Establishment of orthotopic animal models for investigating tumor microenvironment, extracellular matrix interactions, and metastasis in esophageal squamous cell carcinoma

Abstract

Increasing evidence identifies tumor-stromal interactions as an important factor in cancer. In the past decades, different esophageal squamous cell carcinoma (ESCC) orthotopic animal models were established. However, these models were not able to capture the microenvironment observed in the clinical samples. As a result, an improved in vivo ESCC orthotopic animal model with the capability of bioluminescence imaging was established that provides a real-time monitoring platform for functional and signaling investigation of tumor-stromal interactions. ESCC is localized to the lower two-thirds of the esophagus. Targeting this portion of the esophagus has been one of the aims in establishing this orthotopic model. The model was established by injection of luciferase-labelled ESCC cells into the muscularis externa of the intra-esophageal wall in the mid-section of the esophagus of nude mice. Histological examination indicates this orthotopic model is highly reproducible with 100% tumorigenesis among the four ESCC cell lines tested. This new model recapitulates many clinical and histopathological properties of human ESCC, including esophageal luminal stricture by squamous cell carcinoma with nodular tumor growth, adventitia invasion, lymphovascular invasion, and perineural infiltration. It was tested using an AKT shRNA knockdown of ESCC cell lines and the in vivo tumor suppressive effects of AKT knockdown were observed. In conclusion, this ESCC orthotopic mouse model allows investigation of gene functions of cancer cells in a more natural tumor microenvironment and has advantages over previous established models. It provides a versatile platform with potential application for metastasis and therapeutic regimen testing.