The impact of cathepsins on liver hepatocellular carcinoma: Insights from genetic and functional analyses

Liver Hepatocellular Carcinoma (LIHC), ranked as the second deadliest cancer globally, poses a major health challenge because of its widespread occurrence and poor prognosis. The mechanisms underlying LIHC development and progression remain unclear. Cathepsins are linked to tumorigenesis in other cancers, but their role in LIHC is underexplored. This study employed integrative analyses, including Mendelian Randomization (MR), bulk RNA-sequencing (bulk-seq), single-cell RNA sequencing (scRNA-seq), immunohistochemical (IHC) analysis, and cellular experiments with siRNA technology, to investigate the role of cathepsin E (CTSE) in LIHC. MR analysis identified CTSE as a factor associated with increased LIHC risk. Prognostic analysis using TCGA data showed that higher CTSE levels are linked to poorer survival, establishing CTSE as an independent prognostic risk factor. Integrative transcriptome analysis revealed close relation of CTSE to the extracellular matrix. scRNA-seq from TISCH2 demonstrated that CTSE is predominantly expressed in malignant LIHC cells. IHC confirmed higher CTSE expression in LIHC tissues compared to peritumoral tissues. Functional assays, such as qRT-PCR, Western blot, cell proliferation, and colony formation experiments, demonstrated that siRNA-mediated CTSE knockdown in HepG2 and Huh7 cell lines notably suppressed cell proliferation and altered the FAK/Paxillin/Akt signaling cascade. This research enhances our comprehension of LIHC development, emphasizing CTSE as a promising prognostic marker and potential therapeutic target. Inhibiting CTSE could slow the progression of LIHC, presenting novel opportunities for therapeutic approaches.