(all p > 0.05) (Figure 3). To confirm the hypothesis that this effect was not specific to strain ATCC90028, we tested three unrelated clinical selleck chemical strains and found that HS had the same effect on all three clinical strains as well (data not shown). Figure 3 Effect of human serum on planktonic growth of C. albicans. Twenty-four-hour Akt inhibitor growth curves showing 50% HS, 50% heat-inactivated HS, and 50% proteinase K-treated HS against C. albicans ATCC90028 in RPMI 1640. Symbols: ◆, growth control; ■, 50% HS; ▲, 50% heated HS; ×, 50% proteinase K-treated HS. Effect of human serum on expression of adhesion-related genes To elucidate the potential molecular mechanism behind the ability of HS to prevent growth of C. albicans biofilms, total RNA was isolated from biofilms of four C. albicans strains grown in RPMI 1640 medium with or without 50% HS at three time points (60 min, 90 min and 24 h). The expression levels of specific genes that were previously implicated in mediating the adhesion of C. albicans cells were determined by real-time RT-PCR. HS had varying effects on different genes in different Nutlin-3a datasheet tested strains
(data not shown), but the general trend of these genes was consistent. HS down-regulated the expression of the adhesion-related genes ALS1 (1.1 to 3.0-fold) and ALS3 (1.5 to 3.8-fold), but up-regulated the expression of the hypha-related genes HWP1 (1.1 to 2.4-fold) and ECE1 (1.1 to 4.2-fold) at all three time points (Figure 4). Particularly, expression levels of ALS1 (2.5 and 3.0-fold) and ALS3 (3.7 and 3.8-fold) showed significant differences at both 90 min and 24 h (p < 0.05 or p < 0.01) (Figure 4B,C). Only at the 90-min time point were the transcription levels STK38 of HWP1 (2.4-fold) and ECE1 (4.2-fold) significantly higher (p < 0.05 or p < 0.01) (Figure 4B). The transcription level of BCR1 was
significantly higher at 90 min (3.3-fold, p < 0.01) (Figure 4B), but BCR1 levels were significantly lower at both 60 min (2.8-fold, p < 0.05) and 24 h (5.6-fold, p < 0.01) (Figure 4A,C). Figure 4 Expression of C. albicans adhesion-related genes. Candida albicans cells were incubated in the absence or presence of HS (50%) and the expression of target genes was determined by RT-PCR. Housekeeping gene ACT1 was used as an internal control. Each gene was assessed in triplicate, and the experiment itself was performed in biologic duplicate. The data shown here are a representative graph of strain ATCC90028. A) Expression of genes ALS1, ALS3, HWP1, ECE1, and BCR1 following the treatment with HS for 60 min. B) Different expression of the target genes following treatment with HS for 90 min. C) Target gene expression level following treatment with HS for 24 h. Discussion To make the transition from a commensal organism to a systemic pathogen, C. albicans must first enter the bloodstream.