azole resistance in C. albicans can be due to the upregulation of multidrug transporters belonging to the ABC-transporters and the Major Facilitators (MF). Some azole-resistant strains upregulate ABC-transporters CDR1 and CDR2 (type I), while other upregulate the MF CaMDR1 (type II). Upregulation of these genes can also be achieved by exposure to fluphenazine (FPZ), resulting in specific upregulation of CDR1 and CDR2 and by exposure to benomyl (BEN), resulting in CaMDR1 upregulation. Drug exposure therefore mimics the gene expression profiles observed in clinical isolates. Since the expression of many other genes can still differ between these conditions and between clinical isolates, we subjected a laboratory strain (CAF2-1) after drug exposure and clinical strains to microarray analysis to measure the expression of their global genomes. We used microarrays containing 6300 ORF and hybridized them with cDNA from CAF2-1 exposed to BEN (50 µg/ml) and FPZ (20 µg/ml) for 20 min and from two matched pairs of azole-susceptible and resistant strains (Type I and Type II). The results obtained show that BEN and FPZ exposure changed the expression of 212 and 298 genes at least 2-fold as compared to CAF2-1, respectively. In the two pairs of type I and type II clinical strains, gene expression was changed for 191 and 296 genes at least 2-fold as compared to each susceptible strains, respectively. Coordinate expression of 45 (among them the most upregulated were CDR1, CDR2, HSP12, IFU5 and RTA3) and 65 (among them the most upregulated were CaMDR1, IFD1, 5, 4, 7, GRP2, CIP1) genes was measured between FPZ and type I isolates and BEN and type II isolates, respectively. These results show that in vitro drug-induced gene expression only partially mimic expression profiles observed in azole-resistant clinical strains. Clinical strains undergo other modulation of gene expression that probably reflects adaptation to the host conditions.
Full conference title:
43rd Interscience Conference on Antimicrobial Agents
- ICAAC 43rd