Development of a Novel Highly Spontaneous Metastatic Model of Esophageal Squamous Cell Carcinoma Using Renal Capsule Technology

PURPOSE: Increasing evidence has demonstrated that animal models are imperative to investigate the potential molecular mechanism of metastasis and discover anti-metastasis drugs; however, efficient animal models to unveil the underlying mechanisms of metastasis in esophageal squamous cell carcinoma (ESCC) are limited. METHODS: ESCC cell EC9706 with high invasiveness was screened by repeated Transwell assays. Its biological characteristics were identified by flow cytometry as well as by the wound healing and CCK-8 assays. Besides, the levels of epithelial–mesenchymal transition-related markers were examined using Western blotting. Parental (EC9706-I(0)) and subpopulation (EC9706-I(3)) cells were employed to establish the renal capsule model. Next, the tumor growth was detected by a live animal imaging system, and hematoxylin and eosin staining was applied to evaluate the metastatic status in ESCC. RESULTS: EC9706-I(3) cells showed rapid proliferation ability, S phase abundance, and high invasive ability; obvious upregulation in N-cadherin, Snail, Vimentin, and Bit1; and downregulation in E-cadherin. EC9706-I(3) cells were less sensitive to the chemotherapy drug 5-fluorouracil than EC9706-I(0) cells; however, both cell lines reached a tumorigenesis rate of 100% in the renal capsule model. The live animal imaging system revealed that the tumors derived from EC9706-I(0) cells grew more slowly than those from EC9706-I(3) cells at weeks 3–14. The EC9706-I(3) xenograft model displayed a spontaneous metastatic site, including kidney, heart, liver, lung, pancreas, and spleen, with a distant metastatic rate of 80%. CONCLUSION: Our data suggested that the metastatic model was successfully established, providing a novel platform for further exploring the molecular mechanisms of metastasis in ESCC patients.