COMBINATION TOXICITY OF ETOPOSIDE (VP-16) AND PHOTOSENSITIZATION WITHA WATER-SOLUBLE ALUMINUM PHTHALOCYANINE IN K562 HUMAN LEUKEMIC-CELLS

Etoposide (VP-16) is an anti-cancer drug commonly used against several types of tumours and leukaemia, either alone or in combination chemot herapy. Photodynamic therapy (PDT) is another, relatively new modality for treatment of various malignancies. The interactions between VP-16 and PDT, using aluminium tetrasulphophthalocyanine as photosensitiser , in K562 human leukaemic cells were investigated. Cell responses to i ndividual and combined drug treatment under different experimental con ditions revealed synergistic drug toxicity. The latter was evident fro m various events of cell response, including supra-additive accumulati on of cells in G(2)/M cell cycle phase and endonucleolytic DNA fragmen tation (apoptosis). The involvement of the cellular antioxidant system in the synergistic interactions of photosensitisation and VP-16 is pr oposed.