The hallmarks of human
malignant gliomas are their marked invasiveness and vascularity. Because angiogenesis and
tumor invasion have been associated with extracellular matrix degradation and intercellular tight junctions, the involvement of
zonulin in
glioma biology is in the focus. We selected for histological examination five cases of
glioblastoma WHO IV (nomenclature of the World Health Organization) and one case each from
astrocytoma WHO III,
meningioma WHO III, and
meningioma WHO I as control samples. The
meningioma WHO I is regarded as benign, whereas the
meningioma WHO III is recognized as the transition form of malignant
tumors in humans. The visualization of a newly designed antibody against human
zonulin was studied in triple-labeling studies using fluorescence immunocytochemistry and compared with the expression of c-kit and
glial fibrillary acidic protein in differently developed human
gliomas. We found that increasing the expression of c-kit is accompanied by an increase of
zonulin expression. Both are correlated to the degree of
malignancy of human
brain tumors. The expression of
zonulin is correlated to the degradation of the blood-brain barrier as revealed by Griffonia simplicifolia
lectin. In differently graded
tumors, we found differently graded involvement of blood vessels in the
tumor development, explaining patients' survival.