Single-cell lipidomic analysis of the epithelial-mesenchymal transition using mass spectrometry imaging

The epithelial-mesenchymal transition (EMT) is a metastasis-promoting process whose heterogeneity has been extensively studied at a gene expression level. EMT involves reprogramming of lipid metabolism; however, there has been little focus lipid level heterogeneity. Here, we use mass spectrometry imaging (MSI) to measure glycerophospholipids at the single-cell level during EGF-induced EMT in MDA-MB-468 breast cancer cells. Cells undergoing EMT had reduced levels of PA, PS, PE, and PI-species and increased levels of PG-species and LPI (18:0). Multivariate analysis on the spatially resolved MSI-data revealed a heterogeneous metabolic response. Lipid levels were particularly affected by cell organization, as dispersed cells were more "EMT-like" than cohesive cells. The fraction of dispersed cells increased during EMT, indicating that pathways regulating adhesion and motility also regulate lipid metabolism. Gene expression analysis verified that EMT affected genes involved in glycerophospholipid biosynthesis. This work demonstrates heterogeneous regulation of glycerophospholipids in cancer cell populations undergoing EMT.