Abstract

Skin pigmentation correlates with melanoma incidence, and melanin subtypes are known to play key roles in melanoma pathogenesis. Here, we propose the use of CARS and SFA microscopy to selectively visualize melanins in live cells.

The annual global incidence of melanoma, the deadliest form of skin cancer, exceeds 232,000 cases worldwide, resulting in over 55,000 deaths. It has long been known that skin pigmentation strongly correlates with skin cancer incidence and, in the specific case of melanoma, carcinogenesis may in fact arise independently of ultraviolet irradiation. Indeed, the ultraviolet-radiation-independent pathway to melanoma pathogenesis is thought to be largely mediated by pheomelanin – the red/blond melanin subtype. Other studies have also shown that some resistant melanoma cell lines can overcome administration of drugs by increasing melanin production and thereby sequestering therapeutics in melanosomes, the organelles responsible for melanin production bound for cellular export. In order to further study melanoma pathogenesis and therapeutic resistance, novel imaging modalities to selectively image melanin subtypes have been developed: on one hand, coherent anti-Stokes Raman scattering (CARS) microscopy can uniquely identify pheomelanin, while on the other, sum-frequency absorption (SFA) microscopy can be used to visualize total melanin distribution.

© 2017 Optical Society of America