Visualizing Subcellular Enrichment of Glycogen in Live Cancer Cells by Stimulated Raman Scattering

Abstract

Glycogen, a branched glucose polymer, helps regulate glucose homeostasis through immediate storage and release of glucose. Reprogramming of glycogen metabolism has recently been suggested to play an emerging role in cancer progression and tumorigenesis. However, regulation of metabolic rewiring for glycogen synthesis and breakdown in cancer cells remains less understood. Despite 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 this 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. This 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.

Unveiling Cancer Metabolism through Spontaneous and Coherent Raman Spectroscopy and Stable Isotope Probing

“…Zhang et al generated a comprehensive study to visualize the metabolic dynamics of macromolecules, such as DNA, protein, lipids, and glycogen, from glucose, in various cancer cell lines, and a mouse model with glioblastoma xenograft [137] (Figure 7C). The pathway from glucose to glycogen, which is important glucose storage in cancer cells, was also investigated by subcellular visualization of deuterated glycogen from deuterated glucose [138]. Hu et al developed a protocol for synthesizing deuterated glucose with an alkyne tag, 3-O-propargyl-D-glucose [139].…”

Toward Raman Subcellular Imaging of Endothelial Dysfunction

“…A similar approach applied to melanoma cell lines with varying degrees of cellular differentiation revealed differences in glycogen-accumulation phenotype and metabolic activity. 94 Additionally, deuterated fat accumulation was observed in the intestines of mice pup breast-fed by a mother drinking deuterated water. 95 Beside glucose SRS, peracetylated N -(4-pentynoyl)mannosamine (Ac4ManNAl) glycan can be studied with SRS.…”

Coherent Raman scattering microscopy: capable solution in search of a larger audience

“…For instance, uptake and subsequent esterification of deuterated fatty acids or cholesterol offer a direct view of the cellular machinery a work. [35][36][37] This principle can be extended to deuterated amino acids to follow protein synthesis de novo, 38,39 deuterated glucose analogs to monitor lipogenesis, 40,41 glycogen, 42 and biomass production, 43 as well as D 2 O to study protein and lipid metabolism in live animals. 44 The ability to directly examine metabolic pathways in live biological systems offers a unique view of fundamental processes such as cellular homeostasis, tissue growth, aging, and oncogenesis.…”