Abstract 2838: CtBP1 expression depletion on primary tumor deregulates miRNA expression and impairs development of spontaneous metastases on a prostate cancer and metabolic syndrome model
Authors: Dalton Guillermo N. , Scalise Georgina , Porretti Juliana , Massillo Cintia , Farré Paula L. , Luca Paola De , Siervi Adriana De 
Published: July 2017

Prostate cancer (PCa) is the second cancer in incidence in men worldwide. Approximately 20 % of cases continue with advanced or metastatic disease, and at this stage, it turns out incurable due to the lack of effective therapies. Hence, the need to identify new actionable targets is crucial. Metabolic syndrome (MeS) is a physiopathological disorder that increases PCa risk and aggressiveness. C-terminal Binding Protein (CtBP1) is a transcriptional corepressor that is activated by NADH binding. Previously our group established a MeS and PCa mice model that identified to CtBP1 as a novel link associating both diseases. Moreover, cell adhesion molecules play a significant role in cancer progression and metastasis. Thus, we found that CtBP1 diminished the capability of PCa cell lines to adhere to a collagen matrix, directly modulating expression of several cell adhesion genes, including repression of the epithelial marker CDH1 and induction of the mesenchymal marker VIM. The aim of this work was to investigate MeS/CtBP1 impact over PCa progression from in situ prostate carcinoma to metastatic disease. RNA was isolated from xenografts generated on MeS mice from CtBP1 depleted PC3 cells (PC3.shCtBP1) or control (PC3.PGIPZ); and hybridized to a miRNA expression microarray (Affymetrix GeneChip® miRNA 4.0). After data normalization and analysis we identified and validated a list of 11 miRNAs regulated by CtBP1 relevant to cell adhesion and PCa progression. To investigate CtBP1 role in spontaneous PCa metastasis, NOD SCID gamma (NSG) mice were fed with control or high fat diets during 12 weeks to induce MeS. Then PC3.shCtBP1 or PC3.PGIPZ cells were injected s.c. on MeS and control animals. Body weight and tumor size were measured 1 and 3 times a week, respectively. Thirty days after cell inoculation, tumors were around 1 cm, with no significant differences between treatments; however mice showed around 20% weight loss. Mice were sacrificed and tumors, lungs and livers were collected for RNA isolation and histopathological analysis. Using human GAPDH specific primers and RT-qPCR from lungs, we found that CtBP1 depletion led to a significant decrease of lung metastases, especially in the MeS group. In addition, Hematoxylin & Eosin stains from lung sections detected the lowest number and size of metastatic foci in the CtBP1 depleted xenografts generated in MeS animals. Gene expression comparison between primary tumors and metastases showed that epithelial markers, such as E-cadherin, were induced in xenografts and almost undetected in metastasis. Accordingly, mesenchymal markers expression, such as Vimentin, was low in xenografts and triggered on metastases. Our study uncovers for the first time the role of CtBP1 in PCa progression and its molecular targets in MeS mice.

Citation Format: Guillermo N. Dalton, Georgina Scalise, Juliana Porretti, Cintia Massillo, Paula L. Farré, Paola De Luca, Adriana De Siervi. CtBP1 expression depletion on primary tumor deregulates miRNA expression and impairs development of spontaneous metastases on a prostate cancer and metabolic syndrome model [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 2838. doi:10.1158/1538-7445.AM2017-2838