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

Background and Purpose: Although the mechanism of action 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. Materials and Methods: For the purpose of the study, the minimum inhibitory concentration (MIC) of caspofungin against C. glabrata (ATCC ۹۰۰۳۰) was determined using the broth microdilution reference method (CLSI M۲۷-A۲ and M۲۷-S۴). The annexin V and propidium iodide staining was performed to determine the way through which caspofungin acts 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 MCA۱ and NUC, was studied using the real-time polymerase chain reaction assay. Results: According to the obtained MIC value (۰.۵ μg/mL), C. glabrata, exposed to ۰.۲۵, ۰.۵, and ۱ μg/mL of caspofungin, exhibited the features of late apoptosis/necrosis after ۱۸ h of incubation. Furthermore, the use of ۰.۲۵, ۰.۵, and ۱ μg/ml caspofungin induced apoptosis (early/late) in ۱۴.۶۷%, ۱۷.۰۴%, and ۱۵.۸۹% of the cells, respectively. The results showed a significant difference between the percentages of early-apoptotic cells at the three concentrations (p <۰.۰۵). In addition, the rate of necrosis was significantly greater than that of apoptosis in response to caspofungin. Accordingly, necrosis occurred in ۷۱.۲۶%, ۷۱.۲۶%, and ۶۱.۲۶% of the cells at the caspofungin concentrations of ۰.۲۵, ۰.۵, and ۱ μg/mL, respectively (p <۰.۰۵). The analysis of the data in the REST software demonstrated a significant increase in the expression of MCA۱ and NUC۱ genes (p <۰.۰۵). Conclusion: As the findings of the present study indicated, caspofungin promoted both necrosis and apoptosis of C. glabrata cells at concentrations higher than or equal to the MIC value.

کلیدواژه ها:

Candida glabrata ، Caspofungin ، Flow Cytometry ، MCA۱ ، NUC۱