Abstract 7057: Validation of OXPHOS gene amplification as a driver of treatment resistance in non-small cell lung cancer
Authors: Benej Martin , Benejova Katarina , Hoyd Rebecca , Wheeler Caroline , Spakowicz Daniel , Denko Nicholas C. 
Published: March 2024

Abstract
Lung cancer is the leading cause of cancer deaths in the U.S. and worldwide. Up to 90% of all lung cancers are non-small cell lung cancer (NSCLC). NSCLC is a complex and highly aggressive disease typical for poor prognosis and high rates of treatment resistance. Clinical management of NSCLC varies according to the stage. High-dose stereotactic body radiation therapy (SBRT) is the standard of care for localized non-resectable NSCLC. However, tumor hypoxia is a significant barrier to effective radiation therapy. In the last decade, first line NSCLC treatment has been substantially reinforced with the introduction of immunotherapy targeting immune checkpoints such as programmed cell death 1 (PD-1), yet long-term disease control occurs in less than 25% of NSCLC patients. Therefore, understanding the mechanisms of treatment resistance is essential to address the dire need of introducing novel synergistic therapies to enhance anti-cancer treatment response in refractory NSCLC tumors. The basis of tumor hypoxia has traditionally been attributed to the oxygen supply deficit as malformed tumor vasculature fails to meet the high demand of the rapidly proliferating tumor mass. However, our preliminary analysis of NSCLC patient datasets in the Cancer Genome Atlas (TCGA) PanCancer dataset revealed a significant correlation between high-level expression of nuclear genes encoding mitochondrial subunits essential for oxidative phosphorylation (OXPHOS), and high-level expression of hypoxia-regulated genes (Buffa hypoxia score). Furthermore, we have observed a direct correlation between copy number amplification (CNA) of several OXPHOS genes and hypoxia levels in patient samples. Because mitochondrial function consumes up to 90% of available cellular oxygen, its activity may be indirectly regulating oxygen availability in the tumor microenvironment by rapidly consuming oxygen upon its delivery to the tumor. Moreover, we have identified that almost 40% of NSCLC patients harbor CNA of these essential OXPHOS genes. To provide mechanistic insight into these clinical observations, we have generated mouse syngeneic NSCLC cell lines with modified mRNA expression levels of OXPHOS genes (representing deletion, diploid and amplified number of copies) identified in our screen and observed a direct effect on the rates of mitochondrial oxygen consumption in these cells. Our study investigates the previously unknown role of OXPHOS gene copy number in driving mitochondrial oxygen demand and thus contributing to tumor hypoxia and treatment resistance in NSCLC.
Citation Format: Martin Benej, Katarina Benejova, Rebecca Hoyd, Caroline Wheeler, Daniel Spakowicz, Nicholas C. Denko. Validation of OXPHOS gene amplification as a driver of treatment resistance in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7057.