Abstract
Lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD) are two major pathological types of non-small cell lung cancer (NSCLC), characterized by distinct patterns of lipid metabolism. However, the molecular mechanisms underlying lipid metabolism reprogramming specific to LUSC remain poorly understood. This study aims to fill this gap by identifying and characterizing EHHADH (enoyl-CoA, hydratase/3-hydroxyacyl CoA dehydrogenase) as a key regulator of medium-chain fatty acid metabolism in LUSC. The peroxisomal L-bifunctional enzyme is one of the important elements to control the peroxisomal fatty acid beta-oxidation pathway. Through high-expression genes related to lipid metabolism were identified by data mining, the expression and regulatory effects of EHHADH in different cell lines were investigated. EHHADH was highly expressed in LUSC cells and exhibited different expression patterns from those in LUAD cells. Knockdown of EHHADH in LUSC cell lines led to a marked reduction in cell proliferation. RNA sequencing following EHHADH silencing demonstrated significant changes in the expression of lipid metabolism-related genes in different cell lines, such as AZGP1, CAV1, CYP3A4, NR2F2, NR3C2, and RARG. Lipidomics analysis further demonstrated that EHHADH plays a crucial role in regulating intracellular and extracellular lipid profiles. EHHADH knockdown resulted in increased levels of long-chain fatty acids and storage lipids, while decreased levels of medium-chain fatty acids. Conversely, overexpression of EHHADH reduced long-chain fatty acids and storage lipids, while increasing specific medium-chain fatty acids. These metabolic alterations were consistent with changes in lipid metabolism-related protein expression, supporting the molecular mechanistic role of EHHADH in lipid regulation. In conclusion, EHHADH functions as an important regulator of lipid metabolism in LUSC and plays a key role in the occurrence, progression, and treatment of lung cancer. The important impact of EHHADH in lipid metabolism disorders suggests potential utility as a biomarker for diagnosis and a target for personalized treatment strategies in lung cancer.