N-myristoyltransferases (NMTs) catalyze the protein N-terminal modification N-myristoylation, a lipidation event which affects >150 proteins and is involved in protein localization, stability, and function. NMT has been suggested as a target in cancers, but there has been a lack of rationale to identify patients who may respond to NMT inhibition. Additionally, the mechanism of action of NMT inhibitors (NMTi) is difficult to dissect, as NMT substrates feature in multiple biological pathways, and many studies have focused only on a single substrate. Here, a combination of bioinformatic, biochemical, proteomic, and cellular biology techniques have been combined to show that deregulation of MYC-family proteins sensitizes cells to NMT inhibition. Cell lines sensitive to NMTi were identified through screening of hundreds of cancer cell lines, and the transcriptome of sensitive and insensitive lines compared to obtain a “Sensitive to NMTi” gene set. This gene set correlated well with MYC-related gene sets and mutation, amplification, or chromosomal rearrangement in MYC(N) were predictive for NMTi sensitivity, suggesting that MYC deregulated cancer cells are sensitive to NMTi. This was verified by cytotoxicity assays in B-cell lymphoma and neuroblastoma lines, where highly MYC(N) expressing lines exhibited increased NMTi sensitivity, including in the SHEP21N and P493-6 lines, in which MYC(N) levels can be regulated. Furthermore, proteomic profiling identified multiple pathways which are affected by NMTi, and these were further validated. In particular, an impact on Complex I formation was seen, and mitochondrial dysfunction in high MYC(N) cells upon NMTi was seen through the loss of basal and maximal respiration, ATP production and spare respiratory capacity. Loss of Complex I formation was shown to be caused by the loss of the NMT substrate NDUFAF4 upon NMTi treatment. Furthermore, application of an orally bioavailable NMTi eliminated tumors in mouse models of both diffuse large B-cell lymphoma and neuroblastoma and were well tolerated with no changed in body weight, suggesting that NMT inhibitors are well tolerated and efficacious in vivo.

Citation Format: James Zhang, Gregor A. Lueg, Monica Faronato, Evon Poon, Andrii Gorelik, Andrea G. Grocin, Eva Caamano-Gutierrez, Francesco Falciani, Roberto Solari, Robin Carr, Andrew S. Bell, Edward Bartlett, Jennie Hutton, Miriam Llorian-Sopena, Probir Chakravarty, Bernadette Brzezicha, Martin Janz, Matther J. Garnett, Louis Chesler, Dinis P. Calado, Edward W. Tate. Dysregulation of MYC-family proteins sensitizes cancers to NMT inhibition: identification of NMTi sensitivity and mechanism. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4871.