Novel Cell-Killing Mechanisms of Hydroxyurea and the Implication toward Combination Therapy for the Treatment of Fungal Infections.
We have previously reported that an  erg11  mutation affecting ergosterol synthesis and a  hem13  mutation in the heme synthesis pathway significantly sensitize the fission yeast  Schizosaccharomyces pombe  to hydroxyurea (HU) (1, 2). Here we show that treatment with inhibitors of Erg11 and heme biosynthesis phenocopies the two mutations in sensitizing wild-type cells to HU. Importantly, HU synergistically interacts with the heme biosynthesis inhibitor sampangine and several Erg11 inhibitors, the antifungal azoles, in causing cell lethality. Since the synergistic drug interactions are also observed in the phylogenetically divergent  Saccharomyces cerevisiae  and the opportunistic fungal pathogen  Candida albicans , the synergism is likely conserved in eukaryotes. Interestingly, our genetic data for  S. pombe  has also led to the discovery of a robust synergism between sampangine and the azoles in  C. albicans  Thus, combinations of HU, sampangine, and the azoles can be further studied as a new method for the treatment of fungal infections.
Singh A, Agarwal A, Xu YJ