Journal Article

Genome-wide expression profiling reveals genes associated with amphotericin B and fluconazole resistance in experimentally induced antifungal resistant isolates of <i>Candida albicans</i>

Katherine S. Barker, Sarah Crisp, Nathan Wiederhold, Russell E. Lewis, Bart Bareither, James Eckstein, Robert Barbuch, Martin Bard and P. David Rogers

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 54, issue 2, pages 376-385
Published in print August 2004 | ISSN: 0305-7453
Published online August 2004 | e-ISSN: 1460-2091 | DOI: http://dx.doi.org/10.1093/jac/dkh336
Genome-wide expression profiling reveals genes associated with amphotericin B and fluconazole resistance in experimentally induced antifungal resistant isolates of Candida albicans

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Objectives: The aim of this study was to identify changes in the gene expression profile of Candida albicans associated with the acquisition of experimentally induced resistance to amphotericin B and fluconazole.

Methods: C. albicans SC5314 was passed in increasing concentrations of amphotericin B to generate isolate SC5314-AR. Susceptibility testing by Etest revealed SC5314-AR to be highly resistant to both amphotericin B and fluconazole. The gene expression profile of SC5314-AR was compared with that of SC5314 using DNA microarray analysis. Sterol composition was determined for both strains.

Results: Upon examination of MICs of antifungal compounds, it was found that SC5314-AR was resistant to both amphotericin B and fluconazole. By microarray analysis a total of 134 genes were found to be differentially expressed, that is up-regulated or down-regulated by at least 50%, in SC5314-AR. In addition to the cell stress genes DDR48 and RTA2, the ergosterol biosynthesis genes ERG5, ERG6 and ERG25 were up-regulated. Several histone genes, protein synthesis genes and energy generation genes were down-regulated. Sterol analysis revealed the prevalence of sterol intermediates eburicol and lanosterol in SC5314-AR, whereas ergosterol was the predominant sterol in SC5314.

Conclusion: Along with changes in expression of these ergosterol biosynthesis genes was the accumulation of sterol intermediates in the resistant strain, which would account for the decreased affinity of amphotericin B for membrane sterols and a decreased requirement for lanosterol demethylase activity in membrane sterol production. Furthermore, other genes are implicated as having a potential role in the polyene and azole antifungal resistant phenotype.

Keywords: microarrays; polyenes; azoles; antifungal resistance; C. albicans

Journal Article.  4640 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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