Lipid MALDI profile classifies non-small cell lung cancers according to the histologic type

We investigated whether direct tissue matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) analysis on lipid may assist with the histopathologic diagnosis of non-small cell lung cancers (NSCLCs). Twenty-one pairs of frozen, resected NSCLCs and adjacent normal tissue samples were initially analyzed using histology-directed, MALDI MS. 2,5-dihydroxybenzoic acid/α-cyano-4-hydroxycinnamic acid were manually deposited on areas of each tissue section enriched in epithelial cells to identify lipid profiles, and mass spectra were acquired using a MALDI-time of flight instrument. A lipid profile that could differentiate cancer and adjacent normal samples with a median accuracy of 92.9% was discovered. Several phospholipids including phosphatidylcholines (PC) {34:1} were overexpressed in lung cancer.Squamous cell carcinomas and adenocarcinomas were found to have different lipid profiles. Discriminatory lipids correctly classified the histology of 80.4% of independent NSCLC surgical tissue samples (41 out of 51) in validation set. MALDI MS image of 11 discriminatory lipids validated their differential expression according to the histologic type in cancer cells of bronchoscopic biopsy samples. PC {32:0} [M+Na]⁺ (m/z 756.68) and ST-OH {42:1} [M-H]^- (m/z 906.89) were overexpressed in adenocarcinomas. Thus, lipid profiles accurately distinguish tumor from adjacent normal tissue and classify non-small cell lung cancers according to the histologic type.