Cell State of Origin Impacts Development of Distinct Endometriosis-Related Ovarian Carcinoma Histotypes

Clear cell ovarian carcinoma (CCOC) and endometrioid ovarian carcinoma (ENOC) are ovarian carcinoma histotypes, which are both thought to arise from ectopic endometrial (or endometrial-like) cells through an endometriosis intermediate. How the same cell type of origin gives rise to two morphologically and biologically different histotypes has been perplexing, particularly given that recurrent genetic mutations are common to both and present in nonmalignant precursors. We used RNA transcription analysis to show that the expression profiles of CCOC and ENOC resemble those of normal endometrium at secretory and proliferative phases of the menstrual cycle, respectively. DNA methylation at the promoter of the estrogen receptor (ER) gene (ESR1) was enriched in CCOC, which could potentially lock the cells in the secretory state. Compared with normal secretory-type endometrium, CCOC was further defined by increased expression of cysteine and glutathione synthesis pathway genes and downregulation of the iron antiporter, suggesting iron addiction and highlighting ferroptosis as a potential therapeutic target. Overall, these findings suggest that while CCOC and ENOC arise from the same cell type, these histotypes likely originate from different cell states. This "cell state of origin" model may help to explain the presence of histologic and molecular cancer subtypes arising in other organs.

SIGNIFICANCE

Two cancer histotypes diverge from a common cell of origin epigenetically locked in different cell states, highlighting the importance of considering cell state to better understand the cell of origin of cancer.

A framework for assessing interactions for risk stratification models: the example of ovarian cancer

Generally, risk stratification models for cancer use effect estimates from risk/protective factor analyses that have not assessed potential interactions between these exposures. We have developed a 4-criterion framework for assessing interactions that includes statistical, qualitative, biological, and practical approaches. We present the application of this framework in an ovarian cancer setting because this is an important step in developing more accurate risk stratification models. Using data from 9 case-control studies in the Ovarian Cancer Association Consortium, we conducted a comprehensive analysis of interactions among 15 unequivocal risk and protective factors for ovarian cancer (including 14 non-genetic factors and a 36-variant polygenic score) with age and menopausal status. Pairwise interactions between the risk/protective factors were also assessed. We found that menopausal status modifies the association among endometriosis, first-degree family history of ovarian cancer, breastfeeding, and depot-medroxyprogesterone acetate use and disease risk, highlighting the importance of understanding multiplicative interactions when developing risk prediction models.

A putative role for ALDH inhibitors and chemoprevention of BRCA-mutation-driven tumors

Aldehyde dehydrogenase (ALDH) enzymatic activity is a marker of cancer-initiating cells (CIC) in many tumor types. Our group and others have found that ALDH1A family inhibitors (ALDHi) can preferentially induce death of ovarian CIC in established ovarian cancer. We sought to determine if ALDHi, by targeting CIC at the time of tumor initiation, could function as a chemopreventive for ovarian cancer. As BRCA1/2 mutation carriers represent a population who could benefit from an ovarian cancer chemopreventive, we focused on BRCA mutation-associated tumor cell lines and murine tumor models. We found that, compared to BRCA wild-type cells, BRCA mutant ovarian cancer cells are more sensitive to the ALDHi673A. Similarly, while 673A treatment of wild-type fallopian tube epithelial (FTE) cells is non-toxic, 673A induces death in FTE cells with BRCA1 knockdown. Using a murine fallopian tube organoid model of ovarian carcinogenesis, we show that 673A reduced organoid complexity and significantly reduce colony formation of BRCA-mutant cells. Organoids that persisted after 673A treatment were predominantly BRCA1wt, but NF1 mutant, suggesting a resistance mechanism. Finally, using the BPRN (Brca1, Trp53, Rb1, Nf1 inactivated) mouse model of tubo-ovarian cancer, we evaluated the impact of intermittent 673A therapy on carcinogenesis. 673A treatment resulted in a significant reduction in serous tubal intraepithelial carcinoma (STIC) lesions and carcinomas. Collectively, the findings suggest that ALDHi, such as 673A, could serve as chemopreventive agents for BRCA1/2 mutation carriers.

Metabolic collateral lethal target identification reveals MTHFD2 paralogue dependency in ovarian cancer

Recurrent loss-of-function deletions cause frequent inactivation of tumour suppressor genes but often also involve the collateral deletion of essential genes in chromosomal proximity, engendering dependence on paralogues that maintain similar function. Although these paralogues are attractive anticancer targets, no methodology exists to uncover such collateral lethal genes. Here we report a framework for collateral lethal gene identification via metabolic fluxes, CLIM, and use it to reveal MTHFD2 as a collateral lethal gene in UQCR11-deleted ovarian tumours. We show that MTHFD2 has a non-canonical oxidative function to provide mitochondrial NAD+, and demonstrate the regulation of systemic metabolic activity by the paralogue metabolic pathway maintaining metabolic flux compensation. This UQCR11-MTHFD2 collateral lethality is confirmed in vivo, with MTHFD2 inhibition leading to complete remission of UQCR11-deleted ovarian tumours. Using CLIM's machine learning and genome-scale metabolic flux analysis, we elucidate the broad efficacy of targeting MTHFD2 despite distinct cancer genetic profiles co-occurring with UQCR11 deletion and irrespective of stromal compositions of tumours.

High Prediagnosis Inflammation-Related Risk Score Associated with Decreased Ovarian Cancer Survival

BACKGROUND

There is suggestive evidence that inflammation is related to ovarian cancer survival. However, more research is needed to identify inflammation-related factors that are associated with ovarian cancer survival and to determine their combined effects.

METHODS

This analysis used pooled data on 8,147 women with invasive epithelial ovarian cancer from the Ovarian Cancer Association Consortium. The prediagnosis inflammation-related exposures of interest included alcohol use; aspirin use; other nonsteroidal anti-inflammatory drug use; body mass index; environmental tobacco smoke exposure; history of pelvic inflammatory disease, polycystic ovarian syndrome, and endometriosis; menopausal hormone therapy use; physical inactivity; smoking status; and talc use. Using Cox proportional hazards models, the relationship between each exposure and survival was assessed in 50% of the data. A weighted inflammation-related risk score (IRRS) was developed, and its association with survival was assessed using Cox proportional hazards models in the remaining 50% of the data.

RESULTS

There was a statistically significant trend of increasing risk of death per quartile of the IRRS [HR = 1.09; 95% confidence interval (CI), 1.03-1.14]. Women in the upper quartile of the IRRS had a 31% higher death rate compared with the lowest quartile (95% CI, 1.11-1.54).

CONCLUSIONS

A higher prediagnosis IRRS was associated with an increased mortality risk after an ovarian cancer diagnosis. Further investigation is warranted to evaluate whether postdiagnosis exposures are also associated with survival.

IMPACT

Given that pre- and postdiagnosis exposures are often correlated and many are modifiable, our study results can ultimately motivate the development of behavioral recommendations to enhance survival among patients with ovarian cancer.

Joint IARC/NCI International Cancer Seminar Series Report: expert consensus on future directions for ovarian carcinoma research

Recently, ovarian cancer research has evolved considerably because of the emerging recognition that rather than a single disease, ovarian carcinomas comprise several different histotypes that vary by etiologic origin, risk factors, molecular profiles, therapeutic approaches and clinical outcome. Despite significant progress in our understanding of the etiologic heterogeneity of ovarian cancer, as well as important clinical advances, it remains the eighth most frequently diagnosed cancer in women worldwide and the most fatal gynecologic cancer. The International Agency for Research on Cancer and the United States National Cancer Institute jointly convened an expert panel on ovarian carcinoma to develop consensus research priorities based on evolving scientific discoveries. Expertise ranged from etiology, prevention, early detection, pathology, model systems, molecular characterization and treatment/clinical management. This report summarizes the current state of knowledge and highlights expert consensus on future directions to continue advancing etiologic, epidemiologic and prognostic research on ovarian carcinoma.

Altering the Microbiome Inhibits Tumorigenesis in a Mouse Model of Oviductal High-Grade Serous Carcinoma

Studies have shown bacteria influence the initiation and progression of cancers arising in sites that harbor rich microbial communities, such as the colon. Little is known about the potential for the microbiome to influence tumorigenesis at sites considered sterile, including the upper female genital tract. The recent identification of distinct bacterial signatures associated with ovarian carcinomas suggests microbiota in the gut, vagina, or elsewhere might contribute to ovarian cancer pathogenesis. Here, we tested whether altering the microbiome affects tumorigenesis in a mouse model of high-grade serous carcinoma (HGSC) based on conditional oviduct-specific inactivation of the Brca1, Trp53, Rb1, and Nf1 tumor suppressor genes. Cohorts of control (n = 20) and antibiotic-treated (n = 23) mice were treated with tamoxifen to induce tumor formation and then monitored for 12 months. The antibiotic cocktail was administered for the first 5 months of the monitoring period in the treatment group. Antibiotic-treated mice had significantly fewer and less advanced tumors than control mice at study endpoint. Antibiotics induced changes in the composition of the intestinal and vaginal microbiota, which were durable in the fecal samples. Clustering analysis showed particular groups of microbiota are associated with the development of HGSC in this model. These findings demonstrate the microbiome influences HGSC pathogenesis in an in vivo model that closely recapitulates the human disease. Because the microbiome can modulate efficacy of cancer chemo- and immunotherapy, our genetically engineered mouse model system may prove useful for testing whether altering the microbiota can improve the heretofore poor response of HGSC to immunotherapies. SIGNIFICANCE: This study provides strong in vivo evidence for a role of the microbiome in ovarian cancer pathogenesis.

