Exosomal circPTPRK promotes angiogenesis after radiofrequency ablation in hepatocellular carcinoma

Radiofrequency ablation (RFA) is an effective treatment for hepatocellular carcinoma (HCC), but the recurrence rate remains high due to angiogenesis in residual cancer cells. We used thermal stimulation to simulate the post-RFA microenvironment. The expression profile of circRNAs between normal control HCC cell-derived exosomes and exosomes after heat stimulation were analyzed by RNA sequencing. Quantitative real-time PCR was applied to evaluate the expression of circPTPRK in exosomes and human umbilical vein endothelial cells (HUVECs). Then, the functions of heat-stimulated HCC cell-derived exosomes and exosomal circPTPRK on HUVECs were unveiled. Transcriptome sequencing was utilized to determine targeted genes of circPTPRK. Heat-stimulated HCC cell-derived exosomes augmented cell proliferation, migration, and angiogenesis of HUVECs. In total, 229 differentially expressed circRNAs were obtained, including 211 upregulated circRNAs and 18 downregulated circRNAs in heat-stimulated HCC cell-derived exosomes. The expression of circPTPRK was remarkably increased in heat-stimulated HCC cell-derived exosomes and the HUVECs incubated with them. Heat-stimulated HCC cell-derived exosomes with circPTPRK knockdown significantly inhibited cell proliferation, migration, and angiogenesis of HUVECs. Mechanistic studies indicated that PLA2G4E is a downstream target of circPTPRK, and PLA2G4E overexpression reversed the inhibitory effect of circPTPRK knockdown on HUVEC angiogenesis. Our results indicated that exosomal circPTPRK activated HUVEC angiogenesis by upregulating PLA2G4E expression.