PTGDR and hepatocellular carcinoma: PCED1B-AS1 enhances HCC immunosuppression by sponging hsa-miR-194-5p, increasing PD-L1 and PD-L2 expression. It blocks hsa-miR-194-5p’s inhibition of PD-Ls, leading to their overexpression. HCC exosomes containing PCED1B-AS1 spread this mechanism to other HCC cells, T cells, and macrophages.