Design of PKC-Targeting Benzolactams as Gli Inhibitors

Dysregulated Hedgehog signaling, driven by oncogenic Gli transcription factors, plays a central role in many cancers and other Gli-dependent diseases. Inhibition of Gli through Smoothened-independent mechanisms represents a promising strategy to overcome resistance to clinical Hedgehog pathway inhibitors. Herein we report the synthesis and structure-activity relationship analysis of benzolactam analogues derived from TPPB, a potent inhibitor of Gli signaling that suppresses Gli activity via a protein kinase C (PKC)-mediated mechanism. Strategic chemical modifications were introduced across positions of the benzolactam core to assess their effects on biological activity using Gli-reporter cell-based assays. Our findings identified key structural features required for PKC-mediated Gli inhibition, and computational modeling revealed novel interactions between the PKC C1 domain and benzolactam analogues with nanomolar potency. Together, these studies provide a framework for designing therapeutics targeting Gli-driven diseases resistant to current treatments.