Characterization of the lipids from human renal and urothelial neoplasms, by magnetic resonance spectroscopy and chromatography

This work reports a study on the characterization of the lipid obtained from cortical and medullary normal human kidney tissue, medullary tissue infiltrated by clear cell carcinomas (RCC), malignant renal neoplasms (RCC) and an urothelial carcinoma. The total lipid fractions were analyzed by 13C and 1H magnetic resonance spectroscopy and thin-layer chromatography, whereas the different lipid fractions were characterized by gas chromatography and high-performance liquid chromatography. The analysis evinced significant differences in the renal tissues here examined. It was confirmed that lipids obtained from healthy renal parenchyma are mainly composed by triglycerides, which are mostly formed by oleic and palmitoleic acids. Although the free cholesterol and phospholipid contents varied, phosphatidylcholine (PC) was the most representative phospholipid in all samples, as shown by the 13C NMR spectra. The medullary renal tissues infiltrated by RCC had considerable amounts of esterified cholesterol and free fatty acids, being higher in those areas that were closer to the neoplasm. The cortex renal tissues had a lower triglyceride level as compared to the medullary ones, but they exhibited significant amounts of α-tocopherol, Q10 coenzyme and phospholipids. The silica thin-layer chromatography (TLC) evinced the presence of esterified cholesterol and dolichols. Regarding RCC samples, they exhibited large amounts of esterified cholesterol, α-tocopherol, Q10 coenzyme, free fatty acids and phospholipids. In these neoplasms, PC was also the most representative phospholipids, and dolichols were detected in negligible amounts. On the other hand, the urothelial carcinoma displayed a quite different lipid profile as compared to that of the RCC. In fact, it showed low levels of triglycerides, whereas the TLC bands of squalene, dolichols, phospholipids, free and esterified cholesterol and fatty acids were particularly intense. These results confirm the potential role of esterified cholesterol as prognostic and diagnostic factor of neoplasies, with a particular capability to indicate the tumor diffusion in healthy renal parenchyma. This work also underlines the importance and great advantage of applying complementary techniques (such as spectroscopy and chromatography) to the analysis of lipids in neoplasms, providing a more complete and detailed profile of these components.