Thesis

Chemical synthesis and pharmacological testing of novel CXCL12 inhibitors with characterisation of signalling pathways regulating CXCL12 expression in bone cancer

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Awarding institution
  • University of Strathclyde
Date of award
  • 2025
Thesis identifier
  • T17458
Person Identifier (Local)
  • 202166623
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Abstract
  • The chemokine, CXCL12 (SDF-1), is produced by diverse cell types and promotes cancer progression within the tumour microenvironment through its effects. A number of inhibitors for the CXCL12 receptor, CXCR4, have been developed for the treatment of certain cancers. However, these drugs have limited clinical success and toxicity issues, raising concerns about long-term effects. Studies have shown the essential role of MAPK and NF-κB pathways in the regulation of chemokine production. Therefore, the current study aimed to investigate the role of MAPK and the NF-B pathway in the regulation of CXCL12 induced by IL-1β in the human osteosarcoma cell line (U2OS) model. Furthermore, a preliminary study of 5000 commercial compounds assessed for inhibition of IL-1β-induced CXCL12 reporter activity identified a number of hits. Thus, an additional part of the thesis aimed to synthesise and pharmacologically evaluate novel CXCL12 inhibitors and examine their mechanism (s) of inhibition. Initially, the target KM compounds were successfully synthesised, and thermal stability analysis showed constant temperature stability. These compounds were candidates for pharmacological studies following assessment of signalling cascades in IL-1β-induced CXCL12 expression in the latter part of the thesis In validating candidate signalling pathways studies showed no role for JNK and p38 MAPK in CXCL12 regulation. IL-1β strongly stimulated the IKKα-dependent NFκB pathway, which aligns with previous research. Pharmacological inhibition of TAK-1 and IKK alpha implicated IKK alpha in CXCL12 induction, with no discernible role of IKKβ-dependent NFκB pathway. However, molecular experiments using siRNA knockdown confirmed that whilst siRNA IKKα plays an essential role in non-canonical pathway regulation, it does not impact CXCL12 induction. This suggests that with respect to CXCL12 regulation, the compounds SU1261 and 5Z-7-oxo exhibit off-target effects. Surprisingly, MEKK3, which has no regulatory involvement in any IL-1-induced MAPK or NFB pathway was implicated in CXCL12 induction. Synthesised CXCL12 inhibitors were characterised, two compounds, KM8 and KM11, showed significant inhibition of CXCL12 production stimulated by IL-1β. For these compounds, inhibition of CXCL12 induction did not correlate with any effects on MAPK or NFB pathways, which were not affected. This implies inhibition of another pathway leading to CXCL12 induction, possibly MEKK3 or another axis.
Advisor / supervisor
  • Plevin, Robin
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