Depot-Medroxyprogesterone Acetate Use Is Associated with Decreased Risk of Ovarian Cancer: The Mounting Evidence of a Protective Role of Progestins

BACKGROUND

Combined oral contraceptive use is associated with a decreased risk of invasive epithelial ovarian cancer (ovarian cancer). There is suggestive evidence of an inverse association between progestin-only contraceptive use and ovarian cancer risk, but previous studies have been underpowered.

METHODS

The current study used primary data from 7,977 women with ovarian cancer and 11,820 control women in seven case-control studies from the Ovarian Cancer Association Consortium to evaluate the association between use of depot-medroxyprogesterone acetate (DMPA), an injectable progestin-only contraceptive, and ovarian cancer risk. Logistic models were fit to determine the association between ever use of DMPA and ovarian cancer risk overall and by histotype. A systematic review of the association between DMPA use and ovarian cancer risk was conducted.

RESULTS

Ever use of DMPA was associated with a 35% decreased risk of ovarian cancer overall (OR, 0.65; 95% confidence interval, 0.50-0.85). There was a statistically significant trend of decreasing risk with increasing duration of use (P _trend < 0.001). The systematic review yielded six studies, four of which showed an inverse association and two showed increased risk.

CONCLUSIONS

DMPA use appears to be associated with a decreased risk of ovarian cancer in a duration-dependent manner based on the preponderance of evidence. Further study of the mechanism through which DMPA use is associated with ovarian cancer is warranted.

IMPACT

The results of this study are of particular interest given the rise in popularity of progestin-releasing intrauterine devices that have a substantially lower progestin dose than that in DMPA, but may have a stronger local effect.

Menopausal hormone therapy prior to the diagnosis of ovarian cancer is associated with improved survival

PURPOSE

Prior studies of menopausal hormone therapy (MHT) and ovarian cancer survival have been limited by lack of hormone regimen detail and insufficient sample sizes. To address these limitations, a comprehensive analysis of 6419 post-menopausal women with pathologically confirmed ovarian carcinoma was conducted to examine the association between MHT use prior to diagnosis and survival.

METHODS

Data from 15 studies in the Ovarian Cancer Association Consortium were included. MHT use was examined by type (estrogen-only (ET) or estrogen+progestin (EPT)), duration, and recency of use relative to diagnosis. Cox proportional hazards models were used to estimate the association between hormone therapy use and survival. Logistic regression and mediation analysis was used to explore the relationship between MHT use and residual disease following debulking surgery.

RESULTS

Use of ET or EPT for at least five years prior to diagnosis was associated with better ovarian cancer survival (hazard ratio, 0.80; 95% CI, 0.74 to 0.87). Among women with advanced stage, high-grade serous carcinoma, those who used MHT were less likely to have any macroscopic residual disease at the time of primary debulking surgery (p for trend <0.01 for duration of MHT use). Residual disease mediated some (17%) of the relationship between MHT and survival.

CONCLUSIONS

Pre-diagnosis MHT use for 5+ years was a favorable prognostic factor for women with ovarian cancer. This large study is consistent with prior smaller studies, and further work is needed to understand the underlying mechanism.

Abstract IA14: Integrated molecular characterization of the genome, transcriptome, and immune microenvironment in oviductal high-grade serous carcinomas arising in genetically engineered mice

Robust preclinical models of ovarian high-grade serous carcinoma (HGSC) are needed to advance our understanding of HGSC pathogenesis and to test novel strategies aimed at improving clinical outcomes for women with the disease. Genetically engineered mouse models of HGSC have been developed that recapitulate the likely cell of origin (fallopian tube epithelium), underlying genetic defects, histology, and biologic behavior of human HGSCs, but the degree to which the mouse tumors acquire the somatic genomic changes, gene expression profiles, and immune microenvironment that characterize human HGSCs remains unclear. We used integrative molecular characterization of oviductal HGSCs arising in the context of Brca1, Trp53, Rb1, and Nf1 (BPRN) inactivation to determine whether the mouse tumors recapitulate human HGSCs across multiple domains of molecular features. Targeted DNA sequencing showed that the mouse BPRN tumors, but not endometrioid carcinoma-like tumors based on different genetic defects (e.g., Apc, Pten, Arid1a), acquire somatic mutations and widespread copy number alterations similar to those observed in human HGSCs. RNA sequencing showed that the mouse HGSCs most closely model the immunoreactive and mesenchymal subsets of human HGSCs. A combined immunogenomic analysis showed that the immune microenvironment of BPRN tumors models key aspects of tumor-immune dynamics in human HGSC, with enrichment of immunosuppressive cell subsets (myeloid-derived suppressor cells and regulatory T cells) as observed in the immunoreactive and mesenchymal subsets of human tumors. These findings, as well as early proof-of-principle studies, support the BPRN model as a robust preclinical experimental platform to help overcome barriers to clinical success in preventing, diagnosing, and treating this lethal cancer.

Citation Format: Kathleen R. Cho. Integrated molecular characterization of the genome, transcriptome, and immune microenvironment in oviductal high-grade serous carcinomas arising in genetically engineered mice [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr IA14.

Abstract B50: Direct interrogation of the incessant ovulation hypothesis in a high-fidelity mouse model of high-grade serous cancer

The biologic basis for factors that modify risk of developing high-grade serous carcinoma remains understudied. In particular, the “Incessant Ovulation” hypothesis remains a plausible model to unify the observed risks associated with more ovulations (increasing age, early menarche/late menopause) as well as protection conferred by oral contraceptive use, multiparity, and breastfeeding. We used genetically engineered mouse models (GEMMs) of HGSC to directly interrogate the role of aging and multiparity as deleterious and protective risk factors, respectively, for HGSC development. Specifically, we utilized oviductal-restricted tamoxifen-inducible Cre recombinase to drive conditional bi-allelic inactivation of key tumor-suppressor genes (Brca1, Trp53, Rb1, Nf1) in the murine fallopian tube (oviduct). In our genetically engineered mice, autochthonous tumors arise with high penetrance in response to tamoxifen treatment, albeit with prolonged latency. As a consequence, the models allow us to evaluate effects of multiparity and aging on tumor development and progression. To test effects of multiparity, two cohorts of mice were tested, one with two floxed alleles of all 4 TSGs (BPRN), and another in which one allele of Nf1 was wild-type (BPRNfl/+). Mice were treated with tamoxifen and then continuously caged with a breeding male for a total of up to 9 pregnancies. Control mice were treated with tamoxifen and then remained nulliparous until sacrifice. The total number of pregnancies ranged from 5 to 9 for each mouse in the multiparous groups. Mice were euthanized 62 weeks post-TAM or earlier, if humane endpoints were reached. No apparent differences in diagnosis at study endpoint was observed in the multiparous BPRN versus nulliparous group (p=0.34, Mantel-Haenszel Chi-square test of association). Interestingly, the control mice showed a trend for worse diagnosis compared to the BPRNfl/+ mice at study endpoint (p=0.02). In the aging cohort, control BPRN mice were exposed to tamoxifen at 8 weeks of age and followed to humane endpoints. The experimental group was aged to 9 months, exposed to tamoxifen and then followed to humane endpoints. Survival post-TAM was observed to be shortened in the older animals (median 45.5 weeks versus 57 weeks in control mice, log rank test p=0.0033). Using Cox proportional hazard models, aging was associated with a hazard ratio of 2.8 with 95% CI of 1.4-5.9. Collectively these data suggest that multiple pregnancies alone delays HGSC development and progression in certain genetic contexts, while in contrast, tumor induction in aged mice is associated with significantly shorter survival. Together, these results help credential these GEMMs as useful tools with which to explore the biologic basis for risk factors presumed to underly the development of HGSC.

Citation Format: Yali Zhai, Kevin McCool, Rork Kuick, Lixing Chen, Eric R. Fearon, Kathleen R. Cho. Direct interrogation of the incessant ovulation hypothesis in a high-fidelity mouse model of high-grade serous cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr B50.

