Alteration of Surface Glycoproteins After Photodynamic Therapy

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 2x10(5) B16 cells. After 7-10 days, the presence of a tumor with a diameter of 3.6mm was observed. Photosan-3((R)) and 5-aminolevulinic acidALA 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, =655nm, energy density of 10J.cm(-2), and power density of 45mW.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 -mannose and -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. (AU)