Abstract 5044: CtBP1 regulates olfactory and adhesion pathways in prostate cancer and metabolic syndrome
Authors: Dalton Guillermo N. , Porretti Juliana , Massillo Cintia , Scalise Georgina , Farré Paula Lucía , Moiola Cristian P. , Paez Alejandra , Gueron Geraldine , De Luca Paola , De Siervi Adriana 
Published: July 2016

Metabolic syndrome (MeS) is a cluster of pathophysiological disorders that comprise at least three of the following factors: abdominal obesity, elevated triglycerides, dyslipidemia, high blood pressure and impaired glucose tolerance. Several studies associated MeS with increased risk for several cancer types, including prostate cancer (PCa). C-terminal binding protein 1 (CtBP1) is a potent transcriptional co-repressor of tumor suppressor genes. This protein is activated by low NAD+/NADH ratio produced by highly energetic environment such as high fat diet (HFD) intake. Previously, we identified CtBP1 as a novel molecular link between MeS and prostate tumor growth. The aim of this work was to assess the CtBP1 related pathways in PCa and MeS. We developed a MeS in vivo model by chronically feeding male nude mice with HFD. Control diet (CD) fed animals were maintained at the same conditions. These mice were inoculated with PC3 stable CtBP1 depleted or control cells. RNA obtained from xenografts was used for Genome-wide expression profiles (Affymetrix) and Gene Set Enrichment Analysis (GSEA). These analyses yielded several important pathways regulated by CtBP1, such as “Cell Adhesion” (COL17A1, PRRS2, CDH3, ITGB4, LCN2, CDH1, GJB5, TGM2 and SPARC) and “Olfactory” (OR4C45, OR5P2, GUCA1C and CLCA2). CtBP1 significantly diminished the capability of PCa cell lines to adhere to a collagen matrix, repressing the epithelial marker CDH1 and inducing the mesenchymal marker VIM expressions. Interestingly, CtBP1 associated to ITGB4 promoter gene, strongly repressing its expression. CtBP1 depletion increased the plasma membrane of the cell attached to the substrate and the number of filopodia.

From olfactory pathway, we particularly focus on Chloride Channel Accessory 2 (CLCA2), a reported breast cancer tumor suppressor gene that function inhibiting epithelial to mesenchymal transition (EMT) and invasion processes. We found that CtBP1 regulates the transcription of CLCA2 in xenografts generated on HFD-fed mice. Using a panel of luciferase reporter plasmids with variable length of the CLCA2 promoter region, we determined that CtBP1 represses CLCA2 promoter activity in PC3 cells. Moreover, we established that CtBP1 associates to the CLCA2 proximal promoter region by chromatin immunoprecipitation (ChIP). Finally, several proteins regulate CLCA2 promoter activity independently (p53, ET2 and BRCA1) or dependently of CtBP1 (p300 and HDAC2). Altogether, these results demonstrated a new role for CtBP1 in the regulation of cellular adhesion, EMT and invasion reinforcing a potential function for this protein in cancer progression. Hence, CtBP1 pathway might help to identify new molecular candidates for better prediction of PCa progression in a subset of patients with MeS

Citation Format: Guillermo N. Dalton, Juliana Porretti, Cintia Massillo, Georgina Scalise, Paula Lucía Farré, Cristian P. Moiola, Alejandra Paez, Geraldine Gueron, Paola De Luca, Adriana De Siervi. CtBP1 regulates olfactory and adhesion pathways in prostate cancer and metabolic syndrome. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5044.