Alteration Of Invasiveness And Metastatic Potential Of Hepatocellular Carcinoma After Chemotherapy, Its Molecular Basis And Intervention-an Experimental Study

BackgroundHepatocellular carcinoma (HCC) is one of the most common malignancies in many countries. Radical treatment, such as surgical resection and orthotopic liver transplantation, is feasible only for patients with small tumors. For the majority of patients with unresectable HCC, the response rate of systemic chemotherapy was reported to be approximately 20%, and no survival benefit was observed. The reasons for this remain unclear. Biological deterioration after chemotherapy has recently been noted. Animal studies revealed that chemotherapy may promote cancer metastasis through damaging the vascular endothelium and inhibiting the host antitumor system, which is called the "opposite effect" of chemotherapy. Chemotherapy may also directly influence tumor cells. In vitro studies showed that tumor cells gain enhanced metastatic potential after chronic exposure to chemotherapeutic agents. However it is not clear whether in vivo chemotherapy acts in the same way. In the present study, we employed an orthotopic nude mouse model of human hepatocellular carcinoma (HCC) to study the alteration of metastatic potential within residual HCC after in vivo chemotherapy. We also investigated its molecular basis and approach to improve clinical outcome of chemotherapy for patients with HCC. MethodsMHCC97L-oxa and HepG2-oxa cells were established by exposing MHCC97L (with moderate metastatic potential) and HepG2 (with low metastatic potential) cells to 2μmol/L oxaliplatin in vitro. The motility, invasion, proliferation and phenotype were compared between oxa-treated cells and their parental cells. A nude mouse model of human hepatocellular carcinoma was employed using orthotopic implantation of MHCC97L cells to study the alteration of growth, metastasis and molecular background of residual cancer after in vivo chemotherapy. We also investigated the effects of the traditional Chinese herbal extract Songyou Yin (comprises of 5 herbs) on the biological features of residual cancer after chemotherapy.ResultsCompared with the untreated parental cells, MHCC97L-oxa and HepG2-oxa showed enhanced motility (19.17±2.64 vs.29.50±5.28, P=0.002 and 12.33±2.73 vs.21.17±3.13, P<0.001 respectively) and invasion (0.89 fold increase, P<0.001 and 1.58 fold increase, P=0.001 respectively). Residual cancer after oxaliplatin treatment exhibited epithelial-mesenchymal transition (EMT) with upregulation of E-cadherin and downregulation of N-cadherin, vimentin and transcription factor snail. These observations were verified by in vitro study. The Chinese herbal extract Songyou Yin (4.2 and 8.4g/kg) attenuated EMT and inhibited the enhanced metastatic potential of residual HCC in nude mice (13/15 vs.6/15, P= 0.021 and 13/15 vs.3/15, P= 0.001 respectively) and prolonged survival (53.83±4.71 days vs.66.67±5.61 days, P= 0.002 and 53.83±4.71 days vs.81.17±7.36 days, P= 0.001 respectively).Conclusions1. The surviving HCC cells after in vitro and in vivo oxaliplatin treatment undergo EMT and demonstrate increased metastatic potential.2. The traditional Chinese herbal extract Songyou Yin attenuates the enhanced metastatic potential of residual HCC after oxaliplatin treatment and prolongs survival in nude mice bearing human HCC.Potential application of this work.1. Clarifying the alterations of the metastatic potential within residual hepatocellular carcinoma after chemotherapy and the molecular basis may help to provide instructions for clinical chemotherapy and minimize the recurrence and metastasis of residual cancer.2. The attenuation of the enhanced metastatic potential within residual hepatocellular carcinoma after chemotherapy by Songyou Yin provides a novel approach for improving response of chemotherapy in patients with HCC.Originalities of this work1. For the first time we reported that residual hepatocellular carcinoma has enhanced metastatic potential after in vivo chemotherapy.2. For the first time we reported the attenuation of EMT by the traditional Chinese medicine Songyou Yin and its potential in improving the response of chemotherapy in patients with HCC.