Prenylation dynamics of RAS oncogenes: a chemical biology investigation into alternative prenylation phenomena
File(s)
Author(s)
Hassan, Sarah
Type
Thesis
Abstract
Protein prenylation comprises a class of post-translational modifications that regulates the localization and function of over 100 proteins, including RAS oncogenes. Farnesyl transferase (FTase) and geranylgeranyl transferase type 1 (GGTase-1) catalyze the attachment of a farnesyl or geranylgeranyl isoprenoid to a canonical C-terminal motif. Efforts to disrupt this process, such as the development FTase and GGTase inhibitors (FTIs, GGTIs), have largely been futile due to complex compensatory prenylation mechanisms. KRAS, a well-characterized oncogene, is geranylgeranylated in the presence of FTIs, allowing it to undergo membrane localization and exert downstream function, effectively subverting therapeutic efficacy. In contrast, HRAS remains unprenylated upon FTI treatment, making it uniquely susceptible to FT inhibition. However, it remains unknown as to what drives alternative prenylation dynamics upon inhibition of prenyltransferases, and platforms traditionally used in the study of protein lipidation are not currently fit to robustly interrogate this system. Deconvoluting prenyl substrate criteria and potential interaction partners that mediate or inhibit this switch could reveal novel drug targets in RAS-driven cancers. Moreover, alternatively prenylated RAS species may be exposed to new vulnerabilities that can be leveraged for combinatorial drug therapy. This project outlines an investigation into alternative prenylation mechanisms and potential regulators of these processes, particularly in response to farnesylation inhibition, and how this might be exploited in a therapeutic context. Utilizing a dual chemical probe system, prenylation profile changes can be evaluated on a global scale to deconvolute the activity of RAS binding partners and their responses to an FTI.
I then introduce the use of a novel CRISPR screening platform to conduct mutagenesis scanning of known RAS regulatory domains to explore their roles in alternative prenylation. Finally, RAS isoforms are funneled into proximity-based interactome mapping to identify putative drug targets that can potentiate FTI activity. Together, these techniques enable the deconvolution of complex prenylation dynamics and may contribute to the revelation of novel lipidation-dependent vulnerabilities in cancer.
I then introduce the use of a novel CRISPR screening platform to conduct mutagenesis scanning of known RAS regulatory domains to explore their roles in alternative prenylation. Finally, RAS isoforms are funneled into proximity-based interactome mapping to identify putative drug targets that can potentiate FTI activity. Together, these techniques enable the deconvolution of complex prenylation dynamics and may contribute to the revelation of novel lipidation-dependent vulnerabilities in cancer.
Version
Open Access
Date Issued
2023-11-14
Date Awarded
01/02/2024
License URL
Advisor
Tate, Edward W.
Sponsor
Imperial College London
Publisher Department
Chemistry
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)