Abstract B65: Defining the tumor immune landscape in a mouse model of high-grade serous carcinoma

Clinical efficacy of immune checkpoint therapy in high-grade serous carcinoma (HGSC) has been disappointing to date and highlights the need to better understand the relationship between HGSC and its associated immune microenvironment. Tractable model systems for interrogating the tumor microenvironment in HGSC could be used to address this unmet need. We have generated genetically engineered mouse models (GEMMs) of HGSC utilizing oviduct-restricted tamoxifen-regulated Cre recombinase to drive conditional inactivation of key tumor suppressor genes (Brca1, Trp53, Rb1, Nf1) observed to be recurrently altered in human HGSC samples. These autochthonous tumors arise from the murine fallopian tube (oviduct) in the context of an intact immune system. We employed RNA sequencing (RNA-seq) of bulk tumors from 19 mouse HGSCs to compare their gene expression profiles to those of normal oviduct and ovary tissues (4 each), and 6 mouse endometrioid-like oviductal carcinomas based on conditional inactivation of Apc and Pten. We employed immunogenomic analysis of the RNA-seq data to characterize the intratumoral infiltrate of 28 immune cell types in these samples in silico. The analysis revealed a prevalence of gene expression signatures associated with immunosuppressive cell types, including myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) in the mouse HGSCs, not observed in the other sample groups. Human HGSCs with available RNA-seq data (from TCGA samples) showed similar enrichment of MDSC and Treg gene signatures in the subset of human HGSCs classified as mesenchymal or immunoreactive expression subtypes. To further validate the findings in the mouse HGSCs, we used immunohistochemistry to detect subsets of tumor-infiltrating lymphocytes (TILs) in the tumor tissues. Specifically, CD8+ TIL infiltrates recapitulated epithelial (E-TIL), stromal (S-TIL) and combined epithelial/stromal (ES-TIL) patterns described in human HGSCs. Moreover, FoxP3+ Tregs were frequently observed to be co-infiltrated with CD8+ TILs as expected in an immunosuppressive tumor microenvironment. Gene set enrichment analysis showed that NF-kappa B signaling is among the top five pathways upregulated in HGSCs versus normal oviducts, suggesting a plausible mechanism by which tumor cells can alter and respond to the microenvironment during tumor development. These studies provide an experimental paradigm for improving our understanding of the role of the tumor microenvironment in HGSC pathogenesis and may aid in efforts to enhance the efficacy of immunotherapies in this lethal disease.

Citation Format: Kevin W. McCool, Rork Kuick, Yali Zhai, Zach Freeman, Rong Wu, Eric Fearon, Kathleen R. Cho. Defining the tumor immune landscape in a mouse model of high-grade serous carcinoma [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr B65.

Cervical Cancer, Version 3.2019, NCCN Clinical Practice Guidelines in Oncology

Cervical cancer is a malignant epithelial tumor that forms in the uterine cervix. Most cases of cervical cancer are preventable through human papilloma virus (HPV) vaccination, routine screening, and treatment of precancerous lesions. However, due to inadequate screening protocols in many regions of the world, cervical cancer remains the fourth-most common cancer in women globally. The complete NCCN Guidelines for Cervical Cancer provide recommendations for the diagnosis, evaluation, and treatment of cervical cancer. This manuscript discusses guiding principles for the workup, staging, and treatment of early stage and locally advanced cervical cancer, as well as evidence for these recommendations. For recommendations regarding treatment of recurrent or metastatic disease, please see the full guidelines on NCCN.org.

Epigenetic driver mutations in ARID1A shape cancer immune phenotype and immunotherapy

Whether mutations in cancer driver genes directly affect cancer immune phenotype and T cell immunity remains a standing question. ARID1A is a core member of the polymorphic BRG/BRM-associated factor chromatin remodeling complex. ARID1A mutations occur in human cancers and drive cancer development. Here, we studied the molecular, cellular, and clinical impact of ARID1A aberrations on cancer immunity. We demonstrated that ARID1A aberrations resulted in limited chromatin accessibility to IFN-responsive genes, impaired IFN gene expression, anemic T cell tumor infiltration, poor tumor immunity, and shortened host survival in many human cancer histologies and in murine cancer models. Impaired IFN signaling was associated with poor immunotherapy response. Mechanistically, ARID1A interacted with EZH2 via its carboxyl terminal and antagonized EZH2-mediated IFN responsiveness. Thus, the interaction between ARID1A and EZH2 defines cancer IFN responsiveness and immune evasion. Our work indicates that cancer epigenetic driver mutations can shape cancer immune phenotype and immunotherapy.

Murine Oviductal High-Grade Serous Carcinomas Mirror the Genomic Alterations, Gene Expression Profiles, and Immune Microenvironment of Their Human Counterparts

Robust preclinical models of ovarian high-grade serous carcinoma (HGSC) are needed to advance our understanding of HGSC pathogenesis and to test novel strategies aimed at improving clinical outcomes for women with the disease. Genetically engineered mouse models of HGSC recapitulating the likely cell of origin (fallopian tube), underlying genetic defects, histology, and biologic behavior of human HGSCs have been developed. However, the degree to which the mouse tumors acquire the somatic genomic changes, gene expression profiles, and immune microenvironment that characterize human HGSCs remains unclear. We used integrated molecular characterization of oviductal HGSCs arising in the context of Brca1, Trp53, Rb1, and Nf1 (BPRN) inactivation to determine whether the mouse tumors recapitulate human HGSCs across multiple domains of molecular features. Targeted DNA sequencing showed the mouse BPRN tumors, but not endometrioid carcinoma-like tumors based on different genetic defects (e.g., Apc and Pten), acquire somatic mutations and widespread copy number alterations similar to those observed in human HGSCs. RNA sequencing showed the mouse HGSCs most closely resemble the so-called immunoreactive and mesenchymal subsets of human HGSCs. A combined immuno-genomic analysis demonstrated the immune microenvironment of BPRN tumors models key aspects of tumor-immune dynamics in the immunoreactive and mesenchymal subtypes of human HGSC, with enrichment of immunosuppressive cell subsets such as myeloid-derived suppressor cells and regulatory T cells. The findings further validate the BPRN model as a robust preclinical experimental platform to address current barriers to improved prevention, diagnosis, and treatment of this often lethal cancer. SIGNIFICANCE: The acquired gene mutations, broad genomic alterations, and gene expression and immune cell-tumor axis changes in a mouse model of oviductal serous carcinoma closely mirror those of human tubo-ovarian high-grade serous carcinoma.

Abstract AP16: MODELING ENDOMETRIOID AND HIGH GRADE SEROUS CARCINOMAS IN THE MOUSE USING CRISPR/CAS9-MEDIATED SOMATIC GENE EDITING IN FALLOPIAN TUBE EPITHELIUM

Genetically engineered mouse models (GEMMs) have contributed significantly to our understanding of the role of specific gene defects in human cancers. GEMMs that recapitulate many of the molecular and biological characteristics of various histologic subtypes of ovarian carcinomas have already been developed. However, conventional methods of GEMM development based on Cre-lox technology require the time-consuming and labor-intensive processes of transgenic line production and cross-breeding, a problem that is exacerbated when developing cancer GEMMs based on multiple genetic defects. The RNA-guided Cas9 nuclease from the microbial clustered regularly interspaced short palindromic repeats (CRISPR) adaptive immune system potentially offers a more rapid and versatile alternative platform for tumor modeling in the mouse, as it can be used to target multiple genomic loci simultaneously by specifying a 20-nt targeting sequence for each gene of interest. The development of gynecological cancer GEMMs using CRISPR/Cas9-mediated conditional gene editing has not yet been reported. We have tested this approach to generate endometrioid carcinoma (EC) and high-grade serous carcinoma (HGSC) in the mouse oviductal epithelium.

We first selected potentially optimal 20-nt sequences (guide RNAs) targeting the murine orthologs of the Apc and Pten tumor suppressor genes for the EC model, and the Brca1, Trp53, Rb1, and Nf1 genes for the HGSC model. Efficient cutting mediated by each guide RNA was validated in vitro by the Surveyor nuclease assay in NIH3T3 mouse fibroblasts. Next, we generated two transgenic mouse lines: one carrying a transgene with guide RNAs targeting Apc and Pten in tandem as a single guide RNA (sgAP) and a second carrying a transgene with a single guide RNA targeting Brca1, Trp53, Rb1, and Nf1 (sgBPRN). These transgenic lines were then crossed with Ovgp1-iCre-ERT2 and Rosa26LSL-Cas9-EGFP (Jackson laboratory) mice to allow for conditional (Tamoxifen-regulated) inactivation of Apc-Pten or Brca1-Trp53-Rb1-Nf1 specifically in the FTE. Endometrioid carcinomas were identified in Ovgp1-iCreERT2;Rosa26LSL-Cas9-EGFP;sgAP mice by 20 weeks post tamoxifen and early HGSC was present in an Ovgp1-iCreERT2; Rosa26LSL-Cas9-EGFP;sgBPRN mouse 34 weeks post tamoxifen treatment. The tumors derived from Cre-CRISPR/Cas9-sgRNA technology showed similar morphology and immunophenotypic characteristics to tumors arising in the models using Cre-lox technology based on the same genetic defects. Insertions/deletions (Indels) in tumor DNA were found in all of the targeted genes near the expected cut-sites, and confirmed by Sanger sequencing of cloned PCR products. All of the Indels resulted in predicted premature protein truncation and loss of function. Our results show that CRISPR/Cas9-sgRNA system genome editing can be used successfully to model gynecological cancers in mice.

Citation Format: Rong Wu, Carmine Stolfi, Yali Zhai, Eric R. Fearon, and Kathleen R. Cho. MODELING ENDOMETRIOID AND HIGH GRADE SEROUS CARCINOMAS IN THE MOUSE USING CRISPR/CAS9-MEDIATED SOMATIC GENE EDITING IN FALLOPIAN TUBE EPITHELIUM [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr AP16.

