An algorithm for standardization of tumor Infiltrating lymphocyte evaluation in head and neck cancers

PURPOSE

The prognostic and predictive significance of pathologist-read tumor infiltrating lymphocytes (TILs) in head and neck cancers have been demonstrated through multiple studies over the years. TILs have not been broadly adopted clinically, perhaps due to substantial inter-observer variability. In this study, we developed a machine-based algorithm for TIL evaluation in head and neck cancers and validated its prognostic value in independent cohorts.

EXPERIMENTAL DESIGN

A network classifier called NN3-17 was trained to identify and calculate tumor cells, lymphocytes, fibroblasts and "other" cells on hematoxylin-eosin stained sections using the QuPath software. These measurements were used to construct three predefined TIL variables. A retrospective collection of 154 head and neck squamous cell cancer cases was used as the discovery set to identify optimal association of TIL variables and survival. Two independent cohorts of 234 cases were used for validation.

RESULTS

We found that electronic TIL variables were associated with favorable prognosis in both the HPV-positive and -negative cases. After adjusting for clinicopathologic factors, Cox regression analysis demonstrated that electronic total TILs% (p = 0.025) in the HPV-positive and electronic stromal TILs% (p < 0.001) in the HPV-negative population were independent markers of disease specific outcomes (disease free survival).

CONCLUSIONS

Neural network TIL variables demonstrated independent prognostic value in validation cohorts of HPV-positive and HPV-negative head and neck cancers. These objective variables can be calculated by an open-source software and could be considered for testing in a prospective setting to assess potential clinical implications.

Multi-ancestry genome-wide association study of kidney cancer identifies 63 susceptibility regions

Here, in a multi-ancestry genome-wide association study meta-analysis of kidney cancer (29,020 cases and 835,670 controls), we identified 63 susceptibility regions (50 novel) containing 108 independent risk loci. In analyses stratified by subtype, 52 regions (78 loci) were associated with clear cell renal cell carcinoma (RCC) and 6 regions (7 loci) with papillary RCC. Notably, we report a variant common in African ancestry individuals ( rs7629500 ) in the 3' untranslated region of VHL, nearly tripling clear cell RCC risk (odds ratio 2.72, 95% confidence interval 2.23-3.30). In cis-expression quantitative trait locus analyses, 48 variants from 34 regions point toward 83 candidate genes. Enrichment of hypoxia-inducible factor-binding sites underscores the importance of hypoxia-related mechanisms in kidney cancer. Our results advance understanding of the genetic architecture of kidney cancer, provide clues for functional investigation and enable generation of a validated polygenic risk score with an estimated area under the curve of 0.65 (0.74 including risk factors) among European ancestry individuals.

Identification of BRCA1/2 mutation female carriers using circulating microRNA profiles

Identifying germline BRCA1/2 mutation carriers is vital for reducing their risk of breast and ovarian cancer. To derive a serum miRNA-based diagnostic test we used samples from 653 healthy women from six international cohorts, including 350 (53.6%) with BRCA1/2 mutations and 303 (46.4%) BRCA1/2 wild-type. All individuals were cancer-free before and at least 12 months after sampling. RNA-sequencing followed by differential expression analysis identified 19 miRNAs significantly associated with BRCA mutations, 10 of which were ultimately used for classification: hsa-miR-20b-5p, hsa-miR-19b-3p, hsa-let-7b-5p, hsa-miR-320b, hsa-miR-139-3p, hsa-miR-30d-5p, hsa-miR-17-5p, hsa-miR-182-5p, hsa-miR-421, hsa-miR-375-3p. The final logistic regression model achieved area under the receiver operating characteristic curve 0.89 (95% CI: 0.87-0.93), 93.88% sensitivity and 80.72% specificity in an independent validation cohort. Mutated gene, menopausal status or having preemptive oophorectomy did not affect classification performance. Circulating microRNAs may be used to identify BRCA1/2 mutations in patients of high risk of cancer, offering an opportunity to reduce screening costs.

Abstract 2363: Ovarian tumor-intrinsic FAK-dependent regulation of the matrisome

High-grade serous ovarian cancer (HGSOC) is deadliest of gynecological malignancies. Ovarian tumor cells can directly spread throughout the peritoneal space as single cells that grow into tumorspheres concomitant with the generation of malignant ascites that contains growth factors and extracellular matrix (ECM) proteins. Greater than 70% of advanced stage HGSOC patients exhibit gains or amplifications for the Focal Adhesion Kinase (FAK) gene, a tyrosine kinase that is activated by ECM proteins. In other solid tumors, changes in ECM and associated proteins (termed the Matrisome) are generated in part by tumor associated fibroblasts. Herein we compared transcriptional (RNA sequencing) and proteomic (mass spectrometry) changes using two ascites generating models: MOVCAR, a SV40 T antigen under control of the Mullerian inhibitory substance type II receptor; and KMF, a spontaneously aggressive ID8 derivative containing KRas, Myc, and FAK gene amplifications. FAK inactivation was generated by crossing MOVCAR with FAK floxed mice or CRISPR to disrupt FAK expression in KMF. Comparisons were made with FAK-null or cells re-expressing FAK wildtype or a FAK kinase-inactive point mutant (K454R) by lentiviral transduction with tumor cells grown as spheroids in vitro or harvested after intraperitoneal tumor growth in mice. FAK expression and activity were required for optimal tumor growth in mice and a common set of differentially expressed genes were identified upon FAK loss and re-expression. Gene ontology analyses revealed significant differences in Matrisome, morphogenesis, and epithelial proliferation within spheroids and tumors lacking FAK. Parallel protein mass spectrometry analyses revealed that thirty-four Matrisome proteins were down regulated (&gt; log2 fold change) including collagens -1, -3 and -5, fibulin-1 and -2, elastin, tenascin, and fibronectin. Several of these proteins were regulated by FAK expression and not necessarily intrinsic FAK activity. Bioinformatic analysis of the TCGA ovarian tumor database showed that FAK, collagen-3 and collagen-5 expression negatively correlate with patient survival. As FAK is highly tyrosine phosphorylated in tumor spheroids isolated from patients and from our mouse models, our results support the hypothesis that elevated tumor-intrinsic FAK expression results in increased ECM production that can feed-forward to drive increased FAK activity. These results may impact the clinical testing of small molecule inhibitors of FAK activity.

Citation Format: Marjaana Ojalill, Joanna Zhang, Ujjwal Suwal, Pekka Rappu, Jyrki Heino, Denise C. Connolly, Dwayne G. Stupack, David D. Schlaepfer. Ovarian tumor-intrinsic FAK-dependent regulation of the matrisome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2363.

Ovarian Cancers with Low CIP2A Tumor Expression Constitute an APR-246-Sensitive Disease Subtype

Identification of ovarian cancer patient subpopulations with increased sensitivity to targeted therapies could offer significant clinical benefit. We report that 22% of the high-grade ovarian cancer tumors at diagnosis express CIP2A oncoprotein at low levels. Furthermore, regardless of their significantly lower likelihood of disease relapse after standard chemotherapy, a portion of relapsed tumors retain their CIP2A-deficient phenotype. Through a screen for therapeutics that would preferentially kill CIP2A-deficient ovarian cancer cells, we identified reactive oxygen species inducer APR-246, tested previously in ovarian cancer clinical trials. Consistent with CIP2A-deficient ovarian cancer subtype in humans, CIP2A is dispensable for development of MISIIR-Tag-driven mouse ovarian cancer tumors. Nevertheless, CIP2A-null ovarian cancer tumor cells from MISIIR-Tag mice displayed APR-246 hypersensitivity both in vitro and in vivo. Mechanistically, the lack of CIP2A expression hypersensitizes the ovarian cancer cells to APR-246 by inhibition of NF-κB activity. Accordingly, combination of APR-246 and NF-κB inhibitor compounds strongly synergized in killing of CIP2A-positive ovarian cancer cells. Collectively, the results warrant consideration of clinical testing of APR-246 for CIP2A-deficient ovarian cancer tumor subtype patients. Results also reveal CIP2A as a candidate APR-246 combination therapy target for ovarian cancer.

Development of a Multiprotein Classifier for the Detection of Early Stage Ovarian Cancer

Simple Summary

When ovarian cancer is detected early, the survival rate is high. Unfortunately, existing blood tests are neither sensitive nor specific enough to screen women for ovarian cancer. The purpose of this study was to determine the levels of 92 cancer-related proteins in the blood of women with ovarian cancer compared to healthy women in order to develop a test for ovarian cancer detection. We tested the blood of more than 400 women and identified four proteins that, when combined, successfully detected over 90% of the women with ovarian cancer. We then tested more than 700 additional blood samples and found that the combination of the four proteins successfully distinguished the majority of the blood samples from women with both early and late stages of ovarian cancer compared to healthy women. These four proteins show promise in the development of a test to detect the early stages of ovarian cancer.

Abstract

Background: Individual serum biomarkers are neither adequately sensitive nor specific for use in screening the general population for ovarian cancer. The purpose of this study was to develop a multiprotein classifier to detect the early stages of ovarian cancer, when it is most treatable. Methods: The Olink Proseek Multiplex Oncology II panel was used to simultaneously quantify the expression levels of 92 cancer-related proteins in sera. Results: In the discovery phase, we generated a multiprotein classifier that included CA125, HE4, ITGAV, and SEZ6L, based on an analysis of sera from 116 women with early stage ovarian cancer and 336 age-matched healthy women. CA125 alone achieved a sensitivity of 87.9% at a specificity of 95%, while the multiprotein classifier resulted in an increased sensitivity of 91.4%, while holding the specificity fixed at 95%. The performance of the multiprotein classifier was validated in a second cohort comprised of 192 women with early stage ovarian cancer and 467 age-matched healthy women. The sensitivity at 95% specificity increased from 74.5% (CA125 alone) to 79.2% with the multiprotein classifier. In addition, the multiprotein classifier had a sensitivity of 95.1% at 98% specificity for late stage ovarian cancer samples and correctly classified 80.5% of the benign samples using the 98% specificity cutpoint. Conclusions: The inclusion of the proteins HE4, ITGAV, and SEZ6L improved the sensitivity and specificity of CA125 alone for the detection of early stages of ovarian cancer in serum samples. Furthermore, we identified several proteins that may be novel biomarkers of early stage ovarian cancer.

