The present disclosure relates to compositions and methods for reducing expression of MYC gene in a cell. In some embodiments, an expression repressor comprises a targeting moiety that binds a MYC promoter, anchor sequence, or super-enhancer. In some embodiments, the expression repressor comprises an effector moiety that represses transcription or methylates DNA. Systems comprising two expression repressors are also disclosed. The compositions can be used, for example, to treat cancers such as HCC or NSCLC.