Expression of tyrosine kinases FAK and Pyk2 in 331 human astrocytomas

The progression of malignancy from astrocytomas to glioblastomas remains clinically as well as histopathologically unpredictable. The focal adhesion kinase (FAK) and the proline-rich tyrosine kinase (Pyk2) show a high expression in glioma cell lines and have an influence on increased cell proliferation and migration of glioma cells in vitro and in vivo. The aim of this study was to correlate the coexpression of FAK and Pyk2 to the WHO grade of malignancy in human astrocytomas. Immunohistochemical staining scores of FAK and Pyk2 were analyzed in 331 astrocytomas and correlated to each other and to the WHO grade. Significant coexpression of FAK and Pyk2 in astrocytomas was demonstrated. Pyk2 expression occurred much more frequently and with higher expression scores within the different WHO grades. Beyond this, a significant correlation between the WHO grade of malignancy of astrocytomas and the expression of FAK, as well as of Pyk2, was detected. This connection and the roles of these two tyrosine kinases in the progression of tumors should be confirmed by further studies.