The LIN28B/let-7 axis is a novel therapeutic pathway in Multiple Myeloma

MYC is a major oncogenic driver of Multiple Myeloma (MM) and yet almost no therapeutic agents exist that target MYC in MM. Here we report that the let-7 biogenesis inhibitor LIN28B correlates with MYC expression in MM and is associated with adverse outcome. We also demonstrate that the LIN28B/let-7 axis modulates the expression of MYC, itself a let-7 target. Further, perturbation of the axis regulates the proliferation of MM cells in vivo in a xenograft tumor model. RNA sequencing and gene set enrichment analyses of CRISPR-engineered cells further suggest that the LIN28/let-7 axis regulates MYC and cell cycle pathways in MM. We provide proof-of-principle for therapeutic regulation of MYC through let-7 with an LNA-GapmeR containing a let-7b mimic in vivo, demonstrating that high levels of let-7 expression repress tumor growth by regulating MYC expression. These findings reveal a novel mechanism of therapeutic targeting of MYC through the LIN28B/let-7 axis in MM that may impact other MYC dependent cancers as well. Overall design: RNA sequencing of MOLP-8 cells transduced with lentiCRISPRv2 scrambled control or containing a sgRNA against LIN28B. Both control and LIN28B KO cells were sequenced in triplicate.

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Manier S, Powers JT, Sacco A, Glavey SV, Huynh D, Reagan MR, Salem KZ, Moschetta M, Shi J, Mishima Y, Roche-Lestienne C, Leleu X, Roccaro AM, Daley GQ, Ghobrial IM