CACUL1 promotes hepatocellular carcinoma progression through enhanced tumor cell proliferation and macrophage-mediated immune suppression
Background Although cullin-family E3 ubiquitin ligases regulate diverse oncogenic pathways, the role of CACUL1 in hepatocellular carcinoma (HCC) remains poorly characterized. Methods We performed pan-cancer expression and survival analysis using TCGA and GEO databases, validated findings through immunohistochemistry, and conducted functional studies in HCC cell lines using CRISPR-mediated CACUL1 knockout. Transcriptome sequencing, functional assays (CCK-8, wound-healing, transwell invasion), and single-cell RNA-sequencing were performed to elucidate mechanisms. Results Pan-cancer analysis identified CACUL1 overexpression in HCC and gastric cancer (P < 0.001), with prognostic significance in 16 tumor types, including HCC (log-rank P < 0.01). CACUL1 expression independently predicted poor HCC prognosis (multivariable Cox, P < 0.05) and correlated with advanced clinicopathological features and reduced immune checkpoint expression. CACUL1 knockout inhibited HCC cell proliferation and migration but not invasion, with transcriptomic analysis revealing PI3K/AKT signaling pathway enrichment. Co-culture experiments demonstrated that CACUL1 promotes M2 macrophage polarization through Notch1 suppression, with pharmacological Notch inhibition phenocopying this effect. Conclusion CACUL1 functions as a dual-axis oncogenic driver in HCC through enhanced tumor cell proliferation associated with PI3K/AKT signaling and immune evasion via Notch1-dependent macrophage polarization, positioning it as a candidate prognostic biomarker and therapeutic target.