Photodynamic therapy combined with a cysteine proteinase inhibitor synergistically decrease VEGF production and promote tumour necrosis in a rat mammary carcinoma

Authors

  • B. Zsebik,

    1. University of Debrecen, Medical and Health Science Center, Faculty of Medicine, Department of Biophysics and Cell Biology, 98 Nagyerdei krt., 4012 Debrecen, Hungary,
    2. Department of Pathology, Wroclaw Medical University, 1 Marcinkowskiego St., 50-368 Wroclaw, Poland, and
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  • K. Symonowicz,

    1. Department of Pathology, Wroclaw Medical University, 1 Marcinkowskiego St., 50-368 Wroclaw, Poland, and
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  • Y. Saleh,

    1. Department of Forensic Medicine, Molecular Technical Unit, Wroclaw Medical University, 52 Sklodowskiej-Curie, 50-369 Wroclaw, Poland
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  • P. Ziolkowski,

    1. Department of Pathology, Wroclaw Medical University, 1 Marcinkowskiego St., 50-368 Wroclaw, Poland, and
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  • A. Bronowicz,

    1. Department of Pathology, Wroclaw Medical University, 1 Marcinkowskiego St., 50-368 Wroclaw, Poland, and
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  • G. Vereb

    1. University of Debrecen, Medical and Health Science Center, Faculty of Medicine, Department of Biophysics and Cell Biology, 98 Nagyerdei krt., 4012 Debrecen, Hungary,
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György Vereb, Department of Biophysics and Cell Biology, Faculty of Medicine, Medical and Health Science Centre, University of Debrecen, Hungary, H-4012 Debrecen, P.O.B. 39. Tel./Fax: +36 52 412623; E-mail: vereb@dote.hu and Piotr Ziolkowski, Department of Pathology, Wroclaw Medical University, 1 Marcinkowskiego St., 50-368 Wroclaw, Poland. Tel.: +48 71 7841225; Fax: +48 71 7840057; E-mail: ziolkows@interia.pl

Abstract

Abstract. Objectives: Photodynamic therapy (PDT) and inhibition of cathepsin B proteases by cystatin (cysteine proteinase inhibitor, CPI) are potential new tumour treatment modalities. We have investigated the efficacy of PDT and CPI alone and in combination on a solid mammary carcinoma transplanted into Wistar rats. Materials and Methods: Intraperitoneally injected single doses of chlorine e6 or HpD as photosensitizers were excited at 630 nm (90 J/cm2). CPI (500 µg per animal) was injected around the tumour daily during the 8-day treatment. Inoculation of tumour was either on day 1 of the protocol, or 8 days before. On day 8, tumour size was measured, tumour necrosis and vascularization were determined based on haematoxylin and eosin (H&E)-stained sections and serum vascular endothelial growth factor (VEGF) levels measured using an enzyme-linked immunosorbent assay kit. Results: No differences (two-way anova) were found for treatments started with various time lags. At doses where CPI or PDT alone had no or negligible effect, their combination caused a marked (P < 0.001) decrease in serum VEGF, paralleled by a significant decrease in tumour size and number of capillary vessels, and a significant increase in necrosis (up to 80% of the tumour tissue). Conclusions: The combination of PDT and CPI could be a useful approach in tumour therapy as the two agents appear to be synergistic and probably decrease VEGF production by the tumour tissue.

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