Investigating the Role of Cereblon in Mitochondrial Function and Fatty Acid Metabolism in Non-Small Cell Lung Cancer

Abstract

PART I Cereblon, as a mitochondrial function regulator in non-small cell lung cancer CRBN (Cereblon), a substrate receptor of the CRL4 (Cullin4-RING E3 ubiquitin ligase) complex, has emerged as a key player in cancer metabolism. While its role in influencing metabolic phenotypes has been suggested, the precise functions of CRBN in cellular metabolism and cancer progression remain underexplored. This study investigates the impact of CRBN downregulation in lung cancer, focusing on mitochondrial metabolism and cellular functions. Data from The Cancer Genome Atlas (TCGA) and the Clinical Proteomic Tumor Analysis Consortium (CPTAC) revealed significant reductions in CRBN expression at both mRNA and protein levels in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). This downregulation was further confirmed in most lung cancer cell lines examined. Functional analyses of CRBN knockout (KO) cells revealed substantial alterations in mitochondrial metabolism, including enhanced oxidative phosphorylation, increased mitochondrial membrane potential (ΔΨm), and elevated production of mitochondrial reactive oxygen species (mROS). CRBN deficiency also accelerated tricarboxylic acid (TCA) cycle flux and increased mitochondrial calcium accumulation, contributing to elevated ΔΨm and potentially compromised mitochondrial integrity. Additionally, CRBN KO cells demonstrated increased cell migration, which could be mitigated by inhibiting mitochondrial calcium import. These findings suggest that CRBN plays a pivotal role in regulating mitochondrial function and metabolic activity in non-small cell lung cancer. The loss of CRBN enhances mitochondrial metabolism and contributes to increased cancer cell migration, providing new insights into the metabolic adaptations associated with CRBN deficiency in cancer progression. PART II Cereblon, as a fatty acid metabolism regulator in non-small cell lung cancer Lipid metabolism is pivotal in cancer progression, with cancer cells often relying on altered lipid synthesis, uptake, and storage to support rapid proliferation and survival in adverse environments. Dysregulated lipid metabolism enhances metabolic flexibility, enabling cancer cells to adapt to nutrient scarcity and oxidative stress. This study investigates the role of cereblon (CRBN), a key regulator in the ubiquitin-proteasome system, in lipid storage and phospholipid synthesis. Using fatty acid beta-oxidation assays and lipidomics, I demonstrate that CRBN-deficient cells exhibit reduced lipid droplet formation mimicking previously reported in vivo phenotypes while maintaining catabolic rates of fatty acids. Notably, there is an upregulation of exogenous fatty acid transport in CRBN knockout cells, revealing a complex interplay in lipid metabolism. Lipidomic analysis confirms diminished neutral lipid storage and an increased pool of phospholipids between the endoplasmic reticulum and mitochondria. Additionally, enhanced formation of mitochondria-associated membranes (MAM) in CRBN-deficient cells suggests significant intracellular organelle communication regarding metabolic processes. These findings illuminate the metabolic implications of CRBN in lipid homeostasis, highlighting its potential as a therapeutic target in cancer and metabolic diseases.