Tohoku J. Exp. Med., 2010, 220(4)

Potentiating Effect of β-Glucans on Photodynamic Therapy of Implanted Cancer Cells in Mice

DALIA AKRAMIENE,¹ CESLAVA ALEKSANDRAVICIENE,² GRAZINA GRAZELIENE,² RIMANTAS ZALINKEVICIUS,³ KESTUTIS SUZIEDELIS,² JANINA DIDZIAPETRIENE,² ULF SIMONSEN,⁴ EDGARAS STANKEVICIUS¹ and EGIDIJUS KEVELAITIS¹

¹Department of Physiology, Kaunas University of Medicine, Kaunas, Lithuania
²Institute of Oncology, Vilnius University, Vilnius, Lithuania
³Institute of Endocrinology, Kaunas University of Medicine, Kaunas, Lithuania
⁴Department of Pharmacology, University of Aarhus, Aarhus, Denmark

Photodynamic therapy (PDT) combines a drug or photosensitizer with a specific type of light to kill cancer cells. The cellular damage induced by PDT leads to activation of the DNA damage repair, which is an important factor for modulating tumor sensitivity to this treatment. β-Glucans are natural polysaccharides that bind complement receptor 3 on the effector cells, thereby activating them to kill tumor cells during PDT. The hypothesis of the present study was that adjuvant therapy with β-glucans would increase the efficacy of PDT. C57BL/6 female mice were subcutaneously implanted with Lewis lung carcinoma cells. Ten days after implantation, the mice were administered intravenously sodium porfimer (10 mg/kg) 24 h prior to laser irradiation, with or without oral administration of β-glucan (400 μg/d/mouse, 5 days) from either barley, baker's yeast, or marine brown algae that contains the storage glucan, laminarin. Tumor volume and necrotic area in excised tumors were measured. The expression of proliferating cell nuclear antigen (PCNA) was determined as an indicator of the activity of the DNA damage repair system. PDT in combination with each β-glucan significantly reduced tumor growth (P < 0.05, n = 10) and expression of PCNA (P < 0.001, n = 9), and increased necrosis in tumor tissues (P < 0.001, n = 9). Furthermore, each structurally different <β-glucan exerted similar potentiating effects on PDT. The present findings show that β-glucans enhance the tumor response to PDT, resulting in pronounced necrosis of PDT-treated tumors and suppression of the DNA damage repair system.

keywords —— photodynamic therapy; β-glucan; proliferating cell nuclear antigen; complement receptor 3; DNA damage repair

© 2010 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2010, 220, 299-306

Correspondence: Dalia Akramiene, Department of Physiology, Kaunas University of Medicine, A. Mickeviciaus 9, LT-44307 Kaunas, Lithuania.

e-mail: dalia.akramiene@takas.lt