Effective timing of surgical resection of colorectal cancer liver metastases during chemotherapy

Abstract

Background/Aim: The aim of the present study was to further develop our previous study on c-Met expression in colorectal cancer and epithelial-mesenchymal transition (EMT) induced by hepatocyte growth factor (HGF), to investigate EMT in the process of liver metastases, and evaluate the effects of chemotherapy on EMT cells as a therapeutic strategy for colorectal liver metastasis. Materials and Methods: CT26 colon cancer cells were treated with 5-FU and oxaliplatin with or without HGF. The signaling pathway was evaluated by western blotting analysis, and drug resistance was evaluated by the MTT (3-(4,5-dimethyl-2-tetrazolyl)-2,5-diphenyl-2H tetrazolium bromide) assay. Results: Under pretreatment with HGF for 96 h, 5 μM and 10 μM of 5-FU mediated significant growth inhibition by 72.5±3.9% and 76.2±2.4%, respectively, compared to HGF alone, and by 105.1±2.8% and 103.5±2.9%, respectively, without HGF. The expression of E2F1 was decreased significantly to 50.5±3.8% after 24 hours by HGF with a reduction of both cyclin D1 to 52.1±7.0% and E to 73.7±3.8%. Thymidylate synthase was also decreased in a time-dependent manner to 80.6±2.0% after 24 h and to 52.7±1.5% after 96 h. Conclusion: The presence of HGF was found to increase the 5-FU-induced death signal, JNK pathway, and inhibition of cell growth. As its mechanism, HGF was shown to decrease E2F-1 by reducing cyclin D or E by cell-cycle activation, resulting in inactivation of thymidylate synthase. The chemotherapeutic effect of 5-FU was increased in HGF- but not TGF-β-induced EMT.