Prague Med. Rep. 2017, 118, 128-138

5-fluorouracil Toxicity Mechanism Determination in Human Keratinocytes: in vitro Study on HaCaT Cell Line

Jan Hartinger1, Pavel Veselý2, Martin Šíma1, Irena Netíková1, Eva Matoušková3, Luboš Petruželka4

1Department of Clinical Pharmacology and Pharmacy, Institute of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
2Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
3Department of Burns Medicine, Third Faculty of Medicine, Charles University and University Hospital Královské Vinohrady, Prague, Czech Republic
4Department of Oncology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic

Received June 29, 2017
Accepted December 5, 2017

5-fluorouracil (5-FU) and capecitabine therapy is often accompanied by palmar-plantar erythrodysesthesia (PPE) which is manifestation of 5-FU toxicity in keratinocytes. The main mechanisms of 5-FU action are thymidylate synthase (TS) inhibition which can be abrogated by thymidine and strengthened by calciumfolinate (CF) and incorporation of fluorouridinetriphosphate into RNA which can be abrogated by uridine. For proper PPE treatment 5-FU mechanism of action in keratinocytes needs to be elucidated. We used the 5-FU toxicity modulators uridine, thymidine and CF to discover the mechanism of 5-FU action in human keratinocyte cell line HaCaT. To measure the cellular viability, we used MTT test and RTCA test. CF did not augment 5-FU toxicity and 5-FU toxicity was weakened by uridine. Therefore, the primary mechanism of 5-FU toxicity in keratinocytes is 5-FU incorporation into RNA. The uridine protective effect cannot fully develop in the presence of CF. Thymidine addition to 5-FU and uridine treated cells not only prevents the toxicity-augmenting CF effect but it also prolongs the 5-FU treated cells survival in comparison to uridine only. Therefore, it can be assumed that in the presence of uridine the 5-FU toxicity mechanism is switched from RNA incorporation to TS inhibition. Although particular 5-FU toxicity mechanisms were previously described in various cell types, this is the first time when various combinations of pyrimidine nucleosides and CF were used for 5-FU toxicity mechanism elucidation in human keratinocytes. We suggest that for PPE treatment ointment containing uridine and thymidine should be further clinically tested.


This study was supported by the Charles University grant UNCE 204022.


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