Tumor FAK orchestrates immunosuppression in ovarian cancer via the CD155/TIGIT axis

High-grade serous ovarian cancer (HGSOC) is a lethal malignancy characterized by an immunosuppressive tumor microenvironment containing few tumor infiltrating lymphocytes (TILs) and an insensitivity to checkpoint inhibitor immunotherapies. Gains in the PTK2 gene encoding focal adhesion kinase (FAK) at Chr8 q24.3 occur in ∼70% of HGSOC tumors, and elevated FAK messenger RNA (mRNA) levels are associated with poor patient survival. Herein, we show that active FAK, phosphorylated at tyrosine-576 within catalytic domain, is significantly increased in late-stage HGSOC tumors. Active FAK costained with CD155, a checkpoint receptor ligand for TIGIT (T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains), in HGSOC tumors and a selective association between FAK and TIGIT checkpoint ligands were supported by patient transcriptomic database analysis. HGSOC tumors with high FAK expression were associated with low CD3 mRNA levels. Accordingly, late-stage tumors showed elevated active FAK staining and significantly lower levels of CD3+ TILs. Using the KMF (Kras, Myc, FAK) syngeneic ovarian tumor model containing spontaneous PTK2 (FAK) gene gains, the effects of tumor intrinsic genetic or oral small molecule FAK inhibitior (FAKi; VS-4718) were evaluated in vivo. Blocking FAK activity decreased tumor burden, suppressed ascites KMF-associated CD155 levels, and increased peritoneal TILs. The combination of FAKi with blocking TIGIT antibody (1B4) maintained elevated TIL levels and reduced TIGIT+ T regulatory cell levels, prolonged host survival, increased CXCL13 levels, and led to the formation of omental tertiary lymphoid structures. Collectively, our studies support FAK and TIGIT targeting as a rationale immunotherapy combination for HGSOC.

CIP2A Interacts with TopBP1 and Drives Basal-Like Breast Cancer Tumorigenesis

Basal-like breast cancers (BLBC) are characterized by defects in homologous recombination (HR), deficient mitotic checkpoint, and high-proliferation activity. Here, we discover CIP2A as a candidate driver of BLBC. CIP2A was essential for DNA damage-induced initiation of mouse BLBC-like mammary tumors and for survival of HR-defective BLBC cells. CIP2A was dispensable for normal mammary gland development and for unperturbed mitosis, but selectively essential for mitotic progression of DNA damaged cells. A direct interaction between CIP2A and a DNA repair scaffold protein TopBP1 was identified, and CIP2A inhibition resulted in enhanced DNA damage-induced TopBP1 and RAD51 recruitment to chromatin in mammary epithelial cells. In addition to its role in tumor initiation, and survival of BRCA-deficient cells, CIP2A also drove proliferative MYC and E2F1 signaling in basal-like triple-negative breast cancer (BL-TNBC) cells. Clinically, high CIP2A expression was associated with poor patient prognosis in BL-TNBCs but not in other breast cancer subtypes. Small-molecule reactivators of PP2A (SMAP) inhibited CIP2A transcription, phenocopied the CIP2A-deficient DNA damage response (DDR), and inhibited growth of patient-derived BLBC xenograft. In summary, these results demonstrate that CIP2A directly interacts with TopBP1 and coordinates DNA damage-induced mitotic checkpoint and proliferation, thereby driving BLBC initiation and progression. SMAPs could serve as a surrogate therapeutic strategy to inhibit the oncogenic activity of CIP2A in BLBCs. SIGNIFICANCE: These results identify CIP2A as a nongenetic driver and therapeutic target in basal-like breast cancer that regulates DNA damage-induced G₂-M checkpoint and proliferative signaling.

Cholesterol and CDON Regulate Sonic Hedgehog Release from Pancreatic Cancer Cells

Background: Sonic Hedgehog (Shh) is a tightly regulated membrane-associated morphogen and a known driver of tumorigenesis in pancreatic ductal adenocarcinoma (PDAC). After processing, Shh remains at the plasma membrane of Shh producing cells, thereby limiting its distribution and signal strength. In PDAC, the release of Shh from tumor cells is necessary to promote a tumor-permissive microenvironment. Mechanisms regulating Shh sequestration and/or release from tumor cells to signal distant stromal cells are not well known. Previously, our laboratory demonstrated that the Drosophila transmembrane protein Boi, sequesters Hh at the membrane of Hh-producing cells. In response to dietary cholesterol or in the absence of boi, Hh is constitutively released to promote proliferation in distant cells. In this study, we investigated the conservation of this mechanism in mammals by exploring the role of the human boi homolog, CDON, in PDAC.

Methods: Using PDAC cell-lines BxPC-3, Capan-2, and MIA PaCa-2, along with normal pancreatic epithelial cells (PDEC), we investigated Shh expression via Immunoblot and real-time, quantitative polymerase chain reaction in addition to Shh release via enzyme-linked immunoassay following cholesterol treatment and/or transfection with either RNA interference to reduce CDON expression or with human CDON to increase expression.

Results: Consistent with our Boi model, CDON suppresses Shh release, which is alleviated in response to dietary cholesterol. However, over-expressing CDON suppresses cholesterol-mediated Shh release in some PDAC contexts, which may be relative to the mutational burden of the cells.

Conclusion: Identifying mechanisms that either sequester or stimulate Shh release from the tumor cell membrane may provide new avenues to reduce signaling between the tumor and its surrounding environment, which may restrain tumor development.

Abstract A61: FAK activity sustains intrinsic and acquired ovarian cancer resistance to platinum chemotherapy

Gene copy number alterations, tumor cell stemness, and development of platinum chemotherapy resistance contribute to high-grade serous ovarian cancer (HGSOC) recurrence. Stemness phenotypes involving Wnt-beta-catenin, aldehyde dehydrogenase activities, intrinsic platinum resistance, and tumorsphere formation are here associated with spontaneous genetic gains in KRAS, MYC, and FAK (KMF) genes, in a new aggressive murine model of ovarian cancer. Noncanonical signaling via FAK sustained KMF and human tumorsphere proliferation as well as resistance to cisplatin cytotoxicity. Platinum-resistant tumorspheres can acquire a dependence on FAK for growth. Accordingly, increased FAK tyrosine phosphorylation was observed within HGSOC patient tumors surviving neoadjuvant chemotherapy. Combining a FAK inhibitor with platinum overcame chemoresistance, triggering tumor cell apoptosis. FAK transcriptomic analyses across knockout and reconstituted cells identified 135 genes elevated by a FAK activity-dependent, beta-catenin, and Myc signaling axis including pluripotency and DNA repair genes. Identified target increases in HGSOC tumors may reflect oncogenic FAK signaling.

Citation Format: Carlos J. Díaz Osterman, Duygu Ozmadenci, Elizabeth G. Kleinschmidt, Kristin N. Taylor, Allison M. Barrie, Shulin Jiang, Lisa M. Bean, Florian J. Sulzmaier, Jian Li, Xiao Lei Chen, Guo Fu, Marjaana Ojalill, Pekka Rappu, Jyrki Heino, Adam A. Mark, Guorong Xu, Kathleen M. Fisch, David T. Weaver, Jonathan A. Pachter, Balázs Győrffy, Michael T. McHale, Denise C. Connolly, Alfredo Molinolo, Dwayne G. Stupack, David D. Schlaepfer. FAK activity sustains intrinsic and acquired ovarian cancer resistance to platinum chemotherapy [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 A61.

Abstract A24: Cell adhesion molecule (CAM)-related downregulated by oncogenes (CDON) promotes ovarian cancer adhesion and survival

Ovarian carcinoma (OC) broadly describes epithelial tumors involving the ovary and represents the most lethal gynecologic malignancy. The most frequently diagnosed OCs are high-grade serous carcinomas (HGSC), and the majority of these cancers are diagnosed at late stage, stage III or IV (51% and 29% respectively), with widespread disease dissemination. In addition, a significant number of patients develop malignant ascites. A key feature of tumor cells in present in ascites is the capacity to form multicellular aggregates that promote tumor cell survival and continued disease growth and spread. Cell adhesion molecule (CAM)-related downregulated by oncogenes (CDON) is a cell surface glycoprotein with established roles in normal development and associated with some tumor types. CDON signaling occurs via ligand-dependent mechanisms as a hedgehog co-receptor and ligand-independent mechanisms via interactions with cadherins. Little is known about the role of CDON in ovarian cancer, but given the importance of cadherin-mediated cell adhesion in disease dissemination, we asked whether CDON plays a role in HGSC growth and progression. We find that CDON is expressed in ovarian carcinoma (OC) cells, and protein levels are elevated by expression of oncogenes or by growth under nonadherent conditions. Depletion of CDON expression revealed that it plays an important role in HGSC cells regardless of growth conditions, resulting in decreased growth (proliferation) in cells grown under nonadherent conditions as multicellular aggregates or under adherent conditions as 2D monolayers. Alterations in signaling related to both cell adhesion and survival occur upon CDON downregulation, including decreased cadherin protein expression, integrin expression, and focal adhesion kinase activation. Depletion of CDON in OC cells results in significant tumor growth inhibition in xenograft and allograft models, suggesting that CDON plays an important role in promoting ovarian tumor growth. Treatment of OC spheroids with novel anti-CDON antibodies results in collapse of 3D cellular structures and induction of apoptosis, supporting a key role for CDON in OC cellular adhesion in tumor cell survival. These data indicate that CDON may play an essential role in OC spread since altered cell-cell adhesion and survival as multicellular aggregates is crucial for disease dissemination in patients. Taken together, our results nominate CDON as an important protein promoting HGSC growth and progression and as a novel therapeutic target for the treatment of this disease.

Citation Format: Valerie L. Sodi, Shane W. O'Brien, Chao Wu, Roland L. Dunbrack, Tiffiney R. Hartman, Alana M. O'Reilly, Denise C. Connolly. Cell adhesion molecule (CAM)-related downregulated by oncogenes (CDON) promotes ovarian cancer adhesion and survival [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 A24.

Functional proteomics interrogation of the kinome identifies MRCKA as a therapeutic target in high-grade serous ovarian carcinoma

High-grade serous ovarian carcinoma (HGSOC) is the most lethal gynecological cancer with few effective, targeted therapies. HGSOC tumors exhibit genomic instability with frequent alterations in the protein kinome; however, only a small fraction of the kinome has been therapeutically targeted in HGSOC. Using multiplexed inhibitor beads and mass spectrometry, we mapped the kinome landscape of HGSOC tumors from patients and patient-derived xenograft models. The data revealed a prevalent signature consisting of established HGSOC driver kinases, as well as several kinases previously unexplored in HGSOC. Loss-of-function analysis of these kinases in HGSOC cells indicated MRCKA (also known as CDC42BPA) as a putative therapeutic target. Characterization of the effects of MRCKA knockdown in established HGSOC cell lines demonstrated that MRCKA was integral to signaling that regulated the cell cycle checkpoint, focal adhesion, and actin remodeling, as well as cell migration, proliferation, and survival. Moreover, inhibition of MRCKA using the small-molecule BDP9066 decreased cell proliferation and spheroid formation and induced apoptosis in HGSOC cells, suggesting that MRCKA may be a promising therapeutic target for the treatment of HGSOC.

