Targeted Metabolomics Identifies Plasma Biomarkers in Mice with Metabolically Heterogeneous Melanoma Xenografts

SIMPLE SUMMARY: Studying the metabolome, the complete set of metabolites found in a biological sample, helps to understand how metabolism differs between healthy and diseased individuals. Malignant skin cancers (melanomas) differ greatly in their mutational landscapes and metabolism among individuals. Understanding these differences is important for accurate treatment of melanoma patients. The aim of our study was to characterize the metabolomes of genetically different human melanoma cell lines transplanted into mice. We found that melanomas, regardless of mutation status, differed greatly in their lipid profiles, which are important metabolites for energy production. Moreover, we identified seven metabolites with the potential to distinguish healthy from melanoma-bearing mice. We hope that the metabolomic differences detected in the mouse model may be reproducible in humans and potentially lead to metabolism-based therapeutic approaches for melanoma patients. ABSTRACT: Melanomas are genetically and metabolically heterogeneous, which influences therapeutic efficacy and contributes to the development of treatment resistance in patients with metastatic disease. Metabolite phenotyping helps to better understand complex metabolic diseases, such as melanoma, and facilitates the development of novel therapies. Our aim was to characterize the tumor and plasma metabolomes of mice bearing genetically different melanoma xenografts. We engrafted the human melanoma cell lines A375 (BRAF mutant), WM47 (BRAF mutant), WM3000 (NRAS mutant), and WM3311 (BRAF, NRAS, NF1 triple-wildtype) and performed a broad-spectrum targeted metabolomics analysis of tumor and plasma samples obtained from melanoma-bearing mice as well as plasma samples from healthy control mice. Differences in ceramide and phosphatidylcholine species were observed between melanoma subtypes irrespective of the genetic driver mutation. Furthermore, beta-alanine metabolism differed between melanoma subtypes and was significantly enriched in plasma from melanoma-bearing mice compared to healthy mice. Moreover, we identified beta-alanine, p-cresol sulfate, sarcosine, tiglylcarnitine, two dihexosylceramides, and one phosphatidylcholine as potential melanoma biomarkers in plasma. The present data reflect the metabolic heterogeneity of melanomas but also suggest a diagnostic biomarker signature for melanoma screening.