Abstract GMM-061: MOLECULAR CHARACTERIZATION OF MOUSE MODELS OF HIGH-GRADE SEROUS CARCINOMA ARISING IN THE OVIDUCT

We recently developed genetically engineered mouse models (GEMMs) of oviductal high-grade serous carcinoma (HGSC) based on conditional inactivation of several different combinations of tumor suppressor genes (Brca1, Trp53, Rb1, and Nf1) that are recurrently mutated in human HGSCs. The histopathological features of the mouse tumors closely mimic their human tumor counterparts. In order to characterize how well the mouse tumors recapitulate the molecular characteristics of human HGSCs, targeted exome sequencing was used to analyze the 32 most commonly mutated genes in human HGSC, in 60 mouse tumors arising in the context of Brca1, Trp53, Rb1, and/or Nf1 inactivation. We employed the sequence data to assess DNA copy number alterations (CNAs) and single nucleotide variants (SNVs) in the mouse tumors.

Compared to 14 normal tissues and 8 oviductal tumors arising in the context of Apc, Pten, ± Arid1a inactivation, the mouse HGSCs showed a high level of genomic instability, with many widely distributed CNAs – very similar to the widespread CNAs observed in human HGSCs. Targeted exome sequencing also showed that a subset of the mouse tumors acquired alterations observed in human HGSCs, including amplification of cMyc, and deletion of Pten. Variant analysis identified nonsynonymous SNVs in Csmd3, Crebbp, Pten, Mettl17, and Zymynd8 and a frameshift deletion of Pten. Sanger sequencing confirmed the presence of these somatic mutations in the mouse tumors and their absence in matched normal tissues. Loss of PTEN expression was observed in those tumors that acquired somatic Pten alterations.

These data show that HGSCs arising in our GEMMs have very similar molecular characteristics to their human tumor counterparts. The somatic alterations are likely acquired during the relatively lengthy period (several months) between tumor initiation and progression to overt malignancy. These features render the models particularly well suited for studying the early phases of HGSC development and for translational applications aimed at identifying effective strategies for HGSC prevention and early detection.

Citation Format: Yali Zhai, Yisheng Wang, Stephanie M. Schulman, Kevin Hu, Albert Liu, Scott A. Tomlins, Eric R. Fearon, and Kathleen R. Cho. MOLECULAR CHARACTERIZATION OF MOUSE MODELS OF HIGH-GRADE SEROUS CARCINOMA ARISING IN THE OVIDUCT [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr GMM-061.

Uterine Neoplasms, Version 1.2018, NCCN Clinical Practice Guidelines in Oncology

Endometrial carcinoma is a malignant epithelial tumor that forms in the inner lining, or endometrium, of the uterus. Endometrial carcinoma is the most common gynecologic malignancy. Approximately two-thirds of endometrial carcinoma cases are diagnosed with disease confined to the uterus. The complete NCCN Guidelines for Uterine Neoplasms provide recommendations for the diagnosis, evaluation, and treatment of endometrial cancer and uterine sarcoma. This manuscript discusses guiding principles for the diagnosis, staging, and treatment of early-stage endometrial carcinoma as well as evidence for these recommendations.

Lineage tracing suggests that ovarian endosalpingiosis does not result from escape of oviductal epithelium

Most high-grade serous carcinomas are thought to arise from Fallopian tube epithelium (FTE), but some likely arise outside of the tube, perhaps from ectopic tubal-type epithelium known as endosalpingiosis. Importantly, the origin of endosalpingiosis is poorly understood. The proximity of the tubal fimbriae to the ovaries has led to the proposal that disruptions in the ovarian surface that occur during ovulation may allow detached FTE to implant in the ovary and form tubal-type glands and cysts. An alternative model suggests that cells present in ectopic locations outside the Müllerian tract retain the capacity for multi-lineage differentiation and can form glands with tubal-type epithelium. We used double transgenic Ovgp1-iCreER^T2 ;R26R^LSL-eYFP mice, which express an eYFP reporter protein in OVGP1-positive tissues following transient tamoxifen (TAM) treatment, to track the fate of oviductal epithelial cells. Cohorts of adult mice were given TAM to activate eYFP expression in oviductal epithelium, and ovaries were examined at time points ranging from 2 days to 12 months post-TAM. To test whether superovulation might increase acquisition of endosalpingiosis, additional cohorts of TAM-treated mice underwent up to five cycles of superovulation and ovaries were examined at 1, 6, and 12 months post-TAM. Ovaries were sectioned in their entirety to identify endosalpingiosis. Immunohistochemical staining for PAX8, tubulin, OVGP1, and eYFP was employed to study endosalpingiosis lesions. Ovarian endosalpingiosis was identified in 14.2% of TAM-treated adult mice. The endosalpingiotic inclusion glands and cysts were lined by secretory and ciliated cells and expressed PAX8, tubulin, OVGP1, and eYFP. Neither age nor superovulation was associated with a significant increase in endosalpingiosis. Endosalpingiosis was also occasionally present in the ovaries of pre-pubertal mice. The findings imply that ovarian endosalpingiosis in the mouse does not likely arise as a consequence of detachment and implantation of tubal epithelium and other mechanisms may be relevant. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Abstract B76: Oncogenic Kras and Pik3ca can cooperate with inactivation of various tumor suppressor genes to generate high-grade serous carcinomas in the mouse oviduct

Recent studies suggest that most “ovarian” high-grade serous carcinomas (HGSCs) actually originate from precursors in the fallopian tubal epithelium (FTE) known as serous tubal intraepithelial carcinomas (STICs). We have developed Ovgp1-iCreERT2 mice in which the Ovgp1 promoter controls expression of tamoxifen-regulated Cre recombinase in the oviductal epithelium—equivalent to human FTE. We recently employed Ovgp1-iCreERT2 mice to show that FTE-specific inactivation of several different combinations of tumor suppressor genes (TSGs) that are recurrently mutated in human HGSCs—namely Brca1, Trp53, Rb1, and Nf1---results in STICs that progress to HGSC or Müllerian carcinosarcoma over several months, and to widely metastatic disease in a subset of mice. The histopathologic features of the mouse tumors closely resemble those of their human tumor counterparts.

The PI3K and RAS signaling pathways are frequently dysregulated in human HGSCs, often via amplification (and much less frequently mutation) of PIK3CA and KRAS, respectively. We wished to determine if mutant Kras or Pik3ca can cooperate with inactivation of various combinations of the aforementioned TSGs to generate oviductal HGSCs in the mouse, and were particularly interested in generating tumors in the context of intact Brca1/2. We found that conditional mutation of Kras (G12D) can cooperate with Brca1, Trp53, Rb1, and/or Nf1 inactivation in the generation of HGSCs in the mouse. Only two TSGs alterations (Trp53 and Rb1) were required for tumor development in the context of mutant Kras. HGSCs and/or carcinosarcomas developed rapidly in the context of mutant Kras and bi-allelic inactivation of Trp53 and Rb1, even when Brca1 and Brca2 were intact. HGSC and/or carcinosarcoma also developed in the oviducts following conditional mutation of Pik3ca (E545K) and various combinations of inactivated Brca1, Trp53, Rb1, and/or Nf1 alleles. When compared to our prior study of mouse tumors arising in the context of TSG inactivation alone, our data show that that 1) oncogenic Kras or Pik3ca accelerates tumor development and progression in mice carrying floxed Brca1, Trp53, Rb1, and/or Nf1 alleles compared to mice with the same TSG defects but without mutant Kras or Pik3ca; 2) oviductal tumorigenesis in the mouse requires fewer TSGs defects when mutant Kras or Pik3ca is also present; and 3) oviductal HGSCs can arise in the context of wild-type Brca1/2. Collectively, these models recapitulate the heterogeneity of human HGSC and should prove useful for testing new approaches for prevention, early detection, and treatment.

Citation Format: Yali Zhai, Stephanie Schulman, Neil Khandwala, Eric R. Fearon, Kathleen R. Cho. Oncogenic Kras and Pik3ca can cooperate with inactivation of various tumor suppressor genes to generate high-grade serous carcinomas in the mouse oviduct. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B76.

Abstract P6-08-09: Incidence and risk factors for congestive heart failure in early breast cancer received anthracycline and/or trastuzumab; big-data analysis of Korean health insurance review and assessment service database

Background: Anthracycline (AC) and/or trastuzumab (T) are the most commonly used for neo-/adjuvant therapy for early breast cancer. However, use of those regimens are limited owing to congestive heart failure (CHF). Although reported incidence from pivotal trials is very low and acceptable, no big data-based population study has not been conducted in Koreans yet. The aim of this study was to analyze the incidence, time to occurrence, and risk factors for CHF in patients with early breast cancer, who were treated with AC and/or T therapy, in Korea.

Methods: We used the Health Insurance Review and Assessment Service database and included women with no prior history of CHF who were aged &gt;19 years and diagnosed as having early breast cancer between 2007 and 2016. Only patients who had received breast cancer surgery and AC and/or T therapy were included. Patients with metastatic cancer codes were excluded.

Result: In total, 86,086 patients were included for this analysis. The incidence and median time to occurrence of CHF according to chemotherapy type were, 3.27% and 683.5 days in the AC only group, 6.39% and 374 days in the AC followed by T group, and 4.43% and 286 days in the T with or without non-AC group, respectively.

