Vascularization, proliferative activity and the p53 status in glioblastomas

<p style="text-align: justify;">Glioblastomas (GBMs) are among the most vascularized human tumors and the presence of microvascular proliferation is one of the diagnostic hallmarks of these malignancies. The aim of the present study was to investigate the extent of vascularization and its relation to proliferative activity and the p53 status in GBMs. Tissue samples from 100 selected primary GBMs were analyzed by immunohistochemistry for the expression of CD34 in vascular endothelial cells and Ki-67 antigen (using the MIB-1 antibody) and p53 in tumor cells. The microvessel density (MVD), a measure of the extent of tumor vascularization, was evaluated in CD34-immunostained sections in three hot spots and presented as the mean for each tumor specimen. We found that the high MVD was more frequent in tumors showing the high MIB-1-labeling index (MIB-1 LI) as compared to those with the low MIB-1 LI, but the difference was not statistically significant. Also, the extent of vascularization did not differ significantly between p53-negative and p53-positive tumors. Both the level of MVD and the proportion of GBMs with low versus high MVD did not differ significantly in relation to the expression levels of p53 (low vs. high or overexpression). No association was found between MVD and tumor cell MIB-1 LI and the p53 status in primary GBMs. These data suggest that the effect of p53 on primary GBM vascularization failed to detect possibly due to the influence of certain factors, including the presence of other or additional molecular alterations in the tumor cells and the hypoxic microenvironment of tumors. They also support the hypothesis that the effect of p53 on angiogenesis may be tumor-type specific.</p>