USP7 and hepatocellular carcinoma: The TME includes adipocytes [3, 134], and one study showed that the exo-circ-deubiquitination (exo-circ-DB) derived from adipocytes upregulated the expression levels of USP7 and Cyclin A2 by sponging miR-34a and activating the USP7/CyclinA2 signalling pathway, thereby promoting the tumorigenesis and metastasis of HCC [135].