PO-346 Defining microRNA mediated regulation of metabolic pathways involved in colon cancer progression (BST1-microRNA interactions)

Abstract

IntroductionColorectal cancer (CRC) is the third most common cause of cancer related death in the world. Progressive accumulation of mutations in oncogenic and tumour suppressor pathways (e.g., KRAS and p53) and also microRNA (miR) deregulation are associated with CRC development. Very little has been done to dissect specific CRC pathways involved in miR regulation in response to stress and metabolic changes. Therefore, we previously characterised gene (mRNA) and miR expression as well as metabolic changes in different CRC genotypes. Here, we investigated the interaction between miR-mediated regulation of bone marrow stromal cell antigen 1 (BST1) or CD157, a metabolic gene involved in the conversion of nicotinamide adenine dinuclease (NAD) to paracrine factor cyclic ADP ribose (cADPR), following the acquisition of KRAS mutation in metastatic CRC.Material and methodsA combination of array analysis data, in-silico prediction tools and nuclear magnetic resonance (NMR) system were used to analyse gene and miR expression changes associated with different rounds of knock in/out mutations in Apc, Kras, and p53 CRC mouse models and their tumour-derived organoids (TDOs). Subsequently, we genetically modified human CRC cell lines and patients KRAS mutant (mut) TDOs from CRC metastases to modulate the candidate gene and miR. Organoids formation, growth rate and viability were measured with IncuCyte® Live-Cell Analysis System and Celigo® imaging cytometer.Results and discussionsWe identified mRNA/miR networks involved in cancer metabolic pathways and assessed miRs of potential interest among the candidates. MiR-203 appeared as one of the most significant candidates. Furthermore target validation and analysis of human tissues microarrays showed an association between KRAS mutations, miR-203 down-regulation and over-expression of BST1, which was identified as a direct target of miR-203 regulation in our studies. Repressing BST1 and over-expressing miR-203 had a significant effect on the proliferation and migration abilities of organoids in 3D culture in normal and calorie-deprived conditions.ConclusionThis project aimed at characterising the functional consequences of miR-203 loss and BST1 up regulation in normal and nutrient-deprived conditions in order to find a promising candidate as a therapeutic target in KRAS mut CRC. Although we showed KRAS mut CRC cells lost a growth advantage with miR-203 and BST1 deregulation ex vivo, work is on going to confirm the consequence of their interaction in vivo.