Cell Reports: Methods (Jul 2024)
Tongue orthotopic xenografts to study fusion-negative rhabdomyosarcoma invasion and metastasis in live animals
Abstract
Summary: PAX3/7 fusion-negative rhabdomyosarcoma (FN-RMS) is a childhood mesodermal lineage malignancy with a poor prognosis for metastatic or relapsed cases. Limited understanding of advanced FN-RMS is partially attributed to the absence of sequential invasion and dissemination events and the challenge in studying cell behavior, using, for example, non-invasive intravital microscopy (IVM), in currently used xenograft models. Here, we developed an orthotopic tongue xenograft model of FN-RMS to study cell behavior and the molecular basis of invasion and metastasis using IVM. FN-RMS cells are retained in the tongue and invade locally into muscle mysial spaces and vascular lumen, with evidence of hematogenous dissemination to the lungs and lymphatic dissemination to lymph nodes. Using IVM of tongue xenografts reveals shifts in cellular phenotype, migration to blood and lymphatic vessels, and lymphatic intravasation. Insight from this model into tumor invasion and metastasis at the tissue, cellular, and subcellular level can guide new therapeutic avenues for advanced FN-RMS. Motivation: Current models for studying fusion-negative rhabdomyosarcoma (FN-RMS) are limited in terms of their physiological relevance and ability to inform on invasion and metastasis. As a step toward advancing our understanding of molecular mechanisms of advanced FN-RMS, we developed an orthotopic tongue xenograft model of FN-RMS for intravital multi-photon microscopy. Longitudinal non-invasive intravital microscopy of cell line-based xenografts in live animals allows the dissection of the cellular behavior and related molecular basis in vivo. Combined with the tongue xenograft model, the system facilitates the examination of cellular behavior in FN-RMS local invasion, dissemination, and metastasis.
