Investigations into intracellular mechanisms of chemokine signalling in cancer

Lai, Wing Yee (2023) Investigations into intracellular mechanisms of chemokine signalling in cancer. Doctoral thesis, University of East Anglia.

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Abstract

Aim: Chemokine signalling plays a critical regulatory role in cancer, which was found to be either tumour-promoting or tumour-suppressive. Although chemokine signalling is a potential target for anti-cancer drugs, the success in drug design is hindered by the complexity of biased signalling and signalling redundancy in the signalling system. Our aim is to understand cell-specific mechanisms and isoform-specific roles of signalling proteins underlying context-dependent chemokine signalling system in cancer cells.

Methodology: Experimentation was undertaken in breast cancer MCF-7 and MDA-MB-231 cells, leukaemic T-lymphocyte Jurkat cell and monocytic leukaemic THP-1 cells, to investigate cellular responses from the activation of endogenously expressed chemokine receptors. Small molecule inhibitors and RNA interventions were employed to determine the involvement of target proteins in cellular responses using intracellular Ca2+ mobilisation, chemotaxis and receptor internalisation assays. Immunocytochemistry was applied to reveal the change in localisation and quantities of cell surface chemokine receptors and intracellular proteins following chemokine stimulation.

Results: CXCL12-induced CXCR4 internalisation in Jurkat cells is caveolae-dependent, while CCL3-induced CCR5 internalisation in MCF-7 cells is independent of clathrin. Arrestin-2 (Arr-2) responds to CCL3 stimulation, whereas Arrestin-3 (Arr-3) responds to CXCL12 stimulation in MCF-7 cells. Inhibition of protein kinase D (PrKD) blocks Ca2+ mobilisation induced by CXCL12 in MCF-7 cells but not for THP-1 cells. Basal PrKD potentially negatively regulate actin cytoskeletal rearrangement in cell migration in MCF-7 cells.

Conclusion: Our study shows that chemokine signalling pattern vary between cancer cell types due to the activation of different receptor-chemokine partners and involvement of diverse combinations of signalling proteins in isoform-specific manner. Overall, the research in this thesis has highlighted the necessity of verifying specific signalling mechanisms in different cell lines in chemokine research.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Pharmacy
Depositing User:	Chris White
Date Deposited:	25 Oct 2023 09:36
Last Modified:	25 Oct 2023 09:36
URI:	https://ueaeprints.uea.ac.uk/id/eprint/93466
DOI:

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