Development of small molecule splice-switchers as inducers of apoptosis

Student thesis: Doctoral Thesis

Abstract

Alternative splicing is the primary source of protein diversity in eukaryotes. Alternative splicing allows the production of multiple isoforms from the same genetic blueprint (DNA). Over 95% of all eukaryotic genes undergo alternative splicing, and although this facilitates great protein diversity, it can instigate disease when the process goes wrong for example in cancer. The Bcl-2 protein family are essential gatekeeper regulators of apoptosis. One such protein, Bcl-x is of particular interest as a therapeutic target. It has two splicing isoforms; pro apoptotic Bcl-xS and the anti-apoptotic Bcl-xL; the latter of which is upregulated in a variety of cancers. Thus, exogenous regulation of Bcl-x splicing, which biases the pathway towards the pro-apoptotic Bcl-xS isoform could provide a new a novel mechanism for cancer therapy. In 2018, Eperon and co-workers found that the ellipticine analogue GQC-05 induces a splice switch in Bcl-x towards the pro-apoptotic isoform Bcl-xS. This thesis will report the steps taken towards developing a structure activity relationship (SAR) of the interaction between GQC-05 and Bcl-x in an effort to elucidate the splice-switch mode of action. Chapter 1 discusses the biological importance of splicing and its effect on disease progression. In particular, the recent developments highlighting Bcl-x as a desirable target for novel cancer therapies. Chapter 2 describes a modular one-pot synthesis of 7H-pyridocarbazoles through sequential palladium catalysed Buchwald-Hartwig amination and direct arylation. This method was transferrable to the synthesis of carbazole natural products as well as providing a convergent step-efficient route to the known DNA intercalator, Ditercalinium. Chapter 3 explores the mechanism of the direct arylation step through designed control reactions and modelling reactivity through DFT calculations. Finally, Chapter 4 details the application of the methods developed in Chapter 2 to the synthesis of natural products Calothrixin B and Ellipticine. This chapter discusses the limitations of the one-pot synthesis on substrates that are more complex and presents a UV light mediated synthesis as a solution. Finally, the ellipticine analogues synthesised in this thesis were tested in Bcl-x in vitro splicing assays to expand the SAR of the interaction to inform the design of a structural-biological probe.
Date of Award21 Oct 2021
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorGlenn Burley (Supervisor) & John Parkinson (Supervisor)

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