The multivariate Cox regression analysis revealed that the adjusted hazard ratio (HR) for CHF was increased with older age; in those aged ≥65 years versus &lt;50 years (HR, 2.79; 95% confidence interval [CI], 2.50–3.12). The HR in the AC followed by T group was significantly higher than that in the AC only group (HR, 2.21; 95% CI, 2.05-2.37). The T with or without non-AC group also showed a significantly higher HR than the AC only group (HR, 1.67; 95% CI, 1.37-2.04). CCI scores of ≥2 were significant predictors of CHF; score 2 versus 0 (HR, 1.30; 95% CI, 1.18-1.45), and score ≥3 versus 0 (HR, 1.87; 95% CI, 1.69-2.06). In addition, preexisting medical conditions were significant predictors for CHF: hypertension (HR, 1.58; 95% CI, 1.45-1.72), diabetes (HR, 1.17; 95% CI, 1.07-1.28), and ischemic heart disease (HR, 1.60; 95% CI, 1.45-1.76).

Conclusion: This is the first big data-based population study in Korea on the development of CHF after treatment with AC and/or T. The overall incidence of CHF was 3% to 6%, with a median time to occurrence of 1 to 2 years. Adjusted HR increased with older age, AC followed by T therapy, CCI scores ≥2, and preexisting conditions.

Table 1. Incidence and median time to occurrence of congestive heart failure according to chemotherapy typeChemotherapy typeTotalCHF event (%)Median time to occurenceAC only66,6992,182 (3.27%)683.5AC followed by T17,0621,090 (6.39%)374T ± non-AC2,325103 (4.43%)286

Table 2. Cox proportional hazards model for congestive heart failure, adjusted for age, chemotherapy type, and Charlson comorbidity index scoreVariableP-valueHR95% CIAge (ref &lt;50 years)   50-64 years&lt;0.00011.541.43-1.66≥65 years&lt;0.00012.792.50-3.12Chemotherapy type (ref AC only)   AC folloewed by T&lt;0.00012.212.05-2.37T ± non-AC&lt;0.00011.671.37-2.04Charlson comorbidity index score (ref 0)   10.12061.080.98-1.192&lt;0.00011.301.18-1.45≥3&lt;0.00011.871.69-2.06

Citation Format: Choi JY, Cho EY, Lee JW, Kim JW, Choi YJ, You JY, Bae SY, Jung SP, Cho KR, Park KH. Incidence and risk factors for congestive heart failure in early breast cancer received anthracycline and/or trastuzumab; big-data analysis of Korean health insurance review and assessment service database [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-08-09.

Serous Tubal Intraepithelial Carcinoma or Not? Metastases to Fallopian Tube Mucosa Can Masquerade as In Situ Lesions

CONTEXT

- Nonuterine high-grade serous carcinomas (HGSCs) are believed to arise most often from precursors in the fallopian tube referred to as serous tubal intraepithelial carcinomas (STICs). A designation of tubal origin has been suggested for all cases of nonuterine HGSC if a STIC is identified.

OBJECTIVE

- To highlight that many different types of nongynecologic and gynecologic carcinomas, including HGSC, can metastasize to the tubal mucosa and mimic de novo STIC.

DATA SOURCES

- A mini-review of several recently published studies that collectively examine STIC-like lesions of the fallopian tube.

CONCLUSIONS

- The fallopian tube mucosa can be a site of metastasis from carcinomas arising elsewhere, and pathologists should exercise caution in diagnosing STIC without first considering the possibility of metastasis. Routinely used immunohistochemical stains can often be used to determine if a STIC-like lesion is tubal or nongynecologic in origin. In the context of uterine and nonuterine HGSC, STIC may represent a metastasis rather than the site of origin, particularly when widespread disease is present.

Vulvar Cancer, Version 1.2017, NCCN Clinical Practice Guidelines in Oncology

Vulvar cancer is a rare gynecologic malignancy. Ninety percent of vulvar cancers are predominantly squamous cell carcinomas (SCCs), which can arise through human papilloma virus (HPV)-dependent and HPV-independent pathways. The NCCN Vulvar Cancer panel is an interdisciplinary group of representatives from NCCN Member Institutions consisting of specialists in gynecological oncology, medical oncology, radiation oncology, and pathology. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Vulvar Cancer provide an evidence- and consensus-based approach for the management of patients with vulvar SCC. This manuscript discusses the recommendations outlined in the NCCN Guidelines for diagnosis, staging, treatment, and follow-up.

High-grade serous carcinomas arise in the mouse oviduct via defects linked to the human disease

Recent studies have suggested that the most common and lethal type of 'ovarian' cancer, i.e. high-grade serous carcinoma (HGSC), usually arises from epithelium on the fallopian tube fimbriae, and not from the ovarian surface epithelium. We have developed Ovgp1-iCreER^T2 mice in which the Ovgp1 promoter controls expression of tamoxifen-regulated Cre recombinase in oviductal epithelium - the murine equivalent of human fallopian tube epithelium (FTE). We employed Ovgp1-iCreER^T2 mice to show that FTE-specific inactivation of several different combinations of tumour suppressor genes that are recurrently mutated in human HGSCs - namely Brca1, Trp53, Rb1, and Nf1 - results in serous tubal intraepithelial carcinomas (STICs) that progress to HGSC or carcinosarcoma, and to widespread metastatic disease in a subset of mice. The cancer phenotype is highly penetrant and more rapid in mice carrying engineered alleles of all four tumour suppressor genes. Brca1, Trp53 and Pten inactivation in the oviduct also results in STICs and HGSCs, and is associated with diffuse epithelial hyperplasia and mucinous metaplasia, which are not observed in mice with intact Pten. Oviductal tumours arise earlier in these mice than in those with Brca1, Trp53, Rb1 and Nf1 inactivation. Tumour initiation and/or progression in mice lacking conditional Pten alleles probably require the acquisition of additional defects, a notion supported by our identification of loss of the wild-type Rb1 allele in the tumours of mice carrying only one floxed Rb1 allele. Collectively, the models closely recapitulate the heterogeneity and histological, genetic and biological features of human HGSC. These models should prove useful for studying the pathobiology and genetics of HGSC in vivo, and for testing new approaches for prevention, early detection, and treatment. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Impact of oviductal versus ovarian epithelial cell of origin on ovarian endometrioid carcinoma phenotype in the mouse

Endometrioid carcinoma (EC) is a relatively indolent ovarian carcinoma subtype that is nonetheless deadly if detected late. Existing genetically engineered mouse models (GEMMs) of the disease, based on transformation of the ovarian surface epithelium (OSE), take advantage of known ovarian EC driver gene lesions, but do not fully recapitulate the disease features seen in patients. An EC model in which the Apc and Pten tumour suppressor genes are conditionally deleted in murine OSE yields tumours that are biologically more aggressive and significantly less differentiated than human ECs. Importantly, OSE is not currently thought to be the tissue of origin of most ovarian cancers, including ECs, suggesting that tumour initiation in Müllerian epithelium may produce tumours that more closely resemble their human tumour counterparts. We have developed Ovgp1-iCreER^T2 mice in which the Ovgp1 promoter controls expression of tamoxifen (TAM)-regulated Cre recombinase in oviductal epithelium - the murine equivalent of human Fallopian tube epithelium. Ovgp1-iCreER^T2 ;Apc^fl/fl ;Pten^fl/fl mice treated with TAM or injected with adenovirus expressing Cre into the ovarian bursa uniformly develop oviductal or ovarian ECs, respectively. On the basis of their morphology and global gene expression profiles, the oviduct-derived tumours more closely resemble human ovarian ECs than do OSE-derived tumours. Furthermore, mice with oviductal tumours survive much longer than their counterparts with ovarian tumours. The slow progression and late metastasis of oviductal tumours resembles the relatively indolent behaviour characteristic of so-called Type I ovarian carcinomas in humans, for which EC is a prototype. Our studies demonstrate the utility of Ovgp1-iCreER^T2 mice for manipulating genes of interest specifically in the oviductal epithelium, and establish that the cell of origin is an important consideration in mouse ovarian cancer GEMMs. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Abstract TMEM-018: IN VITRO MODELS OF HGSC BASED ON MURINE OVIDUCTAL EPITHELIAL ORGANOIDS

Mouse models of high-grade serous carcinoma (HGSC) arising from oviductal epithelium provide excellent in vivo systems with which to define the cellular and molecular events associated with HGSC development and progression. However, tumors in mice typically develop over months rather than weeks, and tumor progression in vivo cannot be easily monitored. Murine organoid models that closely mimic the biology of fallopian tube epithelium would facilitate research exploring HGSC pathogenesis.

We have developed Ovgp1-iCreERT2 mice in which the Ovgp1 promoter controls expression of tamoxifen (TAM)-inducible Cre recombinase in the oviductal epithelium – the murine equivalent of human fallopian tube epithelium. We have established long-term, 3-dimensional oviductal epithelial organoid cultures from Ovgp1-iCreERT2;R26LSL-EYFP double transgenic mice, and show that the organoids contain both ciliated and secretory cells, and express oviductal epithelial markers including cytokeratin 8, ER, PAX8 and OVGP1. Organoids treated in vitro with 4-hydroxy-tamoxifen (4-OH-TAM) activate the EYFP reporter.

Oviductal epithelial organoids established from Ovgp1-iCreERT2;Brca1del/fl; Trp53mut/fl;Rb1fl/fl (BPR) mice and treated in vitro with 4-OH-TAM show selection for the recombined tumor suppressor gene alleles by passage 6, accompanied by morphological and behavioral changes associated with neoplastic transformation. Stable organoid cultures can also be established from the oviductal epithelium of BPR mice treated in vivo with Tamoxifen (TAM).