Abstract NT-094: TARGETED INHIBITION OF HSP90 IMPAIRS DNA-DAMAGE RESPONSE PROTEINS AND INCREASES THE SENSITIVITY OF OVARIAN CARCINOMA CELLS TO PARP INHIBITORS

Poly (ADP-ribose) Polymerase inhibitors (PARPi) are a promising class of inhibitors for the treatment of high grade serous ovarian carcinoma (HGSOC). The greatest activity of these agents is seen in patients with defects in DNA damage repair (DDR) mechanisms, including mutation or epigenetic inactivation of BRCA1 and BRCA2 genes and alterations in expression and/or function of DNA repair genes/proteins. PARPi are approved as second-line and maintenance therapies in recurrent HGSOCs. Notably, clinical trials have shown that single agent PARPi show activity in a significant number of HGSOC patients in the absence of alterations in BRCA genes, particularly in patients with platinum sensitive disease, possibly those with tumors exhibiting defects in homologous recombination (HR), or ‘BRCAness'. To extend the benefit of these agents beyond patients with inherent defects in HR, we wished to test the idea that combination of PARPi with agents that functionally abrogate HR could extend the benefit of PARPi's. An attractive molecular target for this purpose is heat shock protein 90 (HSP90) based on its essential role in mediating the maturation and stability of several key proteins required for the DDR. The goal of this study was to test the hypothesis that targeted inhibition of HSP90 with a small-molecule inhibitor ganetespib (STA-9090) would sensitize non-BRCA mutant OC cells to the PARPi talazoparib (BMN-673). To test this hypothesis, we used established OC cell lines (OVCAR3, UWB1.289), and novel OC cells lines (OC-38, OC-1) derived in our laboratory from de-identified tumors isolated from patients with HGSOC. Cells were treated with talazoparib and ganetespib alone and in combination, and the effects of drug treatment on expression of DDR proteins, ionizing radiation (IR)-induced RAD51+ and γH2AX+ foci, and cell viability was assessed. Ganetespib treatment led to dose- and time-dependent depletion of HSP90 client proteins participating in DDR including BRCA1 and 2, MRE11, CDK1, CHK1, RAD51. Treatment with ganetespib also led to a significant reduction in the percentage of RAD51+ nuclei following IR. The quantity of DNA double-strand break marker γH2Ax foci/nucleus decreased over time in vehicle treated, but not in ganetespib-treated cells. We next conducted a comprehensive analysis of cytotoxicity in cells treated with ganetespib and talazoparib alone, in combination and at differing molar ratios. Combination indexes (CI) were calculated to assess additive, synergistic and antagonistic effects using the methods of Greco plus the bootstrap to determine statistical significance. Ganetespib sensitized BRCA1-null UWB1.289 cells to the effects of talazoparib (CI=0.73, p&lt;0.0005). Among the non-BRCA mutant cell lines analyzed, the combination of ganetespib and talazoparib were synergistic in some patient-derived cell lines, but antagonistic in others. Together, our data suggest that ganetespib effectively disrupts critical DDR pathway proteins in HGSOC cells and may sensitize non-BRCA-mutant OC cells to PARPi. From clinical perspective, this implicates the potential of sensitization of some HGSOC patients without HR pathway alterations to PARPi, and potentially other DNA-damage inducing agents.

Citation Format: Rashid Gabbasov, I. Daniel Benrubi, Shane W. O'Brien, John J. Krais, Neil Johnson, Samuel Litwin, Denise C. Connolly. TARGETED INHIBITION OF HSP90 IMPAIRS DNA-DAMAGE RESPONSE PROTEINS AND INCREASES THE SENSITIVITY OF OVARIAN CARCINOMA CELLS TO PARP INHIBITORS [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 NT-094.

RPL22L1 induction in colorectal cancer is associated with poor prognosis and 5-FU resistance

We have previously demonstrated that loss of the tumor suppressive activity of ribosomal protein (RP) RPL22 predisposes to development of leukemia in mouse models and aggressive disease in human patients; however, the role of RPL22 in solid tumors, specifically colorectal cancer (CRC), had not been explored. We report here that RPL22 is either deleted or mutated in 36% of CRC and provide new insights into its mechanism of action. Indeed, Rpl22 inactivation causes the induction of its highly homologous paralog, RPL22L1, which serves as a driver of cell proliferation and anchorage-independent growth in CRC cells. Moreover, RPL22L1 protein is highly expressed in patient CRC samples and correlates with poor survival. Interestingly, the association of high RPL22L1 expression with poor prognosis appears to be linked to resistance to 5-Fluorouracil, which is a core component of most CRC therapeutic regimens. Indeed, in an avatar trial, we found that human CRC samples that were unresponsive to 5-Fluorouracil in patient-derived xenografts exhibited elevated expression levels of RPL22L1. This link between RPL22L1 induction and 5-Fluorouracil resistance appears to be causal, because ectopic expression or knockdown of RPL22L1 in cell lines increases and decreases 5-Fluorouracil resistance, respectively, and this is associated with changes in expression of the DNA-repair genes, MGMT and MLH1. In summary, our data suggest that RPL22L1 might be a prognostic marker in CRC and predict 5-FU responsiveness.

FAK activity sustains intrinsic and acquired ovarian cancer resistance to platinum chemotherapy

Gene copy number alterations, tumor cell stemness, and the development of platinum chemotherapy resistance contribute to high-grade serous ovarian cancer (HGSOC) recurrence. Stem phenotypes involving Wnt-β-catenin, aldehyde dehydrogenase activities, intrinsic platinum resistance, and tumorsphere formation are here associated with spontaneous gains in Kras, Myc and FAK (KMF) genes in a new aggressive murine model of ovarian cancer. Adhesion-independent FAK signaling sustained KMF and human tumorsphere proliferation as well as resistance to cisplatin cytotoxicity. Platinum-resistant tumorspheres can acquire a dependence on FAK for growth. Accordingly, increased FAK tyrosine phosphorylation was observed within HGSOC patient tumors surviving neo-adjuvant chemotherapy. Combining a FAK inhibitor with platinum overcame chemoresistance and triggered cell apoptosis. FAK transcriptomic analyses across knockout and reconstituted cells identified 135 targets, elevated in HGSOC, that were regulated by FAK activity and β-catenin including Myc, pluripotency and DNA repair genes. These studies reveal an oncogenic FAK signaling role supporting chemoresistance.

Quantification of multiphoton and fluorescence images of reproductive tissues from a mouse ovarian cancer model shows promise for early disease detection

Ovarian cancer is the deadliest gynecologic cancer due predominantly to late diagnosis. Early detection of ovarian cancer can increase 5-year survival rates from 40% up to 92%, yet no reliable early detection techniques exist. Multiphoton microscopy (MPM) is a relatively new imaging technique sensitive to endogenous fluorophores, which has tremendous potential for clinical diagnosis, though it is limited in its application to the ovaries. Wide-field fluorescence imaging (WFI) has been proposed as a complementary technique to MPM, as it offers high-resolution imagery of the entire organ and can be tailored to target specific biomarkers that are not captured by MPM imaging. We applied texture analysis to MPM images of a mouse model of ovarian cancer. We also conducted WFI targeting the folate receptor and matrix metalloproteinases. We find that texture analysis of MPM images of the ovary can differentiate between genotypes, which is a proxy for disease, with high statistical significance (p  <  0.001). The wide-field fluorescence signal also changes significantly between genotypes (p  <  0.01). We use the features to classify multiple tissue groups to over 80% accuracy. These results suggest that MPM and WFI are promising techniques for the early detection of ovarian cancer.

Rgnef promotes ovarian tumor progression and confers protection from oxidative stress

Ovarian cancer is the fifth-leading cause of cancer death among women. The dissemination of ovarian tumors and growth as spheroids accompanies late-stage disease. In cell culture, ovarian tumor cell spheroids can exhibit elevated resistance to environmental stressors, such as reactive oxygen species. Homeostatic balance of the antioxidant response is a protective mechanism that prevents anoikis, a form of programmed cell death. Signaling pathways activated by integrin receptors suppress anoikis. Rgnef (ARHGEF28/p190RhoGEF) is a guanine nucleotide exchange factor that is activated downstream of integrins. We find that Rgnef protein levels are elevated in late-stage serous ovarian cancer, high Rgnef mRNA levels are associated with decreased progression-free and overall survival, and genomic ARHGEF28 loss is associated with increased patient survival. Using transgenic and transplantable Rgnef knockout mouse models, we find that Rgnef is essential for supporting three-dimensional ovarian spheroid formation in vitro and tumor growth in mice. Using RNA-sequencing and bioinformatic analyses, we identify a conserved Rgnef-supported anti-oxidant gene signature including Gpx4, Nqo1, and Gsta4; common targets of the NF-kB transcription factor. Antioxidant treatment enhanced growth of Rgnef-knockout spheroids and Rgnef re-expression facilitated NF-κB-dependent tumorsphere survival. These studies reveal a new role for Rgnef in ovarian cancer to facilitate NF-κB-mediated gene expression protecting cells from oxidative stress.

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.

Targeted blockade of HSP90 impairs DNA-damage response proteins and increases the sensitivity of ovarian carcinoma cells to PARP inhibition

Pharmacological inhibition of PARP is a promising approach in treating high grade serous ovarian carcinoma (HGSOC). PARP inhibitors (PARPi) are most active in patients with defects in DNA damage repair (DDR) mechanisms, such as alterations in expression/function of DNA repair and homologous recombination (HR) genes/proteins, including BRCA1 and BRCA2. Benefit of PARPi could be extended towards HR-proficient patients by combining PARPi with agents that functionally abrogate HR. An attractive molecular target for this purpose is heat shock protein 90 (HSP90), which mediates the maturation and stability of several key proteins required for DDR. Here, we tested the hypothesis that targeted inhibition of HSP90 with a small-molecule inhibitor ganetespib would sensitize non-BRCA mutant ovarian carcinoma (OC) cells to PARP inhibition by talazoparib. We used commercially available cell lines, along with several novel HGSOC OC cell lines established in our laboratory. Ganetespib treatment destabilized HSP90 client proteins involved in DNA damage response and cell cycle checkpoint, and disrupted γ-irradiation-induced DNA repair. The effects of the combination of ganetespib and talazoparib on OC cell viability and survival were also analyzed, and among the non-BRCA mutant cell lines analyzed, the combination was synergistic in several cell lines (OVCAR-3, OC-1, OC-16). Together, our data suggest that ganetespib-mediated inhibition of HSP90 effectively disrupts critical DDR pathway proteins and may sensitize OC cells without 'BRCAness' to PARPi. From a clinical perspective, this suggests that HSP90 inhibition has the potential to sensitize some HGSOC patients without HR pathway alterations to PARPi, and potentially other DNA-damage inducing agents.

