The PP2A signaling axis regulates multiple oncogenic drivers of castration resistant prostate cancer (CRPC). We show that targeting the endogenous PP2A regulator, SET (I2PP2A), is a viable strategy to inhibit prostate cancers that are resistant to androgen deprivation therapy.
Our data is corroborated by analysis of prostate cancer patient cohorts showing significant elevation of SET transcripts. Tissue microarray analysis reveals that elevated SET expression correlates with clinical cancer grading, duration of neoadjuvant hormone therapy (NHT) and time to biochemical recurrence. Using prostate regeneration assays, we show that in vivo SET overexpression is sufficient to induce hyperplasia and prostatic intraepithelial neoplasia. Knockdown of SET induced significant reductions in tumorgenesis both in murine and human xenograft models. To further validate SET as a therapeutic target, we conducted in vitro and in vivo treatments using OP449 - a recently characterized PP2A-activating drug (PAD). OP449 elicits robust anti-cancer effects inhibiting growth in a panel of enzalutamide resistant prostate cancer cell lines. Using the Pten conditional deletion mouse model of prostate cancer, OP449 potently inhibited PI3K-Akt signaling and impeded CRPC progression. Collectively, our data supports a critical role for the SET-PP2A signaling axis in CRPC progression and hormone resistant disease.
Scientific reports. 2015 Nov 13*** epublish ***
Xiaoyong Hu, Consuelo Garcia, Ladan Fazli, Martin Gleave, Michael P Vitek, Marilyn Jansen, Dale Christensen, David J Mulholland
The 6th People's Hospital, Shanghai Jiaotong University, Shanghai, 200233, China. , Icahn School of Medicine, Mount Sinai Medical Center, New York, NY, 10029, USA. , The Prostate Centre at Vancouver General Hospital Vancouver, British Columbia, Canada. , The Prostate Centre at Vancouver General Hospital Vancouver, British Columbia, Canada. , Oncotide Pharmaceuticals, Research Triangle Park, NC, 27709, USA. , Oncotide Pharmaceuticals, Research Triangle Park, NC, 27709, USA. , Oncotide Pharmaceuticals, Research Triangle Park, NC, 27709, USA. , Icahn School of Medicine, Mount Sinai Medical Center, New York, NY, 10029, USA.