We show that long-lived 3-dimensional organoids can be generated from normal oviductal tissue; can undergo Cre-mediated recombination in vitro to inactivate tumor suppressor genes relevant to human HGSC pathogenesis; and can acquire properties associated with neoplastic transformation in a relatively short period of time (weeks). As we have already generated Ovgp1-iCreERT2 mice with various combinations of constitutional and Cre-inducible mutant tumor suppressor gene (Trp53, Rb1, Brca1, Pten, Nf1, Apc) and oncogene (PIK3CA, KRAS) alleles, the roles of specific genetic alterations in HGSC pathogenesis can be explored in a relatively rapid and controlled experimental system.

Citation Format: Yali Zhai, Eric R. Fearon, and Kathleen R. Cho. IN VITRO MODELS OF HGSC BASED ON MURINE OVIDUCTAL EPITHELIAL ORGANOIDS [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr TMEM-018.

Abstract AP25: INHIBITION OF HDAC ACTIVITY SELECTIVELY INHIBITS ARID1A–MUTATED OVARIAN CLEAR CELL CARCINOMA THROUGH A NOVEL P53 REGULATORY MECHANISM

PURPOSE OF THE STUDY: ARID1A is mutated ~50% and 30% of clear cell (OCCC) and endometrioid (OEC) ovarian cancers, respectively. Over 90% of the ARID1A mutations observed in ovarian cancer are frame-shift or nonsense mutations that result in loss of ARID1A protein expression. In several cancers including OCCC, ARID1A and p53 mutations are often mutually exclusive. OCCC carries a worse prognosis compared to the other histosubtypes of ovarian cancer. Thus, there is an urgent clinical need for improved therapeutic strategies.

EXPERIMENTAL PROCEDURE: To investigate the role of specific HDACs in the context of ARID1A expression, we examined the effect of knocking down HDACs in an isogenic OCCC cell line with and without ARID1A expression. Utilizing a panel of ARID1A-mutated and wildtype OCCC cell lines, we evaluated the effect of HDAC knockdown and inhibition through a variety of 2D and 3D assays. We also examined the consequence of HDAC inhibition on tumor growth, survival, and dissemination in an in vivo mouse model of ovarian cancer.

SUMMARY OF THE DATA: We have discovered that ARID1A is involved in the repression of HDACs, and ARID1A-inactivation promotes aberrant transcriptional regulation of HDACs. Importantly, we uncovered a novel HDAC-dependent regulatory mechanism of p53. Several HDAC inhibitors are currently in clinical trials. We found HDAC inhibitors were more selective in ARID1A-mutated OCCC cell lines compared to ARID1A-wildtype cells. We observed that HDAC inhibition led to a significant increase in apoptosis in ARID1A-mutated cells. In an orthotopic intra-bursal xenograft model using ARID1A wildtype and deficient cells, the HDAC inhibitor suppressed primary tumor growth and inhibited tumor cell dissemination only in the ARID1A-mutated tumors. Significantly, HDAC inhibition significantly improved the survival of mice bearing ARID1A-mutated tumors.

CONCLUSIONS: These findings imply that HDAC inhibition represents a novel therapeutic strategy for ARID1A-deficient cancers. This study further elucidates the observed mutual exclusivity of ARID1A and p53. Importantly, we have uncovered a novel regulatory mechanism of p53 mediated through ARID1A and HDACs. Clinically, this study describes a precision medicine approach to the treatment of ARID1A-mutated OCCC.

Citation Format: Benjamin G. Bitler, Pyoung Hwa Park, Yang Hai, Katherine M. Aird, Yemin Wang, David G. Huntsman, Kathleen R. Cho, David W. Christianson, Rugang Zhang. INHIBITION OF HDAC ACTIVITY SELECTIVELY INHIBITS ARID1A–MUTATED OVARIAN CLEAR CELL CARCINOMA THROUGH A NOVEL P53 REGULATORY MECHANISM [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr AP25.

BRAFV600E cooperates with CDX2 inactivation to promote serrated colorectal tumorigenesis

While 20–30% of colorectal cancers (CRCs) may arise from precursors with serrated glands, only 8–10% of CRCs manifest serrated morphology at diagnosis. Markers for distinguishing CRCs arising from ‘serrated’ versus ‘conventional adenoma’ precursors are lacking. We studied 36 human serrated CRCs and found CDX2 loss or BRAF mutations in ~60% of cases and often together (p=0.04). CDX2^Null/BRAF^V600E expression in adult mouse intestinal epithelium led to serrated morphology tumors (including carcinomas) and BRAF^V600E potently interacted with CDX2 silencing to alter gene expression. Like human serrated lesions, CDX2^Null/BRAF^V600E-mutant epithelium expressed gastric markers. Organoids from CDX2^Null/BRAF^V600E–mutant colon epithelium showed serrated features, and partially recapitulated the gene expression pattern in mouse colon tissues. We present a novel mouse tumor model based on signature defects seen in many human serrated CRCs – CDX2 loss and BRAF^V600E. The mouse intestinal tumors show significant phenotypic similarities to human serrated CRCs and inform about serrated CRC pathogenesis.

DOI:http://dx.doi.org/10.7554/eLife.20331.001

The disparate origins of ovarian cancers: pathogenesis and prevention strategies

Ovarian cancer is the fifth cause of cancer-related death in women and comprises a histologically and genetically broad range of tumours, including those of epithelial, sex cord-stromal and germ cell origin. Recent evidence indicates that high-grade serous ovarian carcinoma, clear cell carcinoma and endometrioid carcinoma primarily arise from tissues that are not normally present in the ovary. These histogenetic pathways are informing risk-reduction strategies for the prevention of ovarian and ovary-associated cancers and have highlighted the importance of the seemingly unique ovarian microenvironment.

Uterine Sarcoma, Version 1.2016: Featured Updates to the NCCN Guidelines

The NCCN Guidelines for Uterine Neoplasms provide interdisciplinary recommendations for treating endometrial carcinoma and uterine sarcomas. These NCCN Guidelines Insights summarize the NCCN Uterine Neoplasms Panel's 2016 discussions and major guideline updates for treating uterine sarcomas. During this most recent update, the panel updated the mesenchymal tumor classification to correspond with recent updates to the WHO tumor classification system. Additionally, the panel revised its systemic therapy recommendations to reflect new data and collective clinical experience. These NCCN Guidelines Insights elaborate on the rationale behind these recent changes.

Abstract 672: Differential effects of p53 mutations on cancer invasion and metastasis in a mouse model of colon cancer

Inactivation of the APC (adenomatous polyposis coli) tumor suppressor gene plays an important role in initiating most adenomas and colorectal cancers (CRCs). Somatic mutations in the TP53 tumor suppressor gene and KRAS oncogene are found in roughly 60% and 40% of CRCs, respectively, and contribute to tumor progression. In the vast majority of human CRCs, TP53 missense mutations lead to high levels of mutant p53 protein expression and the loss of the other wild type TP53 allele. To evaluate the role of TP53 missense mutations in CRC progression, we generated a genetically engineered mouse model of colorectal carcinoma, via combined targeting of Apc, Kras, and Trp53 alleles in mouse colon epithelium, focusing on comparing phenotypic effects of the murine equivalent of the human R273H mutation (i.e., murine R270H mutation) or a large deletion mutation of mouse Trp53. Inactivation of one allele Apc and activation of an oncogenic Kras allele in colon epithelium generated serrated and hyperplastic morphologic epithelium and adenomas. The addition of either the R270H missense mutation or the Trp53 null mutation to the Apc and Kras mutations led to markedly shortened survival of the mice, due to the development of multiple colon tumors in each mouse ranging from adenomas to late stage adenocarcinomas. Evidence of invasion into the smooth muscle and serosa area was found in both compound mice with missense or deletion mutations in Trp53, with the Trp53R270H mutant mice displaying an increased prevalence of deeply invasive tumors relative to the mice with deletion of Trp53. Furthermore, we found that the missense mutant Trp53R270H allele in combination with Apc and Kras mutations, but not the null-mutant Trp53 allele, was strongly linked to metastases to lymph nodes and lung. We have developed a useful mouse model of metastatic colon cancer that recapitulates the role of TP53 mutations in cooperating with APC and KRAS mutations in human CRC development and progression. In addition, our findings strongly suggest a powerful role for missense mutant p53 proteins compared to TP53 null mutations in promoting invasion and metastasis in CRC progression.

Citation Format: Ying Feng, Naoya Sakamoto, Maranne Green, Megan Greenn, Kathleen R. Cho, Eric R. Fearon. Differential effects of p53 mutations on cancer invasion and metastasis in a mouse model of colon cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 672.

