Objective: To explore the changes of metastatic potential of residual hepatocellular carcinoma (HCC) after in vivo chemotherapy and its mechanism.
Methods: Nude mouse models of orthotopic HCC in the nude mouse livers was established using human hepatocellular carcinoma cell line MHCC97L cells. Oxaliplatin (10 mg/kg, once per week) was administered intraperitoneally (i.p.) to mice in the trial group. Mice in the control group received 0.2 ml of 0.9% sodium chloride on the same days. On day 7 after the third injection, all mice were sacrificed and tumor fragments of equal volume (2 mm×2 mm×2 mm) from each mouse of the oxaliplatin-treated and untreated groups were reinoculated into the livers of each new recipient mouse correspondingly. The growth, metastasis and molecular phenotype of the reinoculated tumors in both groups were determined.
Results: In the new recipient mice, compared with untreated tumors, oxaliplatin pre-treated tumors grew significantly slower [(2624.59 ± 491.60) mm(3) vs. (3849.72 ± 827.09) mm(3), P < 0.001], but gave more spontaneous metastasis to the lung (10/12 vs. 3/12, P = 0.012). A decreased expression of E-cadherin and increased expression of N-cadherin, vimentin and transcription factor Snail were detected in the oxaliplatin pre-treated tumors by immunohistochemistry, which provided the evidence of epithelial mesenchymal transition (EMT) in these tumors.
Conclusion: Residual hepatocellular carcinomas after in vivo chemotherapy grow slower but gain enhanced metastatic potential to the lung, associated with epithelial mesenchymal transition.