Molecular indicators and tumour models of extracapsular spread in metastatic oral squamous cell carcinoma



Molecular indicators and tumour models of extracapsular spread in metastatic oral squamous cell carcinoma. PhD thesis, University of Liverpool.

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Abstract

Introduction Extracapsular spread (ECS) is the single most adverse prognosticator for recurrence and death in metastatic oral squamous cell carcinoma (OSCC) and relapse is common in both primary and metastatic sites. It is rarely exploited for biological investigation with limited study of its molecular determinants and the absence of a tumour model. The absence of a biomarker also means exhaustive histological examination after surgery is required for diagnosis. ECS is a late manifestation of the metastatic cascade and would be expected to be intimately related to interactions between tumour cells and the microenvironment. The importance of the tumour microenvironment has been highlighted by the discovery of a promising new stromal biomarker, alpha smooth muscle actin (ASMA), which has shown even greater prognostic value than ECS. The aims of this study are to identify and validate biomarkers for ECS and to develop and utilise ECS+ve primary cell culture-derived cell lines in organotypic models to investigate epithelial and mesenchymal interactions. Methods 102 patients treated with primary surgery for OSCC were utilised for biomarker discovery and validation. Diagnostic accuracy of MRI scanning for ECS was determined and compared to a previously determined 8-gene expression signature from primary site tissue, which was validated using quantitative real-time polymerase chain reaction (qRT-PCR). SERPINE1 and ASMA expression was assessed for prognostic capability by immunohistochemistry (IHC) on a case-matched tissue microarray with separate analysis of the tumour centre and the advancing-front. The explant technique was used with cell-type specific media to isolate fibroblast and keratinocyte single-cell populations from 47 OSCC biopsy tissues. Metastatic status of the originating tumours was correlated with establishment of cell lines, cell phenotypes, proliferation index, invasion in organotypic cultures and drug sensitivities. Short tandem repeat profiling and microsatellite instability analysis were used to determine the tissue of origin. Results MRI (n=88) showed very poor sensitivity for the detection of ECS (7%), while the 8 gene signature had a sensitivity of 78%. The qRT-PCR findings poorly correlated with the microarray findings, but SERPINE 1 and HEXIM1 were selected for IHC as the best performing genes from prediction models using receiver operating characteristic curves (AUC 0.59 and 0.64 respectively). IHC indicated that both SERPINE1 and ASMA expression at the tumour-advancing front was highly significantly associated with nodal/ECS status (p10 passages and both were associated with ECS and distant metastasis (p

Item Type: Thesis (PhD)
Additional Information: Date: 2014-07 (completed)
Uncontrolled Keywords: oral cancer, tumour models, biomarkers
Divisions: Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology
Depositing User: Symplectic Admin
Date Deposited: 09 Dec 2015 16:36
Last Modified: 17 Dec 2022 00:13
Supervisors:
  • Dhanda, Jagtar
URI: https://livrepository.liverpool.ac.uk/id/eprint/19295