Expression of c-Met correlates with grade of malignancy in human astrocytic tumours: an immunohistochemical study

Authors


Dr M. Koono Second Department of Pathology, Miyazaki Medical College, 5200 Kihara, Kiyotake, Miyazaki 889–16, Japan.

Abstract

Aims:

Recent studies suggest the involvement of hepatocyte growth factor/scatter factor (HGF/SF) in glioma cell invasion and tumour progression. We investigated the distribution and rate of tumour cells that express c-Met protein, which is the cell-surface receptor for HGF/SF, in astrocytic tumours. The type of cells that express c-Met in tumour tissues was also identified.

Methods and results:

c-Met expression was screened immunohistochemically in a total of 43 astrocytic tumours, including 14 low-grade astrocytomas (A), 13 anaplastic astrocytomas (AA) and 16 glioblastoma multiforme (GBM). c-Met reactivity was demonstrated predominantly in the cytoplasm of tumour cells. Bizarre large tumour cells tended to stain intensely. Higher c-Met expression levels (≥ 2 +, more than 25% cells were positive) were noted in 21.4% of (A) vs. 53.8% in (AA) and 87.5% in (GBM) (< 0.001), indicating a clear relationship between c-Met protein staining and higher grade astrocytic tumours. Moreover, c-Met immunoreactivity was also shown in tumour microvasculature, reactive astrocytes, and neurones in the cortex infiltrated by glioma cells. In 85.7% of cases containing infiltrated cortex, neurones were positive vs. no neurones in non-neoplastic regions (< 0.002).

Conclusions:

This evidence suggests that c-Met expression in the brain could be associated with astrocytoma progression and also reactive process. Immunohistochemical determination of c-Met-expressing cell types helps to understand possible roles of c-Met in tumour tissues.

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