An investigation into the role of AVIL, an actin-binding protein, in glioblastoma metabolism

Glioblastoma (GBM) is one of the deadliest cancers characterized, is highly aggressive, invasive, and incurable, with an average survival of 15 months. The Li Lab identified AVIL as a novel proto-oncogene, which is aberrantly expressed in the tissue of cancers like glioblastoma. AVIL is a calcium dependent actin binding protein, implicated in cytoskeletal dynamics. Under physiological conditions, the expression of AVIL is limited to a handful of cell types: tuft cells, kidney podocytes, and sensory neurons, suggesting a tightly regulated role. In addition, our lab generated an AVIL KO mouse model that has no side effects and are fertile with viable offspring. Previous work has led to the development of a first-in-class small molecule inhibitor against AVIL (C1). While the upregulation of AVIL is observed in GBM, the molecular mechanisms involved are still unknown. This project aims to define the interactions and pathways involving AVIL with the goal of determining a molecular mechanism regarding alterations in metabolic phenotype. To elucidate the molecular mechanism of AVIL, we used a comprehensive bioinformatic analysis to pinpoint pathways and downstream targets . We conducted an unbiased screen of the protein using mass spectrometry on glioblastoma (U87) cells treated with C1 over a period of 72 hours. We also utilized RNA sequencing of GBM cells treated with C1 and astrocytes transduced with AVIL. Furthermore, we utilized Seahorse Mitochondrial Stress Tests as a screen for metabolism and mitochondrial function to validate our bioinformatic observations. One candidate mechanism we observed in the MS data suggested that treatment with the inhibitor induced a proteomic change from a glycolytic to an oxidative-phosphorylation profile, indicating a potential metabolic modulatory role of AVIL . This is particularly interesting because actin-glycolytic enzyme interactions are linked to the cytoskeletal regulation of metabolism. In addition, RNA sequencing data presented glycolysis as a top gene set that is differentially expressed after treatment with C1. After exogenous expression of AVIL in human astrocytes, there is an increase in basal metabolic rate and maximal respiration. Defining the metabolic interactions of AVIL will help determine the signaling pathways that are perturbed by AVIL expression and reveal downstream effectors. I hypothesize that AVIL expression regulates glycolysis via interactions with glycolytic enzymes offering a potential therapeutic strategy for GBM.