An Assessment of Universal Tumour Associated Antigens in Primary Liver Neoplasms

Abstract

Rates of primary liver cancer are increasing in the Western world, a fact yet to be reflected in research with most currently undertaken in Asia. Whilst here in the UK, during a diagnostic and therapeutic workup within the NHS, surgically resected tumours are routinely kept in storage for up to thirty years. Meaning there is a huge, currently unused, resource that could potentially be included in clinical research. The regional specialist centre in the Southwest of England has been performing liver resections since 2005, no basic-science research has been performed using these archived specimens. In this research I have assessed the presence of genetic alterations, attempted to quantify the transcriptome, and measured protein expression in patients with liver cancer using a digital pathology platform. Telomerase and Survivin, the two targets of these endeavours, have previously been shown to be expressed in numerous cancer types, earning the title ‘universal tumour associated antigen.’ The techniques used in this research project are, mostly, already used in healthcare diagnostics, meaning there is potential for vastly increasing the power of these results should the study be increased. Genetic alterations in the promoter sequences were amplified and sequenced using DNA from archived samples. Attempts to quantify the transcribed component which have been locked away in tiny exosomes (which lack degradation enzymes) were made using a quantitative polymerase chain reaction. Protein expression was detected in tumours and background liver tissues using immunohistochemistry and quantified using digital pathology techniques on whole-slide images. Haematological protein levels were assessed using the enzyme linked immunosorbent assay. All of these characteristics were then compared with clinical measures such as tumour size, grade, stage, vascular invasion, overall survival, and diseases associated with liver carcinogenesis. Lessons learned from my work, particularly the techniques used on the source material, could be used in any NHS department without the need for significant financial investment required for a formal research facility. Access to these precious resources allows a more accurate representation of these antigens in the local clinical cohort. Below I have provided evidence that Telomerase promoter mutations are an HCC-specific alteration, and are present in tumours with vascular invasion. There is also early evidence that these mutations may correlate with a reduced overall survival. The Survivin promoter has been found to be a germline characteristic, whilst Survivin protein expression has been found to correlate with numerous adverse clinical features including tumour stage, grade, vascular invasion, perineural invasion and overall survival. These results are very encouraging and could possibly even be used as a risk-stratification tool during future routine clinical liver tumour workup, as an aid to identify patients at a higher risk of adverse clinical outcomes.