Sirnas

For circMTCL1 or C1QBP overexpression in vitro, 436 or 858 bp cDNA fragments containing the circMTCL1 or C1QBP were cloned into a pLCDHor Y0009367 vector (GenePharma, Suzhou, China) between EcoRI and BamHI or between BspEI-BglII restriction sites. For circMTCL1 or C1QBP knockdown, cells were transfected with siRNAs (GenePharma, Suzhou, China) against circMTCL1 or C1QBP. siRNA sequences are shown in Tables S8 and S9.The plasmids or siRNAs were transiently transfected into cells following the manufacturer’s instructions using an X-treme GENE siRNA (4,476,093,001, Roche, Basel, Switzerland) or DNA Transfection Reagent (6,366,244,001,Roche, Basel, Switzerland).
For in vivo studies, a lentiviral vector containing circMTCL1 shRNA was synthesised in Hanbio (Shanghai, China), which was used for TU212 cell transfection to establish stable cell lines overexpressing circMTCL1. Lentiviral transfections were performed following the manufacturer’s instructions.

Specific short interfering RNAs (siRNAs) or control siRNA to knock down lnc RNA AC007639.1 were purchased from the Shanghai GenePharma (Shanghai, China). 30nM of siRNAs (Table S1) were used for transfection in the HCC cells using X-tremeGENE reagent (Roche Applied Science, Shanghai, China).