Clinical significance of aggressive hepatectomy for colorectal liver metastasis, evaluated from the HGF/c-Met pathway

Liver metastasis is one of the most critical factors in deciding the prognosis of patients with colorectal cancer (CRC). Hepatectomy is the most curative treatment for liver metastasis of CRC. The high amount of hepatocyte growth factor (HGF) is produced to promote liver regeneration by hepatectomy. Theoretically, HGF produced after hepatectomy stimulates the progression of CRC cells with c-Met in residual liver. This study was aimed to evaluate the value of hepatectomy towards liver metastasis of CRC in relation to the HGF/c-Met pathway. Ninety-four patients with CRC (including 24 liver metastasis cases) were operated at Gifu University Hospital (2002-2004). For these cases, the expression of c-Met in the primary and liver metastatic sites was evaluated by immunohistochemistry and Western blot. Experiments were also conducted on CT26 murine CRC cell line and a mouse liver metastasis model. In clinical study, the c-Met expression in liver metastatic sites was lower than in the primary sites in 87% of 24 cases. In basic study, the expression of c-Met protein in the liver tumor was significantly lower than in culture cells according to Western blot (p=0.033). The growth of residual liver tumors was not significantly different between 30% hepatectomy group and no operation group. The over-expression of c-Met was closely associated with CRC liver metastases. On the other hand, in liver metastatic lesions, the c-Met expression was reduced in comparison to primary lesions. Therefore, even if serum HGF levels increased due to liver resection during the regeneration period, residual liver metastases of CRC was not promoted in its progression. Aggressive hepatectomy would still be acceptable and favorable as a curative therapy.