Novel Application of Ion Mobility Mass Spectrometry Reveals Complex Ganglioside Landscape in Diffuse Astrocytoma...

Diffuse astrocytoma is a primary brain tumor known for its gradual and diffuse infiltration into the surrounding brain tissue. Given this characteristic, the investigation of the peritumoral region holds potential biological and clinical relevance. In this study, ion mobility spectrometry mass spectrometry (IMS MS) was optimized and applied for the first time for the analysis of gangliosides present in the peritumoral tissue of diffuse astrocytoma. Ganglioside profiling and structural characterization were conducted using high-resolution nanoelectrospray ionization (nanoESI) IMS MS, along with tandem mass spectrometry (MS/MS) via low-energy collision-induced dissociation (CID) in the negative ion mode. Using IMS MS-based separation and screening, we observed a greater diversity of ganglioside species in the peritumoral tissue than previously reported. Notably, an elevated expression was detected for several species, including GT1(d18:1/18:0), GT1(d18:1/20:0), GM2(d18:1/16:2), GD1(d18:1/16:0), GD2(d18:1/20:0), Fuc-GT3(d18:1/24:4), and Fuc-GD1(d18:1/18:2). Although preliminary, these observations prompt consideration of whether these species could be implicated in processes such as microenvironmental modulation, tumor cell infiltration and invasion, maintenance of cellular interactions, or regulation of immune responses. Additionally, their potential utility as biomarkers may merit further exploration. In the subsequent phase of the study, structural analysis using IMS MS, CID tandem MS, and fragmentation data supported the identification of GT1b(d18:1/20:0) isomer in the peritumoral tissue. However, given the exploratory nature of the study and reliance on limited sampling, further investigation across broader sample sets is necessary to extend these findings.