Evaluation of Endoglin as an Angiogenesis Marker in Glioblastoma

Angiogenesis is essential for growth and metastasis of solid malignancies. Tumor vessel count and expression of vascular endothelial growth factor (VEGF), a potent angiogenic factor, have been associated with prognosis. This study was designed to assess vessels density by using CD31 and CD105 (Endoglin) and their correlation with expression of VEGF and proliferative index (Ki67) in Glioblastoma multiforme (GBM).

We examined these parameters in GBM specimens from 50 adult patients; referred to Al-Zahra hospital Pathology Lab between 2001 to 2006.These patients did not receive pre-operative therapy. Paraffin-embedded tumor specimens were immunohistochemically stained for CD31, CD105 (Endoglin), VEGF and Ki67 (proliferation index) monoclonal antibodies. Microvessel density (MVD) was evaluated by immunostaining for CD31 and CD105.Then the results were compared between the two and also with VEGF receptors and Ki67 index.

CD105-MVD was significantly higher in Glioblastoma compared with peritumoral normal (14.28 vs. 6.68: P=0.012). We did not find such difference for CD31. The mean of CD105-MVD was significantly higher than CD31-MVD in Glioblastoma tissue (P<0.001) although there was a significant positive relationship between them (Pearson's r=0.630 P<0.001).The VEGF scoring for tumoral tissue was 12 % (score:1), 46% (score:2) and 42% (score:3).For peritumoral normal tissue were 92% (score:1) and 8% (score:2) . So they reach to statistical significance (Chi Square, P = 0001). Both MVD of CD105 and CD31 have significant relationship with VEGF (P<0.001).

We suggest that Endoglin can be used as a specific and sensitive marker for evaluation of angiogenesis in Glioblastoma.