Comparison of Reproductive Function in Female TgMISIIR-TAg Transgenic and Wildtype C57BL/6 Mice

Transgenic TgMISIIR-TAg (TAg) mice express the oncogenic virus SV40 in Mullerian epithelial cells. Female TAg mice spontaneously develop epithelial ovarian carcinoma, the most common type of ovarian cancer in women. Female TAg mice are infertile, but the reason has not been determined. We therefore investigated whether female TAg mice undergo puberty, demonstrate follicular development, maintain regular cycles, and ovulate. Ovarian cancers in women commonly develop after menopause. The occupational chemical 4-vinylcyclohexene diepoxide (VCD) accelerates follicle degeneration in the ovaries of rats and mice, causing early ovarian failure. We therefore used VCD dosing of mice to develop an animal model for menopause. The purpose of this study was to characterize reproductive parameters in female TAg mice and to investigate whether the onset of ovarian failure due VCD dosing differed between female TAg and WT C57BL/6 mice. As in WT female mice, TAg female mice underwent puberty (vaginal opening) and developed cyclicity in patterns that were similar between the groups. Vehicle-only TAg mice had fewer ovulations (numbers of corpora lutea) than WT animals. VCD exposure delayed the onset of puberty (day of first estrus) in TAg as compared with WT mice. Morphologic evaluation of ovaries revealed many more degenerating follicles in TAg mice than WT mice, and more VCD-dosed TAg mice were in ovarian failure than VCD-dosed WT mice. These results suggest that despite showing similar onset of sexual maturation, TAg mice have increased follicular degeneration and fewer ovulations than WT. These features may contribute to the inability of female TAg mice to reproduce.

Functional genomic landscape of acute myeloid leukaemia

The implementation of targeted therapies for acute myeloid leukaemia (AML) has been challenging because of the complex mutational patterns within and across patients as well as a dearth of pharmacologic agents for most mutational events. Here we report initial findings from the Beat AML programme on a cohort of 672 tumour specimens collected from 562 patients. We assessed these specimens using whole-exome sequencing, RNA sequencing and analyses of ex vivo drug sensitivity. Our data reveal mutational events that have not previously been detected in AML. We show that the response to drugs is associated with mutational status, including instances of drug sensitivity that are specific to combinatorial mutational events. Integration with RNA sequencing also revealed gene expression signatures, which predict a role for specific gene networks in the drug response. Collectively, we have generated a dataset-accessible through the Beat AML data viewer (Vizome)-that can be leveraged to address clinical, genomic, transcriptomic and functional analyses of the biology of AML.

NEDD9 promotes oncogenic signaling, a stem/mesenchymal gene signature, and aggressive ovarian cancer growth in mice

Neural precursor cell expressed, developmentally downregulated 9 (NEDD9) supports oncogenic signaling in a number of solid and hematologic tumors. Little is known about the role of NEDD9 in ovarian carcinoma (OC), but available data suggest elevated mRNA and protein expression in advanced stage high-grade cancers. We used a transgenic MISIIR-TAg mouse OC model combined with genetic ablation of Nedd9 to investigate its action in the development and progression of OC. A Nedd9-/- genotype delayed tumor growth rate, reduced incidence of ascites, and reduced expression and activation of signaling proteins including SRC, STAT3, E-cadherin, and AURKA. Cell lines established from MISIIR-TAg;Nedd9-/- and MISIIR-TAg;Nedd9+/+ mice exhibited altered migration and invasion. Growth of these cells in a syngeneic allograft model indicated that systemic Nedd9 loss in the microenvironment had little impact on tumor allograft growth, but in a Nedd9 wild-type background Nedd9-/- allografts exhibited significantly reduced growth, dissemination, and oncogenic signaling compared to Nedd9+/+ allografts. Gene expression analysis revealed that Nedd9+/+ tumors exhibited more mesenchymal "stem-like" transcriptional program, including increased expression of Aldh1a1 and Aldh1a2. Conversely, loss of Nedd9 resulted in increased expression of differentiation genes, including fallopian tube markers Foxj1, Ovgp1, and Pax8. Collectively, these data suggest that tumor cell-intrinsic Nedd9 expression promotes OC development and progression by broad induction of oncogenic protein signaling and stem/mesenchymal gene expression.

Abstract 1991: Vulnerability of platinum-resistant ovarian cancer to FAK inhibition

Platinum (CP)-resistant ovarian cancer (OC) has few effective treatment options. Adaptive chemotherapy resistance occurs in part through cancer stem cell (CSC) generation. Wnt/beta-catenin signaling is a driver of CSC survival via induction of gene expression, including aldehyde dehydrogenase (ALDH) enzymes. The gene for focal adhesion kinase (FAK) is commonly amplified in advance-stage OC and this is associated with decreased patient survival. How FAK is activated in OC and whether this is connected to CSC survival is unknown. Here, we find that FAK Y397 phosphorylation (a marker of FAK activation) is increased in non-necrotic Pax8-positive OC tumor tissue after neo-adjuvant chemotherapy compared to paired pre-treatment tumor biopsy samples. FAK activation occurs after CP plus paclitaxel treatment of xenograft tumors, within 60 min of CP treatment of OC cells, and FAK Y397 levels are constitutively-elevated in OC cells pre-adapted to exhibit elevated CP resistance. Pharmacological FAK inhibition (VS-4718, 0.1 µM) selectively prevented CP-resistant tumorsphere formation in vitro and combined with CP to promote cell apoptosis. Combinatorial VS-4718, CP, and paclitaxel chemotherapy exhibited additive inhibitory effects in preventing CP-resistant tumor growth in mice. VS-4718 monotherapy of tumor-bearing mice reduced tumor-associated ALDH activity and resulted in an 85-fold reduction in secondary tumors formed in limiting dilution assays. CRISPR-mediated FAK knockout in OVCAR3 cells combined with stable re-expression of FAK wildtype or a kinase-inactive FAK (K454R) mutant revealed that intrinsic FAK activity was essential for beta-catenin activation, ALDH-1A1 expression, and OVCAR3 tumorsphere growth. As activated constructs of beta-catenin but not YAP1 rescued FAK KO OVCAR3 phenotypes, these studies provide important insights into a FAK signaling linkage to beta-catenin in promoting CSC survival and adaptive resistance to CP chemotherapy. These studies provide the foundational support for a Phase I-II clinical trial for treatment of recurrent platinum-resistant ovarian cancer (NCT03287271) termed ROCKIF: Re-sensitization of carboplatin-resistant Ovarian Cancer by Kinase Inhibition of FAK. As FAK is activated in tumor cells surviving carboplatin-paclitaxel chemotherapy, co-targeting of this FAK/beta-catenin adaptive resistance pathway may expose a vulnerability of CP-resistant tumors.

Citation Format: Carlos J. Diaz Osterman, Lisa M. Bean, Florian J. Sulzmaier, Kristin N. Taylor, Shulin A. Jiang, Isabelle Tancioni, Kristen Anderson, Christine Jean, Xiao Lei Chen, Elizabeth G. Kleinschmidt, Vihren N. Kolev, David T. Weaver, Jonathan A. Pachter, Denise C. Connolly, Alfredo Molinolo, David D. Schlaepfer. Vulnerability of platinum-resistant ovarian cancer to FAK inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1991.

In Vitro and In Vivo evaluation of a novel folate-targeted theranostic nanoemulsion of docetaxel for imaging and improved anticancer activity against ovarian cancers

Ovarian cancer ranks fifth in cancer related deaths for women in USA. The high mortality rate associated with ovarian cancer is due to diagnosis at later stages of disease and the high recurrence rate of 60-80%. Recurrent ovarian cancers are more likely to present as multidrug resistance (MDR) leading to unfavorable response from 2^nd and 3^rd line chemotherapy. Nanoemulsions (NEs) are emerging as an attractive drug delivery system to overcome MDR challenges. NEs can also minimize exposure of therapeutic cargo to normal tissues potentially reducing side effects. In >80% of ovarian cancers, Folate Receptor-α (FR-α) is expressed at 10- to 100-fold higher levels than on non-pathological tissues. Therefore, folate (FA) is being evaluated as an active targeting moiety for FR-α⁺ ovarian cancer. To improve therapeutic outcome with reduced toxicity, we developed NMI-500, a FA targeted gadolinium (Gd) annotated NE loaded with docetaxel (DTX). NMI-500 has been developed as theranostic agents as Gd will enable physician to acquire real time pharmacodynamics data on NE + DTX accumulation in target lesions. In present study, characterization for key translational metrics of NMI-500 showed size distribution in range of 120 to 150 nm and zeta potential around -45 mV. Active targeting of FA was evaluated against FR-α⁺ KB cells and results demonstrated significant improvement in cell association which was surface ligand density dependent. We found that NMI-500 was able to inhibit tumor growth in a spontaneous transgenic ovarian cancer model with improved safety profile and this growth inhibition could be longitudinally followed by MRI. These results indicate NMI-500 warrants advancement to clinical trials.

The BRCA1-Δ11q Alternative Splice Isoform Bypasses Germline Mutations and Promotes Therapeutic Resistance to PARP Inhibition and Cisplatin

Breast and ovarian cancer patients harboring BRCA1/2 germline mutations have clinically benefitted from therapy with PARP inhibitor (PARPi) or platinum compounds, but acquired resistance limits clinical impact. In this study, we investigated the impact of mutations on BRCA1 isoform expression and therapeutic response. Cancer cell lines and tumors harboring mutations in exon 11 of BRCA1 express a BRCA1-Δ11q splice variant lacking the majority of exon 11. The introduction of frameshift mutations to exon 11 resulted in nonsense-mediated mRNA decay of full-length, but not the BRCA1-Δ11q isoform. CRISPR/Cas9 gene editing as well as overexpression experiments revealed that the BRCA1-Δ11q protein was capable of promoting partial PARPi and cisplatin resistance relative to full-length BRCA1, both in vitro and in vivo Furthermore, spliceosome inhibitors reduced BRCA1-Δ11q levels and sensitized cells carrying exon 11 mutations to PARPi treatment. Taken together, our results provided evidence that cancer cells employ a strategy to remove deleterious germline BRCA1 mutations through alternative mRNA splicing, giving rise to isoforms that retain residual activity and contribute to therapeutic resistance. Cancer Res; 76(9); 2778-90. ©2016 AACR.

