Magnetic resonance image-guided proteomics of human glioblastoma multiforme

To investigate the correlation between gadolinium contrast-enhancement patterns on T1-weighted magnetic resonance (MR) images and spatial changes in protein expression profiles in human glioblastoma multiforme (GBM) and the use of imaging as a noninvasive technique to evaluate the heterogeneity of solid tumors prior to microarray analysis.

Four patients with MR images and confirmed diagnosis of GBM were enrolled in the study. Intraoperative stereotaxy was used in conjunction with MR images to identify contrast-enhanced (CE) and nonenhanced (NE) regions of the tumor during surgical resection. Total protein was extracted from resected tumor samples using standard techniques and subjected to proteomic analysis using surface enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF-MS).

We found that protein profiles from CE and NE regions within a given tumor have qualitative and semiquantitative proteomic pattern differences, suggesting an altered gene expression profile that correlates with detectable tissue imaging parameters. We also found that CE regions within the same tumor exhibited distinct differences in protein expression profiles, despite similar histological features. In addition, there were marked similarities in the proteomic patterns among the NE regions across all patients, while the CE regions were distinct, suggesting that the CE regions have complex protein profiles unique to individuals.

The results demonstrate that major differences in protein expression patterns within a tumor can be correlated to radiographic findings. Image-guided proteomics holds promise for characterizing tissue prior to microarray analysis designed to identify specific diagnostic markers and therapeutic targets within solid tumors.