<title>Enhancement of the efficiency of photodynamic therapy by combination with the microtubule inhibitor vincristine</title>

Abstract

ABSTRACT Combination effects of photodynamic therapy (PDT) with meso-tetra (di-adjacent-sulfonatophenyl)porphine (TPPS2a) and the microtubule (MT) inhibitor, vincristine (VCR), were studied in the CaD2mouse tumor model in mice. A synergistic effect was found when VCR, at an almost nontoxic dose (1mg/kg), was injected i.p. into the mice 6 hr before PDT. The thta on mitotic index show a 4-5 fold accumulation of the cells in mitosis 6 hr after injection of VCR into the mice. Cell cycle and ploidydistributions in tumor tissues were determined by means of image analysis with measurement of integrated optical density after Feulgen reaction on monolayers. Ploidy distribution of the tumors was not significantly changed 6 and 12 hr after administration of VCR only, while an increasing aneuploidy was observed 24 and 48 hr after VCR treatment. No prominent changes of the cell cycle and ploidy distributions were found in the tumor tissues after PDT or PDT combined with VCR. Keywords: Photodynamic therapy, Microtubule, Sulfonated tetraphenyl porphines, Vincristine.2. INTRODUCTIONIt has been demonstrated that PDT with a number of dyes [Photofrmn, tetra (3-hydroxyphenyl)