Abstract TMEM-027: TARGETING RGNEF (P190RHOGEF/ARHGEF28) IMPAIRS OVARIAN TUMOR INITIATION AND PROGRESSION

Rho GTPase regulatory and integrin signaling pathways are associated with poor high-grade serous ovarian carcinoma (HGSOC) patient survival1. Focal adhesion kinase (FAK) transmits signals from integrins and promotes HGSOC tumor progression through mechanisms involving tumor-stromal cell interactions2. We previously found that the Rho guanine nucleotide exchange factor Rgnef (also named p190RhoGEF or Arhgef28) activates FAK as well as RhoA GTPase activity in mouse fibroblasts3. Here we find that Rgnef protein expression is elevated in Stage 3-4 HGSOC and that Rgnef knockout prevents spontaneous ovarian tumor formation in the MISIIR-T-antigen (TAg) induced C57BL/6 mouse model. At 17 weeks, Rgnef-/-;TAg ovarian tumors were significantly smaller (p&lt;0.001) than Rgnef+/+;TAg controls. Primary Rgnef-/-;TAg and Rgnef+/+;TAg tumor cells were isolated and expanded ex vivo. Although loss of Rgnef did not alter growth as 3D spheroids, Rgnef-/-;TAg orthotopic (ovarian bursa) and intraperitoneal tumors were significantly smaller (p&lt;0.01) than Rgnef+/+;TAg tumors in MISIIR-TAg-Low C57BL/6 syngeneic mice. Notably, FAK activation (as measured by FAK Y397 phosphorylation) was decreased in Rgnef-/-;TAg ascites-associated tumor cells. Together, these studies show that Rgnef loss impedes tumor growth independently of stromal Rgnef status and supports the notion that an Rgnef-FAK signaling linkage facilitates ovarian tumor initiation and progression.

1.Zhang, H., et al. Integrated Proteogenomic Characterization of Human High-Grade Serous Ovarian Cancer. Cell 166 (2016).

2.Sulzmaier, F.J., Jean, C. & Schlaepfer, D.D. FAK in cancer: mechanistic findings and clinical applications. Nat. Rev. Cancer 14, 598-610 (2014).

3.Miller, N.L., et al. A non-canonical role for Rgnef in promoting integrin-stimulated focal adhesion kinase activation. J. Cell Sci. 126, 5074-5085 (2013).

Citation Format: Elizabeth G. Kleinschmidt, Nichol L.G. Miller, Isabelle Tancioni, Denise C. Connolly, David D. Schlaepfer. TARGETING RGNEF (P190RHOGEF/ARHGEF28) IMPAIRS OVARIAN TUMOR INITIATION AND PROGRESSION [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-027.

Abstract NTOC-087: DYNAMIC REPROGRAMMING OF THE KINOME OVERCOMES BET PROTEIN INHIBITION IN OVARIAN CANCER

High-grade serous ovarian carcinoma (HGS-OvCa) is the most common and deadly form of ovarian cancer, and currently lacks effective targeted therapies. Recently, proteins involved in chromatin remodeling such as the BET bromodomain protein BRD4 have emerged as an exciting new class of targets for the treatment of cancer. Targeted BRD4 inhibition has been shown to cause tumor regression and apoptosis in a number of cancers, including HGS-OvCa. Consequently, small molecule BET bromodomain inhibitors (BETi) are actively being pursued in clinical trials. In our preliminary studies, we discovered that the BET inhibitor JQ1 dramatically reduced MYC protein levels resulting in inhibited cell growth and survival in a panel of HGS-OvCa cell lines. Importantly, although JQ1 initially caused significant growth arrest and apoptosis, the majority of HGS-OvCa cell lines acquired drug resistance. Detailed molecular characterization of JQ1- resistant HGS-OvCa cells showed the return of MYC protein levels accompanied by elevated PI3K-AKT activity, suggesting the acquired resistance stems from activated kinase signaling. Our laboratory has designed a novel mass spectrometry approach that globally measures kinase activity to identify the kinase networks responsible for drug resistance. Using this technology, we analyzed global kinase activity in JQ1-resistant cells and observed the activation of several receptor-tyrosine kinases (RTKs), including EGFR, FGFRs and IGF1R known to strongly drive PI3K-AKT pro-survival signaling pathways. These findings suggest that BETi therapies may have limited success as single agent therapies due to “adaptive kinome reprogramming” and will likely require combination strategies involving inhibitors targeting protein kinases and BET bromodomain proteins.

Citation Format: Alison M. Kurimchak, Claude Shelton, Kelly E. Duncan, Katherine J. Johnson, Jennifer Brown, Shane O'Brien, Rashid Gabbasov, Lauren S. Fink, Yuesheng Li, Nicole Lounsbury, Magid Abou-Gharbia, Wayne E. Childers, Denise C. Connolly, Jonathan Chernoff, Jeffrey R. Peterson, James S. Duncan. DYNAMIC REPROGRAMMING OF THE KINOME OVERCOMES BET PROTEIN INHIBITION IN OVARIAN CANCER [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 NTOC-087.

Follicle-Stimulating Hormone Receptor Is Expressed by Most Ovarian Cancer Subtypes and Is a Safe and Effective Immunotherapeutic Target

PURPOSE

To define the safety and effectiveness of T cells redirected against follicle-stimulating hormone receptor (FSHR)-expressing ovarian cancer cells.

EXPERIMENTAL DESIGN

FSHR expression was determined by Western blotting, immunohistochemistry, and qPCR in 77 human ovarian cancer specimens from 6 different histologic subtypes and 20 human healthy tissues. The effectiveness of human T cells targeted with full-length FSH in vivo was determined against a panel of patient-derived xenografts. Safety and effectiveness were confirmed in immunocompetent tumor-bearing mice, using constructs targeting murine FSHR and syngeneic T cells.

RESULTS

FSHR is expressed in gynecologic malignancies of different histologic types but not in nonovarian healthy tissues. Accordingly, T cells expressing full-length FSHR-redirected chimeric receptors mediate significant therapeutic effects (including tumor rejection) against a panel of patient-derived tumors in vivo In immunocompetent mice growing syngeneic, orthotopic, and aggressive ovarian tumors, fully murine FSHR-targeted T cells also increased survival without any measurable toxicity. Notably, chimeric receptors enhanced the ability of endogenous tumor-reactive T cells to abrogate malignant progression upon adoptive transfer into naïve recipients subsequently challenged with the same tumor. Interestingly, FSHR-targeted T cells persisted as memory lymphocytes without noticeable PD-1-dependent exhaustion during end-stage disease, in the absence of tumor cell immunoediting. However, exosomes in advanced tumor ascites diverted the effector activity of this and other chimeric receptor-transduced T cells away from targeted tumor cells.

CONCLUSIONS

T cells redirected against FSHR⁺ tumor cells with full-length FSH represent a promising therapeutic alternative against a broad range of ovarian malignancies, with negligible toxicity even in the presence of cognate targets in tumor-free ovaries. Clin Cancer Res; 23(2); 441-53. ©2016 AACR.

Targeted Blockade of JAK/STAT3 Signaling Inhibits Ovarian Carcinoma Growth

Ovarian carcinoma is the fifth leading cause of death among women in the United States. Persistent activation of STAT3 is frequently detected in ovarian carcinoma. STAT3 is activated by Janus family kinases (JAK) via cytokine receptors, growth factor receptor, and non-growth factor receptor tyrosine kinases. Activation of STAT3 mediates tumor cell proliferation, survival, motility, invasion, and angiogenesis, and recent work demonstrates that STAT3 activation suppresses antitumor immune responses and supports tumor-promoting inflammation. We hypothesized that therapeutic targeting of the JAK/STAT3 pathway would inhibit tumor growth by direct effects on ovarian carcinoma cells and by inhibition of cells in the tumor microenvironment (TME). To test this, we evaluated the effects of a small-molecule JAK inhibitor, AZD1480, on cell viability, apoptosis, proliferation, migration, and adhesion of ovarian carcinoma cells in vitro. We then evaluated the effects of AZD1480 on in vivo tumor growth and progression, gene expression, tumor-associated matrix metalloproteinase (MMP) activity, and immune cell populations in a transgenic mouse model of ovarian carcinoma. AZD1480 treatment inhibited STAT3 phosphorylation and DNA binding, and migration and adhesion of cultured ovarian carcinoma cells and ovarian tumor growth rate, volume, and ascites production in mice. In addition, drug treatment led to altered gene expression, decreased tumor-associated MMP activity, and fewer suppressor T cells in the peritoneal TME of tumor-bearing mice than control mice. Taken together, our results show pharmacologic inhibition of the JAK2/STAT3 pathway leads to disruption of functions essential for ovarian tumor growth and progression and represents a promising therapeutic strategy.

Abstract 3157: An Rgnef (p190RhoGEF/Arhgef28) signaling axis regulates ovarian cancer progression

Ovarian cancer is a leading cause of cancer death in women, is usually diagnosed in late stage, and currently has insufficient effective targeted therapies. The primary mode of metastasis is unique in that dissemination occurs via tumor cell shedding into the peritoneal cavity, survival and growth within ascites, and re-adhesion and proliferation of tumor cells at sites within the abdomen. Therefore, molecules and pathways involving cell adhesion and survival in non-adherent environments are of particular interest. Rgnef (p190RhoGEF/Arhgef28) is a Rho family guanine exchange factor that associates with focal adhesion kinase (FAK) and functions both as a downstream target of FAK tyrosine kinase activity and a regulator of FAK activity following integrin stimulation. FAK regulates cell adhesion, migration, and survival. Expression of FAK is associated with poor clinical outcome, its activity (as measured by FAK Y397 phosphorylation) is frequently increased in serous ovarian carcinomas, and it is currently under investigation as a therapeutic target in ongoing clinical trials. Immunohistochemical analysis of human tumor tissue arrays with antibodies specific for Rgnef and FAK pY397 reveal a positive correlation between Rgnef expression and FAK activation and increased stage/grade of serous-type ovarian cancer. Stable knockdown of Rgnef in human ovarian carcinoma cells grown as subcutaneous or intraperitoneal xenografts in mice suggest that Rgnef may play roles in both primary tumor growth and ascites-associated cell survival and spread. Here, we use a transgenic model of spontaneous ovarian cancer (MISIIR-T-Antigen) to test the role of Rgnef in ovarian cancer progression. Female Rgnef+/+;TAg+ and Rgnef-/-;TAg+ mice were monitored by ultrasound imaging from age 12 to 17 weeks before euthanasia. Rgnef-/-;TAg+ tumors were significantly smaller (p=0.0006) and contained fewer Ki67 positive cells than Rgnef+/+;TAg+ controls at 17 weeks. Tumors and ovarian carcinoma cells isolated from Rgnef-/-;TAg+ mouse ascites have reduced FAK pY397 and increased E-cadherin expression compared to controls, suggesting that loss of Rgnef results in a less aggressive tumor phenotype. These findings identify Rgnef as a component in signaling pathways promoting FAK activation and regulating ovarian tumor progression.

