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Updated: Feb 7, 2026
An In Vitro Approach to Photodynamic Therapy
Published on: August 17, 2018
Alteration of Surface Glycoproteins After Photodynamic Therapy
Roberta Kelly de Faria Souza1, Isabel Chaves Silva Carvalho1, Carolina Genúncio da Cunha Menezes Costa1
11 Laboratory Dynamics of Cellular Compartments, Institute of Research and Development-IP&D, Universidade do Vale do Paraíba-UNIVAP , São José dos Campos, São Paulo, Brazil .
Background:
Cell membranes have been identified as an important intracellular cancer treatment target, since the glycoconjugates present on the cell surface are involved in numerous cell functions. Photodynamic therapy (PDT) is a therapeutic modality employed in the treatment of tumors that uses visible light to activate a photosensitizer.
Objective:
This study analyzed the expression of surface carbohydrates after PDT with two different photosensitizers, 5-aminolevulinic acid (ALA) and Photosan-3.
Methods:
Mice were injected subcutaneously with 2 × 105 B16 cells. After 7-10 days, the presence of a tumor with a diameter of 3.6 mm was observed. Photosan-3® and 5-aminolevulinic acid-ALA were used in the PDT treatment. Control animals (not submitted to either laser treatment or photosensitizer injection) and treated animals were euthanized 15 days post-treatment. The tumors were irradiated with a red diode laser, λ = 655 nm, energy density of 10 J.cm-2, and power density of 45 mW.cm-2. After 2 weeks of treatment with PDT, the mice were euthanized, the tumors were collected, and the cell surfaces were labeled with lectins concanavalin A (ConA) and wheat germ agglutinin (WGA).
Results:
Fluorescence microscopy analysis of the cell surfaces with lectins ConA and WGA showed the presence of α-mannose and α-glucose.
Conclusions:
The combined effects of either Photosan-3 or ALA and red laser light on melanoma suggest an inhibitory glycosylation action from PDT on the surface of B16-F10 cells.
Insights
Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) or Photosan-3 with red laser light inhibited glycosylation on B16-F10 melanoma cell surfaces. This study reveals PDT
Area of Science:
- Biochemistry
- Oncology
- Photomedicine
Background:
- Cell membranes are crucial intracellular targets for cancer treatment due to cell surface glycoconjugates.
- Photodynamic therapy (PDT) utilizes visible light to activate photosensitizers for tumor treatment.
Purpose of the Study:
- To investigate the impact of PDT on surface carbohydrate expression in melanoma cells.
- To compare the effects of two photosensitizers, 5-aminolevulinic acid (ALA) and Photosan-3, on melanoma cell surface glycosylation.
Main Methods:
- B16 melanoma cells were implanted in mice, and tumors were treated with PDT using either ALA or Photosan-3 and red laser light.
- Tumor tissues were collected 15 days post-treatment and cell surfaces were labeled with lectins (Concanavalin A and Wheat Germ Agglutinin).
- Fluorescence microscopy was used to analyze the expression of specific carbohydrates on the cell surface.
Main Results:
- Fluorescence microscopy detected the presence of α-mannose and α-glucose on the cell surfaces.
- These carbohydrates were identified using Concanavalin A (ConA) and Wheat Germ Agglutinin (WGA) lectins.
Conclusions:
- PDT, when combined with Photosan-3 or ALA and red laser light, demonstrates an inhibitory effect on glycosylation.
- This suggests PDT can modulate cell surface carbohydrate expression in B16-F10 melanoma cells.
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