Analysis of MFGE8 expression and regional localization in glioblastoma tumor samples at diagnosis and relapse.

e14016 Background: Milk fat globule-EGF factor 8 protein (MFGE8) is an immunomodulatory protein with an increasingly recognized role in cancer. It plays a role in tumor progression, and its expression is associated with poor prognosis. However, its expression patterns and prognostic significance in glioblastoma (GBM), the most common brain tumor in adults, remain unclear. This study investigates the localization and clinical relevance of MFGE8 in GBM. Methods: We identified 11 adult patients at our center who had both an initial diagnosis and a relapse biopsy of GBM. The specimens were analyzed using immunofluorescence staining for MFGE8, glial fibrillary acidic protein (GFAP), CD68, CD163, IL-6, P16, and Lamin B1. Tumor, necrotic, and parenchymal regions were identified via hematoxylin and eosin (H&E) staining by a central nervous system pathologist. Expression levels were quantified using the Visiopharm Integrator System software for automated image and co-expression analysis. Results: MFGE8 was highly co-expressed with GFAP and predominantly localized in tumor regions compared to necrotic or parenchymal areas. Increased MFGE8 expression correlated with a shorter progression-free survival (Spearman correlation: -0.69, p = 0.0289), highlighting its association with poor prognosis. Interestingly, in patients relapsing within 24 months, a marked reduction in Lamin B1 expression was observed in tumor regions (19.49% vs. 3.06%, p = 0.0390). Meanwhile, MFGE8 expression remained consistent between diagnostic and relapsed specimens (MFI: 11.87 vs. 12.84, p = 0.1602). Conclusions: The strong co-expression of MFGE8 with GFAP highlights its involvement in glioblastoma pathogenesis and progression. The role of Lamin B1 expression in GBM remains underexplored. Although Lamin B1 loss is linked to senescence, it may also promote cancer progression, as observed in lung cancer. These findings suggest that Lamin B1 and MFGE8 could represent potential biomarkers for aggressive tumor behavior.