PROSTATE CANCER CELL CAPTURE USING IMMOBILIZED INHIBITORS OF PROSTATE-SPECIFIC MEMBRANE ANTIGEN
Prostate cancer, especially its metastasis to the bone, is the leading cause of death for men in the US. The development of bone metastasis is a complex process that is potentially established by prostate circulating tumor cancers (PCTCs) through the lymphatic system and the blood circulation system. These PCTCs in the circulation represent an intrinsic property of the tumor and can provide unique information related to the nature of the prostate tumors. Unfortunately, current information that is gathered for detecting, isolating, and enriching PCTCs, which based on the epithelial cell adhesion molecule (EpCAM) as a biomarker, is limited and controversial. The main reason is that the invasive PCTCs lose the EpCAM antigens during the epithelial mesenchymal transition (EMT) in the metastatic process. On the other hand, prostate-specific membrane antigen (PSMA), has been recognized as the most well-established biomarker for prostate cancer. Its utilization as a novel target in both diagnostic and therapeutic interventions is intriguing. However, there are limited amounts of research on its usages as a validated biomarker in PCTC isolation, enrichment and detection. Herein, the thesis will focus on two studies, which are the detection of prostate tumor cells using chemoafinity labels and cell capture using immobilize inhibitor of PSMA. We have successfully demonstrated the specific binding to PSMA on prostate cancer cells by a fluorescent phosphoramidate PSMA inhibitor and the quantification and detection of prostate cancer cells in blood by flow cytometry. In addition, we have illustrated that the irreversible PSMA inhibitor biotin-PEG12-CTT-54 can effectively serve as a pre-targeting bait to capture of PSMA+ cells using stretptavidin coated magnetic beads. High selectivity, recovery, and viability was achieved for the capture of PSMA+ cells in both model experiments with mixtures of LNCaP cells and WBCs as well as blood samples spiked with LNCaP cells. More importantly, captured cells could be subsequently propagated in vitro. This methodology for the detection, isolation, and culture of PCTCs from peripheral blood can serve as an effective tool for the detection of metastatic prostate cancer, treatment monitoring, and the development of personalized therapy based on the responsiveness of PCTCs to chemotherapeutic strategies.