Genome-Wide Expression Profiling of the Response to Azole, Polyene, Echinocandin, and Pyrimidine Antifungal Agents inCandida albicans

Abstract

Antifungal agents exert their activity through a variety of mechanisms, some of which are poorly understood. We examined changes in the gene expression profile of Candida albicans following exposure to representatives of the four currently available classes of antifungal agents used in the treatment of systemic fungal infections. Ketoconazole exposure increased expression of genes involved in lipid, fatty acid, and sterol metabolism, including NCP1, MCR1, CYB5, ERG2, ERG3, ERG10, ERG25, ERG251, and that encoding the azole target, ERG11. Ketoconazole also increased expression of several genes associated with azole resistance, including CDR1, CDR2, IFD4, DDR48, and RTA3. Amphotericin B produced changes in the expression of genes involved in small-molecule transport (ENA21), and in cell stress (YHB1, CTA1, AOX1, and SOD2). Also observed was decreased expression of genes involved in ergosterol biosynthesis, including ERG3 and ERG11. Caspofungin produced changes in expression of genes encoding cell wall maintenance proteins, including the ␤-1,3-glucan synthase subunit GSL22, as well as PHR1, ECM21, ECM33, and FEN12. Flucytosine increased the expression of proteins involved in purine and pyrimidine biosynthesis, including YNK1, FUR1, and that encoding its target, CDC21. Real-time reverse transcription-PCR was used to confirm microarray results. Genes responding similarly to two or more drugs were also identified. These data shed new light on the effects of these classes of antifungal agents on C. albicans.Candida albicans is the most common human fungal pathogen and is the fourth leading cause of bloodstream infections in the United States (6,14,24). Currently only four antifungal drug classes are available for the management of systemic infections due to Candida species. Recently we examined changes in the genome-wide expression profile of Saccharomyces cerevisiae in response to representatives of the polyene, pyrimidine, azole, and echinocandin antifungal agents in an effort to identify class-specific and mechanism-independent changes in gene expression (1). In the present study, we extend this analysis to the pathogenic fungus C. albicans. By using the same representative drugs and similar growth conditions as in our previous study, we are able to show similarities and differences in the responses to these antifungal agents between S. cerevisiae and C. albicans. Gene expression profiling experiments revealed drug-specific responses consistent with their mechanisms of action, responses indicative of other pathways that may be affected by these agents, and responses that reflect known and potential mechanisms of resistance to these antifungal drugs. MATERIALS AND METHODSAntifungal agents. Ketoconazole (KTZ) and flucytosine (5-FC) were obtained from Sigma (St. Louis, MO). Amphotericin B (AMB) was obtained from ICN Biomedicals (Aurora, OH). The commercially available preparation of caspofungin (CPF) acetate for injection (Cancidas) was used. Stock solutions of various concentrations were made in dimethyl sulfoxide (DMS...

Regulatory Circuitry Governing Fungal Development, Drug Resistance, and Disease

“…Global gene expression studies have revealed that when C. albicans is exposed to amphotericin B, 256 genes are differentially expressed. These genes are involved primarily in protein synthesis, small-molecule transport, cell stress responses, and sterol metabolism (340). This suggests that there is a multitude of factors responsible for tolerance and resistance to polyenes besides target alteration.…”

Candida albicansCell Wall Proteins

“…The hgt4⌬/⌬ strain showed reduced the capacity to form filaments. XOG1 expression increased (1.6-fold) upon exposure to ketoconazole (transcriptional profiling [210]). The expression of a subunit of ␤-1,3-glucan synthase also increased.…”

Characterization of the Same Mutations in FCA1 Gene Associated With 5-FC Resistance of Candida albicans

“…The mechanisms of resistance to 5-FC in clinical C. albicans isolates focus on the proteins involved in pyrimidine salvage pathway and the alterations in gene expression (21,22). Mutations in the cytosine deaminase gene FCY1 (named FCA1 gene in C. albicans) or cytosine permease gene FCY2, which may result in the poor uptake of drug, are the most common causes of drug resistance (23,24).…”