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Autori: Gina Manda, Monica Neagu, Carolina Constantin and Rodica Mariana Ion
Editorial: Elsevier, Journal of Porphyrins and Phthalocyanines, 10, p.760, 2006.
The aim of the study was to correlate the uridine uptake via the alternative pathway of nucleotide biosynthesis and apoptosis associated to in vitro photodynamic (PDT) cellular treatment.
We have investigated the effects exerted by porphyrins, namely 5,10,15,20-tetra-1-naphthyl-porphyrin (TNP) and 5,10,15,20-tetra-p-sulphonate-phenyl-porphyrin (TSPP). Various neoplastic and normal cells were studied: the lymphoblastic cell line K562, the histiocytic lymphoma U937, the Jurkat leukaemic T cell lymphoblasts, the breast adenocarcinoma MCF7 and human peripheral normal mononuclear cells, respectively.
Cell loading.According to previous results optimal cell loading conditions were: 2×100,000 cell/mL and 24h-loading.
Irradiation. PDT activation was achieved by irradiation with He-Ne laser light 30 mW, l=632,8nm, at 250C, total irradiation time = 50 min, in O2 saturated solution.
Tritium-uridine incorporation measures cellular activation/proliferation by mean of RNA synthesis detection.
Cell apoptosis was quantifiyed by flow cytometry using annexin V-propidium iodide test.
Results. Porphyrin-loading does not innatly induce significant apoptosis in all the studied cell types both normal and neoplastic cells, but after PDT treatment they display both phosphatidyl serine on the outer surface of the membrane and DNA damage. No major differences were recorded between neoplastic and normal cells. Taking into account that PDT is a locally driven therapy, the effects exerted on immune cells might not be relevant. Uridine uptake follows the apoptotic events induced by PDT suggesting that activated porphyrines impede cellular metabolic pathways hence RNA synthesis. Various tested cell lines have particular sensitivity regarding the same porphyrines and in vitro PDT protocol. Spanning the same concentration range of porphyrines, results show that normal cells or immune cells derived lines (U937 with monocytic like characteristics, Jurkat T cell) have an lower LC50 compared to adherent adenocarcinoma cells, proving the increased sensitivity of this type of cells.
Conclusion. Tritium-labeled uridine incorporation is a good marker for measuring the effect of experimental PDT and it is applicable in various cell types, normal, tumoral non-adherent or adherent cell lines.
Grant supported by Excellence National Research Network CEEX Nr.36/2005; Nr.18/2005
Cuvinte cheie: porphyrin, photodynamic therapy