CtBP1 regulates olfactory and adhesion pathways in prostate cancer and metabolic syndrome

DALTON N; PORRETTI J; MASSILLO CL; SCALISE G; FARRÉ PL; MOIOLA CP; PAEZ A; GUERON G; DE LUCA P; DE SIERVI A

New Orleans

Congreso; AACR Annual Meeting 2016; 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 studiesassociated MeS with increased risk for several cancer types, including prostate cancer (PCa). Cterminalbinding protein 1 (CtBP1)is a potent transcriptional corepressorof tumor suppressor genes. This protein is activated by low NAD+/NADH ratio produced byhighly energetic environment such as high fat diet (HFD) intake. Previously, we identified CtBP1 as a novel molecular link betweenMeS and prostate tumor growth. The aim of this work was to assess the CtBP1 related pathways in PCa and MeS. We developed aMeS in vivo model by chronically feeding male nude mice with HFD. Control diet (CD) fed animals were maintained at the sameconditions. These mice were inoculated with PC3 stable CtBP1 depleted or control cells. RNA obtained from xenografts was usedfor Genomewideexpression profiles (Affymetrix) and Gene Set Enrichment Analysis (GSEA). These analyses yielded severalimportant 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 ofPCa cell lines to adhere to a collagen matrix, repressing the epithelial marker CDH1 and inducing the mesenchymal marker VIMexpressions. Interestingly, CtBP1 associated to ITGB4 promoter gene, strongly repressing its expression. CtBP1 depletion increasedthe 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 tumorsuppressor gene that function inhibiting epithelial to mesenchymal transition (EMT) and invasion processes. We found that CtBP1regulates the transcription of CLCA2 in xenografts generated on HFDfedmice. Using a panel of luciferase reporter plasmids withvariable 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 andinvasion reinforcing a potential function for this protein in cancer progression. Hence, CtBP1 pathway might help to identify newmolecular candidates for better prediction of PCa progression in a subset of patients with MeS