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Onyewu C, Blankenship JR, Del Poeta M, Heitman J. Ergosterol biosynthesis inhibitors become fungicidal when combined with calcineurin inhibitors against Candida albicans, Candida glabrata, and Candida krusei. Antimicrob Agents Chemother 2003; 47:956-64. [PMID: 12604527 PMCID: PMC149324 DOI: 10.1128/aac.47.3.956-964.2003] [Citation(s) in RCA: 199] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2002] [Revised: 11/14/2002] [Accepted: 12/16/2002] [Indexed: 12/24/2022] Open
Abstract
Azoles target the ergosterol biosynthetic enzyme lanosterol 14alpha-demethylase and are a widely applied class of antifungal agents because of their broad therapeutic window, wide spectrum of activity, and low toxicity. Unfortunately, azoles are generally fungistatic and resistance to fluconazole is emerging in several fungal pathogens. We recently established that the protein phosphatase calcineurin allows survival of Candida albicans during the membrane stress exerted by azoles. The calcineurin inhibitors cyclosporine A (CsA) and tacrolimus (FK506) are dramatically synergistic with azoles, resulting in potent fungicidal activity, and mutant strains lacking calcineurin are markedly hypersensitive to azoles. Here we establish that drugs targeting other enzymes in the ergosterol biosynthetic pathway (terbinafine and fenpropimorph) also exhibit dramatic synergistic antifungal activity against wild-type C. albicans when used in conjunction with CsA and FK506. Similarly, C. albicans mutant strains lacking calcineurin B are markedly hypersensitive to terbinafine and fenpropimorph. The FK506 binding protein FKBP12 is required for FK506 synergism with ergosterol biosynthesis inhibitors, and a calcineurin mutation that confers FK506 resistance abolishes drug synergism. Additionally, we provide evidence of drug synergy between the nonimmunosuppressive FK506 analog L-685,818 and fenpropimorph or terbinafine against wild-type C. albicans. These drug combinations also exert synergistic effects against two other Candida species, C. glabrata and C. krusei, which are known for intrinsic or rapidly acquired resistance to azoles. These studies demonstrate that the activity of non-azole antifungal agents that target ergosterol biosynthesis can be enhanced by inhibition of the calcineurin signaling pathway, extending their spectrum of action and providing an alternative approach by which to overcome antifungal drug resistance.
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Affiliation(s)
- Chiatogu Onyewu
- Departments of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710, USA
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107
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Cruz M, Goldstein AL, Blankenship JR, Del Poeta M, Davis D, Cardenas ME, Perfect JR, McCusker JH, Heitman J. Calcineurin is essential for survival during membrane stress in Candida albicans. EMBO J 2002; 21:546-59. [PMID: 11847103 PMCID: PMC125859 DOI: 10.1093/emboj/21.4.546] [Citation(s) in RCA: 259] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2001] [Revised: 12/12/2001] [Accepted: 12/18/2001] [Indexed: 12/25/2022] Open
Abstract
The immunosuppressants cyclosporin A (CsA) and FK506 inhibit the protein phosphatase calcineurin and block T-cell activation and transplant rejection. Calcineurin is conserved in microorganisms and plays a general role in stress survival. CsA and FK506 are toxic to several fungi, but the common human fungal pathogen Candida albicans is resistant. However, combination of either CsA or FK506 with the antifungal drug fluconazole that perturbs synthesis of the membrane lipid ergosterol results in potent, synergistic fungicidal activity. Here we show that the C.albicans FK506 binding protein FKBP12 homolog is required for FK506 synergistic action with fluconazole. A mutation in the calcineurin B regulatory subunit that confers dominant FK506 resistance (CNB1-1/CNB1) abolished FK506-fluconazole synergism. Candida albicans mutants lacking calcineurin B (cnb1/cnb1) were found to be viable and markedly hypersensitive to fluconazole or membrane perturbation with SDS. FK506 was synergistic with fluconazole against azole-resistant C.albicans mutants, against other Candida species, or when combined with different azoles. We propose that calcineurin is part of a membrane stress survival pathway that could be targeted for therapy.
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Affiliation(s)
- M.Cristina Cruz
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
| | - Alan L. Goldstein
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
| | - Jill R. Blankenship
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
| | - Maurizio Del Poeta
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
| | - Dana Davis
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
| | - Maria E. Cardenas
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
| | - John R. Perfect
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
| | - John H. McCusker
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
| | - Joseph Heitman
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology and Medicine, and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, Departments of Biochemistry and Microbiology and Immunology, Medical University of South Carolina, Charleston, SC and Department of Microbiology, University of Minnesota, Minneapolis, MN, USA Corresponding author at: Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA e-mail:
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