Morphological responses to SK-03-92 in Morphological responses to SK-03-92 in eukaryotic cells

Abstract

SK-03-92, a modified form of a stilbene produced by Comptonia peregrina, has been shown to effectively kill a variety of gram-positive bacteria, but is not toxic in a mouse model. In this work, several morphological responses of wild-type Saccharomyces cerevisiae (yeast) to SK-03-92 treatment were observed by light microscopy. Although none of these morphological changes correlated with cell death, the responses did follow a general sequence. Previous studies of yeast mutants suggested that the mitochondria were a target of SK-03-92. Mitochondrial staining of wild-type and mutant yeast did reveal a statistically significant correlation between the proportion of cells killed by SK- 03-92 and the percentage of cells containing mitochondrial abnormalities, confirming that mitochondria are a primary target of SK-03-92 in yeast. A human monocytic cancer cell line, THP-1, was also treated with a range of SK-03-92 concentrations, again revealing a statistically significant correlation between mitochondrial abnormalities and cell death, with punctate mitochondria observed with apoptotic death at low concentrations of SK- 03-92, and diffuse mitochondria observed with necrotic death at high concentrations of SK-03-92. Together, these results indicate that mitochondria are likely the target of SK- 03-92 in eukaryotic cells.