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 photodyna mic therapy (PDT) on human pancreatic cancer cells ill vitro and in an anim al model. Methods: Human pancreatic tumour cell lines were submitted to PDT with pheo phorbide a (Phn), a chlorophyll derivative, in culture and after grafting i nto 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 intrap eritoneally) with a 100-J/cm(2) PDT session. The effect of PDT was assessed ill 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 integ rity. 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 photosensiti zer supply and weak energy application. It exerted this tumoricidal effect via apoptosis induction with a gentle protocol, and apoptosis and/or necros is with a stronger protocol.