Abstract

Despite the global effort to discover and improve ways to detect, treat, and monitor cancer, it still remains the second leading cause of death in the United States and poses a major health and economic burden worldwide. While traditional treatments like surgery, chemotherapy, radiation therapy, and hormone therapy have been successful and have decreased cancer mortality, cancer incidence in all sites continues to rise. Consequently, there is an immediate need to find new therapeutics for the treatment of cancer. In recent years, and with the continuing push towards personalized medicine, cancer biomarkers have become crucial to detect, treat, and monitor cancer. Thymidine kinase 1 (TK1) has been identified as a cancer biomarker with diagnostic, prognostic, and therapeutic potential. TK1 is a nucleotide salvage pathway enzyme responsible for maintaining a balance in the cell nucleotide pool and providing the cell with thymidine monophosphate, which upon further phosphorylation is incorporated into DNA during cell replication. TK1 has been found to be upregulated in the serum of cancer patients. Serum TK1 (sTK1) has been used as an early diagnostic and prognostic biomarker in many types of cancer and has been shown to be a better proliferation biomarker than Ki67. In this dissertation, we described the characterization of TK1 as a cancer biomarker that associates with the plasma membrane of hematological malignancies such as Burkitt's lymphoma, acute lymphoblastic leukemia, acute promyelocytic leukemia, acute T cell lymphoma, and solid malignancies such as lung, breast, and colon cancer. We also describe the different oligomeric TK1 forms that are found on the cell membrane and show that membrane TK1 has activity. We assess the clinical relevance of TK1 in all these malignancies, looking at tissue expression as well as gene expression from patients from The Cancer Genome Atlas database. We find that TK1 is not expressed on the surface of normal cells, whether they are proliferating or not, making TK1 a unique cancer biomarker, with the potential to be used in targeted therapy. We also find that TK1 expressed on the surface may be involved in the invasion potential of cancer cells. The knowledge gained from this study will help researchers working in clinical research and cancer immunotherapeutics to potentially use TK1 as a biomarker and cancer target, and thus providing another weapon against cancer. In this dissertation, we described the characterization of TK1 as a cancer biomarker that associates with the plasma membrane of hematological malignancies such as Burkitt's lymphoma, acute lymphoblastic leukemia, acute promyelocytic leukemia, acute T cell lymphoma, and solid malignancies such as lung, breast, and colon cancer. We also describe the different oligomeric TK1 forms that are found on the cell membrane and show that membrane TK1 has activity. We assess the clinical relevance of TK1 in all these malignancies, looking at tissue expression as well as gene expression from patients from The Cancer Genome Atlas database. We find that TK1 is not expressed on the surface of normal cells, whether they are proliferating or not, making TK1 a unique cancer biomarker, with the potential to be used in targeted therapy. We also find that TK1 expressed on the surface may be involved in the invasion potential of cancer cells. The knowledge gained from this study will help researchers working in clinical research and cancer immunotherapeutics to potentially use TK1 as a biomarker and cancer target, and thus providing another weapon against cancer.

Degree

PhD

College and Department

Life Sciences; Microbiology and Molecular Biology

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2018-06-01

Document Type

Dissertation

Handle

http://hdl.lib.byu.edu/1877/etd10151

Keywords

thymidine kinase 1, TK1, cancer biomarker

Language

english

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Included in

Microbiology Commons

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