Potentiation of hydroxyurea cytotoxicity by iron-chelating agent in murine tumor models in vitro

The biochemical modulation of tumor cell response to increase the cytotoxicity of Hydroxyurea (HU), directed at the ribonucleotide reductase enzyme, has been studied in in vitro. Mice bearing ascites tumor models such as L1210 leukemia, Sarcoma 180 (S180) and Ehrlich ascites tumor (EAT) were employed in this study. The cytotoxicity of HU alone at various concentrations was dose dependent and showed the following order of sensitivity; L1210 greater than EAT greater than S180. The hydrophobic iron-chelating agent 2,2-bipyridyl significantly potentiated the antitumor activity of HU in all the murine tumor models studied. In contrast, hydrophilic iron-chelator, Desferal, did not show any cytotoxicity when combined with HU. The present study demonstrated the factors influencing the amelioration of HU cytotoxicity and possible therapeutic use of iron-chelating agents alone and with HU for better therapeutic results in clinics.