Development and optimization of orthotopic liver metastasis xenograft mouse models in uveal melanoma

Abstract

Background: Patients with metastatic uveal melanoma (MUM) in the liver usually die within 1 year. The development of new treatments for MUM has been limited by the lack of diverse MUM cell lines and appropriate animal models. We previously reported that orthotopic xenograft mouse models established by direct injection of MUM cells into the liver were useful for the analysis associated with tumor microenvironment in the liver. However, considering that patients with UM metastasize to the liver hematogenously, direct liver injection model might not be suitable for investigation on various mechanisms of liver metastasis. Here, we aim to establish new orthotopic xenograft models via hematogenous dissemination of tumor cells to the liver, and to compare their characteristics with the hepatic injection model. We also determine if hepatic tumors could be effectively monitored with non-invasive live imaging. Methods: tdtTomate-labeled, patient-derived MUM cells were injected into the liver, spleen or tail vein of immunodeficient NSG mice. Tumor growth was serially assessed with In Vivo Imaging System (IVIS) images once every week. Established hepatic tumors were evaluated with CT scan and then analyzed histologically. Results: We found that splenic injection could consistently establish hepatic tumors. Non-invasive imaging showed that the splenic injection model had more consistent and stronger fluorescent intensity compared to the hepatic injection model. There were no significant differences in tumor growth between splenic injection with splenectomy and without splenectomy. The splenic injection established hepatic tumors diffusely throughout the liver, while the hepatic injection of tumor cells established a single localized tumor. Long-term monitoring of tumor development showed that tumor growth, tumor distribution in the liver, and overall survival depended on the number of tumor cells injected to the spleen. Conclusion: We established a new orthotopic hepatic metastatic xenograft mouse model by splenic injection of MUM cells. The growth of orthotopic hepatic tumors could be monitored with non-invasive IVIS imaging. Moreover, we evaluated the therapeutic effect of a MEK inhibitor by using this model. Our findings suggest that our new orthotopic liver metastatic mouse model may be useful for preclinical drug screening experiments and for the analysis of liver metastasis mechanisms.

The long non-coding RNASAMMSONis essential for uveal melanoma cell survival

“…The fact that we did not observe tumor DNA in blood may be indicative of the latter. Additional studies in uveal melanoma xenograft models that metastasize (36–38) should further assess the impact of SAMMSON knockdown on metastatic disease. Our in vitro data, based on multiple cell lines with a different genetic background, and in vivo data, based on two genetically different UM PDX models, suggest that the genetic background of the tumor does not influence the response to SAMMSON inhibition, further highlighting the broad relevance of SAMMSON inhibition as a potential therapeutic strategy.…”

Animal models of uveal melanoma

“…Cell lines from human metastatic UM are in use and their origins described elsewhere ( 84 ). Intrahepatic injection or implantation, splenic injection, intracardiac delivery or direct intravenous injection via the tail vein have been described ( 43 , 106 , 135 , 136 ). One group developed a mouse model with EGFP-luciferase-labeled human OMM1.3 cells into the retroorbital space of mice with SCID.…”

“…One study reported a tumor engraftment rate of 83% with this method, with the ability to follow tumors by computed tomography ( 107 ). Another study showed that splenic injections of patient-derived metastatic UM cells formed tumors diffusely throughout the liver compared to the hepatic injection that formed a single tumor ( 136 ). Additional treatments for human metastatic UM with radiotherapy, chemotherapy, gene therapy, and other agents have been explored ( 4 ).…”

Modeling pancreatic cancer in mice for experimental therapeutics

“…The most common and reliable models for liver metastasis are splenic and portal vein injection models that consistently form hepatic metastases and are considered suitable for evaluating targeted therapies and immunotherapy based approaches (Figure 1A; panel 2) [129][130][131]. The highly consistent portal vein injection model has been used for liver metastasis in the multiple cancers including the colon, pancreas, breast, and uvea [132][133][134][135]. However, the portal vein injection model is surgically more cumbersome where a surgeon must flip all the abdominal organs to expose the portal vein.…”