The Heterogeneity in the Response of A549 Cells to Toyocamycin Observed Using Hopping Scanning Ion Conductance Microscopy

Scanning ion conductance microscopy (SICM) is a noninvasive topographic mapping technique used in imaging live cells, unlike electron microscopy and certain applications of fluorescence microscopy, which can disrupt cell integrity. In this study, we used SICM to track the morphological changes of the same A549 cells to uncover the cell-to-cell heterogeneity in their response to the drug. We found that toyocamycin (TOY) induced rapid reorganization of the actin cytoskeleton in A549 cells, causing them to become circular, irregular, or ellipsoidal in shape. Mapping of the dynamic changes in morphology revealed membrane blebbing and a significant decrease in volume over time. Using high-throughput SICM, we mapped the morphology of multiple single cells treated with TOY, which revealed that A549 showed characteristics of apoptosis and necrosis. The drug treatment does not significantly change the average root-mean-square (RMS) roughness of the cells. However, the drug leads to an increase in membrane height, possibly indicating early apoptotic changes. Plotting the individual RMS roughness of the cells showed a cell with an increase in roughness and the presence of pores, which is also an indication of necrosis behavior. Our results demonstrate that SICM is an effective technique for revealing the evolution of heterogeneity in single cells in their responses to anticancer drugs over time.