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Title: The role of Fanconi anaemia genes in head and neck squamous cell carcinoma
Author: Alsobahi, Fatmah
ISNI:       0000 0004 7233 8545
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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Background: Fanconi Anaemia (FA) is an autosomal or X-linked rare inherited recessive disease caused by defective mutation in one of 21 different genes. FA genes are involved in the DNA damage response and when mutated result in chromosomal instability. Patients with Fanconi Anaemia are found to be at high risk of developing Head and Neck squamous cell carcinoma (HNSCC). Given the relative specificity of this effect, we hypothesized that alterations in the expression and posttranslational activation of FANC genes contribute to the pathogenesis of non-FA HNSCC. Aims: Firstly to determine if the expression of FANC genes are altered in non-FA HNSCC, then to define the effect of the alterations in FANC genes on both FA HNSCC and non-FA HNSCC cells in response to DNA damaging agents. Finally, to identify possible factors in the oral environment which may cause DNA damage. Methods: mRNA and protein expression level were measured for different FA-associated genes in normal oral keratinocytes, FA and non-FA HNSCC cells and immunohistochemistry was used to assess protein expression of FANCA, FANCC, FANCD2, and KI67 in normal oral mucosa, non-FA HNSCC and FA-HNSCC tissues. Then, mRNA and protein expression were measured before and after cisplatin treatment of HNSCC cells. Immunofluorescence and comet assay were used to assess DNA damage before and after cisplatin and Lipopolysaccharide from Porphyromonas gingivalis (LPS-PG) treatment. Mitochondrial reactive oxygen species production was assessed in cells after treatment with LPS-PG. Results: FANC genes showed significantly higher mRNA and protein expression in non-FA HNSCC compared to normal. In addition, the expression of FANCD2, FANCA and FANCC were higher in non-FA HNSCC tissues compared to normal tissue. Cells treated with cisplatin showed significantly higher expression of FANCA, FANCC and FANCD2 compared to untreated while only non-FA HNSCC showed significant reduction after washout. FANCD2, 53BP1 and ?H2AX nuclear foci and DNA fragmentation were increased in non-FA HNSCC and FA-HNSCC, however the DNA damage were largely repaired in non-FA HNSCC compared to FA-HNSCC after washout. Cells treated with LPS-PG showed a similar phenotype. Reactive oxygen species showed a significant increase after treatment with LPS-PG in both non-FA and FA-HNSCC. Conclusion: Expression of certain FANC genes are altered in non-FA HNSCC. Activation of the FA pathway in response to DNA damage occurs in non-FA HNSCC, but not FA-HNSCC after treatment with Cisplatin and LPS-PG. The current study provides evidence that LPS-PG leads to the production of superoxide by damaging the mitochondria. This data provides novel insight into the reason behind increased the risk of developing HNSCC in FA patients.
Supervisor: Hunter, Keith Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available