Abstract 1841: Adaptive upregulation of carbamoyl phosphate synthetase-1 (CPS-1) in glucose-deprived metastatic lung adenocarcinoma cells
Authors: Wong Kin Lok , Chan Andrew M. 
Published: August 2019

Abstract
Advanced lung cancers frequently metastasize to the brain, where nutrient deprivation from tumour microenvironments at either primary, invading or metastatic sites may exert a selective pressure on tumour cells. Our lab has identified a rare brain metastasis cell line of lung cancer origin: A1115, that possessed heightened basal glycolytic activity. Characterization of the metabolic profiles of A1115 and 4 other lung adenocarcinoma cell lines revealed A1115 to have the highest dependence on glycolysis and the lowest utilization of mitochondrial oxidative phosphorylation (OXPHOS) for metabolism. Thus, we hypothesized that A1115 is hypersensitive to glucose starvation. A1115 relied heavily on glycolysis on survival and propagation, while inhibiting mitochondrial OXPHOS had less effect. Glucose deprivation induced the nutrient sensor AMP-activated protein kinase (AMPK) to be elevated in A1115, while the proliferative capacity of A1115 was drastically reduced by an AMPK activator, AICAR, suggesting AMPK to be detrimental to cell viability of A1115 under glucose deprivation. To understand how such metastatic cell line could survive the low glucose environment in blood circulation and during the invasion into the brain parenchyma, we established clonal A1115 sublines that could propagate under low glucose (LG) environment. LG sublines regained hypersensitivity to glucose deprivation upon exposure to normal glucose concentrations suggest an adaptive response. We hypothesised that tumour cells maintain cell viability under glycolytic stress conditions by undergoing metabolic reprogramming, this involves changes in metabolite utilization and transcriptional activity of key metabolic enzymes. A parallel metabolomics (targeted LC/MS) and transcriptomics (RNAseq) analysis was conducted comparing A1115 LG sublines with the parental control. Metabolomics analysis revealed that LG sublines under glucose deprivation harboured a significant metabolite increase in amino acids: glutamate, arginine, aspartic acid and pyrimidine: cytidine, whereas integrated pathway analysis of metabolomics and transcriptomics revealed upregulation in both pyrimidine metabolism and alanine, aspartate and glutamate metabolism. Moreover, increased carbamoyl phosphate synthetase 1 (CPS-1) expression was observed in LG sublines, an initiating enzyme for pyrimidine biosynthesis and urea cycle, silencing CPS-1 decreased cell viability on LG in normal conditioned media, suggesting that the disruption of pathway could impede survival. Overall, our results suggest that lung adenocarcinoma may undergo reprogramming towards a starkly different constituent of transcriptional activation leading to metabolite flux and signalling activation to allow viable adaption to glucose deprivation in the microenvironment.
Citation Format: Kin Lok Wong, Andrew M. Chan. Adaptive upregulation of carbamoyl phosphate synthetase-1 (CPS-1) in glucose-deprived metastatic lung adenocarcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1841.