PDT with genetically encoded photosensitizer miniSOG on a tumor spheroid model: A comparative study of continuous-wave and pulsed irradiation

Diana V Yuzhakova; Marina V Shirmanova; Vladimir V Klimenko; Maria M Lukina; Alena I Gavrina; Anastasya D Komarova; Dmitry A Gorbachev; Natalya V Sapogova; Konstantin A Lukyanov; Vladislav A Kamensky

doi:10.1016/j.bbagen.2021.129978

PDT with genetically encoded photosensitizer miniSOG on a tumor spheroid model: A comparative study of continuous-wave and pulsed irradiation

Biochim Biophys Acta Gen Subj. 2021 Dec;1865(12):129978. doi: 10.1016/j.bbagen.2021.129978. Epub 2021 Sep 3.

Affiliations

¹ Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Sq., 603005 Nizhny Novgorod, Russia. Electronic address: yuzhakova-diana@mail.ru.
² Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Sq., 603005 Nizhny Novgorod, Russia.
³ Saint-Petersburg Clinical Scientific and Practical Center of Specialized Types of Medical Care (Oncological), 68A Leningradskaya St., Pesochny Settlement, 197758 St. Petersburg, Russia.
⁴ Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 16/10 Miklukho-Maklaya St., GSP-7, 117997 Moscow, Russia.
⁵ Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov St., 603950 Nizhny Novgorod, Russia.
⁶ Center of Life Sciences, Skolkovo Institute of Science and Technology, 30/1 Bolshoy Boulevard, 121205 Moscow, Russia.

PMID: 34487824
DOI: 10.1016/j.bbagen.2021.129978

Abstract

Background: Therapeutic effects of PDT depend on many factors, including the amount of singlet oxygen, localization of photosensitizer and irradiation protocol. The present study was aimed to compare the cytotoxic mechanisms of PDT under continuous-wave (CW) and pulsed irradiation using a tumor spheroid model and a genetically encoded photosensitizer miniSOG.

Methods: ¹O₂ detection in miniSOG and flavin mononucleotide (FMN) solutions was performed. Photobleaching of miniSOG in solution and in HeLa tumor spheroids was analyzed. Tumor spheroid morphology and growth and the cell death mechanisms after PDT in CW and pulsed modes were assessed.

Results: We found a more rapid ¹O₂ generation and a higher photobleaching rate in miniSOG solution upon irradiation in pulsed mode compared to CW mode. Photobleaching of miniSOG in tumor spheroids was also higher after irradiation in the pulsed mode. PDT of spheroids in CW mode resulted in a moderate expansion of the necrotic core of tumor spheroids and a slight inhibition of spheroid growth. The pulsed mode was more effective in induction of cell death, including apoptosis, and suppression of spheroid growth.

Conclusions: Comparison of CW and pulsed irradiation modes in PDT with miniSOG showed more pronounced cytotoxic effects of the pulsed mode. Our results suggest that the pulsed irradiation regimen enables enhanced ¹O₂ production by photosensitizer and stimulates apoptosis.

General significance: Our results provide more insights into the cellular mechanisms of anti-cancer PDT and open the way to improvement of light irradiation protocols.

Keywords: 3D tumor spheroid model; Continuous-wave irradiation; Fluorescence imaging; PDT; Pulsed irradiation; miniSOG.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cell Death
Photosensitizing Agents
Triazenes*

Substances

Photosensitizing Agents
Triazenes
1-phenyl-3,3-dimethyltriazene