Unraveling Microviscosity Changes Induced in Cancer Cells by Photodynamic Therapy with Targeted Genetically Encoded
Liubov E Shimolina1, Aleksandra E Khlynova1, Vadim V Elagin1
1Institute of Experimental Oncology and Biomedical Technologies, Privolzhsky Research Medical University, Minin and Pozharsky Square, 10/1, 603005 Nizhny Novgorod, Russia.
Background:
Despite the fundamental importance of cell membrane microviscosity, changes in this biophysical parameter of membranes during photodynamic therapy (PDT) have not been fully understood.
Methods:
In this work, changes in the microviscosity of membranes of live HeLa Kyoto tumor cells were studied during PDT with KillerRed, a genetically encoded photosensitizer, in different cellular localizations. Membrane microviscosity was visualized using fluorescence lifetime imaging microscopy (FLIM) with a viscosity-sensitive BODIPY2 rotor.
Results:
Depending on the localization of the phototoxic protein, different effects on membrane microviscosity were observed. With nuclear localization of KillerRed, a gradual decrease in microviscosity was detected throughout the entire observation period, while for membrane localization of KillerRed, a dramatic increase in microviscosity was observed in the first minutes after PDT, and then a significant decrease at later stages of monitoring. The obtained data on cell monolayers are in good agreement with the data obtained for 3D tumor spheroids.
Conclusions:
These results indicate the involvement of membrane microviscosity in the response of tumor cells to PDT, which strongly depends on the localization of reactive oxygen species attack via targeting of a genetically encoded photosensitizer.
Insights
Photodynamic therapy (PDT) alters cell membrane microviscosity. KillerRed photosensitizer localization dictates whether microviscosity increases or decreases, impacting tumor cell response.
Area of Science:
- Biophysics
- Cell Biology
- Photochemistry
Background:
- Cell membrane microviscosity is crucial for cellular functions.
- Its role in photodynamic therapy (PDT) remains unclear.
Purpose of the Study:
- Investigate changes in cell membrane microviscosity during PDT.
- Examine the impact of photosensitizer localization on these changes.
Main Methods:
- Utilized live HeLa Kyoto tumor cells and photodynamic therapy (PDT).
- Employed KillerRed, a genetically encoded photosensitizer.
- Visualized membrane microviscosity using fluorescence lifetime imaging microscopy (FLIM) with a BODIPY2 rotor.
Main Results:
- Nuclear KillerRed localization led to a progressive decrease in microviscosity.
- Membrane-localized KillerRed initially increased microviscosity, followed by a decrease.
- Findings were consistent in both cell monolayers and 3D tumor spheroids.
Conclusions:
- Cell membrane microviscosity is involved in tumor cell response to PDT.
- The localization of the photosensitizer and subsequent reactive oxygen species attack significantly influences microviscosity changes.
