Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.784843
Title: Comparative immunohistochemical and molecular investigations of metabolic and stromal events in HPV positive and HPV negative oropharyngeal squamous cell carcinoma
Author: Ben Salah, K. S.
ISNI:       0000 0004 7970 3883
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2018
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Abstract:
Background: It has been shown that HPV positive (HPV+) oropharyngeal squamous cell carcinoma (OPSCC) are characterised by extensive nodal disease, but are associated with significantly better prognosis than HPV negative (HPV-) OPSCC. It has also been proposed that glycosaminoglycans (GAGs) and myofibroblasts are components of the desmoplastic stroma that characterizes many advanced carcinomas. They are considered to play an important role in the pathogenesis of head and neck squamous cell carcinomas (HNSCC) and their presence is of high prognostic value. A 'three compartment tumour metabolism' model has been proposed in head and neck cancer comprising a proliferative, monocarboxylate transporter1 (MCT1)-expressing carcinoma cell population at the tumour advancing front (front) with both a deeper population of monocarboxylate transporter 4 (MCT4)+ cancer cells and (MCT4)+ cancer associated fibroblasts (CAFs) providing a source of metabolic fuels via a lactate shuttle. This thesis investigates the presence and distribution of GAGs and myofibroblasts in HPV+ and HPV- OPSCC, and their correlation with clinicopathological features. We also investigate the metabolic activities of OPSCC in relation to HPV status. Materials and methods: The metabolic status of 45 HPV+ and 63 HPV- OPSCC was determined by immunohistochemical staining using antibodies to MCT1, MCT4, Cell proliferation (Ki-67), and mitochondria (TOMM20). Results: The presence of desmoplasia was determined by histological examination of H&E stained whole sections and by Alcian Blue staining at pH 2.5 (GAGs) and alpha smooth muscle actin (aSMA: myofibroblasts). Histopathological staining of tissue micro array (TMAs) from archival tissue blocks of 45 patients with HPV+ and 63 with HPV- OPSCC. Only in HPV+ OPSCC, depth of invasion correlated with the presence of histologically defined desmoplasia at both the tumour core and front (p<0.0005 and p=0.045), but these associations were not observed for individual components of desmoplasia determined by histopathological methods. Data from HPV+ OPSCCs shows that GAGs are more often found at the tumour front and was generally less prevalent at the tumour core (65% in the front vs 48% in tumour core), whereas in HPV- OPSCC the converse was true. Myofibroblasts are found throughout these tumours, which suggests that the invasion process in HPV+ OPSCCs is mainly driven by GAGs and myofibroblasts are more bystanders. The presence of myofibroblasts in the tumour core is distinctive for HPV+ OPSCC and may indicate that this cell type plays a different role in these tumours compared with HPV- OSCC. No correlation was observed between histological desmoplasia and survival outcome in OPSCC. Using (TMAs) we assessed levels of MCT1, MCT4, Ki-67 and TOMM20 and their intracellular distribution. We were able to show that carcinoma cells in both HPV+ and HPV- OPSCC are highly proliferative, rich in mitochondria and consume mitochondrial fuels (Ki-67+ /TOMM20+ /MCT1+). These proliferating cells co-exist with non-proliferating stromal cells which express MCT4 and, presumably, excrete metabolic fuels. Although all CAFs in HPV+ tumours were strongly TOMM20 positive only 58% of CAFs in HPV- OPSCCs were (p = 0.005). While 85% of HPV+ OPSCC tumours co-express MCT1 and MCT4 in the same cells, only 50% of HPVOPSCC do so, indicating that the three compartment model is more compatible with data from HPV- OPSCC. Strong MCT4 CAF immunoreactivity was less prevalent in HPV- than in HPV+ OPSCCs (p = 0.031). By means of co-culturing between two epithelial cancer cells and two fibroblasts with different HPV, and probing for MCT1 and MCT4, up-regulation of MCT1 was achieved in the epithelial cancer cell lines when co-cultured with fibroblasts originating from HPV- tumours. Based on tissue data and preliminary functional data, there may be some differences in metabolism in HPV+ and HPV- tumours. Conclusions: Carcinoma cells in both HPV+ and HPV- OPSCC are highly proliferative, rich in mitochondria and consume mitochondrial fuels (Ki67+/TOMM20+/MCT1+). These proliferating cells co-exist with non-proliferating stromal cells which express MCT4 and, presumably, excrete metabolic fuels. While 85% of HPV+ OPSCC tumours co-express MCT1 and MCT4 in the same cells, only 50% of HPV- OPSCC do so, indicating that the three compartment model is more compatible with data from HPV- OPSCC. Differences in the stromal compartment metabolism are also observed between HPV+ and HPV- tumours.
Supervisor: Risk, Janet M. ; Triantafyllou, Asterios ; Shaw, Richard ; Schache, Andrew Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.784843  DOI:
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