Propofol suppresses proliferation, migration, invasion, and tumor growth of liver cancer cells via suppressing cancer susceptibility candidate 9/phosphatase and tensin homolog/AKT serine/threonine kinase/mechanistic target of rapamycin kinase axis

Propofol is a commonly used drug for sedation and general anesthesia during cancer surgery. Previous studies indicate that propofol exerts anti-tumor effect in various cancers. The aim of this study was to investigate the underlying molecular mechanism of propofol in liver cancer. The effects of propofol on liver cancer cells were evaluated by cell viability assay, colony formation assay, and tumor xenograft model. Dysregulated lncRNAs of propofol-treated liver cancer cells were evaluated by transcriptome RNA sequencing. The underlying molecular mechanisms of lncRNA cancer susceptibility candidate 9 (CASC9) in propofol-induced anti-tumor effects were evaluated by western blot, quantitative real-time polymerase chain reaction (qRT-PCR), wound scratch healing assay, transwell cell migration and invasion assay, TUNEL staining, fluorescence in situ hybridization, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP). We found that propofol suppressed proliferation, migration, invasion, and tumor xenograft growth of liver cancer cells in a dose-dependent manner. Exosomes transfer from propofol-treated cells inhibited proliferation, migration, and invasion and promoted apoptosis of liver cancer cells. Transcriptional profiling of propofol-treated liver cancer cells identified CASC9 as significantly downregulated lncRNA in cells and exosomes. Enforced CASC9 expression partially rescued the inhibitory effects of propofol on liver cancer cells. Furthermore, CASC9 was found to interact directly with EZH2 and epigenetically regulated PTEN expression. Restoration of CASC9 partially abrogated the inhibition of propofol on Akt/mTOR signaling. Our results indicated that propofol exerted anti-tumor effects by downregulating CASC9, and subsequently suppressed Akt/mTOR signaling. Our findings provided a novel insight into propofol-induced anti-tumor effects in liver cancer.