Citation Format: Nichol L. G. Miller, Isabelle Tancioni, Sean Uryu, Elizabeth G. Kleinschmidt, Denise C. Connolly, David D. Schlaepfer. An Rgnef (p190RhoGEF/Arhgef28) signaling axis regulates ovarian cancer progression. [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 3157. doi:10.1158/1538-7445.AM2014-3157

Abstract 989: NEDD9 expression promotes epithelial ovarian cancer growth and dissemination

NEDD9 (Neural precursor cell Expressed, Developmentally Downregulated 9) is a scaffolding protein with roles in focal adhesion signaling, cell motility and regulation of centrosome function. NEDD9 has been reported as an important player in development and progression of several different solid tumors; however, its role in gynecologic cancers is poorly understood. In this study we investigated the role of NEDD9 in development and progression of epithelial ovarian cancer (EOC) using murine models. Three mouse strains were used: MISIIR-TAg mice that develop spontaneous ovarian carcinomas; MISIIR-TAg-Low mice that express the TAg transgene, but do not develop tumors; and Nedd9 null mice. To determine the effects of loss of Nedd9 on ovarian carcinoma development, MISIIR-TAg and Nedd9-/- mice were crossed and spontaneous ovarian tumor growth in MISIIR-TAg;Nedd9-/- and MISIIR-TAg;Nedd9+/+ mice was monitored and quantified by longitudinal magnetic resonance imaging (MRI). MISIIR-TAg-Nedd9-/- mice, compared to MISIIR-TAg-Nedd9+/+ mice, exhibited delayed tumor development and decreased tumor burden. Correspondingly, microarray analysis of tumors showed that several key oncogenic signaling pathways were upregulated in MISIIR-TAg-Nedd9+/+ mice compared to MISIIR-TAg-Nedd9-/- mice. Murine ovarian carcinoma (MOVCAR) cell lines were established from MISIIR-TAg-Nedd9-/- and MISIIR-TAg-Nedd9+/+ mice and essential tumorigenic features compared using in vitro assays. Interestingly, although these cells displayed no differences in adhesion or proliferation, Nedd9-/- MOVCAR cells were more aggressive than Nedd9+/+ cells in assays of migration and invasion. However, when grown as orthotopic allografts in permissive MISIIR-TAg-Low;Nedd9+/+ hosts, in vivo tumor growth was delayed and the number of metastatic tumor nodules was decreased in mice engrafted with Nedd9-/- cells compared to those injected with Nedd9+/+ cells. To study the potential role of Nedd9 in the tumor microenvironment, immune cell populations were compared in: 1) orthotopic allografts of Nedd9+/+ MOVCAR cells grown in MISIIR-TAg-Low;Nedd9-/- and MISIIR-TAg-Low;Nedd9+/+ hosts; or 2) spontaneous ovarian tumors in MISIIR-TAg-Nedd9-/- and MISIIR-TAg-Nedd9+/+ mice. In the allograft model, the number and total volume of metastatic tumor nodules was not significantly different in Nedd9-/- or Nedd9+/+ hosts; however, genotype-associated differences in tumor infiltrating NK-cell numbers were observed. Comparison of the spontaneous tumor models showed that the number of tumor infiltrating macrophages and NK-cells were decreased in MISIIR-TAg-Nedd9-/- mice. Collectively, these data suggest that Nedd9 promotes development and progression of EOC, through induction of oncogenic signaling and by pro-tumorigenic alterations of the immune cell microenvironment.

Citation Format: Rashid Gabbasov, Laura E. Bickel, Shane W. O'Brien, Samuel Litwin, Sachiko Seo, Erica A. Golemis, Denise C. Connolly. NEDD9 expression promotes epithelial ovarian cancer growth and dissemination. [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 989. doi:10.1158/1538-7445.AM2014-989

Abstract 3916: HSP90 mediates tumor-associated matrix metalloproteinase 2 and Cathepsin L protease activities in ovarian carcinoma

Ovarian cancer is the fifth leading cause of cancer-related deaths among women in the United States. At diagnosis, disease has commonly spread beyond the ovary. Ovarian cancer cells dislodge from primary tumor and spread locally throughout the abdominal cavity and lymphatics. Cancer cell shedding and colonization at other sites involves the degradation of extra cellular matrix (ECM) by tumor-associated proteases, such as matrix metalloproteinase (MMPs) and cathepsin proteases. Heat shock protein 90 (HSP90) is an ATP-dependent molecular chaperone that interacts with and stabilizes MMPs in some solid tumors. Whether HSP90 regulates cathepsin activity is currently unknown. To determine the role of HSP90 on tumor-associated MMP and cathepsin protease activities in ovarian carcinoma, HSP90 activity was inhibited using pharmacologic and RNA interference (RNAi) approaches. A small molecule inhibitor, ganetespib, and two HSP90 targeting siRNAs were used to determine the effects of HSP90 inhibition on ovarian carcinoma cell line invasion using transwell and spheroid invasion assays. The effects of ganetespib or HSP90 targeting siRNA treatment on MMP and cathepsin protease activities were assayed by gelatin zymography (MMPs), enzyme assay (cathepsins) and by dynamic imaging using protease cleavable imaging probes. The effects of ganetespib treatment on in vivo orthotopic tumor growth, dissemination and tumor associated protease activities were determined using human ovarian carcinoma xenograft models. In vitro, ganetespib treatment or expression of HSP90-targeted siRNAs inhibited transwell and spheroid invasion, and MMP-2 and cathepsin L protease activities. In vivo, ganetespib treatment resulted in decreased growth of primary tumors and disseminated tumor nodules and decreased tumor-associated MMP and cathepsin activities. Importantly, significant inhibition of MMP and cathepsin activities was detected prior to differences in tumor volume, demonstrating rapid functional response to the drug. These results show that HSP90 regulates ovarian carcinoma-associated proteolytic activities that are essential to tumor progression and dissemination. They also point to the potential utility of HSP90 inhibition as a therapeutic strategy for the treatment of ovarian cancer.

Citation Format: Shane W. O'Brien, Fang Xiao, Marsia A. Maglaty, Joshua S. Trinadad, Lainie P. Martin, David A. Proia, Denise C. Connolly. HSP90 mediates tumor-associated matrix metalloproteinase 2 and Cathepsin L protease activities in ovarian carcinoma. [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 3916. doi:10.1158/1538-7445.AM2014-3916

Abstract 1113: Targeting the JAK2/STAT3 pathway in ovarian cancer

Ovarian cancer is the fifth leading cause of death and the most lethal gynecological cancer among women in the United States. Persistent activation of signal transducer and activator of transcription 3 (STAT3), a cytoplasmic transcription factor, is frequently detected in EOC. STAT3 transduces signals from cytokines such as interleukin 6 (IL-6) via interactions with the IL-6 receptor and Janus kinases (JAK). JAK2 activates STAT3 by phosphorylation, leading to dimerization and translocation of STAT3 to the nucleus where it activates transcription of target genes regulating proliferation, survival and motility. Importantly, in addition to tumor cells, STAT3 signaling is also critical for immune cell activity and, in particular, inflammatory response. The inflammatory tumor microenvironment is important for ovarian cancer progression; therefore, we hypothesized that disruption of the STAT3 pathway would block ovarian tumor progression by: 1) directly inhibiting the growth of tumor cells; and 2) reducing a pro-tumorigenic inflammatory microenvironment. To target JAK2-mediated activation of STAT3 we used AZD1480, a JAK2-selective small molecule inhibitor. The effects of AZD1480 treatment on cell proliferation, apoptosis, adhesion and motility were evaluated in cultured human ovarian carcinoma cells. To study the effects of AZD1480 in vivo, we used MISIIR-TAg mice, a transgenic mouse model of ovarian carcinoma. Tumor growth in MISIIR-TAg mice was monitored and quantified in mice by weekly magnetic resonance imaging (MRI). Drug treatment-mediated alterations in gene expression were evaluated by microarray analysis and changes in the inflammatory response were evaluated by flow cytometry analysis of cells extracted from ovarian tumors, spleens and peritoneal washes. AZD1480 treatment significantly reduced primary ovarian tumor growth in transgenic mice. Microarray analysis showed changes in expression of genes involved in the acute immune response, such as Gbp6, Ifi44, Irgm, Igtp, Gzmb and Cd69. Analysis of immune cell populations by flow cytometry showed a significant decrease in the number and percent of T helper and T regulatory cells present in the peritoneal cavity of drug-treated mice compared to controls. As T regulatory cells are associated with a poor prognosis in ovarian cancer patients, the decrease of this subpopulation in drug-treated mice suggests a change in the tumor microenvironment that may contribute to reduced tumor growth. Taken together, these results indicate that targeting JAK2/STAT3 impedes ovarian tumor growth through complex mechanisms, including the reduction of primary tumor growth and inflammation in the tumor microenvironment. These findings highlight the potential utility of targeting the JAK2/STAT3 pathway for the treatment of ovarian cancer patients.

Citation Format: Galina Gritsina, Fang Xiao, Shane W. O'Brien, Marisa A. Maglaty, Ren-Huan Xu, Luis J. Sigal, Samuel Litwin, Denise C. Connolly. Targeting the JAK2/STAT3 pathway in ovarian 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 1113. doi:10.1158/1538-7445.AM2014-1113

Aurora kinase A mediates epithelial ovarian cancer cell migration and adhesion

Aurora kinase A (AURKA) localizes to centrosomes and mitotic spindles where it mediates mitotic progression and chromosomal stability. Overexpression of AURKA is common in cancer, resulting in acquisition of alternate non-mitotic functions. In the current study, we identified a novel role for AURKA in regulating ovarian cancer cell dissemination and evaluated the efficacy of an AURKA-selective small molecule inhibitor, alisertib (MLN8237), as a single agent and combined with paclitaxel using an orthotopic xenograft model of epithelial ovarian cancer (EOC). Ovarian carcinoma cell lines were used to evaluate the effects of AURKA inhibition and overexpression on migration and adhesion. Pharmacological or RNA interference-mediated inhibition of AURKA significantly reduced ovarian carcinoma cell migration and adhesion and the activation-associated phosphorylation of the cytoskeletal regulatory protein SRC at tyrosine 416 (pSRC(Y416)). Conversely, enforced expression of AURKA resulted in increased migration, adhesion and activation of SRC in cultured cells. In vivo tumor growth and dissemination were inhibited by alisertib treatment as a single agent. Moreover, combination of alisertib with paclitaxel, an agent commonly used in treatment of EOC, resulted in more potent inhibition of tumor growth and dissemination compared with either drug alone. Taken together, these findings support a role for AURKA in EOC dissemination by regulating migration and adhesion. They also point to the potential utility of combining AURKA inhibitors with taxanes as a therapeutic strategy for the treatment of EOC patients.

