Towards in vivo melanin radicals detection in melanomas by electron paramagnetic resonance (EPR) spectroscopy: a proof-of-concept study

AbstractMelanoma is the most aggressive skin tumor type. Although complete cure can be achieved when the whole tumor is resected, prognostic dramatically drops when melanoma cells reach deeper tissues and lymph nodes. Hence, there is an urgent need to develop accurate tools allowing (i) discriminating benign nevi from malignant tumors and (ii) being able to characterize melanoma infiltration. For that purpose, we exploited the paramagnetic properties of melanin by using electron paramagnetic resonance (EPR) spectroscopy to measure the melanin content in pigmented (B16F10 cancer cells) and nonpigmented melanomas (WM2664 cancer cells) inoculated intradermally in nude mice. Specifically, we took advantage of a new clinical EPR device (1 GHz), which provides sensitive measurements of radical species in vivo. Results showed that the melanin-specific EPR signal increased with tumor growth in pigmented tumors, whereas no EPR signal could be detected in achromic melanomas. These data plead for the development of ...