Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.755286
Title: Functional role of the chemokine receptor XCR1 and its bioengineered ligand in Oral Squamous Cell Carcinoma (OSCC)
Author: Abdullah Zubir, Amir Zaki
ISNI:       0000 0004 7428 2848
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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Abstract:
Introduction: XCR1 is a chemokine receptor that is activated by the chemokine lymphotactin (hLtn) and has been shown to play an important role in oral squamous cell carcinoma (OSCC) and a few other cancers. hLtn is a metamorphic protein which interconverts between two distinct protein conformations in physiological conditions, where one has the canonical chemokine fold while the other forms a dimer. Due to the complexity, the mechanism of action and precise role of each hLtn conformation in context of cancer is unknown. Aim: Examine the role of XCR1 and its ligand hLtn in OSCC as well as understanding the function of different hLtn conformations in the disease. Methods: Immunohistochemistry was performed on primary and metastatic OSCC tissue sections. Autocrine regulation of XCR1 by hLtn of oral cancer cell lines (OCCL) was investigated using qPCR and flow cytometry. Additionally, the role of tumour microenvironment on XCR1 expression was also investigated using an indirect coculture of fibroblasts (inactive, stimulated, cancer-associated and senescent) with OCCL. Recombinant hLtn variants were designed, produced and purified. The activity of the variants was determined using intracellular calcium flux and functional assays including proliferation, adhesion (collagen I and IV, and fibronectin) and cell migration/chemotaxis assays to study the effect of bioengineered hLtn variants on OCCL. Results: XCR1 and hLtn expression was seen in basal epithelial cells in normal oral mucosa ex vivo and both were upregulated in primary and metastatic carcinoma. Exposure of OCCL (H357 and SCC4) to hLtn in vitro cause a decrease in XCR1 expression. Conditioned media from cancer-associated fibroblasts but not myofibroblasts upregulated the expression of XCR1 and hLtn mRNA in OCCL. Interestingly, senescent fibroblasts downregulate the expression of XCR1 and hLtn in SCC4 cells. hLtn CC3 mutant, with the canonical chemokine fold was highly functional and facilitated proliferation and migration through XCR1. The W55D mutant dimer caused minimal cell proliferation suggesting possible receptor dimerization. Conclusions: These findings confirm that XCR1 and hLtn are expressed in both primary and metastatic OSCC ex vivo. XCR1 expression regulation by its ligand hLtn and crosstalk with fibroblasts are novel findings suggesting a close association with tumour microenvironment. A novel method was used to produce and purify hLtn variants which stimulated OCCL proliferation, adhesion and migration. These discoveries confirm and build upon previous studies and suggest that the hLtn/XCR1 axis may have a bigger role in OSCC biology than originally envisaged.
Supervisor: Khurram, Syed Ali ; Wong, Tuck Seng ; Whawell, Simon Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.755286  DOI: Not available
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