Ulva lactuca polysaccharide inhibits hepatocellular carcinoma growth by induces the expression of CD5L and activates complement cascade

Ulva polysaccharide (ULP) as main active ingredient of Ulva lactuca, has good pharmacological activity. This study further explored its anti-tumor mechanisms in hepatocellular carcinoma (HCC) with wet experiments and bioinformatic analyses. Results indicate that the differential proteins after ULP treatment are mainly enriched in immunomodulatory and complement pathways, among which the immune molecule CD5L and the key proteins of the membrane attack complex (MAC) are significantly upregulated, and the expression of MAC proteins are positively correlated with the expression of CD5L. Moreover, results from TIMER2.0 indicated that CD5L expression had positive correlation with CD8 + T cell infiltration in HCC, and single cell RNA-Seq analysis showed CD5L positive macrophage cells have higher expression of CFP, C1QA, C1QB, and C1QC, which are key molecular of complement cascades. Take together, the results suggest that ULP may exerts its anti-tumor activity by induces the expression of CD5L in HCC.