N-Myc promotes a proliferative progenitor-like cell state to drive basal cell carcinoma progression

Abstract Driver mutations that activate upstream Hedgehog (Hh) signaling are well-known to initiate basal cell carcinoma (BCC); however, the role of recurrent secondary mutations is less well understood. Here, we performed spatial transcriptomics to show that nascent murine BCC-like tumors are initially comprised of two subpopulations that differ in expression of Hh, stem cell, and differentiation markers. Using a newly developed cell culture formulation that we termed “RRi conditions”, we established several mouse BCC cell lines, benchmarked them against existing ASZ BCC cells, and identified novel genes associated with Hh activation ( Wnt7b , Tgfb3 , Cxcl14 ). We further show that inducible N-MYC expression promotes an NICD low ;K10 low ;Ki67+ undifferentiated cell state, similar to that of transit-amplifying hair follicle progenitors, and that genetically ablating N-Myc blunts tumor formation in mice. Finally, we report that an immunomodulatory drug, imiquimod, regresses nascent lesions and destabilizes N-MYC protein, an effect that depends upon GSK3 and proteasome activity. Altogether, our findings demonstrate that BCCs upregulate N-MYC to maintain a proliferative progenitor-like cell state, and support the use of imiquimod to restrict tumor progression.