PUB091 Metabolic and Epigenetic Changes Associated with Lung Cancer Using a CRISPR/Cas9 Mouse Model

Abstract

In NSCLC, loss-of-function (LOF) mutations are found in tumour suppressors, highlighting the importance of these genes in the aetiology of lung cancer. The major tumour suppressors (TS) associated with the development of lung cancer are p53 and the kinase LKB1. Unlike oncogenes that have been successfully exploited therapeutically, LOF alterations in TS are difficult to exploit therapeutically. The goal of our research is to understand how the loss of TS function allows for metabolic and epigenetic adaptation that favour conditions for tumour growth. We developed a CRISPR/Cas9 mouse model of lung cancer representative of tumour suppressors lost in NSCLC that has allowed us to evaluate the role metabolism and epigenetics plays in supporting tumour growth. Since LKB1 and p53 are the most common LOF tumour suppressors found in NSCLC, and Kras is the most commonly abundant of oncogene, using the Cre-dependent Cas9 mouse model developed by the Zhang Lab at the Broad Institute, will allow us to characterize CRISPR developed lung cancers at a molecular level. Mice were treated by inhalation with CRISPR-directed viruses that target the excision of Lkb1, p53 and activation of KRas compared to mice treated with control virus. Post-treatment, circulating blood was collected weekly and lungs were harvested at the end of the study. Harvested lungs were analyzed for metabolic epigenetic profile, while epigenetic profiles were conducted on harvested blood. Lung tumours and circulating blood were harvested from mice, followed by analysis of global epigenetic modifications, and for metabolic enzymes. The metabolic profile of lung tumours harvested from CRISPR/Cas9 mice that lack expression of Lkb1, p53 and express enhanced Kras, was significantly different from the metabolic profile of lungs harvested from control mice, favouring a switch from glycolysis to mitochondrial metabolism. Acetylation and methylation modifications to histones 3 (H3) and H4 were significantly different compared to control mice, as was the macrophage activation profiles. The goal of our study was to 1) identify and characterize aberrant metabolic and epigenetic processes that allow for cancer adaptation and 2) develop non-invasive liquid biopsy that would provide rapid and affordable early diagnostic tool in clinic. We conclude from our study that patients with lung cancers that lack expression of LKB1 are likely to respond favourably to interventions that simultaneously target aberrant metabolism with modifiers of tumour epigenetic landscape. Our findings suggest that loss of LKB1 expression serves as a marker for lung cancers that are metabolically and epigenetically challenged.