Assessing the Global Impact of an Adenylate Kinase Isoenzyme on AMPK and mTOR Signaling Pathways Through Metabolic Profiling in both Brain and Lung Cancer Cell Lines

Abstract

In a variety of human cancers, it is well observed that specific altered bioenergetic programs must be sustained in order to maintain the cancer cell phenotype. Well‐described genes play a role in sustaining energy flux for the cancer cell and recent studies add the regulation of AK4 expression, an adenylate kinase localized to the mitochondrial matrix, to the list. Our results demonstrate that in response to altered AK4 expression in cancer cells, intracellular ATP levels drastically increase. Secondly, we demonstrate that in response to perturbed AK4 expression in cancer cells, two critical homeostatic signaling pathways, the 5′ AMP‐activated protein kinase (AMPK) and a mammalian target of rapamycin (mTOR) pathways, are significantly altered. Both mTOR and AMPK proteins govern a metabolic pathway in which they sense cellular energy levels and nutrient status in response to regulate cancer cell growth and/or proliferation. Lastly, AK4 also has an impact on other bioenergetic pathways. For instance, AK4 can catalyze the reaction GTP + AMP ↔ GDP + ADP24 and sustain critical energy flux of nucleotides in the cell. Because AK4 expression appears to regulate cellular metabolic responses at multiple levels, further analyses by obtaining a metabolomic profile is necessary to highlight the global impact AK4 exerts on all the metabolites in the cancer cell. To do this, cell lines will be engineered without the AK4 gene in glioblastomas, lung adenocarcinomas, and HeLa cells then analyzed to identify all known metabolites in the system. It is hypothesized that without the expression of an AK4 protein there will be indirect or direct disruptions in the global nucleotide pools by either increasing nucleotide biosynthesis or decreasing nucleotide consumption. The outcome of this study will add to the small library of research on AK4 as well as provide a comprehensive understanding on the enzymatic activity and interactions where AK4 exerts its biological effects on cancer cell metabolism.Support or Funding InformationFunded by National Institutes of Health (NIH) National Institute of General Medical Sciences (NIGMS) Grant 1R15GM123382‐01.