Development of a Liquid Biopsy: Using a Synthetic Lectin Array for the Detection of Cancer

Cancer is the second leading cause of death worldwide with 9.6 million deaths in 2019. It is well known that early detection of cancer often leads to a better prognosis. However, due to drawbacks associated with current cancer screens (i.e. invasiveness, high false positive and negative rates) new or updated early detection methods are needed. Chapter one overviews current breast, colon, and prostate detection methods and the drawbacks associated with them. Additionally, this chapter presents an alternative detection method that utilizes an array of boronic acid functionalized synthetic lectins. We describe the development and progression of this array and show the utility of the array when discriminating known cancer associated glycans or colon cell lines. Future chapters focus on the development of a competitive dual dye screening method for the identification of prostate cancer selective synthetic lectins,) transitioning to the use of secreted rather than membrane bound glycoproteins extracts and (C) detecting and diagnosing multiple cancer types using primary human sources, i.e. tissue and blood samples. Chapter 2 reports a dual dye competitive screening method for the identification of 5 boronic acid functionalized synthetic lectins (SLs) that are selective for prostate associated targets with the goal of detecting and staging prostate cancer. This method uses differently labeled normal (RWEP-1) and diseased (PC3) cell membrane extracts in a competitive assay to identify SLs that bind to either the cancerous or non-cancerous extract but not both. Subsequent studies examined the efficacy of these new SL hits in an array format to differentiate 6 prostate cell lines. The SL array was able to, (a) classify the prostate cell lines with 83% accuracy, (b) discriminate the same cell lines based on metastatic potential (normal/ healthy, cancerous/ lowly metastatic and cancerous/ meta-static) with 96% classification accuracy, and (c) demonstrate enhanced selectivity for prostate versus colon derived cell lines. Further analysis delineated the contribution from each SL in these studies, providing a targeted SL array having potential utility as a cancer diagnostic. Chapter 3 provide evidence that the same changes in glycan expression occur on secreted and membrane bound. Having the ability to detect these changes in glycosylation allows for the development of a more liquid biopsy. Additionally, we show that synthetic lectins can be used to detect changes in glycosylation and were able to, a) classify the colon cell lines with 100% accuracy b) discriminate the same cell lines based on metastatic potential (normal, cancerous-lowly metastatic, cancerous-highly metastatic) with 98% accuracy and c) through hierarchical clustering we are able to increase the accuracy of the analysis. Chapter 4 outlines the use of the SL array with multiple cancer types and with primary human sources, such as tissue and blood. The SL array was able to discriminate breast, colon, and prostate cell line and tissue sample based on disease status with a 96% and 88% accuracy. Additionally, the array was able to discriminate blood samples based on the presence of breast and prostate cancer with a 90% accuracy. Further studies highlight the ability of a multi-dimensional analysis to study other factors such as staging and sub-typing