from this analysis were evaluated by quantitative PCR as well as in an independent set of USC represented in quadruplicate on a tissue microarray (TMA).

RESULTS

Overexpression of FOLR1 was observed in 11/16 (69%) of USC and 0/10 normal endometrium cases using frozen tissue specimens. Binary comparison between FOLR1 positive and negative cases identified 121 genes altered by 2-fold at p<0.01 of which 45 are well correlated with FOLR1 expression pattern. Using quantitative PCR, both mesothelin (MSLN) and PTGS1 (COX1) were significantly increased in FOLR1 overexpressing tumors (p=0.014 and p=0.006 respectively). TMA confirmed that overexpression of FOLR1 and MSLN respectively occurred in 23/48 (48%) and 17/54 (32%) of pure USC.

CONCLUSION

Both FOLR1 and MSLN are cell surface targets that are co-expressed at high levels in USC and are appealing targets for biologic therapy.

Gene expression analysis of tumor infiltrating lymphocyte markers in endometrial cancers indicates no significant increases in those cases with microsatellite instability

Microsatellite instability (MSI) is seen in many cancers and is the result of either a germline or somatic defect in the DNA mismatch repair system. Microsatellite instability is common in endometrial cancers occurring in about 25% of cases with endometrioid histology. Tumor infiltrating lymphocytes (TIL) are more prominent in colorectal cancer cases with MSI. The presence of increased TIL is associated with increased survival in these colorectal cancers, and is suggested as one possible mechanism to explain the increased survival rates in colorectal cancer patients with MSI positive cancers. Some degree of evidence indicates that increased TIL is also predictive of increased survival in endometrial cancer. The relative levels and states of activation of TIL in endometrial cancers with and without MSI has not been explored. Our previous data indicates that global gene expression patterns from MSI and non-MSI endometrial cancers are distinct, however TIL markers were not over-represented on statistically relevant gene lists that distinguish these groups. We further examined these pre-existing microarray data by directly querying transcripts present in the T-cell gene ontology (GO) group. No significant differences were observed between MSI and microsatellite stable (MSS) groups. Finally we directly examined a set of T-cell marker transcripts previously utilized to define increased activated and cytotoxic TIL in MSI positive colorectal cancers. Whereas colorectal cancers with MSI have been previously demonstrated to contain higher ratios of CD8/CD3 message levels we observed no difference in endometrial cancers. In addition, levels of CD3 indicated no increases in TIL in MSI positive cases and 2 markers of activation, granzyme B and IL-2R were not different in MSI positive and negative cancers. These data indicate that significant differences in TIL derived transcripts do not occur between endometrioid endometrial cancers with and without microsatellite instability.

Racial disparities in blacks with gynecologic cancers

Black women have a lower incidence of gynecologic cancers but they have a higher mortality associated with their disease. The etiology of the racial disparity in outcome among gynecologic cancer patients is multifactoral and site-specific. Black women with endometrial cancer often present with more advanced stage tumors that are associated with a worse prognosis compared with White women. Evidence suggests that observed disparities in outcome are due to inequalities in treatment or differing biologic etiologies. For cervix cancer, studies have suggested that survival among Black women may be lower than survival among White women that develop this disease. This occurs despite evidence that indicates that Pap smears are utilized similarly by Black and White women for cervix cancer screening. These differences in outcome may become less pronounced when comorbidities are accounted for and inequalities in treatment are eliminated. For ovarian cancer patients, survival has improved with the use of contemporary therapies over the past 30 years in Whites but less so for Blacks. This may be due to differences in the likelihood of primary surgical cytoreductions, which are performed less frequently in some Black women because of extensive metastatic spread or comorbidities. The observed decreases in survival for all 3 gynecologic cancers potentially may be affected by socioeconomic status of the patient in some healthcare settings. An improved understanding of the causative factors associated with racial disparities in gynecologic cancer outcome is necessary to facilitate efforts aimed at correcting this important healthcare problem.

Progestin and estrogen potency of combination oral contraceptives and endometrial cancer risk

OBJECTIVE

Using data from a case-control study of endometrial cancer, we investigated the relationship between the progestin and estrogen potency in combination oral contraceptives (OCs) and the risk of developing endometrial cancer.

METHODS

Subjects included 434 endometrial cancer cases and 2,557 controls identified from the Cancer and Steroid Hormone (CASH) study. OCs were classified into four categories according to the individual potencies of each hormonal constituent (high versus low estrogen or progestin potency). Logistic regression was used to evaluate associations between endometrial cancer risk and combination OC formulations.

RESULTS

With non-users as the referent group, use of OCs with either high potency progestin [odds ratio for endometrial cancer (OR)=0.21, 95% confidence interval (CI)=0.10 to 0.43] or with low potency progestin (OR=0.39, 95% CI=0.25 to 0.60) were both associated with a decreased risk of endometrial cancer. Overall high progestin potency OCs did not confer significantly more protection than low progestin potency OCs (OR=0.52, 95% CI=0.24 to 1.14). However, among women with a body mass index of 22.1 kg/m2 or higher, those who used high progestin potency oral contraceptives had a lower risk of endometrial cancer than those who used low progestin potency oral contraceptives (OR=0.31, 95% CI=0.11 to 0.92) while those with a BMI below 22.1 kg/m2 did not (OR=1.36, 95% CI=0.39 to 4.70).

