| Phospholipid accounts for over 70% of the total lipids in most cell membranes and has a wide variety. Lipid composition in cell membrane is closely associated with cell characteristics. Here, matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS) was employed to in situ determine membrane components of different tumor cell lines and to quickly seek to differentiate these cell lines based on the different expression of lipid molecules.1. In situ characterizing membrane lipid phenotype of breast cancer cells using mass spectrometry profilingMALDI-FTICR MS was employed to in situ determine membrane components of human mammary epithelial cells (MCF-10A) and six different breast cancer cell lines (i.e., BT-20, MCF-7, SK-BR-3, MDA-MB-231, MDA-MB-157, and MDA-MB-361) without any lipid extraction and separation. Partial least-square discriminant analysis (PLS-DA), correlation and cluster analysis indicated that changes in the levels of these membrane lipids were closely correlated with the types of breast cell lines. Elevated levels of polyunsaturated lipids in MCF-10A cells relative to six breast cancer cells and in BT-20 cells relative to other breast cancer cell lines were detected. The Western blotting assays indicated that the expression of five lipogenesis-related enzymes (i.e., fatty acid synthase 1(FASN1), stearoyl-CoA desaturase 1 (SCD1), stearoyl-CoA desaturase 5 (SCD5), choline kinase a (CKa), and sphingomyelin synthase 1(SMS1)) was associated with the types of the breast cells, and that the SCD1 level in MCF-7 cells was significantly increased relative to other breast cell lines. Our findings suggest that elevated expression levels of FASN1, SCD1, SCD5, and CKa may closely correlated with enhanced levels of saturated and monounsaturated lipids in breast cancer cell lines.2. In Situ Lipid Profiling of Human non-small-Cell Lung Cancer Cell Lines by MALDI-FTICR Mass SpectrometryTo further connect lipid phenotype with non-small-cell lung carcinoma (NSCLC) taxonomy, ultrahigh-resolution mass spectrometry was employed to in situ investigate the associations of membrane lipid phenotype of six human NSCLC cell lines (i.e., three subtypes, A549, H1650, and H1975 from adenocarcinomas, H157 and H17O3 from squamous cell carcinomas, and H460 from a large cell carcinoma). Partial least-square discriminant analysis (PLS-DA) indicated that fifteen lipids (i.e., PE(36:1), PI(38:4), SM(42:2), PE(36:4), PE(36:2), PC(36:2), SM(34:1), PA(38:3),C18:0, C22;4, PA(34:2), C20:5 C20:2, C18:2, and CerP(36:2)) with variable importance in the projection (VIP) value of> 1.0 could be used to differentiate six cancer cell lines with the Predicted Residual Sum of Square (PRESS) score of 0.1974. The positive correlation between polyunsaturated fatty acids (PUFAs, C20:4, C22:4, C22:5, and C22:6) and polyunsaturated phospholipids (PE(36:4), PE(38:4), and PI(38:4)) were obviously observed in lung adenocarcinoma cells especially in H1975 cells. Three adenocarcinoma cell lines (i.e., A549, H1650, and H1975) could be separated from other NSCLC cell lines based on the expression of C18:1, C20:1, C20:2, C20:5, and C22:6·3. Dynamically in situ monitoring lipid changes in DHA-treated breast cells by MALDI-FTICR MSDocosahexaenoic acid (C22:6, DHA) is an n-3 polyunsaturated fatty acid and has anti-cancer effects. In this study, low doses of DHA (0,10 and 40 μM) were selected to explore its influence in membrane lipid distribution of human mammary epithelial cells (MCF-10A) and breast cancer cells (MDA-MB-231). The levels of fatty acids (C20:5, C22:4, C20:3, and C20:1), fatty acid elongase indices (C22:4/C20:4, C22:5/C20:5 and C20:1/C18:1), and phosphatidylcholines (PC(30:0), PC(32:0), PC(38:6) and PC(40:7)) changed significantly with an increase of the DHA treatment time in cancer cells. But DHA treatment has little effect on normal cells. The results demonstrated that DHA caused a significant remodeling of lipid profiling in breast cancer cells. |
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