Raman-guided subcellular pharmaco-metabolomics for metastatic melanoma cells

Abstract

Non-invasively probing metabolites within single live cells is highly desired but challenging. Here we utilize Raman spectro-microscopy for spatial mapping of metabolites within single cells, with the specific goal of identifying druggable metabolic susceptibilities from a series of patient-derived melanoma cell lines. Each cell line represents a different characteristic level of cancer cell de-differentiation. First, with Raman spectroscopy, followed by stimulated Raman scattering (SRS) microscopy and transcriptomics analysis, we identify the fatty acid synthesis pathway as a druggable susceptibility for differentiated melanocytic cells. We then utilize hyperspectral-SRS imaging of intracellular lipid droplets to identify a previously unknown susceptibility of lipid mono-unsaturation within de-differentiated mesenchymal cells with innate resistance to BRAF inhibition. Drugging this target leads to cellular apoptosis accompanied by the formation of phase-separated intracellular membrane domains. The integration of subcellular Raman spectro-microscopy with lipidomics and transcriptomics suggests possible lipid regulatory mechanisms underlying this pharmacological treatment. Our method should provide a general approach in spatially-resolved single cell metabolomics studies.

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

“…A study by Tirinato et al demonstrated the capability of functional characterization of lipid droplets in cancer stem cells (CSCs) by Raman spectroscopy, and confirmed lipid droplets as a distinctive mark of CSCs in colorectal cancer [40]. Similarly, lipid upregulation and reprogramming was observed by Raman spectroscopy in cells of prostate cancer [23], lung cancer [41], and melanoma [42,43].…”

“…They monitored lipids along varying depths of mouse skin, as well as DMSO penetrating into the skin. Since then, CRS microscopy was used extensively in lipid imaging with structural diversity tightly associated with their biological functions [43,[46][47][48][49][50][51][52][53][54][55].…”

“…Subsequent experiments showed that inhibition of lipid desaturases effectively eliminated CSCs, suppressed sphere formation, and blocked tumor initiation capacity in vivo. With spontaneous Raman spectroscopy, followed by SRS microscopy and transcriptomics analysis, Du et al investigated and imaged lipids droplets in patient-derived melanoma cells during differentiation [43]. They identified fatty acid synthesis pathway as a druggable susceptibility and a lipid mono-unsaturation within de-differentiated mesenchymal cells, with innate resistance to BRAF inhibition.…”

Raman Imaging: An Impending Approach Towards Cancer Diagnosis

“…The generated CH 2 /CH 3 ratiometric images indeed nicely resolved a decreasing trend from melanocytic M262 cells toward mesenchymal M381 cells, implying that, more differentiated cells are relatively richer in lipids. In addition, hyperspectral SRS microscopy was utilized to analyze the composition of these sub‐cellular LDs at a spatial resolution of ∼450 nm [70] …”

New software tools, databases, and resources in metabolomics: updates from 2020

“…Using with Raman spectroscopy, followed by stimulated Raman scattering (SRS) microscopy and Raman-guided subcellular pharmaco-metabolomics in metastatic melanoma cells revealed intracellular lipid droplets that helped identify a previously unknown susceptibility of lipid mono-unsaturation within de-differentiated mesenchymal cells with innate resistance to BRAF inhibition (Du et al 2020 ). Application of 31 P NMR was shown to hold potential of expanding the coverage of the metabolome by detecting phosphorus-containing metabolites (Bhinderwala et al 2020 ).…”