A mass spectrometric method for in-depth profiling of phosphoinositide regioisomers and their disease-associated regulation

Phosphoinositides are a family of membrane lipids essential for many biological and pathological processes. Due to the existence of multiple phosphoinositide regioisomers and their low intracellular concentrations, profiling these lipids and linking a specific acyl variant to a change in biological state have been difficult. To enable the comprehensive analysis of phosphoinositide phosphorylation status and acyl chain identity, we develop PRMC-MS (Phosphoinositide Regioisomer Measurement by Chiral column chromatography and Mass Spectrometry). Using this method, we reveal a severe skewing in acyl chains in phosphoinositides in Pten -deficient prostate cancer tissues, extracellular mobilization of phosphoinositides upon expression of oncogenic PIK3CA, and a unique profile for exosomal phosphoinositides. Thus, our approach allows characterizing the dynamics of phosphoinositide acyl variants in intracellular and extracellular milieus. Different phosphoinositide isomers are involved in a variety of physiological and pathological processes. Here, the authors combine chiral column chromatography and mass spectrometry to measure phosphoinositide regioisomers, revealing their dynamic changes in intra- and extracellular cancer cell milieus.