Wojakowska Anna, Cole Laura M, Chekan Mykola, Bednarczyk Katarzyna, Maksymiak Magdalena, Oczko-Wojciechowska Małgorzata, Jarząb Barbara, Clench Malcolm R, Polańska Joanna, Pietrowska Monika, Widlak Piotr
Endokrynol Pol. 2018;69(1):2-8. doi: 10.5603/EP.a2018.0003.
The distinction of papillary thyroid carcinomas from benign thyroid lesions has important implication for clinical man-agement. Classification based on histopathological features can be supported by molecular biomarkers, including lipidomic signatures, identified with the use of high-throughput mass spectrometry techniques. Formalin fixation is a standard procedure for stabilization and preservation of tissue samples, therefore this type of samples constitute highly valuable source of clinical material for retrospective molecular studies. In this study we used mass spectrometry imaging to detect lipids discriminating papillary cancer from not cancerous thyroid directly in formalin-fixed tissue sections.
For this purpose imaging and profiling of lipids present in non-malignant and cancerous thyroid tissue specimens were conducted. High resolution MALDI-Q-Ion Mobility-TOF-MS technique was used for lipidomic analysis of formalin fixed thyroid tissue samples. Lipids were identified by the comparison of the exact molecular masses and fragmentation pathways of the protonated molecule ions, recorded during the MS/MS experiments, with LIPID MAPS database.
Several phosphatidylcholines (32:0, 32:1, 34:1 and 36:3), sphingomyelins (34:1 and 36:1) and phosphatidic acids (36:2 and 36:3) were detected and their abundances were significantly higher in cancerous tissue compared to non-cancerous tissue. The same lipid species were detected in formalin-fixed as in fresh-frozen tissue, but [M + Na]+ ions were the most abundant in formalin fixed whereas [M + K]+ ions were predominant in fresh tissue.
Our results prove the viability of MALDI-MSI for analysis of lipid distribution directly in formalin-fixed tissue, and the potential for their use in the classification of thyroid diseases.
甲状腺乳头状癌与良性甲状腺病变的区分对临床管理具有重要意义。基于组织病理学特征的分类可得到分子生物标志物的支持，包括利用高通量质谱技术鉴定的脂质组学特征。福尔马林固定是组织样本稳定和保存的标准程序，因此这类样本构成了回顾性分子研究中非常有价值的临床材料来源。在本研究中，我们使用质谱成像技术直接在福尔马林固定的组织切片中检测区分甲状腺乳头状癌与非癌性甲状腺的脂质。
为此，对非恶性和癌性甲状腺组织标本中的脂质进行了成像和分析。采用高分辨率基质辅助激光解吸电离-四极杆-离子淌度-飞行时间质谱技术对福尔马林固定的甲状腺组织样本进行脂质组学分析。通过将质谱/质谱实验中记录的质子化分子离子的确切分子量和裂解途径与脂质地图数据库进行比较来鉴定脂质。
检测到几种磷脂酰胆碱（32:0、32:1、34:1和36:3）、鞘磷脂（34:1和36:1）和磷脂酸（36:2和36:3），与非癌性组织相比，它们在癌性组织中的丰度显著更高。在福尔马林固定的组织中检测到的脂质种类与新鲜冷冻组织中相同，但在福尔马林固定的组织中[M + Na]+离子最为丰富，而在新鲜组织中[M + K]+离子占主导。
我们的结果证明了基质辅助激光解吸电离质谱成像技术在直接分析福尔马林固定组织中脂质分布方面的可行性，以及其在甲状腺疾病分类中的应用潜力。
