CtBP1 expression depletion on primary tumor deregulates miRNA expression and impairs development of spontaneous metastases on a prostate cancer and metabolic syndrome model

DE LUCA, PAOLA; PORRETTI, JULIANA; DE SIERVI, ADRIANA; MASSILLO, CINTIA; DALTON, GUILLERMO N.; FARRÉ, PAULA L.; SCALISE, GEORGINA D.

Washington DC

Congreso; AACR 108th Annual Meeting; 2017

American Association for Cancer Research

Prostate cancer (PCa) is the second cancer in incidence in men worldwide. Approximately 20 % of cases continue with advanced or metastatic disease, andat 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. Cterminal Binding Protein (CtBP1) is a transcriptional corepressor that is activated by NADH binding. Previously our group established a MeS and PCa mice model that identifıed to CtBP1 as a novel link associating both diseases. Moreover, cell adhesion molecules play a signifıcant 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 identifıed 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 toinduce 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 signifıcant differences between treatments; however mice showed around 20% weight loss. Mice were sacrifıced and tumors, lungs and livers were collected for RNA isolation and histopathological analysis. Using human GAPDH specifıc primers and RT-qPCR from lungs, we found that CtBP1 depletion led to a signifıcant 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 fırst time the role of CtBP1 in PCa progression and its molecular targets in MeS mice.