| Summary: | Aim: The chemokine system not only coordinates leukocyte migration in immunity and inflammation, but it is also implicated in the pathogenesis of many human diseases, including cancer. The expression of chemokines and their receptors is altered in many malignancies and leads to aberrant chemokine receptor signalling. Emerging evidence indicates that the tumour microenvironment has critical roles in all aspects of cancer biology, including growth, angiogenesis, metastasis and progression. One of the important representatives of this system are the chemokine ligand CXCL12 and its receptor, CXCR4 as they are most commonly found on human and murine cancer cells. Our aims are to study and understand if there are any differences in activation of signalling molecules in the downstream signalling cascades in CXC- chemokine receptors in different cell types, and to identify the importance of different effector proteins in migration of cells; the two proteins of interest include Protein Kinase C (PKC) and arrestins. Methodology: Experimentation was undertaken in MCF-7 breast cancer cells and Jurkat leukemic T-lymphocytes which both naturally express the chemokine receptor CXCR4. Small molecule inhibition and protein overexpression was used in chemotaxis and calcium release assays to measure cellular responses. Immunocytochemistry was used to determine the effect of protein blocking and protein overexpression on receptor internalisation, protein localisation and the formation of cellular structures associated with migration. Results: Inhibition of PKC has no effect on Jurkat cell migration, but it blocks MCF-7 cell migration showing that there is a difference in the usage of PKC in different cell types. Arrestin 3 is important for migration in both suspension Jurkat cells and adherent breast cancer MCF-7 cells. Conclusion: Our study shows that CXCL12-induced migration may be arrestin 3 mediated. We have also shown that activation of signalling molecules needed for CXCL12-induced migration can differ between different cell lines. Overall, the research in this thesis has identified potential signalling molecules that can be targeted to interfere with migration of cells.
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