Although forced miR-449c-5p expression alone showed significant tumor-suppressive activity (promoting IFN-γ and TNF-α secretion), increased circUHRF1 expression dramatically inhibited the miR-449c-5p tumor-suppressive function (Additional file 3: Supplementary Fig. 4b), highlighting the critical ability of HCC-derived exosomal circUHRF1 to inhibit the function of NK cells via the miR-449c-5p-related pathway. Here, TNF is linked to hepatocellular carcinoma.