Investigating Notch and Related Pathways for New Biomarkers in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is the 5th commonest cause of cancer related death in the UK with a 5-year survival rate of only 4%. This is due to vague symptoms, late presentation and lack of availability of decent biomarkers, making most PDAC unsuitable for curative resections at the time of diagnosis. Therefore, there is an urgent need for new biomarkers. Previous work in our lab has shown that Notch 1, Notch 3 and Notch 4 signalling pathway are upregulated in PDAC compared to normal pancreas. The aim of this this study was to examine the Notch signalling pathway and related miRNAs as potential biomarkers for PDAC. In this thesis, we describe the method development of a process of detecting Notch Nβ-fragments in the plasma of human at concentrations of 121.67 fmol/μL. Notch Nβ-fragments are released between the two cleavage sites S3 and S4 as part of γ-secretase mediated cleavages following ligand activation. We could detect Notch 3 Nβ-fragments in plasma of PDAC and healthy volunteers but were unable to find any statistically significant differences between them. We were unable to detect Notch 1 Nβ-fragments. We investigated Notch 2 expression in human tissue samples using immunohistochemistry and found Notch 2 to be upregulated in resectable PDAC and further upregulated in non-resectable locally advanced cancer, but down regulated in metastatic PDAC tissue in comparison to non-resectable locally advanced tissue. This suggests the role of Notch 2 proteins as diagnostic and prognostic biomarkers. Using RT-PCR we identified miR-200c, miR–155a and miR–375 which could help differentiate between the plasma of healthy volunteers, PDAC and chronic pancreatitis (CP). Adding age to a binary logistic regression model we could differentiate between PDAC and CP achieving ROC curve values of above 0.95. This suggests the role of these miRNAs as diagnostic biomarkers.