Deciphering mechanisms of melanoma metastasis with main focus on brain metastasis

• Applicant: Dr. Torben Redmer
• Subject Area: Dermatology ; Hematology, Oncology
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 392534127

Melanoma distant metastasis especially to the brain is associated with treatment failure and relapse, hence insight in mechanisms of how melanoma cells acquire a metastatic phenotype and escape therapeutic regimens is essential. Therefore the aim of the proposed project is the identification of new key players and mechanisms of melanoma metastasis with main focus on metastasis to the brain. Furthermore, the uncovering of specific signatures of genes/proteins and pathways will enable the classification of new sub-groups of melanoma metastases with prognostic relevance. Expression of the nerve growth factor receptor CD271 presents a promising candidate classifier. For validation of CD271, matched pairs of extracranial and brain metastases will be initially screened by immunohistochemistry for the levels of CD271 and sub-divided into CD271high, CD271low and CD271neg tumors. RNA-sequencing of at least 10 matched pairs of extracranial and brain metastases as well as of tumor-adjacent or normal brain tissue received from two centers in Berlin and Dresden will provide insight about differentially regulated signaling pathways and will identify growth factors and neurotrophic factors potentially supporting the establishment of brain metastases. In addition, the exploration of the mutational landscape of tumors by exome-sequencing will foster the uncovering of intrinsically regulated metastasis mechanisms and genetic relationships among metastases. For exploration of epigenetic regulatory mechanisms, a methylome analysis of 850k CpG islands of extracranial and brain metastases will be performed. The integrated analysis of expression profiling, methylome analysis and exome sequencing data will provide a comprehensive map of each tumor and will enable the identification of commonly or reversibly regulated genes among melanoma metastases. In parallel, I will study mechanisms of metastasis in mouse models enabling the direct following of the routes of melanoma cells in the organism and tracking of e.g. genetically engineered melanoma cells in organs. To this end, GFP-positive melanoma cells with differences in endogenous CD271 levels will be injected into the spleen of recipient mice. To ascertain the extent of metastasis, blood samples will be taken and analyzed for circulating GFP and/or CD271-positive tumor cells and all organs especially, brain, lungs and liver will be inspected for presence of tumors. RNA-sequencing of established extracranial and brain metastases will in addition provide inside not only into a potential CD271-driven metastasis mechanism but also into mechanisms independent of CD271. Candidate drivers of metastasis will be functionally validated by CRISPR/CAS9 mediated knock-out and in vitro migration assays as well as in vivo models. The results of this study will help to understand the molecular basis of melanoma brain metastasis and will foster the development of new therapeutic strategies.

• DFG Programme: Research Grants
• International Connection: Austria