The expression and activity of thymidine kinase 1 and deoxycytidine kinase are modulated by hydrogen peroxide and nucleoside analogs

A series of 4'-C-(hydroxymethyl) analogs of pyrimidine and purine nucleosides have been prepared utilizing standard methodologies, and the α and β anomers were separated. These analogs are part of our continuing efforts to identify new anticancer drugs as well as to explore the substrate specificities of these analogs with the initial activating enzymes in the metabolic pathway leading to nucleoside triphosphates. Although not cytotoxic to CCRF-CEM cells (an acute lymphoblastic leukemia of T-cell origin), many of these compounds were utilized as substrates for the various human nucleoside kinases, including deoxycytidine kinase, thymidine kinase 1, and thymidine kinase 2. Because the 4'-C-(hydroxymethyl) analog of arabinofuranosyl cytosine was identified as a good substrate with deoxycytidine kinase, its metabolism in CEM cells was evaluated. These results indicated that nucleosides with this modification could be activated in human cells without cytotoxicity, which suggested that they should be examined for antiviral activity.

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Feline thymidine kinase 1: molecular characterization and evaluation of its serum form as a diagnostic biomarker

BMC Veterinary Research ◽

10.1186/s12917-021-03030-5 ◽

2021 ◽

Vol 17 (1) ◽

Author(s):

Liya Wang ◽

Hanan Sharif ◽

Sara Saellström ◽

Henrik Rönnberg ◽

Staffan Eriksson

Keyword(s):

Thymidine Kinase ◽

Inflammatory Disease ◽

High Efficiency ◽

Specific Activity ◽

High Specific Activity ◽

Nucleoside Analogs ◽

Response To Treatment ◽

Malignant Diseases ◽

Diagnostic Biomarker ◽

Thymidine Kinase 1

Abstract Background Thymidine kinase 1 (TK1) catalyzes the initial phosphorylation of thymidine in the salvage pathway synthesis of dTTP, an essential building block of DNA. TK1 is a cytosolic enzyme with its highest level during the S-phase of the cell cycle. In cancer cells TK1 is upregulated and excess TK1 is leaked into the blood. Therefore, serum TK1 has been used as biomarker for cancer diagnosis and prognosis in human medicine. Feline TK1 shows high sequence similarity to TK1 from other species. The aim of this study was to characterize feline TK1 and evaluate if serum TK1 can be used as a diagnostic biomarker. Results Feline TK1 was cloned, expressed and affinity purified. The purified feline TK1 phosphorylated not only pyrimidine deoxyribonucleosides but also pyrimidine ribonucleosides and to some extent purine deoxynucleosides. A number of anticancer and antiviral nucleoside analogs also served as substrates with fairly high efficiency. ATP and dATP were the preferred phosphate donor. Serum TK1 activity in felines with malignant diseases was significantly higher than that in healthy individuals. ROC analysis revealed an area under the curve (AUC) of 0.98 with a sensitivity of 0.83 and a specificity of 0.95 for felines with lymphoma. Serum TK1 activity in felines with IBD or inflammatory disease was within the same range as healthy ones. Furthermore, in felines with lymphoma serum TK1 activity returned to normal levels in response to treatment. Conclusion Feline TK1 has high specific activity and a broader substrate specificity in comparison with TK1 from other species. Serum TK1 activity in felines with malignant diseases is significantly higher than that in normal felines and in felines with inflammatory diseases. These results suggest that serum TK1 may be a promising biomarker for the diagnosis and monitoring of malignant diseases and for the differential diagnosis of certain inflammatory disease.

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Unique Metabolism of a Novel Antivirall-Nucleoside Analog, 2′-Fluoro-5-Methyl-β-l-Arabinofuranosyluracil: a Substrate for Both Thymidine Kinase and Deoxycytidine Kinase

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.42.4.833 ◽

1998 ◽

Vol 42 (4) ◽

pp. 833-839 ◽

Cited By ~ 42

Author(s):

Shwu-Huey Liu ◽

Kristie L. Grove ◽

Yung-Chi Cheng

Keyword(s):

Thymidine Kinase ◽

Nucleoside Analogs ◽

Nucleoside Analog ◽

Nucleoside Transport ◽

Deoxycytidine Kinase ◽

Barr Virus ◽

B Virus ◽

Antiviral Activities ◽

Epstein Barr ◽

Low Cytotoxicity

ABSTRACT 2′-Fluoro-5-methyl-β-l-arabinofuranosyluracil (l-FMAU) is the first l-nucleoside analog with low cytotoxicity discovered to have potent antiviral activities against both hepatitis B virus and Epstein-Barr virus but not human immunodeficiency virus. This spectrum of activity is different from those of the other l-nucleoside analogs examined.l-FMAU enters cells through equilibrative-sensitive and -insensitive nucleoside transport as well as through nonfacilitated passive diffusion. l-FMAU is phosphorylated stepwise in cells to its mono-, di-, and triphosphate forms. In the present study the enzymes responsible for the first step of l-FMAU phosphorylation were identified. This is the first thymidine analog shown to be a substrate not only for cytosolic thymidine kinase and mitochondrial deoxypyrimidine kinase but also for deoxycytidine kinase. This finding suggests that the antiviral activity of l-FMAU will not be limited by the loss or alteration of any of these deoxynucleoside kinases.

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