Elucidating the roles of N-myristoyltransferase in cancers

Myristoyl-CoA:Protein N-myristoyltransferase (NMT) is an enzyme that catalyses the transfer of myristic acid to its target proteins. The addition of the myristate group on proteins is known to alter the localisation, stability and functions of proteins. NMT is essential for cell survival and it has been linked to several diseases including malaria, Leishmaniasis, African sleeping sickness, HIV, Huntingtin disease, epilepsy and cancers. NMT has been suggested to be a potential chemotherapeutic target as the enzyme is overexpressed in many cancer cell lines and many NMT substrates are well-known oncogenesis proteins. Two isoforms of NMT – NMT 1 and NMT 2 – are present and they have been shown to play distinct yet overlapping roles. Despite the importance of NMT in cancers, the mode of action of NMT and the reason for the existence of two isoforms remains to be explored. Elucidating the roles of NMT1 and NMT2 is crucial to understand the chemotherapeutics potential of NMT inhibitors fully. In this research project, sensitive cancer cell lines towards NMT inhibition were identified through a large-scale cancer cell line screening at the Sanger Institute. Reasons behind the sensitivity of cell lines towards NMT inhibition were studied using data analysis, phenotypic studies, pathway analysis and proteomics. CoTMyr proteins and NMT inhibition-affected proteome in BL-41 were also profiled to identify key substrate proteins or pathways responsible for inducing cell death upon NMT inhibitors treatment. A crucial druggable-NMT substrate – Mcl-1 – was also identified using network analysis and the potential of Mcl-1 related drugs and NMT inhibitors to be used as combinatorial treatments was examined. The role of myristoylation in Mcl-1 was investigated. Other than that, proteomics of the siRNA knockdown of HsNMT1 or HsNMT2 was performed to identify the specific roles of NMT1 or NMT2 in cancers. Methods for the study of the protein-protein interaction of NMT using an inhibitor-based probe were developed and optimised.