Flavoprotein miniSOG as a genetically encoded photosensitizer for cancer cells

Biochim Biophys Acta. 2013 Nov;1830(11):5059-67. doi: 10.1016/j.bbagen.2013.07.015. Epub 2013 Jul 20.

Abstract

Background: Genetically encoded photosensitizers are a promising optogenetic instrument for light-induced production of reactive oxygen species in desired locations within cells in vitro or whole body in vivo. Only two such photosensitizers are currently known, GFP-like protein KillerRed and FMN-binding protein miniSOG. In this work we studied phototoxic effects of miniSOG in cancer cells.

Methods: HeLa Kyoto cell lines stably expressing miniSOG in different localizations, namely, plasma membrane, mitochondria or chromatin (fused with histone H2B) were created. Phototoxicity of miniSOG was tested on the cells in vitro and tumor xenografts in vivo.

Results: Blue light induced pronounced cell death in all three cell lines in a dose-dependent manner. Caspase 3 activation was characteristic of illuminated cells with mitochondria- and chromatin-localized miniSOG, but not with miniSOG in the plasma membrane. In addition, H2B-miniSOG-expressing cells demonstrated light-induced activation of DNA repair machinery, which indicates massive damage of genomic DNA. In contrast to these in vitro data, no detectable phototoxicity was observed on tumor xenografts with HeLa Kyoto cell lines expressing mitochondria- or chromatin-localized miniSOG.

Conclusions: miniSOG is an excellent genetically encoded photosensitizer for mammalian cells in vitro, but it is inferior to KillerRed in the HeLa tumor.

General significance: This is the first study to assess phototoxicity of miniSOG in cancer cells. The results suggest an effective ontogenetic tool and may be of interest for molecular and cell biology and biomedical applications.

Keywords: Cancer cell; Flavoprotein; Genetically encoded photosensitizer; Phototoxicity; Tumor xenograft; miniSog.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Cell Death / genetics
  • Cell Line
  • Cell Line, Tumor
  • Cell Membrane / genetics
  • Cell Membrane / metabolism
  • Chromatin / genetics
  • Chromatin / metabolism
  • DNA Damage
  • DNA Repair
  • Dermatitis, Phototoxic / etiology
  • Dermatitis, Phototoxic / genetics
  • Dermatitis, Phototoxic / metabolism
  • Female
  • Flavoproteins / genetics*
  • Flavoproteins / metabolism
  • Genetic Therapy / methods*
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Light / adverse effects
  • Mice
  • Mice, Nude
  • Mitochondria / genetics
  • Mitochondria / metabolism
  • Oxygen / metabolism*
  • Photosensitizing Agents / metabolism*
  • Riboflavin / genetics
  • Riboflavin / metabolism
  • Xenograft Model Antitumor Assays

Substances

  • Chromatin
  • Flavoproteins
  • Photosensitizing Agents
  • Caspase 3
  • Oxygen
  • Riboflavin