Comparative Proteomic Profiling Using Two-Dimensional Gel Electrophoresis and Identification via LC-MS/MS Reveals Protein Biomarkers That Distinguish Aggressive from Non-Aggressive Phenotypes of Who Grade I Meningioma

Introduction: The World Health Organization (WHO) has developed histological criteria to distinguish three grades of meningioma and predict recurrence. A small subset of Grade I meningiomas behave in an aggressive manner akin to Grade II or III lesions despite benign grading. We have defined a clinical subset of aggressive Grade I meningiomas, and seek to use a proteomics based approach to identify protein biomarkers that will predict aggressive phenotypes.

Materials and Methods: 5 aggressive Grade I meningiomas were selected based upon a clinical history of multiple recurrences and progression despite multimodality treatment from a bank of fresh frozen surgical samples. These tumors were matched to a cohort of 5 clinically benign Grade I meningiomas, and protein lysates were pooled for each group. Two-dimensional gel electrophoresis (2DGE) was performed on each pool and differentially expressed proteins were identified by spots at the same location on 2DGE with relative quantification ratios of 1.5 or greater on silver staining densitometry. 22 spots were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), and potential biomarkers were chosen for validation in western blot and tissue microarray analysis based on their role in cancer regulation from bioinformatics searches.

Results: Seven potential biomarkers identified on LC-MS/MS differentially expressed on 2DGE amongst aggressive and benign tumors were chosen for validation: vimentin, galectin-1, gelsolin, HNRNPK, calreticulin, EIF3B, and DDAH-1. Decreased expression of phosphorylated Vimentin, and increased expression of Galectin-1, Gelsolin, and DDAH-1 distinguished aggressive from benign phenotypes on both western blot analysis and tissue microarray.

Conclusions: Expression levels of phosphorylated Vimentin, DDAH-1, Galectin-1 and Gelsolin distinguish clinically aggressive grade I meningiomas and may assist in identifying a small subset of Grade I meningioma that do not behave in the typical benign manner. Such markers may also predict progression to higher-grade lesions1–7.

References

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