Potent Sensitisation of Cancer Cells to Anticancer Drugs by a Quadruple Mutant of the Human Deoxycytidine Kinase

Abstract

Identifying enzymes that, once introduced in cancer cells, lead to an increased efficiency of treatment constitutes an important goal for biomedical applications. Using an original procedure whereby mutant genes are generated based on the use of conditional lentivector genome mobilisation, we recently described, for the first time, the identification of a human deoxycytidine kinase (dCK) mutant (G12) that sensitises a panel of cancer cell lines to treatment with the dCK analogue gemcitabine. Here, starting from the G12 variant itself, we generated a new library and identified a mutant (M36) that triggers even greater sensitisation to gemcitabine than G12. With respect to G12, M36 presents an additional mutation located in the region that constitutes the interface of the dCK dimer. The simple presence of this mutation halves both the IC50 and the proportion of residual cells resistant to the treatment. Furthermore, the use of vectors with self-inactivating LTRs leads to an increased sensitivity to treatment, a result compatible with a relief of the transcriptional interference exerted by the U3 promoter on the internal promoter that drives the expression of M36. Importantly, a remarkable effect is also observed in treatments with the anticancer compound cytarabine (AraC), for which a 10,000 fold decrease in IC50 occurred. By triggering the sensitisation of various cancer cell types with poor prognosis to two commonly used anticancer compounds M36 is a promising candidate for suicide gene approaches.

Bortezomib prevents cytarabine resistance in MCL, which is characterized by down-regulation of dCK and up-regulation of SPIB resulting in high NF-κB activity

“…DCK enzymatic activity is controlled by phosphorylation at Ser-74 [ 29 ], and dephosphorylation decreases enzyme activity [ 30 ]. A more active mutant of dCK, with a 10,000-fold increased sensitivity to nucleoside analogues has been created and could be of interest for suicide gene approaches [ 10 , 31 ]. Of note, in our hands forced overexpression of dCK had a direct effect on sensitivity to cytarabine in our model, indicating that protein levels govern resistance but that post-translational modification adjust the level of resistance.…”

Pharmacogenetics of hepatocellular carcinoma and cholangiocarcinoma

“…Deoxycytidine kinase (DCK) catalyzes the first rate-limiting phosphorylation step in the activation of deoxycytidine analogs. The combination of three mutations, c.511G>A (p.Glu171Lys), c.739G>A, (p.Glu247Lys) and c.745G>A (p.Leu249Met) in DCK sensitizes a panel of cancer cell lines to treatment with gemcitabine [ 104 ] .…”