Genomic Profiling of Penile Squamous Cell Carcinoma Reveals New Opportunities for Targeted Therapy

Penile squamous cell carcinoma (PeSCCA) is a rare malignancy for which there are limited treatment options due to a poor understanding of the molecular alterations underlying disease development and progression. Therefore, we performed comprehensive, targeted next-generation sequencing to identify relevant somatic genomic alterations in a retrospective cohort of 60 fixed tumor samples from 43 PeSCCA cases (including 14 matched primary/metastasis pairs). We identified a median of two relevant somatic mutations and one high-level copy-number alteration per sample (range, 0-5 and 0-6, respectively). Expression of HPV and p16 was detectable in 12% and 28% of patients, respectively. Furthermore, advanced clinical stage, lack of p16 expression, and MYC and CCND1 amplifications were significantly associated with shorter time to progression or PeSCCA-specific survival. Notably, four cases harbored EGFR amplifications and one demonstrated CDK4 amplification, genes for which approved and investigational targeted therapies are available. Importantly, although paired primary tumors and lymph node metastases were largely homogeneous for relevant somatic mutations, we identified heterogeneous EGFR amplification in primary tumor/lymph node metastases in 4 of 14 cases, despite uniform EGFR protein overexpression. Likewise, activating HRAS mutations occurred in 8 of 43 cases. Taken together, we provide the first comprehensive molecular PeSCCA analysis, which offers new insight into potential precision medicine approaches for this disease, including strategies targeting EGFR.

Next-Generation Sequencing of Tubal Intraepithelial Carcinomas

IMPORTANCE

High-grade serous carcinoma (HGSC) is the most prevalent and lethal form of ovarian cancer. HGSCs frequently arise in the distal fallopian tubes rather than the ovary, developing from small precursor lesions called serous tubal intraepithelial carcinomas (TICs, or more specifically, STICs). While STICs have been reported to harbor TP53 mutations, detailed molecular characterizations of these lesions are lacking.

OBSERVATIONS

We performed targeted next-generation sequencing (NGS) on formalin-fixed, paraffin-embedded tissue from 4 women, 2 with HGSC and 2 with uterine endometrioid carcinoma (UEC) who were diagnosed as having synchronous STICs. We detected concordant mutations in both HGSCs with synchronous STICs, including TP53 mutations as well as assumed germline BRCA1/2 alterations, confirming a clonal association between these lesions. Next-generation sequencing confirmed the presence of a STIC clonally unrelated to 1 case of UEC, and NGS of the other tubal lesion diagnosed as a STIC unexpectedly supported the lesion as a micrometastasis from the associated UEC.

CONCLUSIONS AND RELEVANCE

We demonstrate that targeted NGS can identify genetic alterations in minute lesions, such as TICs, and confirm TP53 mutations as early driving events for HGSC. Next-generation sequencing also demonstrated unexpected associations between presumed STICs and synchronous carcinomas, providing evidence that some TICs are actually metastases rather than HGSC precursors.

Abstract IA01: The origins of ovarian cancer

Ovarian cancer is a generic term that can be used for any malignant ovarian tumor. The majority of ovarian cancers are carcinomas, i.e., malignancies with epithelial differentiation. Ovarian carcinomas represent a heterogeneous group of tumors that can be divided into five major types based largely on their light microscopic appearance. Notably, the origins of these different tumor types (high-grade serous carcinoma, low-grade serous carcinoma, endometrioid carcinoma, clear cell carcinoma, and mucinous carcinoma) remain incompletely understood. Indeed, many ovarian cancers may not actually originate in the ovaries, but instead involve the ovaries secondarily. Even those that develop in the ovaries may arise from cell types, for example endometrial- or fallopian tube-type epithelium, that are not considered intrinsic to normal ovaries.

Potential origins and putative precursors of the five major types of ovarian carcinoma will be reviewed and experimental data from mouse models supporting a role for the ovarian surface epithelium and/or fallopian tube epithelium will be presented. A more complete understanding of the origin(s) of each type of ovarian carcinoma is needed to inform the development of effective ovarian cancer prevention, early detection and treatment strategies.

Citation Format: Kathleen R. Cho. The origins of ovarian cancer. [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 IA01.

Arid1a inactivation in an Apc- and Pten-defective mouse ovarian cancer model enhances epithelial differentiation and prolongs survival

Inactivation of the ARID1A tumour suppressor gene is frequent in ovarian endometrioid (OEC) and clear cell (OCCC) carcinomas, often in conjunction with mutations activating the PI3K-AKT and/or canonical Wnt signalling pathways. Prior work has shown that conditional bi-allelic inactivation of the Apc and Pten tumour suppressor genes in the mouse ovarian surface epithelium (OSE) promotes outgrowth of tumours that reflect the biological behaviour and gene expression profiles of human OECs harbouring comparable Wnt and PI3K-AKT pathway defects, although the mouse tumours are more poorly differentiated than their human tumour counterparts. We found that conditional inactivation of one or both Arid1a alleles in OSE concurrently with Apc and Pten inactivation unexpectedly prolonged the survival of tumour-bearing mice and promoted striking epithelial differentiation of the cancer cells, resulting in morphological features akin to those in human OECs. Enhanced epithelial differentiation was linked to reduced expression of the mesenchymal markers N-cadherin and vimentin, and increased expression of the epithelial markers Crb3 and E-cadherin. Global gene expression profiling showed enrichment for genes associated with mesenchymal-epithelial transition in the Arid1a-deficient tumours. We also found that an activating (E545K) Pik3ca mutation, unlike Pten inactivation or Pik3ca H1047R mutation, cannot cooperate with Arid1a loss to promote ovarian cancer development in the mouse. Our results indicate that the Arid1a tumour suppressor gene has a key role in regulating OEC differentiation, and paradoxically the mouse cancers with more initiating tumour suppressor gene defects had a less aggressive phenotype than cancers arising from fewer gene alterations. Microarray data have been deposited in NCBI's Gene Expression Omnibus (GSE67695).

Abstract AS06: Development and characterization of an oviduct-specific model of high-grade serous carcinoma

Recent studies suggest the most common and lethal type of “ovarian” cancer, high-grade serous carcinoma (HGSC), often arises from fallopian tube epithelium rather than the ovarian surface epithelium. Their intraperitoneal location and microscopic size make it very difficult to screen for, or study the biology of early tubal lesions in humans, as most are discovered incidentally in women with hereditary predisposition to ovarian cancer who elect prophylactic salpingo-oophorectomy for cancer risk-reduction. Although most cases of pelvic HGSC probably originate in the fallopian tube, roughly one-third lack evidence of tubal origin. These cases may arise from ectopic tubal-type epithelium (endosalpingiosis) present in the ovary, peritoneum, or at other sites. Mouse models that closely mimic the genetics and biology of human HGSCs may be useful for clarifying how tubal and non-tubal pelvic HGSCs develop and progress.

We have developed transgenic (Ovgp1-iCreERT2) mice allowing conditional (tamoxifen [TAM]-inducible) expression of Cre recombinase exclusively in the oviductal epithelium, using a single transgene. Using double transgenic Ovgp1-iCreERT2;R26LSL-eYFP mice in which TAM treatment activates eYFP reporter protein expression in oviductal epithelial cells, we have shown that tubal-type inclusion glands (endosalpingiosis) expressing both eYFP and OVGP1 are present in a subset of murine ovaries following treatment with TAM. The findings suggest that oviductal epithelium can detach from the oviduct and traffic to the ovaries, where it implants through breaks in the OSE and maintains its tubal-type differentiation. Preliminary data also suggest that the frequency of ovarian endosalpingiosis increases over time and by superovulating the mice. The latter finding raises the possibility that at least some of the protective effects of high parity and oral contraceptive use on human ovarian cancer risk is related to reduced likelihood of acquiring endosalpingiosis from which “ovarian” HGSCs may eventually arise.

We have further shown that Ovgp1-iCreERT2;Trp53fl/fl;Brca1fl/fl mice develop oviductal lesions identical to human serous tubal intraepithelial carcinomas (STICs) after TAM treatment and have identified additional genetic alterations that cooperate with Trp53 and Brca1 inactivation in oviductal HGSC pathogenesis in our model system. Murine models of HGSC that recapitulate their human tumor counterparts provide excellent in vivo systems with which to define the cellular and molecular events associated with HGSC development and progression.

Citation Format: Yali Zhai, Rong Wu, Tom C. Hu, Eric R. Fearon, Kathleen R. Cho. Development and characterization of an oviduct-specific model of high-grade serous carcinoma [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr AS06.

CD24+ Ovarian Cancer Cells Are Enriched for Cancer-Initiating Cells and Dependent on JAK2 Signaling for Growth and Metastasis

Ovarian cancer is known to be composed of distinct populations of cancer cells, some of which demonstrate increased capacity for cancer initiation and/or metastasis. The study of human cancer cell populations is difficult due to long requirements for tumor growth, interpatient variability, and the need for tumor growth in immune-deficient mice. We therefore characterized the cancer initiation capacity of distinct cancer cell populations in a transgenic murine model of ovarian cancer. In this model, conditional deletion of Apc, Pten, and Trp53 in the ovarian surface epithelium (OSE) results in the generation of high-grade metastatic ovarian carcinomas. Cell lines derived from these murine tumors express numerous putative stem cell markers, including CD24, CD44, CD90, CD117, CD133, and ALDH. We show that CD24(+) and CD133(+) cells have increased tumor sphere-forming capacity. CD133(+) cells demonstrated a trend for increased tumor initiation while CD24(+) cells versus CD24(-) cells had significantly greater tumor initiation and tumor growth capacity. No preferential tumor-initiating or growth capacity was observed for CD44(+), CD90(+), CD117(+), or ALDH(+) versus their negative counterparts. We have found that CD24(+) cells, compared with CD24(-) cells, have increased phosphorylation of STAT3 and increased expression of STAT3 target Nanog and c-myc. JAK2 inhibition of STAT3 phosphorylation preferentially induced cytotoxicity in CD24(+) cells. In vivo JAK2 inhibitor therapy dramatically reduced tumor metastases, and prolonged overall survival. These findings indicate that CD24(+) cells play a role in tumor migration and metastasis and support JAK2 as a therapeutic target in ovarian cancer.

