title: Transient state microscopy probes patterns of altered oxygen consumption in cancer cells.
abstract: Altered cellular metabolism plays an important role in many diseases, not least in many forms of cancer, where cellular metabolic pathways requiring lower oxygen consumption are often favored (the so-called Warburg effect). In this work, we have applied fluorescence-based transient state imaging and have exploited the environment sensitivity of long-lived dark states of fluorophores, in particular triplet state decay rates, to image the oxygen consumption of living cells. Our measurements can resolve differences in oxygen concentrations between different regions of individual cells, between different cell types, and also based on what metabolic pathways the cells use. In MCF-7 breast cancer cells, higher oxygen consumption can be detected when they rely on glutamine instead of glucose as their main metabolite, predominantly undergoing oxidative phosphorylation rather than glycolysis. By use of the high triplet yield dye Eosin Y the irradiance requirements during the measurements can be kept low. This reduces the instrumentation requirements, and harmful biological effects from high excitation doses can be avoided. Taken together, our imaging approach is widely applicable and capable of detecting subtle changes in oxygen consumption in live cells, stemming from the Warburg effect or reflecting other differences in the cellular metabolism. This may lead to new diagnostic means as well as advance our understanding of the interplay between cellular metabolism and major disease categories, such as cancer.
authors.affiliation: Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Thiemo
authors.initials: T
authors.lastname: Spielmann
authors.affiliation: Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Lei
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Annica K B
authors.initials: AKB
authors.lastname: Gad
authors.affiliation: Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden.|Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Sofia
authors.initials: S
authors.lastname: Johansson
authors.affiliation: Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden.
authors.forename: Jerker
authors.initials: J
authors.lastname: Widengren
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism; D045744:Cell Line, Tumor; D004801:Eosine Yellowish-(YS) / Q000737:chemistry; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry; D005947:Glucose / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006019:Glycolysis; D006801:Humans; D061986:MCF-7 Cells; D053858:Metabolic Networks and Pathways; D008856:Microscopy, Fluorescence / Q000379:methods*; D009369:Neoplasms / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption
chemical_list: D005456:Fluorescent Dyes; D005973:Glutamine; D005947:Glucose; D004801:Eosine Yellowish-(YS)
keywords: cancer; fluorescence microscopy; metabolism; oxygen; triplet state