LAUSR

Glycogen, a branched glucose polymer, helps regulate glucose homeostasis through immediate storage and release of glucose. Re-programming of glycogen metabolism has recently been suggested to play an emerging role in cancer progression and tumorigene-sis. However, regulation of metabolic rewiring for glycogen synthesis and breakdown in cancer cells remains less understood. De-spite the availability of various glycogen detection methods, selective visualization of glycogen in living cells with high spatial resolution has proven to be highly challenging. Here, we present an optical imaging strategy to visualize glycogen in live cancer cells with minimal perturbation by combining stimulated Raman scattering microscopy with metabolic incorporation of deuterium-labeled glucose. We revealed the subcellular enrichment of glycogen in live cancer cells and achieved specific glycogen mapping through distinct spectral identification. Using our method, different glycogen metabolic phenotypes were characterized in a series of patient-derived BRAF-mutant melanoma cell-lines. Our results indicate that cell-lines manifesting high glycogen storage level showed increased tolerance to glucose deficiency among the studied melanoma phenotypes. Our method opens up the possibility for non-invasive study of complex glycogen metabolism at subcellular resolution and may help reveal new features of glycogen regulation in cancer systems.