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 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

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.

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.