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

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.

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-I₀) and subpopulation (EC9706-I₃) 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.

EC9706-I₃ 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-I₃ cells were less sensitive to the chemotherapy drug 5-fluorouracil than EC9706-I₀ 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-I₀ cells grew more slowly than those from EC9706-I₃ cells at weeks 3-14. The EC9706-I₃ xenograft model displayed a spontaneous metastatic site, including kidney, heart, liver, lung, pancreas, and spleen, with a distant metastatic rate of 80%.

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.