Thesis

Regulation of human CXCL12 expression by IKK? in bone cancer and cancer associated fibroblasts derived from clinical specimens obtained from breast cancer patients

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Awarding institution
  • University of Strathclyde
Date of award
  • 2018
Thesis identifier
  • T15120
Person Identifier (Local)
  • 201450532
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Department, School or Faculty
Abstract
  • Despite great progress in surgery, radio- and chemotherapy, the prognosis and treatment options for osteosarcoma and breast cancer remain extremely poor with a high inclination for metastatic spread to other organs. Compelling evidence has demonstrated that CXCL12/CXCR4 is implicated in human tumour pathogenesis. Therefore, targeting CXCL12 expression is a logical strategy for treating cancer patients.;Moreover, studies have implicated inhibitory Kappa B kinase alpha (IKK?) as a key regulator in the non-canonical NF-?B pathway and it has recently been demonstrated that IKK? can regulate CXCL12 expression. Therefore, the aim of the current study was to investigate the role of the IKK?-mediated non-canonical NF-?B pathway in the regulation of CXCL12 expression in a human bone osteosarcoma cell line (U2OS) and cancer-associated fibroblasts (CAFs) derived from clinical specimens obtained from human breast cancer patients to determine the validity of this approach.;Initially, newly synthesised selective IKK? inhibitors (SU compounds) were characterised in LT?1?2-stimulated U2OS cells and were shown to be moderately potent and selective for the non-canonical NF-?B pathway, whereas they exerted little effect on the classical NF-?B pathway at high micromolar concentrations. In addition, it was unexpectedly found that both TNF? and IL-1? were strong and early activators of the non-canonical NF-?B pathway activated by IKK?, which was established using both siRNA and the selective inhibitors.;Both TNF? and IL-1? but not LT?1?2, stimulated a strong increase in CXCL12 in reporter U2OS cells and when endogenously measured using RT-qPCR. CXCL12 expression was susceptible to both siRNA knock down and IKK? inhibitors, suggesting that the early strong IKK? signal was significant for expression.;We further examined the role of IKK? in CXCL12 expression in CAFs derived from breast cancer patients. ELISA data revealed that CXCL12 protein secretion in CAFs was significantly higher than that of normal fibroblasts (NFs). However, our findings did not demonstrate a significant difference in the activation of the non-canonical NF-?B pathway by LT?1?2. Moreover, the studies conducted using siRNA IKK? and SU compounds showed that CXCL12 expression was not altered in CAFs or NFs. Overall, these findings indicate that IKK? is not required for the regulation of CXCL12 expression in CAFs.;Taken together, these results highlight a novel early kinetically distinct mode of non-canonical NF-?B signalling by IKK?, which is significant in the induction of CXCL12 in bone cells. Therefore, selective IKK? inhibition may be a target for cancer therapy but only for certain types of cancer and is not always linked to CXCL12 inhibition.
Advisor / supervisor
  • Paul, Andy
  • Plevin, Robin
Resource Type
Note
  • This thesis was previously held under moratorium from 12/02/19 to 21/05/2021.
DOI
Date Created
  • 2018
Former identifier
  • 9912691391602996

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