Network analysis identifies an HSP90-central hub susceptible in ovarian cancer

PURPOSE

Epithelial ovarian cancer (EOC) is usually detected at an advanced stage and is frequently lethal. Although many patients respond to initial surgery and standard chemotherapy consisting of a platinum-based agent and a taxane, most experience recurrence and eventually treatment-resistant disease. Although there have been numerous efforts to apply protein-targeted agents in EOC, these studies have so far documented little efficacy. Our goal was to identify broadly susceptible signaling proteins or pathways in EOC.

EXPERIMENTAL DESIGN

As a new approach, we conducted data-mining meta-analyses integrating results from multiple siRNA screens to identify gene targets that showed significant inhibition of cell growth. On the basis of this meta-analysis, we established that many genes with such activity were clients of the protein chaperone HSP90. We therefore assessed ganetespib, a clinically promising second-generation small-molecule HSP90 inhibitor, for activity against EOC, both as a single agent and in combination with cytotoxic and targeted therapeutic agents.

RESULTS

Ganetespib significantly reduced cell growth, induced cell-cycle arrest and apoptosis in vitro, inhibited growth of orthotopic xenografts and spontaneous ovarian tumors in transgenic mice in vivo, and inhibited expression and activation of numerous proteins linked to EOC progression. Importantly, paclitaxel significantly potentiated ganetespib activity in cultured cells and tumors. Moreover, combined treatment of cells with ganetespib and siRNAs or small molecules inhibiting genes identified in the meta-analysis in several cases resulted in enhanced activity.

CONCLUSION

These results strongly support investigation of ganetespib, a single-targeted agent with effects on numerous proteins and pathways, in augmenting standard EOC therapies.

Targeting serous epithelial ovarian cancer with designer zinc finger transcription factors

Ovarian cancer is the leading cause of death among gynecological malignancies. It is detected at late stages when the disease is spread through the abdominal cavity in a condition known as peritoneal carcinomatosis. Thus, there is an urgent need to develop novel therapeutic interventions to target advanced stages of ovarian cancer. Mammary serine protease inhibitor (Maspin) represents an important metastasis suppressor initially identified in breast cancer. Herein we have generated a sequence-specific zinc finger artificial transcription factor (ATF) to up-regulate the Maspin promoter in aggressive ovarian cancer cell lines and to interrogate the therapeutic potential of Maspin in ovarian cancer. We found that although Maspin was expressed in some primary ovarian tumors, the promoter was epigenetically silenced in cell lines derived from ascites. Transduction of the ATF in MOVCAR 5009 cells derived from ascitic cultures of a TgMISIIR-TAg mouse model of ovarian cancer resulted in tumor cell growth inhibition, impaired cell invasion, and severe disruption of actin cytoskeleton. Systemic delivery of lipid-protamine-RNA nanoparticles encapsulating a chemically modified ATF mRNA resulted in inhibition of ovarian cancer cell growth in nude mice accompanied with Maspin re-expression in the treated tumors. Gene expression microarrays of ATF-transduced cells revealed an exceptional specificity for the Maspin promoter. These analyses identified novel targets co-regulated with Maspin in human short-term cultures derived from ascites, such as TSPAN12, that could mediate the anti-metastatic phenotype of the ATF. Our work outlined the first targeted, non-viral delivery of ATFs into tumors with potential clinical applications for metastatic ovarian cancers.

Combined in vivo molecular and anatomic imaging for detection of ovarian carcinoma-associated protease activity and integrin expression in mice

Most patients with epithelial ovarian cancer (EOC) experience drug-resistant disease recurrence. Identification of new treatments is a high priority, and preclinical studies in mouse models of EOC may expedite this goal. We previously developed methods for magnetic resonance imaging (MRI) for tumor detection and quantification in a transgenic mouse model of EOC. The goal of this study was to determine whether three-dimensional (3D) fluorescence molecular tomography (FMT) and fluorescent molecular imaging probes could be effectively used for in vivo detection of ovarian tumors and response to therapy. Ovarian tumor-bearing TgMISIIR-TAg mice injected with fluorescent probes were subjected to MRI and FMT. Tumor-specific probe retention was identified in vivo by alignment of the 3D data sets, confirmed by ex vivo fluorescent imaging and correlated with histopathologic findings. Mice were treated with standard chemotherapy, and changes in fluorescent probe binding were detected by MRI and FMT. Ovarian tumors were detected using probes specific for cathepsin proteases, matrix metalloproteinases (MMPs), and integrin α(v)β(3). Cathepsin and integrin α(v)β(3) probe activation and retention correlated strongly with tumor volume. MMP probe activation was readily detected in tumors but correlated less strongly with tumor volume. Tumor regression associated with response to therapy was detected and quantified by serial MRI and FMT. These results demonstrate the feasibility and sensitivity of FMT for detection and quantification of tumor-associated biologic targets in ovarian tumors and support the translational utility of molecular imaging to assess functional response to therapy in mouse models of EOC.

Xenograft and transgenic mouse models of epithelial ovarian cancer and non-invasive imaging modalities to monitor ovarian tumor growth in situ: applications in evaluating novel therapeutic agents

Epithelial ovarian cancer (EOC) is the most commonly fatal gynecologic malignancy in developed countries. Most EOC patients are diagnosed at an advanced stage when disease has spread beyond the ovary. While many patients initially respond to surgery and chemotherapy, the long-term prognosis is generally unfavorable, with recurrence and development of drug-resistant disease. There is a critical need to identify new therapeutic agents that prolong disease-free intervals and effectively manage recurrent disease. Murine models of ovarian carcinoma are excellent models to study tumor biology in the search for new treatments for EOC. Described in this unit are methods for establishing xenograft or allograft models of EOC using ovarian carcinoma cell lines, in vivo imaging strategies for detection and quantification of EOC in transgenic and in xenograft/allograft models, and procedures for necropsy and pathological evaluation of experimental animals.

Dual inhibition of SRC and Aurora kinases induces postmitotic attachment defects and cell death

Increased activity of SRC family kinases promotes tumor invasion and metastasis, and overexpression of the mitotic regulator Aurora kinase A (AURKA) drives tumor aneuploidy and chromosomal instability. These functions nominate SRC and AURKA as valuable therapeutic targets for cancer, and inhibitors for SRC and Aurora kinases are now being used in the clinic. In this study, we demonstrate potent synergy between multiple inhibitors of Aurora and SRC kinases in ovarian and colorectal cancer cell lines, but not in normal ovarian epithelial cell lines. Combination of Aurora and SRC inhibitors selectively killed cells that have undergone a preceding aberrant mitosis, and was associated with a postmitotic reattachment defect, and selective removal of aneuploid cell populations. Combined inhibition of Aurora kinase and SRC potentiated dasatinib-dependent loss of activated (Y(416)-phosphorylated) SRC. SRC and AURKA share a common interaction partner, NEDD9, which serves as a scaffolding protein with activities in cell attachment and mitotic control, suggesting SRC and AURKA might interact directly. In vitro, we observed physical interaction and mutual cross-phosphorylation between SRC and AURKA that enhanced SRC kinase activity. Together, these findings suggest that combination of SRC and Aurora-targeting inhibitors in the clinic may be a productive strategy.

Abstract 1230: Wnt5a-dependent induction of senescence suppresses epithelial ovarian cancer

Epithelial Ovarian Cancer (EOC) remains the most lethal gynecological malignancy in US and is the fifth leading cause of cancer deaths among American women. Thus, there is an urgent need to understand the etiology of EOC to develop novel therapies for this disease. Wnt5a is classified as a non-canonical Wnt ligand. Here, we demonstrated that Wnt5a is expressed at significantly lower levels in human EOC cell lines and in primary human EOC compared with either normal ovarian surface epithelial cells (p=0.039) or fallopian tube epithelial cells (p&lt;0.001). Importantly, expression of Wnt5a in primary human EOC inversely correlates with tumor stage (p=0.003) but not tumor grade (p=0.086). Interestingly, Wnt5a expression is significantly lower in Type II high-grade serous EOC compared to Type I EOC that includes low-grade serous, mucinous, clear cell and endometrioid subtypes of EOC (p=0.005). In addition, we discovered that hypermethylation of promoter CpG island contributes to Wnt5a downregulation in human EOC cells. Significantly, restoration of Wnt5a expression in human EOC cells promoted senescence of EOC cells and resulted in a dramatic decrease in cell proliferation both in vitro and in vivo in an orthotopic model of EOC in the ovary of SCID mice. Mechanistically, Wnt5a inhibited canonical Wnt/beta-catenin signaling and resulted in the activation of senescence-promoting histone repressor A/PML pathway. In summary, we show that Wnt5a is often expressed at lower levels in primary human EOC and Wnt5a expression suppresses the growth of EOC cells by triggering senescence through antagonizing canonical Wnt signaling. Our data imply that the cell of origin between Type I and Type II EOC is different. These results also suggest that loss of Wnt5a expression is a putative marker of EOC and that non-canonical Wnt signaling is a potent target for developing novel EOC therapeutics.

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 1230. doi:10.1158/1538-7445.AM2011-1230

An orthotopic model of serous ovarian cancer in immunocompetent mice for in vivo tumor imaging and monitoring of tumor immune responses

BACKGROUND

Ovarian cancer is generally diagnosed at an advanced stage where the case/fatality ratio is high and thus remains the most lethal of all gynecologic malignancies among US women. Serous tumors are the most widespread forms of ovarian cancer and the Tg-MISIIR-TAg transgenic represents the only mouse model that spontaneously develops this type of tumors. Tg-MISIIR-TAg mice express SV40 transforming region under control of the Mullerian Inhibitory Substance type II Receptor (MISIIR) gene promoter. Additional transgenic lines have been identified that express the SV40 TAg transgene, but do not develop ovarian tumors. Non-tumor prone mice exhibit typical lifespan for C57Bl/6 mice and are fertile. These mice can be used as syngeneic allograft recipients for tumor cells isolated from Tg-MISIIR-TAg-DR26 mice.

OBJECTIVE

Although tumor imaging is possible, early detection of deep tumors is challenging in small living animals. To enable preclinical studies in an immunologically intact animal model for serous ovarian cancer, we describe a syngeneic mouse model for this type of ovarian cancer that permits in vivo imaging, studies of the tumor microenvironment and tumor immune responses.

