Postirradiated and nonirradiated gliosarcoma: immunophenotypical profile

Analysis of cerebral angiogenesis in human glioblastomas

The formation of new blood vessels is a major hallmark in the process of malignant transformation in human glioblastomas. In diffusely infiltrating gliomas, enhanced angiogenesis is associated with decreased patient survival rates and therefore serves as a central diagnostic criterion according to the WHO (World Health Organization) classification of tumors of the central nervous system (CNS). However, the assessment of what a newly built blood vessel really is and how the extent of glioma-associated angiogenesis can be estimated in vivo is often a highly subjective procedure with imprecise criteria depending on the experience of the neuropathologist. The increased interest in translational medicine and anti-angiogenic treatment strategies implies that basic researchers in glioma angiogenesis are frequently asked to validate their findings in patient material to provide evidence for potential clinical relevance of their results. Therefore, more precise methods and measurement techniques are needed to objectively measure the extent of angiogenesis in human glioblastoma samples. The present synopsis provides an overview about morphological methods to assess the formation of new blood vessels by quantitative imaging using histological and immunohistochemical marker profiles.

Analysis of the TP53 gene in laser-microdissected glioblastoma vasculature

Malignant transformation of human gliomas is accompanied by extensive proliferation of stromal blood vessels. Recent data suggest mesenchymal transdifferentiation of neoplastic cells in various human cancers, including colon and breast cancer as well as gliosarcoma. In this study, we have analyzed proliferating stromal blood vessels in glioblastoma multiforme for the presence of mutations in the tumor suppressor gene TP53. Using tissue arrays derived from glioblastoma specimens, cases with significant immunohistochemical p53 accumulation were selected for molecular genetic detection of TP53 mutations in exons 5 to 8. None of the tumors included in this series displayed properties of gliosarcoma. Proliferating glomeruloid stromal vessels were isolated by laser microdissection from paraffin sections. In six cases, single-strand conformation polymorphism analysis for mutations of the TP53 gene in stromal blood vessels compared with adjacent tumor cells and subsequent DNA sequencing of the resulting DNA fragments were carried out. Glioblastoma cells of these cases exhibited TP53 mutations in exons 5, 7 and 8. None of these tumors showed TP53 mutations in microdissected samples from glomeruloid vessels. The absence of TP53 mutations in vascular stromal components of glioblastoma multiforme supports the hypothesis that microvascular proliferations originate from the tumor stroma and are not derived from transdifferentiated glioblastoma cells.