Yuzhakova DV, Shirmanova MV, Klimenko VV, Lukina MM, Gavrina AI, Komarova AD, Gorbachev DA, Sapogova NV, Lukyanov KA, Kamensky VA. 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;
1865:129978. [PMID:
34487824 DOI:
10.1016/j.bbagen.2021.129978]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 11/19/2022]
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.
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