CONCLUSION

The potency of the progestin in most OCs appears adequate to provide a protective effect against endometrial cancer. Higher progestin-potency OCs may be more protective than lower progestin potency OCs among women with a larger body habitus.

Characterization of an antibody that can detect the Kai1/CD82 murine metastasis suppressor

BACKGROUND

Kai1, also known as CD82, is a member of the tetraspanin family (TM4SF). The human homolog, KAI1, is an activation antigen of T-cells and is a metastasis suppressor for prostate and other cancers. Little is known about the mouse protein because of the lack of antibody reagents.

METHODS

Peptide immunized rabbits were used to generate polyclonal antibody to Kai1. The antibody was analyzed using immunoblotting, flow cytometry, and immunohistochemistry.

RESULTS

This antibody specifically recognizes murine Kai1 protein, crossreacts with rat Kai1 but not with human KAI1. The normal tissue distribution of this protein in mice is shown to be similar to that of the human homolog. Interestingly, mouse prostatic epithelium showed differential expression within the lobes.

CONCLUSION

This antibody, the first described that can specifically detect murine Kai1/CD82, should be very useful in addressing the mechanism of action of Kai1 in metastatic suppression.

Prediction of lymph node metastasis in patients with endometrioid endometrial cancer using expression microarray

PURPOSE

To characterize the gene expression profiles of endometrioid endometrial cancers associated with lymph node metastasis in an effort to identify genes associated with metastatic spread.

EXPERIMENTAL DESIGN

Tumors from 41 patients with endometrioid endometrial cancer grossly confined to the uterine cavity were evaluated. Positive lymph nodes were noted in 12 of 41 patients. RNA was analyzed for gene expression using the Affymetrix HG133A and HG133B GeneChip set, representing 45,000 array features covering >28,000 UniGene clusters. Data analysis was done using multidimensional scaling, binary comparison, and hierarchical clustering. Gene expression for several differentially expressed genes was examined using quantitative PCR.

RESULTS

Gene expression data was obtained from 30,964 genes that were detected in at least 5% of the cases. Supervised analysis of node-positive versus node-negative cases indicated that 450 genes were significantly differentially expressed between the two classes at P < 0.005, 81 of which were differentially expressed by at least 2-fold at P < 0.005. Overexpressed genes included two cell cycle checkpoint genes, CDC2 and MAD2L1, which have previously been described in association with lymph node metastasis in other cancer types. The ZIC2 zinc finger gene was overexpressed in endometrial cancers with positive nodes versus those with negative nodes.

CONCLUSION

Gene expression profiling of the primary tumors in patients with endometrioid endometrial cancers seems promising for identifying genes associated with lymph node metastasis. Future studies should address whether the status of nodal metastasis can be determined from the expression profiles of preoperative tissue specimens.

Reciprocal binding of CTCF and BORIS to the NY-ESO-1 promoter coincides with derepression of this cancer-testis gene in lung cancer cells

Regulatory sequences recognized by the unique pair of paralogous factors, CTCF and BORIS, have been implicated in epigenetic regulation of imprinting and X chromosome inactivation. Lung cancers exhibit genome-wide demethylation associated with derepression of a specific class of genes encoding cancer-testis (CT) antigens such as NY-ESO-1. CT genes are normally expressed in BORIS-positive male germ cells deficient in CTCF and meCpG contents, but are strictly silenced in somatic cells. The present study was undertaken to ascertain if aberrant activation of BORIS contributes to derepression of NY-ESO-1 during pulmonary carcinogenesis. Preliminary experiments indicated that NY-ESO-1 expression coincided with derepression of BORIS in cultured lung cancer cells. Quantitative reverse transcription-PCR analysis revealed robust, coincident induction of BORIS and NY-ESO-1 expression in lung cancer cells, but not normal human bronchial epithelial cells following 5-aza-2'-deoxycytidine (5-azadC), Depsipeptide FK228 (DP), or sequential 5-azadC/DP exposure under clinically relevant conditions. Bisulfite sequencing, methylation-specific PCR, and chromatin immunoprecipitation (ChIP) experiments showed that induction of BORIS coincided with direct modulation of chromatin structure within a CpG island in the 5'-flanking noncoding region of this gene. Cotransfection experiments using promoter-reporter constructs confirmed that BORIS modulates NY-ESO-1 expression in lung cancer cells. Gel shift and ChIP experiments revealed a novel CTCF/BORIS-binding site in the NY-ESO-1 promoter, which unlike such sites in the H19-imprinting control region and X chromosome, is insensitive to CpG methylation in vitro. In vivo occupancy of this site by CTCF was associated with silencing of the NY-ESO-1 promoter, whereas switching from CTCF to BORIS occupancy coincided with derepression of NY-ESO-1. Collectively, these data indicate that reciprocal binding of CTCF and BORIS to the NY-ESO-1 promoter mediates epigenetic regulation of this CT gene in lung cancer cells, and suggest that induction of BORIS may be a novel strategy to augment immunogenicity of pulmonary carcinomas.