Cellular apoptosis: An alternative mechanism of action for caspofungin against Candida glabrata

Background and Purpose: Although the mechanism of action for echinocandins isknown, the physiological mechanisms by which these antifungal agents cause cell deathvia the classical apoptotic pathways are not well-defined yet. Regarding this, the presentstudy aimed to evaluate the mechanisms of caspofungin-induced Candida glabrata celldeath.Materials and Methods: For the purpose of the study, the minimum inhibitoryconcentration (MIC) of caspofungin against C. glabrata (ATCC 90030) was determinedusing the broth microdilution reference method (CLSI M27-A2 and M27-S4). Theannexin V and propidium iodide staining was performed to determine the way throughwhich caspofungin acts against C. glabrata (i.e., through the induction of apoptosisand/or necrosis). Additionally, the possible effect of caspofungin on inducing theexpression of two apoptotic genes, namely MCA1 and NUC, was studied using the realtime polymerase chain reaction assay.Results: According to the obtained MIC value (0.5 µg/mL), C. glabrata, exposed to0.25, 0.5, and 1 µg/mL of caspofungin, exhibited the features of late apoptosis/necrosisafter 18 h of incubation. Furthermore, the use of 0.25, 0.5, and 1 µg/ml caspofungininduced apoptosis (early/late) in 14.67%, 17.04%, and 15.89% of the cells, respectively.The results showed a significant difference between the percentages of early-apoptoticcells at the three concentrations (P<0.05). In addition, the rate of necrosis wassignificantly greater than that of apoptosis in response to caspofungin. Accordingly,necrosis occurred in 71.26%, 71.26%, and 61.26% of the cells at the caspofunginconcentrations of 0.25, 0.5, and 1 µg/mL, respectively (P<0.05). The analysis of the datain the REST software demonstrated a significant increase in the expression of MCA1 andNUC1 genes (P<0.05).Conclusion: As the findings of the present study indicated, caspofungin promoted bothnecrosis and apoptosis of C. glabrata cells at concentrations higher than or equal to theMIC value.