ABSTRACT
The aim of this study is to investigate these enzymes as possible biomarkers in two colorectal cancer cell lines: HT29, SW480, SW620, and Colo205. With 1,168,929 individuals currently diagnosed with colorectal cancer in the United States, there remains a need to find biomarkers to improve diagnosis and expand treatment options for patients. Due to their role in proliferation and cell cycle regulation, we hypothesized an increase in salvage pathway enzyme (APRT, DCK, and HPRT) expression and possible presentation within colon cancer cells. Enzyme surface localization was assessed utilizing confocal microscopy, flow cytometry, and scanning electron microscopy. General protein expression was evaluated utilizing immunohistochemistry and Western blot analysis. While we found no statistically significant presence of either APRT or DCK on the membranes of SW620, Colo205, and HT29 cells, but found significant expression of HPRT on the surface of HT29, SW480, and SW620 cells. The average population fluorescence increased by 28%, 58%, and 40% in HT29, SW620, and SW480 cells, respectively, when compared to isotype controls. Confocal microscopy images revealed direct overlap between SW620 cells stained with a membrane dye and anti-HPRT antibody, indicating co-localization on the plasma membrane. In addition, cells treated with gold labelled HPRT antibody experienced significant changes in gold weight percentage on both SW620 and HT29 cells when compared to isotype controls. When evaluating expression within normal tissue, there was insignificant levels of HPRT binding. These data collectively suggest that HPRT may be a possible biomarker target for the identification and treatment of colorectal cancer.
Abbreviations
HPRT | = | Hypoxanthine Guanine Phosphoribosyltransferase |
APRT | = | Adenine Phosphoribosyltransferase |
DCK | = | Deoxycytidine Kinase |
GSE | = | Gaseous Side Electron |
BSE | = | Back Scatter Electron |
EDAX | = | Energy Dispersive Spectroscopy |
Acknowledgments
We would like to acknowledge Michael D. Anderson for conducting the staining of cells for scanning electron microscopy analysis.
We would also like to thank a team of doctors at the Utah Valley Regional Medical Center for providing healthy tissue samples.
Disclosure of Potential Conflicts of Interest
The authors declare that they have no competing interests
Ethics approval and consent to participate
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.