HRAS mutations are frequent in inverted urothelial neoplasms

Inverted urothelial papilloma (IUP) is an uncommon neoplasm of the urinary bladder with distinct morphologic features. Studies regarding the role of human papillomavirus (HPV) in the etiology of IUP have provided conflicting evidence of HPV infection. In addition, little is known regarding the molecular alterations present in IUP or other urothelial neoplasms, which might demonstrate inverted growth pattern like low-grade or high-grade urothelial carcinoma (UCA). Here, we evaluated for the presence of common driving somatic mutations and HPV within a cohort of IUPs, (n = 7) noninvasive low-grade papillary UCAs with inverted growth pattern (n = 5), and noninvasive high-grade papillary UCAs with inverted growth pattern (n = 8). HPV was not detected in any case of IUP or inverted UCA by either in situ hybridization or by polymerase chain reaction. Next-generation sequencing identified recurrent mutations in HRAS (Q61R) in 3 of 5 IUPs, described for the first time in this neoplasm. Additional mutations of Ras pathway members were detected including HRAS, KRAS, and BRAF. The presence of Ras pathway member mutations at a relatively high rate suggests this pathway may contribute to pathogenesis of inverted urothelial neoplasms. In addition, we did not find any evidence supporting a role for HPV in the etiology of IUP.

Abstract IA6: Murine models of nonserous ovarian cancer: Effects of mutant Trp53, Pik3ca, and Arida1a in a model of endometrioid carcinoma based on Wnt and PI3K/Akt pathway defects

A dualistic pathway model of ovarian carcinoma (OvCA) pathogenesis has been proposed in which type I OvCAs are low grade, genetically stable, and relatively more indolent than type II OvCAs, most of which are high-grade serous carcinomas. Endometrioid OvCA (EOC) is a prototypical type I tumor, often harboring mutations that affect the Wnt and phosphatidylinositol 3-kinase/AKT/mTOR signaling pathways. Molecular and histopathologic analyses indicate type I and II OvCAs share overlapping features, and a subset of EOCs may undergo type I→type II progression accompanied by acquisition of somatic TP53 or PIK3CA mutations. We used a murine model of EOC initiated by conditional inactivation of the Apc and Pten tumor suppressor genes to investigate mutant Trp53 or Pik3ca alleles as key drivers of type I→type II OvCA progression. In the mouse EOC model, the presence of somatic Trp53 or Pik3ca mutations resulted in shortened survival and more widespread metastasis. In contrast, bi-allelic inactivation of Arid1a in addition to Apc and Pten actually prolonged survival and tumors with Arid1a inactivation showed more epithelial differentiation than their counterparts with intact Arid1a alleles. Our findings indicate that the adverse prognosis associated with TP53 and PIK3CA mutations in human cancers can be functionally replicated in mouse models of type I→type II OvCA progression. Moreover, the models should represent a robust platform for assessment of the contributions of Trp53, Pik3ca, and Arid1a mutations to the response of EOCs to conventional and targeted drugs.

Citation Format: Kathleen R. Cho, Rong Wu, Yali Zhai, Isao Sakaguchi. Murine models of nonserous ovarian cancer: Effects of mutant Trp53, Pik3ca, and Arida1a in a model of endometrioid carcinoma based on Wnt and PI3K/Akt pathway defects. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr IA6.

Funding Anatomic Pathology Research: A Retrospective Analysis of an Intramural Funding Mechanism

Context.—In 2006, the department of pathology at our institution established an intramural research funding mechanism to support anatomic pathology research projects for faculty and trainee development. A review committee consisting of faculty members with diverse academic interests evaluated applications; proposals were eligible for a maximum award amount of $30 000 per project with a maximum program cost of $150 000 annually.

Objective.—To report our experience based on a retrospective review of the research proposals submitted to the committee since the inception of the Anatomic Pathology Research Fund and evaluate the outcomes of the funded projects.

Design.—We retrospectively analyzed all project applications that were received by the committee. Outcome data were collected by reviewing progress reports, abstracts for national and international meetings, PubMed search results, and/or direct communication with investigators.

Results.—To date, a total of 59 individual projects have been awarded funding, for a total amount of $349 792, with an average award amount of $5381 per project. A total of 26 faculty members have secured funding for projects through this mechanism, and 27 resident and fellow trainees have been engaged in the funded projects. Spanning 11 subspecialty disciplines in anatomic pathology, 32 abstracts (54%) have been presented at national meetings and 26 (44%) have been published in the peer-reviewed literature to date. One project generated data used to secure an extramural (R01) grant.

Conclusions.—Our funding mechanism could serve as a model used by other academic departments to support research activities, thereby fostering faculty development through scholarly activities.

Type I to type II ovarian carcinoma progression: mutant Trp53 or Pik3ca confers a more aggressive tumor phenotype in a mouse model of ovarian cancer

A dualistic pathway model of ovarian carcinoma (OvCA) pathogenesis has been proposed: type I OvCAs are low grade, genetically stable, and relatively more indolent than type II OvCAs, most of which are high-grade serous carcinomas. Endometrioid OvCA (EOC) is a prototypical type I tumor, often harboring mutations that affect the Wnt and phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin signaling pathways. Molecular and histopathologic analyses indicate type I and II OvCAs share overlapping features, and a subset of EOCs may undergo type I→type II progression accompanied by acquisition of somatic TP53 or PIK3CA mutations. We used a murine model of EOC initiated by conditional inactivation of the Apc and Pten tumor suppressor genes to investigate mutant Trp53 or Pik3ca alleles as key drivers of type I→type II OvCA progression. In the mouse EOC model, the presence of somatic Trp53 or Pik3ca mutations resulted in shortened survival and more widespread metastasis. Activation of mutant Pik3ca alone had no demonstrable effect on the ovarian surface epithelium but resulted in papillary hyperplasia when coupled with Pten inactivation. Our findings indicate that the adverse prognosis associated with TP53 and PIK3CA mutations in human cancers can be functionally replicated in mouse models of type I→type II OvCA progression. Moreover, the models should represent a robust platform for assessment of the contributions of Trp53 or Pik3ca defects in the response of EOCs to conventional and targeted drugs.

Two Distinct Categories of Focal Deletions in Cancer Genomes

One of the key questions about genomic alterations in cancer is whether they are functional in the sense of contributing to the selective advantage of tumor cells. The frequency with which an alteration occurs might reflect its ability to increase cancer cell growth, or alternatively, enhanced instability of a locus may increase the frequency with which it is found to be aberrant in tumors, regardless of oncogenic impact. Here we’ve addressed this on a genome-wide scale for cancer-associated focal deletions, which are known to pinpoint both tumor suppressor genes (tumor suppressors) and unstable loci. Based on DNA copy number analysis of over one-thousand human cancers representing ten different tumor types, we observed five loci with focal deletion frequencies above 5%, including the A2BP1 gene at 16p13.3 and the MACROD2 gene at 20p12.1. However, neither RNA expression nor functional studies support a tumor suppressor role for either gene. Further analyses suggest instead that these are sites of increased genomic instability and that they resemble common fragile sites (CFS). Genome-wide analysis revealed properties of CFS-like recurrent deletions that distinguish them from deletions affecting tumor suppressor genes, including their isolation at specific loci away from other genomic deletion sites, a considerably smaller deletion size, and dispersal throughout the affected locus rather than assembly at a common site of overlap. Additionally, CFS-like deletions have less impact on gene expression and are enriched in cell lines compared to primary tumors. We show that loci affected by CFS-like deletions are often distinct from known common fragile sites. Indeed, we find that each tumor tissue type has its own spectrum of CFS-like deletions, and that colon cancers have many more CFS-like deletions than other tumor types. We present simple rules that can pinpoint focal deletions that are not CFS-like and more likely to affect functional tumor suppressors.

Airway management using a supraglottic airway device without endotracheal intubation for positive ventilation of anaesthetized rats

Endotracheal intubation is often necessary for positive pressure ventilation of rats during open thoracic surgery. Since endotracheal intubation in rats is technically difficult and is associated with numerous complications, many techniques using various devices have been described in the scientific literature. In this study, we compared the effectiveness of airway management of a home-made supraglottic airway device (SAD), which is cheap to fabricate and easy to place with that of an endotracheal intubation tube in enflurane-anaesthetized rats. Twenty male Sprague-Dawley rats (200-300 g) were randomly assigned to two equal groups for positive pressure mechanical ventilation using either the SAD or an endotracheal intubation tube. The carotid artery of each rat was cannulated for continuous blood pressure measurements and obtaining blood samples for determination of oxygen tension, carbon dioxide tension, and blood acidity before, during and after SAD placement or endotracheal intubation. Proper placement of the SAD was confirmed by observing chest wall movements that coincided with the operation of the mechanical ventilator. No complications and adverse events were encountered in the rats in which the SAD was placed, during SAD placement and immediate removal, during their mechanical ventilation through the SAD, and one week after SAD removal. From the results of blood gas analyses, we conclude that anaesthetized rats can be successfully ventilated using an SAD for open thoracic surgery.