Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been increasingly utilized for examining biological samples including biomaterials, cells, and tissues. The primary advantage of this MS technique is that it produces a chemical map of a sample, which includes hundreds of peaks that are detected in parallel. The advent of cluster ion sources has allowed the detection of many high mass lipid species that can be used to characterize biological surfaces [1]. In conjunction with principal component analysis (PCA), we use ToF-SIMS to determine differences in the chemical makeup of the outer membrane of two different cancer cell lines: MDA-231 and MCF-7 cells. There is similar work currently being done that uses Ultra Performance Liquid Chromatography-MS and gene sequencing to start characterizing lipid membrane metabolism in breast cancer tumor tissue [2]. The separation of the two cell lines across PC1 can be clearly seen in Figure 1. The entirety of the loads for PC1 can be seen in Figure 2, with cholesterol strongly loading towards the MDA-231 cells and many diacylglycerol (DAG) species loading towards the MCF-7 cells. Key differences were found in the levels of certain lipid constituents of the cell membrane, which may play a role in the ability of one cell type to be more drug resistant than the other. There are a variety of lipid components that have similar trends which are not discussed in this abstract but may play an important role in understanding this system.

 

This work is the foundation for future studies using human tumor biopsy samples that will help elucidate the link between fatty acid composition within a tumor and the potential drug resistance of that tumor.