Cph1p negatively regulates MDR1 involved in drug resistance in Candida albicans.

The cph1/cph1 efg1/efg1 double mutant in Candida albicans is defective in filamentous growth and is avirulent in a mouse model. We previously reported that Efg1p but not Cph1p is involved in drug resistance by negatively regulating ERG3 in C. albicans. In the current study, we have found that overexpression of CPH1 in Saccharomyces cerevisiae increases susceptibility to the antifungal drug fluconazole. Furthermore, in C. albicans, null mutation of CPH1 increased the expression of MDR1 as well as decreased susceptibility to fluconazole and voriconazole but not to amphotericin B. These findings indicate that although Efg1p and Cph1p may have the same effects on virulence, they have opposite effects on drug resistance in C. albicans.