Decreased expression of heparanase in glioblastoma multiforme

Object. The authors investigated the presence of endoglycosidase heparanase in human glioblastoma multiforme (GBM) and metastatic brain tumors as well as in healthy brain tissue to explore the relationship between the biological characteristics of GBM and the role of heparanase. Methods. Heparanase messenger (m)RNA was almost undetectable in GBMs in vivo, whereas it was frequently seen in metastatic brain tumors according to results of reverse transcription—polymerase chain reaction (RT-PCR). Immunohistochemical analysis of paraffin-embedded tissue sections showed that neoplastic cells in metastatic brain tumors, especially in cells that invaded blood vessels, exhibit intense heparanase immunoreactivity. Heparanase was present in two highly invasive glioma cell lines, U87MG and U251MG, in vitro. These cell lines did not have metastatic capability, which was tested in an experimental pulmonary metastases model in mice. The activity of heparanase in these cell lines was almost the same as that in the highly...