Abstract 5174: Phosphodiesterase 10A inhibition as a novel approach to suppress β-catenin signaling in ovarian cancer cells

Canonical Wnt/β-catenin signaling is known to be associated with platinum resistance in ovarian cancer in which inhibitors hold promise for the treatment of refractory disease. Phosphodiesterase 10A (PDE10A) is a dual cyclic AMP and cyclic GMP phosphodiesterase isozyme recently implicated in colon cancer. PDE10A inhibition in colon cancer cells by siRNA or small molecule inhibitors increased cGMP levels and activated PKG to inhibit β-catenin signaling. A novel PDE10 inhibitor, ADT-061, was identified by screening a library of indene derivatives, and showed strong antineoplastic activity in the Apc+/min-FCCC mouse (Lee K et al., unpublished data). Cyclic GMP and phosphodiesterases participate in the ovarian follicular development, although little is known about PDE10A expression in ovaries, especially with regard to a potential role in ovarian tumorigenesis. PDE10A protein was found to be expressed in various established ovarian cancer cell lines at higher levels than immortalized or primary ovarian surface epithelial cell lines. Pf-2545920, a known PDE10A inhibitor, and ADT-061 inhibited the growth of multiple ovarian tumor cell lines with IC50s around 20µM and 0.5µM, respectively. Both compounds induced apoptosis after 24h treatment, as measured by PI/Annexin-V staining and PARP cleavage. Pf-2545920 and ADT-061 induced phosphorylation of VASP at Ser157 and Ser239 in various ovarian cancer cell lines, indicating activation of cyclic AMP and cyclic GMP signaling, respectively. Treatment also decreased levels of β-catenin and downstream targets of TCF-dependent transcription, including c-MYC, survivin and cyclin-D1. Homozygous knockout PDE10A clones of OV-90 ovarian cancer cells obtained using CRISPR/Cas9 showed decreased clonogenic potential, decreased Pf-2545920-mediated VASP phosphorylation and β-catenin, c-MYC and survivin expression. Ongoing efforts are focused on the development of more potent ADT-061 analogs. These observations support further study of a role of PDE10 in ovarian tumorigenesis and the development of ADT-061 or analogs for the treatment of refractory ovarian cancer as well as the prevention of malignant recurrence. Citation Format: Luciana Madeira Da Silva, Elaine Gavin, Kevin J. Lee, Veronica Ramirez-Alcantara, Kristy L. Berry, Holly T. Taylor, Alla Musiyenko, Ileana V. Aragon, Adam B. Keeton, Jennifer Scalici, Rodney P. Rocconi, Gary A. Piazza. Phosphodiesterase 10A inhibition as a novel approach to suppress β-catenin signaling in ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5174. doi:10.1158/1538-7445.AM2017-5174