AUTHOR=Zheng Lijun , Xu Yi , Wang Chen , Guo Liangsheng 

TITLE=Ketoconazole induces reversible antifungal drug tolerance mediated by trisomy of chromosome R in Candida albicans

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1450557

DOI=10.3389/fmicb.2024.1450557

ISSN=1664-302X

ABSTRACT=<sec id="sec1"><title>Background</title><p>The emergence of tolerance to antifungal agents in <italic>Candida albicans</italic> complicates the treatment of fungal infections. Understanding the mechanisms underlying this tolerance is crucial for developing effective therapeutic strategies.</p></sec><sec id="sec2"><title>Objective</title><p>This study aims to elucidate the genetic and molecular basis of ketoconazole tolerance in <italic>C. albicans</italic>, focusing on the roles of chromosomal aneuploidy, Hsp90, and calcineurin.</p></sec><sec id="sec3"><title>Methods</title><p>The wild-type <italic>C. albicans</italic> strain SC5314 was exposed to increasing concentrations of ketoconazole (0.015–32 μg/mL) to select for tolerant adaptors. Disk diffusion and spot assays were used to assess tolerance. Whole-genome sequencing identified chromosomal changes in the adaptors. The roles of Hsp90 and calcineurin in maintaining and developing ketoconazole tolerance were investigated using specific inhibitors and knockout strains.</p></sec><sec id="sec4"><title>Results</title><p>Adaptors exhibited tolerance to ketoconazole concentrations up to 16 μg/mL, a significant increase from the parent strain’s inhibition at 0.015 μg/mL. All tolerant adaptors showed amplification of chromosome R, with 29 adaptors having trisomy and one having tetrasomy. This aneuploidy was unstable, reverting to euploidy and losing tolerance in drug-free conditions. Both Hsp90 and calcineurin were essential for maintaining and developing ketoconazole tolerance. Inhibition of these proteins resulted in loss of tolerance. The efflux gene <italic>CDR1</italic> was not required for the development of tolerance. Chromosome R trisomy and tetrasomy induce cross-tolerance to other azole antifungal agents, including clotrimazole and miconazole, but not to other antifungal classes, such as echinocandins and pyrimidines, exemplified by caspofungin and 5-flucytosine.</p></sec><sec id="sec5"><title>Conclusion</title><p>Ketoconazole tolerance in <italic>C. albicans</italic> is mediated by chromosomal aneuploidy, specifically chromosome R amplification, and requires Hsp90 and calcineurin. These findings highlight potential targets for therapeutic intervention to combat antifungal tolerance and improve treatment outcomes.</p></sec>