Expression of the c-Met, p53 and Ki-67 Proteins in Astrocytic Tumors

ABSTRACT

OBJECTIVE: The pathologic diagnosis of the astrocytoma has been primarily based on the histologic grading, however, there are some discrepancies among the pathologists on the tumor grading. Met protein, known as the hepatocyte growth factor receptor, is a transmembrane 190 kDa heterodimer with tyrosine kinase activity, encoded by c-met gene. Although c-Met protein is known to be expressed in a variety of tissues and plays important roles in signal transduction, the study on its expression related to clinicopathological prognostic parameters in brain tumor is rare. METHODS: We have evaluated c-Met protein expression in association with p53 and Ki-67 expression in 35 astrocytic tumors (15 diffuse astrocytomas LGA, 11 anaplastic astrocytomas AA, 9 Glioblastoma multiforme GBM) using immunohistochemical method. RESULTS: c-Met immunoreactivity was observed in 2 LGA(13.3%), 5AA(45.5%), 4GBM cases (44.4%), respectively. p53 immunoreactivity was observed in 2 LGA(13.3%), 4AA(36.4%), 4GBM cases (44.4%), respectively. Ki-67 labelling index was 1.7+/-1.0% (LGA), 13.3+/-.2% (AA) and 18.0+/-.1% (GBM), respectively. Each c-Met expression and the Ki-67 labelling index were statistically correlated between low grade and anaplastic astrocytomas. The c-Met and p53 expression rate were not associated with increased Ki-67 labelling index. But, c-Met, p53, Ki-67 expression tended to increase with higher grade of malignancy. CONCLUSION: We conclude that c-Met expression may contribute to the invasiveness and tumor progression of the astrocytoma and c-Met expression is useful in discrimination between low grade astrocytoma and anaplastic astrocytoma.