Midkine promotes uveal melanoma progression by stimulating ABCB5+ cancer stem cells
Final Report Abstract
Uveal melanoma (UM) is a highly aggressive intraocular cancer devoid of effective targeted therapies, with 90% of metastases occurring in the liver, resulting in a bleak prognosis and limited treatment options. Patients at high risk can develop metastases years after primary tumor treatment, and survival rates have remained stagnant for decades. A key factor contributing to this stagnation is the absence of preclinical models accurately replicating the human disease progression, essential for the development and assessment of novel treatments. To enhance patient outcomes, early detection is paramount, offering a greater chance for successful interventions and potential cures, which relies on the identification of biomarkers predicting disease progression and sensitive detection methods of (micro)metastasis. Previously, we identified midkine (MDK) as a potential biomarker capable of predicting disease progression in UM. Analyzing gene expression data from 80 UM primary tumors sourced from the TCGA database, we found a significant correlation between MDK expression levels in primary UM tumors and overall survival among UM patients. This project aimed to develop a metastatic mouse model closely mirroring human disease progression, enabling the quantification and highly sensitive detection of early metastatic seeding events before substantial metastasis growth, facilitating the evaluation of early novel interventions. The second objective was to investigate the impact of elevated MDK levels on metastatic rates. Human primary UM cells were grafted into the eyes of NSG mice, benefiting from the compromised immune systems of these mice to prevent graft rejection. Highly sensitive flow cytometry was used to quantify early micro-metastatic tumor cell seeding and tumor burden. Immunohistochemistry confirmed metastasis employing validated diagnostic melanoma markers (HMB-45 and MART-1). We also engineered human primary UM cells to stably overexpress MDK to explore its effect on in vivo metastasis development. This mouse model consistently generated primary ocular tumors and demonstrated substantial liver metastases at the study's endpoint. Notably, even before macroscopic liver metastases, flow cytometry detected micrometastatic tumor cells in all liver samples, a finding subsequently confirmed by immunohistochemistry. This preclinical mouse model faithfully replicates human disease progression, encompassing the latency period between the primary tumor and liver metastasis development. It offers early detection capabilities and illustrates hepatic tropism in metastasis, providing an invaluable platform for assessing the efficacy of early interventions. Currently, the model is being employed to evaluate novel immune cell therapies and to elucidate the underlying mechanisms behind the pronounced liver tropism observed.
Publications
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Metastatic spread from primary eye tumor after enucleation in a Uveal Melanoma orthotopic human to mouse xenograft model. Invest. Ophthalmol. Vis. Sci. 2023;64(8):895.
Alice van den Broek; Nasrin Refaian; Cindy Hoppe; T.H. Khanh Vu; Martine J. Jager; Bruce Ksander & Margarete Karg
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Midkine Promotes Metastasis and Therapeutic Resistance via mTOR/RPS6 in Uveal Melanoma. Molecular Cancer Research, 20(8), 1320-1336.
Karg, Margarete M.; John, Lukas; Refaian, Nasrin; Buettner, Christian; Rottmar, Tanja; Sommer, Jonas; Bock, Barbara; Resheq, Yazid J.; Ksander, Bruce R.; Heindl, Ludwig M.; Mackensen, Andreas & Bosch, Jacobus J.