METHODS

We first derived a TAg+ mouse cancer cell line (MOV1) from a spontaneous ovarian tumor harvested in a 26 week-old DR26 Tg-MISIIR-TAg female. Then, we stably transduced MOV1 cells with TurboFP635 Lentivirus mammalian vector that encodes Katushka, a far-red mutant of the red fluorescent protein from sea anemone Entacmaea quadricolor with excitation/emission maxima at 588/635 nm. We orthotopically implanted MOV1(Kat) in the ovary of non-tumor prone Tg-MISIIR-TAg female mice. Tumor progression was followed by in vivo optical imaging and tumor microenvironment was analyzed by immunohistochemistry.

RESULTS

Orthotopically implanted MOV1(Kat) cells developed serous ovarian tumors. MOV1(Kat) tumors could be visualized by in vivo imaging up to three weeks after implantation (fig. 1) and were infiltrated with leukocytes, as observed in human ovarian cancers (fig. 2).

CONCLUSIONS

We describe an orthotopic model of ovarian cancer suitable for in vivo imaging of early tumors due to the high pH-stability and photostability of Katushka in deep tissues. We propose the use of this novel syngeneic model of serous ovarian cancer for in vivo imaging studies and monitoring of tumor immune responses and immunotherapies.

Development of a syngeneic mouse model of epithelial ovarian cancer

Background

Most cases of ovarian cancer are epithelial in origin and diagnosed at advanced stage when the cancer is widely disseminated in the peritoneal cavity. The objective of this study was to establish an immunocompetent syngeneic mouse model of disseminated epithelial ovarian cancer (EOC) to facilitate laboratory-based studies of ovarian tumor biology and preclinical therapeutic strategies.

Methods

Individual lines of TgMISIIR-TAg transgenic mice were phenotypically characterized and backcrossed to inbred C57BL/6 mice. In addition to a previously described line of EOC-prone mice, two lines (TgMISIIR-TAg-Low) were isolated that express the oncogenic transgene, but have little or no susceptibility to tumor development. Independent murine ovarian carcinoma (MOVCAR) cell lines were established from the ascites of tumor-bearing C57BL/6 TgMISIIR-TAg transgenic mice, characterized and tested for engraftment in the following recipient mice: 1) severe immunocompromised immunodeficient (SCID), 2) wild type C57BL/6, 3) oophorectomized tumor-prone C57BL/6 TgMISIIR-TAg transgenic and 4) non-tumor prone C57BL/6 TgMISIIR-TAg-Low transgenic. Lastly, MOVCAR cells transduced with a luciferase reporter were implanted in TgMISIIR-TAg-Low mice and in vivo tumor growth monitored by non-invasive optical imaging.

Results

Engraftment of MOVCAR cells by i.p. injection resulted in the development of disseminated peritoneal carcinomatosis in SCID, but not wild type C57BL/6 mice. Oophorectomized tumor-prone TgMISIIR-TAg mice developed peritoneal carcinomas with high frequency, rendering them unsuitable as allograft recipients. Orthotopic or pseudo-orthotopic implantation of MOVCAR cells in TgMISIIR-TAg-Low mice resulted in the development of disseminated peritoneal tumors, frequently accompanied by the production of malignant ascites. Tumors arising in the engrafted mice bore histopathological resemblance to human high-grade serous EOC and exhibited a similar pattern of peritoneal disease spread.

Conclusions

A syngeneic mouse model of human EOC was created by pseudo-orthotopic and orthotopic implantation of MOVCAR cells in a susceptible inbred transgenic host. This immunocompetent syngeneic mouse model presents a flexible system that can be used to study the consequences of altered gene expression (e.g., by ectopic expression or RNA interference strategies) in an established MOVCAR tumor cell line within the ovarian tumor microenvironment and for the development and analysis of preclinical therapeutic agents including EOC vaccines and immunotherapeutic agents.

Distinct expression levels and patterns of stem cell marker, aldehyde dehydrogenase isoform 1 (ALDH1), in human epithelial cancers

Aldehyde dehydrogenase isoform 1 (ALDH1) has been proved useful for the identification of cancer stem cells. However, our knowledge of the expression and activity of ALDH1 in common epithelial cancers and their corresponding normal tissues is still largely absent. Therefore, we characterized ALDH1 expression in 24 types of normal tissues and a large collection of epithelial tumor specimens (six cancer types, n = 792) by immunohistochemical staining. Using the ALDEFUOR assay, ALDH1 activity was also examined in 16 primary tumor specimens and 43 established epithelial cancer cell lines. In addition, an ovarian cancer transgenic mouse model and 7 murine ovarian cancer cell lines were analyzed. We found that the expression levels and patterns of ALDH1 in epithelial cancers are remarkably distinct, and they correlate with their corresponding normal tissues. ALDH1 protein expression levels are positively correlated with ALDH1 enzymatic activity measured by ALDEFLUOR assay. Long-term in vitro culture doesn't significantly affect ALDH1 activity in epithelial tumor cells. Consistent with research on other cancers, we found that high ALDH1 expression is significantly associated with poor clinical outcomes in serous ovarian cancer patients (n = 439, p = 0.0036). Finally, ALDH^br tumor cells exhibit cancer stem cell properties and are resistant to chemotherapy. As a novel cancer stem cell marker, ALDH1 can be used for tumors whose corresponding normal tissues express ALDH1 in relatively restricted or limited levels such as breast, lung, ovarian or colon cancer.

Induction of ovarian leiomyosarcomas in mice by conditional inactivation of Brca1 and p53

BACKGROUND

Approximately one out of every ten cases of epithelial ovarian cancer (EOC) is inherited. The majority of inherited cases of EOC result from mutations in the breast cancer associated gene 1 (BRCA1). In addition to mutation of BRCA1, mutation of the p53 gene is often found in patients with inherited breast and ovarian cancer syndrome.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated the role of loss of function of BRCA1 and p53 in ovarian cancer development using mouse models with conditionally expressed alleles of Brca1 and/or p53. Our results show that ovary-specific Cre-recombinase-mediated conditional inactivation of both Brca1(LoxP/LoxP) and p53(LoxP/LoxP) resulted in ovarian or reproductive tract tumor formation in 54% of mice, whereas conditional inactivation of either allele alone infrequently resulted in tumors (< or =5% of mice). In mice with conditionally inactivated Brca1(LoxP/LoxP) and p53(LoxP/LoxP), ovarian tumors arose after long latency with the majority exhibiting histological features consistent with high grade leiomyosarcomas lacking expression of epithelial, follicular or lymphocyte markers. In addition, tumors with conditional inactivation of both Brca1(LoxP/LoxP) and p53(LoxP/LoxP) exhibited greater genomic instability compared to an ovarian tumor with inactivation of only p53(LoxP/LoxP).

CONCLUSIONS/SIGNIFICANCE

Although conditional inactivation of both Brca1 and p53 results in ovarian tumorigenesis, our results suggest that additional genetic alterations or alternative methods for targeting epithelial cells of the ovary or fallopian tube for conditional inactivation of Brca1 and p53 are required for the development of a mouse model of Brca1-associated inherited EOC.

NEDD9 promotes oncogenic signaling in mammary tumor development

In the past 3 years, altered expression of the HEF1/CAS-L/NEDD9 scaffolding protein has emerged as contributing to cancer metastasis in multiple cancer types. However, whereas some studies have identified elevated NEDD9 expression as prometastatic, other work has suggested a negative role in tumor progression. We here show that the Nedd9-null genetic background significantly limits mammary tumor initiation in the MMTV-polyoma virus middle T genetic model. Action of NEDD9 is tumor cell intrinsic, with immune cell infiltration, stroma, and angiogenesis unaffected. The majority of the late-appearing mammary tumors of MMTV-polyoma virus middle T;Nedd9(-/-) mice are characterized by depressed activation of proteins including AKT, Src, FAK, and extracellular signal-regulated kinase, emphasizing an important role of NEDD9 as a scaffolding protein for these prooncogenic proteins. Analysis of cells derived from primary Nedd9(+/+) and Nedd9(-/-) tumors showed persistently reduced FAK activation, attachment, and migration, consistent with a role for NEDD9 activation of FAK in promoting tumor aggressiveness. This study provides the first in vivo evidence of a role for NEDD9 in breast cancer progression and suggests that NEDD9 expression may provide a biomarker for tumor aggressiveness.

Xenograft and Transgenic Mouse Models of Epithelial Ovarian Cancer and Non Invasive Imaging Modalities to Monitor Ovarian Tumor Growth In situ -Applications in Evaluating Novel Therapeutic Agents

Epithelial ovarian cancer (EOC) is the most commonly fatal gynecologic malignancy in developed countries. Most EOC patients are diagnosed at advanced stage when disease has spread beyond the ovary. While many patients initially respond to surgery and chemotherapy, the long term prognosis is generally unfavorable, with recurrence and development of drug resistant disease. There is a critical need to identify new therapeutic agents that prolong disease-free intervals and effectively manage recurrent disease. Murine models of ovarian carcinoma are excellent models to study tumor biology in the search for new treatments for EOC. Described in this unit are methods for establishing xenograft or allograft models of EOC using ovarian carcinoma cell lines, in vivo imaging strategies for detection and quantification of EOC in transgenic and in xenograft/allograft models, and procedures for necropsy and pathological evaluation of experimental animals.

Expression of activated PIK3CA in ovarian surface epithelium results in hyperplasia but not tumor formation

Background

The Phosphatidylinositol 3′-kinase is a key regulator in various cancer-associated signal transduction pathways. Genetic alterations of its catalytic subunit alpha, PIK3CA, have been identified in ovarian cancer. Our in vivo data suggests that PIK3CA activation is one of the early genetic events in ovarian cancer. However, its role in malignant transformation of ovarian surface epithelium (OSE) is largely unclear.

Methodology/Principal Findings

Using the Müllerian inhibiting substance type II receptor (MISIIR) promoter, we generated transgenic mice that expressed activated PIK3CA in the Müllerian epithelium. Overexpression of PIK3CA in OSE induced remarkable hyperplasia, but was not able to malignantly transform OSE in vivo. The consistent result was also observed in primary cultured OSEs. Although enforced expression of PIK3CA could not induce OSE anchorage-independent growth, it significantly increased anchorage-independent growth of OSE transformed by mutant K-ras.

Conclusions/Significance

While PIK3CA activation may not be able to initiate OSE transformation, we conclude that activation of PIK3CA may be an important molecular event contributing to the maintenance of OSE transformation initiated by oncogenes such as K-ras.