Tetracationic porphyrins inhibit angiogenesis induced by human tumor cellsin vivo

Background: Cationic porphyrin TMPyP4, but not its isomer TMPyP2, inhibits telomerase in tumor cells in vitro and induces chromosome destabilization i n vivo. Materials and Methods: To examine the effects of these porphyrins o n tumor induced angiogenesis, 25-200 mug TMPyP4 or TMPyP2 were injected dai ly for 3 days in mice with intradermally implanted primary human tumor cell s. Alternatively tumor cells were exposed for 90 minutes to 2.5-20 muM porp hyrins prior to implantation in mice. Results: Either subcutaneous injectio ns (greater than or equal to 50 mug/mouse) ol preincubation with greater th an or equal to5 muM porphyrins significantly inhibited angiogenesis. Conclu sion: Antiangiogenic activity is apparently unrelated to the ability of the porphyrins to inhibit telomerase.