Lipid analysis of eight human breast cancer cell lines with ToF-SIMS

In this work, four triple negative (TN) cell lines, three ER+ and PR+ receptor positive (RP) cell lines, and one ER+, PR+, and HER2+ cell line were chemically distinguished from one another using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and principal component analysis (PCA). PCA scores separation was observed between the individual cell lines within a given classification (TN and RP) and there were distinctly different trends found in the fatty acid and lipid compositions of the two different classifications. These trends indicated that the RP cell lines separated out based on the carbon chain length of the lipids while the TN cell lines showed separation based on cholesterol-related peaks (in the positive ion data). Both cell types separated out by trends in fatty acid chain length and saturation in the negative ions. These chemical differences may be manifestations of unique metabolic processes within each of the different cell lines. Additionally, the HER2+ cell line was distinguished from three other RP cell types as having a unique distribution of fatty acids including anticorrelation to 18-carbon chain fatty acids. As these cell lines could not be grown in the same growth media, a combination of chemical fixation, rinsing, C60+ presputtering, and selection of cellular regions-of-interest is also presented as a successful method to acquire ToF-SIMS data from cell lines grown in different media.