Knocking Down <scp>SKA1</scp> Inhibits Hepatocellular Carcinoma Progression via Apoptosis: Integrating Single‐Cell Transcriptomics With In Vivo and In Vitro Validation

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Spindle- and kinetochore-associated complex 1 (SKA1) participates in the regulation of mitosis, playing an essential role in regulating cancer progression. Therefore, this study aims to explore the effects of knocking down SKA1 on HCC. The bioinformatics analysis approaches were adopted to predict SKA1 expression in HCC, the role of SKA1 on the survival rate and prognosis of HCC patients, and the associations between SKA1 expression and gene mutation and immune cell infiltration. The single-cell transcriptome sequencing analysis was employed to explore the cell-cell communications and molecular interactions. The CCK-8, wound healing, Transwell, flow cytometry, and qRT-PCR approaches were used to determine the cell viability, invasion, migration, cell cycle, apoptosis, and SKA1 mRNA expression level of SMMC7721 cells. The tumor volume and weight were measured. The Western blot was applied to determine the protein expression levels of SKA1, survivin, Bax, Bad, Bcl-2, caspase-3, and caspase-9 in SMMC7721 cells and tumor tissue. The bioinformatics analysis results indicated that highly expressed SKA1 was related to a low survival rate and poor prognosis of HCC patients and was involved in the TP53 mutation and multiple immune cell infiltrations. The single-cell transcriptome sequencing analysis affirmed that malignant cells were associated with hepatocytes, ILC, and granulocytes. Meanwhile, various pathways and ligand-receptor pairs were enriched in the cell subpopulation with high SKA1 expression, especially for the Protease-Activated Receptors (PARs) pathway and MDK-SDC1 pair associated with the apoptosis signaling. Knocking down SKA1 reduced the cell viability, invasion, and migration, arrested the cell cycle in the S period, promoted the apoptosis in vitro, decreased the tumor volume and weight in vivo, and down-regulated the survivin and Bcl-2 protein expression levels and up-regulated the caspase 3, caspase 9, Bax, and Bad in vivo and in vitro. Taken together, knocking down SKA1 inhibited HCC progression by promoting the apoptosis signaling pathway.