IGF1R and hepatocellular carcinoma: Reportedly, circRNAs mainly work as miRNA sponges to adsorb miRNAs and modulate targetgenes’ expression, thereby exerting either pro- or anti-cancer effects (30).Circ_0000517 is reported to modulate the expression levels of IGF1R andSMAD6 via sponging miR-326 in HCC (29, 31).