title: Time- and spectrally resolved characteristics of flavin fluorescence in U87MG cancer cells in culture.
abstract: Early detection of cancer is crucial for the successful diagnostics of its presence and its subsequent treatment. To improve cancer detection, we tested the progressive multimodal optical imaging of U87MG cells in culture. A combination of steady-state spectroscopic methods with the time-resolved approach provides a new insight into the native metabolism when focused on endogenous tissue fluorescence. In this contribution, we evaluated the metabolic state of living U87MG cancer cells in culture by means of endogenous flavin fluorescence. Confocal microscopy and time-resolved fluorescence imaging were employed to gather spectrally and time-resolved images of the flavin fluorescence. We observed that flavin fluorescence in U87MG cells was predominantly localized outside the cell nucleus in mitochondria, while exhibiting a spectral maximum under 500 nm and fluorescence lifetimes under 1.4 ns, suggesting the presence of bound flavins. In some cells, flavin fluorescence was also detected inside the cell nuclei in the nucleoli, exhibiting longer fluorescence lifetimes and a red-shifted spectral maximum, pointing to the presence of free flavin. Extra-nuclear flavin fluorescence was diminished by 2-deoxyglucose, but failed to increase with 2,4-dinitrophenol, the uncoupler of oxidative phosphorylation, indicating that the cells use glycolysis, rather than oxidative phosphorylation for functioning. These gathered data are the first step toward monitoring the metabolic state of U87MG cancer cells.
authors.affiliation: International Laser Centre, Department of Biophotonics, Ilkovicova 3, Bratislava 841 04, SlovakiabPavol Jozef Safarik University, Department of Biophysics, Faculty of Science, Jesenna 5, Kosice 040 01, Slovakia.
authors.forename: Julia
authors.initials: J
authors.lastname: Horilova
authors.affiliation: International Laser Centre, Department of Biophotonics, Ilkovicova 3, Bratislava 841 04, SlovakiacComenius University, Institute of Medical Physics, Biophysics, Informatics and Telemedicine, Faculty of Medicine, Sasinkova 2, Bratislava 813 72, Slovakia.
authors.forename: Beata
authors.initials: B
authors.lastname: Cunderlikova
authors.affiliation: International Laser Centre, Department of Biophotonics, Ilkovicova 3, Bratislava 841 04, SlovakiadUniversity of Ss. Cyril and Methodius, Department of Biotechnology, Faculty of Natural Sciences, Nám. J. Herdu 2, Trnava 917 01, Slovakia.
authors.forename: Alzbeta
authors.initials: A
authors.lastname: Marcek Chorvatova
mesh_terms: D019297:2,4-Dinitrophenol / Q000737:chemistry; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003847:Deoxyglucose / Q000737:chemistry; D018450:Disease Progression; D055088:Early Detection of Cancer / Q000379:methods; D005415:Flavins / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D006019:Glycolysis; D006801:Humans; D008853:Microscopy / Q000379:methods; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism; D055095:Optics and Photonics / Q000379:methods; D010085:Oxidative Phosphorylation; D010100:Oxygen / Q000737:chemistry; D010766:Phosphorylation; D013050:Spectrometry, Fluorescence / Q000295:instrumentation* / Q000379:methods*; D013053:Spectrophotometry
chemical_list: D005415:Flavins; D005456:Fluorescent Dyes; D003847:Deoxyglucose; D019297:2,4-Dinitrophenol; D010100:Oxygen