Expression of the ERG11 gene in fluconazole-resistant Trichosporon asahii

Abstract

Objective To investigate the role of the ERG11 gene in the drug resistance of Trichosporon asahii (T.asahii) , and to explore the relationship between the gene expression and drug concentrations. Methods Stable fluconazole-resistant strains of T.asahii were induced in vitro following exposure to a series of concentrations of fluconazole. Fluconazole-sensitive and -resistant strains of T.asahii were separately cultured in the medium containing fluconazole at concentrations of 0, 0.25, 0.5, 1, 2, 4, 8, 16, 32 and 64 μg/ml. Real-time quantitative PCR was performed to determine the mRNA expression of ERG11 gene. Results In fluconazole-free medium, the fluconazole-resistant strain of T.asahii showed significantly increased mRNA expression of the ERG11 gene compared with the fluconazole-sensitive strain (7.542 ± 5.311 vs. 1.014 ± 0.012, t= 3.002, P= 0.03) . Additionally, the mRNA expression of ERG11 gene was also significantly higher in the fluconazole-resistant strains than the fluconazole-sensitive strains in the culture medium containing fluconazole at different concentrations of 0.25 (9.183 ± 3.226 vs. 3.281 ± 2.068) , 0.5 (13.657 ± 5.428 vs. 3.459 ± 1.923) , 1 (15.292 ± 7.007 vs. 3.242 ± 2.530) , 2 (13.720 ± 8.550 vs. 3.651 ± 0.728) , 4 (13.949 ± 2.960 vs. 3.969 ± 1.924) and 8 (13.123 ± 6.429 vs. 3.824 ± 1.875) μg/ml (all P < 0.05) . However, no significant correlation was observed between the mRNA expression of ERG11 gene and fluconazole concentrations (fluconazole-resistant strains: rs= 0.229, P= 0.096; fluconazole-sensitive strains: rs= 0.166, P= 0.357) . Conclusion Overexpression of ERG11 gene is associated with fluconazole resistance in T.asahii, but there is no correlation between the mRNA expression of ERG11 gene and fluconazole concentrations. Key words: Fluconazole; Drug resistance, fungal; Gene expression; Trichosporon asahii; Genes, ERG11