The aim of this study was to evaluate the activity of the p42 MAPK subunit (mitogen activated protein kinase), one of the most important factors of proliferation and differentiation, in metastatic liver tumors. The material comprised liver biopsies collected from 16 patients during large bowel cancer surgery. We evaluated the activity of MAPK from the central part of each tumor, the border region (between tumor and macroscopically uninvolved liver) and samples located far away from the metastases. This was determined by means of the westernblot technique with IgG antibodies directed against MAPK. 13 cases presented with an increased MAPK level in samples collected from liver tumors. In 9 of 13 cases the highest MAP kinase activity was noted in the peripheral part of the tumor. Our results correlate with the supposed role of the kinase cascade in the formation and growth of metastatic liver tumors. The elevated MAPK level in the peripheral part of the tumor can explain the rapid tumor growth and the high percentage of tumor recurrence following surgery. Thus, in cases of liver metastases the tumor tissue should be resected with a wide margin.

Keywords: MAPK, liver metastases