A patient-derived orthotopic xenograft model enabling human high-grade urothelial cell carcinoma of the bladder tumor implantation, growth, angiogenesis, and metastasis.

High-grade urothelial cell carcinoma of the bladder has a poor prognosis when lymph nodes are involved. Despite curative therapy for clinically-localized disease, over half of the muscle-invasive urothelial cell carcinoma patients will develop metastases and die within 5 years. There are currently no described xenograft models that consistently mimic urothelial cell carcinoma metastasis. To develop a patient-derived orthotopic xenograft model to mimic clinical urothelial cell carcinoma progression to metastatic disease, the urothelial cell carcinoma cell line UM-UC-3 and two urothelial cell carcinoma patient specimens were doubly tagged with Luciferase/RFP and were intra-vesically (IB) instilled into NOD/SCID mice with or without lymph node stromal cells (HK cells). Mice were monitored weekly with bioluminescence imaging to assess tumor growth and metastasis. Primary tumors and organs were harvested for bioluminescence imaging, weight, and formalin-fixed for hematoxylin and eosin and immunohistochemistry staining. In this patient-derived orthotopic xenograft model, xenograft tumors showed better implantation rates than currently reported using other models. Xenograft tumors histologically resembled pre-implanted primary specimens from patients, presenting muscle-invasive growth patterns. In the presence of HK cells, tumor formation, tumor angiogenesis, and distant organ metastasis were significantly enhanced in both UM-UC-3 cells and patient-derived specimens. Thus, we established a unique, reproducible patient-derived orthotopic xenograft model using human high-grade urothelial cell carcinoma cells and lymph node stromal cells. It allows for investigating the mechanism involved in tumor formation and metastasis, and therefore it is useful for future testing the optimal sequence of conventional drugs or the efficacy of novel therapeutic drugs.
Competing Interests: CONFLICTS OF INTEREST The authors declare no conflicts of interest.