Introduction: Although the mechanism of activity for echinocandins is known, the physiological mechanisms by which these antifungal agents cause cell death via the classical apoptotic pathways are not well-defined yet. Regarding this, the present study aimed to evaluate the mechanisms of caspofungin-induced Candida glabrata cell death. 
Material and methods: For the purpose of the study, the minimum inhibitory concentration (MIC) of caspofungin against C. glabrata (ATCC 90030) was determined using the broth microdilution reference method (CLSI M27-A2 and M27-S4). The annexin V and propidium iodidestaining was performed to determine the way through which caspofungin exerts activity against C. glabrata (i.e., through the induction of apoptosis and/or necrosis). Additionally, the possible effect of caspofungin on inducing the expression of two apoptotic genes, namely MCA1 and NUC, was studied using the real-time polymerase chain reaction assay.
Results: According to the obtained MIC (0.5 µg/mL), C. glabrata, exposed to 0.25, 0.5, and 1 µg/mL of caspofungin, exhibited the features of late apoptosis/necrosis after 18 h of incubation. Furthermore, the use of 0.25, 0.5, and 1 µg/ml caspofungin induced apoptosis (early/late) in 14.67%, 17.04%, and 15.89% of the cells, respectively. There was a significant difference between the percentages of early-apoptotic cells at the three concentrations (P<0.05). The rate of necrosis was significantly greater in response to caspofungin. Accordingly, necrosis occurred in 71.26%, 71.26%, and 61.26% of the cells at the caspofungin concentrations of 0.25, 0.5, and 1 µg/mL, respectively (P<0.05). The analysis of the data in REST software demonstrated that the expression of MCA1 and NUC1 genes had a significant increase (P<0.05). 
Conclusion: As the findings of the present study demonstrated, caspofungin promotedboth necrosis and apoptosis of C. glabratacells at concentrations higher or equal to the MIC.

2 / Cellular apoptosis: an alternative mechanism of action of caspofungin in Candida glabrata