Gemcitabine resistance due to deoxycytidine kinase deficiency can be reverted by fruitfly deoxynucleoside kinase, DmdNK, in human uterine sarcoma cells

Purpose: Cytotoxic nucleoside analogues are widely used in the treatment of cancers. Resistance to these compounds is frequent and often multifactorial. Deficiency in deoxycytidine kinase (dCK), the rate-limiting activating enzyme, has been reported in a number of in vitro models as well as in various clinical situations. Some strategies to overcome this mechanism of resistance have been proposed there by gene transfer based therapy. Methods: We have developed and characterized a gemcitabine-resistant cell line (Messa 10 K) from the human uterine sarcoma Messa strain, and transfected this cell line with the multisubstrate deoxynucleoside kinase from Drosophila melanogaster (DmdNK) in order to revert the resistance in Messa 10 K cells which was due to dCK-deficiency. Results: Messa 10 K is highly resistant to gemcitabine (122-fold), troxacitabine (> 15-fold) and araC (13,556-fold). Quantitative real-time PCR and western blot analysis showed that dCK was not detectable in Messa 10 K cells, presumably because of a genetic modification. The transfection of Messa 10 K cells with DmdNK significantly increased the sensitivity to gemcitabine. Conclusions: These results show that genetic modifications in non-hematological malignant cells may be associated with resistance to gemcitabine, and that the gene transfer of non-human genes can be used for the reversion of nucleoside analogue resistance due to dCK deficiency.