Photodynamic effects of pyropheophorbide-a methyl ester in nasopharyngeal carcinoma cells.
BACKGROUND
Nasopharyngeal carcinoma (NPC) is one of the most common cancers, and exploring novel therapeutic modalities will improve the clinical outcomes. It has been confirmed that photodynamic therapy can efficiently deactivate malignant cells. The aim of the present study was to explore the photodynamic effects of pyropheophorbide-a methyl ester (MPPa) in CNE2 nasopharyngeal carcinoma cells.


METHODS
CNE2 cells were subjected to photodynamic therapy with MPPa, in which the drug concentration was 0.25 to 4 microM and light energy 1 to 8 J/cm(2). Photodynamic toxicity was investigated 24 h after treatment. Apoptosis was determined using flow cytometry with annexin V-FITC and propidum iodine staining and with nuclear staining with Hoechst 33258. The mitochondrial membrane potential (DeltaPsim) was evaluated by Rhodamine 123 assay.


RESULTS
There was no dark cytotoxicity of MPPa in the CNE2 cells at doses of 0.25-4 microM, and MPPa resulted in dose- and light-dependent phototoxicity. The apoptotic rate 8 h after PDT with MPPa (2 microM) increased to 16.43% under a light energy of 2 J/cm(2). Mitochondrial membrane potential (DeltaPsim) collapsed when the CNE2 cells were exposed to 2 microM MPPa for 20 h and then 2 J/cm(2) irradiation.


CONCLUSIONS
Photodynamic therapy with MPPa significantly enhanced apoptosis and the collapse of DeltaPsim. This can be developed for treating nasopharyngeal carcinoma.
Xu
Chuan Shan
CS
Institute of Ultrasound Imaging, Chongqing University of Medical Sciences, Chongqing, China.
Leung
Albert Wing Nang
AW
D000368:Aged; D016923:Cell Death / Q000187:drug effects; D006801:Humans; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051336:Mitochondrial Membranes / Q000187:drug effects; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011166:Porphyrins / Q000494:pharmacology / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured
D017319:Photosensitizing Agents; D011166:Porphyrins; C452939:pyropheophorbide-a methylester