Toxicity and differential protein analysis following destruxin A treatment of Spodoptera litura (Lepidoptera: Noctuidae) SL-1 cells

Abstract

The cytotoxicity of a destruxin A (DA) treatment of Spodoptera litura SL-1 cells was investigated. An MTT assay showed that DA was highly toxic to SL-1 cells in a concentration- and time-dependent manner. The IC 50 values of DA, after 24 h and 48 h of treatment, were 17.86 μg/mL and 7.80 μg/mL, respectively. Under inverted phase contrast microscopy (IPCM), it was found that prolonged treatment with DA could induce cell rounding, cellular membrane shrinking, formation of apoptotic bodies, vacuole appearance and cytoplasm leak out. Apoptosis induced by DA was further confirmed by fluorescence microscopy (FM) and flow cytometry (FCM) studies. SL-1 cells entered early apoptosis following a treatment with 2.5 μg/mL DA and entered late apoptosis following a treatment with increasing concentrations of DA. Furthermore, two-dimensional gel electrophoresis (2-DE) analysis was used to identify 22 proteins which were differentially expressed (≥2-fold difference) between control cells and DA-treated cells, and the expression level of these proteins was significantly different between the treated and untreated cells. Our results suggest that these differentially expressed proteins may help explain the diverse biological effects caused by the destruxin A treatment of cells; additionally, some of the identified proteins may have roles in SL-1 cellular proliferation and apoptosis.