Identification of <scp>CDKN1A</scp> as a potential key risk factor in <scp>MASLD</scp> progression

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously referred to as non-alcoholic fatty liver disease (NAFLD), is recognized as a highly heterogeneous condition. The elusive mechanisms driving its progression contribute to the lack of reliable diagnostic markers and effective treatments. In this study, we first identified 52 differentially expressed genes (DEGs) in MASLD stage by analyzing two public datasets, GSE126848 and GSE135251, using the DESeq2 and edgeR packages. Subsequently, these DEGs were subjected to protein-protein interaction (PPI) network analysis, revealing the top 10 hub genes. By intersecting the top 10 hub genes with another public dataset GSE260222, we observed that CDKN1A was the sole gene consistently upregulated in the livers of MASLD patients across all analyses. The elevated protein expression of CDKN1A was further validated in the livers of MASLD patients compared to control subjects. Consistently, compared to their respective control groups, both CDKN1A mRNA and protein levels were dramatically increased in the livers of MASLD animal models, including high-fat diet (HFD) induced obese mice, leptin-deficient obese (ob/ob) mice and leptin receptor-deficient (db/db) mice, and in mouse primary hepatocytes treated with free fatty acids (FFA), respectively. Interestingly, we found that CDKN1A transcript levels were progressively and significantly increased with the severity of MASLD in four out of five datasets and positively correlated with both the NAFLD activity score (NAS) and fibrosis stage, two important clinicopathological features of MASLD. Collectively, our results illustrated that CDKN1A may serve as a promising biomarker and therapeutic target for MASLD; however, its role in the disease's pathology warrants further investigation.