Metabolic syndrome (MeS) has been identified as a risk factor for breast cancer. C-terminal binding protein 1 (CtBP1) is a co-repressor of tumor suppressor genes that is activated by low NAD+/NADH ratio. High fat diet (HFD) increases intracellular NADH. We investigated the effect of CtBP1 hyperactivation by HFD intake on mouse breast carcinogenesis. We generated a MeS-like disease in female mice by chronically feeding animals with HFD. MeS increased postnatal mammary gland development and generated prominent duct patterns with markedly increased CtBP1 and Cyclin D1 expression. CtBP1 induced breast cancer cells proliferation. Serum from animals with MeS enriched the stem-like/progenitor cell population from breast cancer cells. CtBP1 increased breast tumor growth in MeS mice modulating multiple genes and miRNA expression implicated in cell proliferation, progenitor cells phenotype, epithelial to mesenchymal transition, mammary development and cell communication in the xenografts. These results define a novel function for CtBP1 in breast carcinogenesis.

Prostate cancer (PCa) is the most common cancer among men. Metabolic syndrome (MeS) is associated with increased PCa aggressiveness and recurrence. Previously, we proposed C-terminal binding protein 1 (CTBP1), a transcriptional co-repressor, as a molecular link between these two conditions. Notably, CTBP1 depletion decreased PCa growth in MeS mice. The aim of this study was to investigate the molecular mechanisms that explain the link between MeS and PCa mediated by CTBP1. We found that CTBP1 repressed chloride channel accessory 2 (CLCA2) expression in prostate xenografts developed in MeS animals. CTBP1 bound to CLCA2 promoter and repressed its transcription and promoter activity in PCa cell lines. Furthermore, we found that CTBP1 formed a repressor complex with ZEB1, EP300 and HDACs that modulates the CLCA2 promoter activity. CLCA2 promoted PCa cell adhesion inhibiting epithelial-mesenchymal transition (EMT) and activating CTNNB1 together with epithelial marker (CDH1) induction, and mesenchymal markers (SNAI2 and TWIST1) repression. Moreover, CLCA2 depletion in PCa cells injected subcutaneously in MeS mice increased the circulating tumor cells foci compared to control. A microRNA (miRNA) expression microarray from PCa xenografts developed in MeS mice, showed 21 miRNAs modulated by CTBP1 involved in angiogenesis, extracellular matrix organization, focal adhesion and adherents junctions, among others. We found that miR-196b-5p directly targets CLCA2 by cloning CLCA2 3'UTR and performing reporter assays. Altogether, we identified a new molecular mechanism to explain PCa and MeS link based on CLCA2 repression by CTBP1 and miR-196b-5p molecules that might act as key factors in the progression onset of this disease.

Metabolic syndrome (MeS) increases prostate cancer (PCa) risk and aggressiveness. C-terminal binding protein 1 (CTBP1) is a transcriptional co-repressor of tumor suppressor genes that is activated by low NAD /NADH ratio. Previously, our group established a MeS and PCa mice model that identified CTBP1 as a novel link associating both diseases. We found that CTBP1 controls the transcription of aromatase (CYP19A1), a key enzyme that converts androgens to estrogens. The aim of this work was to investigate the mechanism that explains CTBP1 as a link between MeS and PCa based on CYP19A1 and estrogen synthesis regulation using PCa cell lines, MeS/PCa mice and adipose co-culture systems. We found that CTBP1 and E1A binding protein p300 (EP300) bind to CYP19A1 promoter and downregulate its expression in PC3 cells. Estradiol, through estrogen receptor beta, released CTBP1 from CYP19A1 promoter triggering its transcription and modulating PCa cell proliferation. We generated NSG and C57BL/6J MeS mice by chronically feeding animals with high fat diet. In the NSG model, CTBP1 depleted PCa xenografts showed an increase in CYP19A1 expression with subsequent increment in intratumor estradiol concentrations. Additionally, in C57BL/6J mice, MeS induced hypertrophy, hyperplasia and inflammation of the white adipose tissue, which leads to a proinflammatory phenotype and increased serum estradiol concentration. Thus, MeS increased PCa growth and Ctbp1, Fabp4 and IL-6 expression levels. These results describe, for the first time, a novel CTBP1/CYP19A1/Estradiol axis that explains, in part, the mechanism for prostate tumor growth increase by MeS.