Lipid MALDI MS profiling accurately distinguishes papillary thyroid carcinoma from normal tissue

Abstract

Background: Histology-directed tissue Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI MS) has been used to identify lipid profiles that can distinguish cancerous epithelium from normal epithelium. Methods: In order to evaluate if lipid profiles may assist with diagnosis, frozen resected tumor samples collected from papillary thyroid carcinoma patients were analyzed using Matrix (DHB/CHCA)-Assisted Laser Desorption/ Ionization (MALDI) Mass Spectrometry (MS), together with adjacent normal tissue samples. Results: Lipid peaks differentially expressed between cancer and normal samples at a feature selection P<0.001 correctly predicted class labels of test set samples (7 pairs) in 100 random training-to-test partitions, at the median class prediction accuracy of 100%. In addition, lipid peaks differentially expressed between 14 pairs of cancer and adjacent normal samples correctly predicted 100% of validation set samples (8 out of 8 samples). Phosphatidylcholines (PC) 32:0 and PC 34:1, sphingomyelin 34:1, and several phosphatidylinositols were overexpressed, while lysophosphatidylcholine 18:3 and lysophosphatidylserine 18:1 were underexpressed in papillary thyroid carcinomas, compared with normal tissue. Conclusions: Lipid MALDI MS profiles accurately distinguish papillary thyroid carcinoma epithelium from normal epithelium, and demonstrate the potential as a diagnostic aid. © 2013 Ryu J, et al.