Human pancreatic carcinoma cells are sensitive to photodynamic therapy in vitro and in vivo

Background: The aim of this study was to assess the efficiency of photodynamic therapy (PDT) on human pancreatic cancer cells in vitro and in an animal model. Methods: Human pancreatic tumour cell lines were submitted to PDT with pheophorbide a (Phn), a chlorophyll derivative, in culture and after grafting into athymic mice. Ph a was tested in culture (10(-10)-10(-5) mol/l) with a 5-J/cm(2) energy treatment and on tumour-bearing Nude mice (30 mg/kg intraperitoneally) with a 100-J/cm(2) PDT session. The effect of PDT was assessed in vitro using proliferative, apoptotic and clonogenic tests and in vivo on tumour growth and on the induction of tumour necrosis. Results: PDT inhibited tumour cell growth in culture by affecting DNA integrity. This tumour cell photodamage started at low concentration (10(-7)mol/l) as corroborated by clonogenic and tumour growth tests. A strong necrosis was achieved in vivo with a single PDT session. Conclusion: PDT destroyed human pancreatic carcinoma after low photosensitizer supply and weak energy application. It exerted this tumoricidal effect via apoptosis induction with a gentle protocol, and apoptosis and/or necrosis with a stronger protocol.