Characterization of photodynamic therapy responses elicited in A431 cells containing intracellular organelle-localized photofrin.
Photodynamic therapy (PDT), a photochemotherapeutic regimen used to treat several diseases, including cancer, exerts its effects mainly through induction of cell death. Using human epidermoid carcinoma A431 cells as a model, we previously showed that distinct cell death types could be triggered by protocols that selectively delivered Photofrin (a clinically approved photosensitizer) to different subcellular sites (Hsieh et al. [2003] J Cell Physiol 194: 363-375]. Here, the responses elicited by PDT in A431 cells containing intracellular organelle-localized Photofrin were further characterized. Two prominent cell phenotypes were observed under these conditions: one characterized by perinuclear vacuole (PV) formation 2-8 h after PDT followed by cell recovery or shrinkage within 48 h, and a second characterized by typical apoptotic features appearing within 4 h after PDT. DCFDA-sensitive reactive oxygen species formed proximal to PVs during the response to PDT, covering areas in which both endoplasmic reticulum (ER) and the Golgi complex were located. Biochemical analyses showed that Photofrin-PDT also induced JNK activation and altered the protein secretion profile. A more detailed examination of PV formation revealed that PVs were derived from the ER. The alteration of ER structure induced by PDT was similar to that triggered by thapsigargin, an ER Ca(2+)-ATPase inhibitor that perturbs Ca(2+) homeostasis, suggesting a role for Ca(2+) in the formation of PVs. Microtubule dynamics did not significantly affect PV formation. This study demonstrates that cells in which intracellular organelles are selectively loaded with Photofrin mount a novel response to ER stress induced by PDT.
Hsieh
Ya-Ju
YJ
Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.
Yu
Jau-Song
JS
Lyu
Ping-Chiang
PC
D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D017323:Dihematoporphyrin Ether / Q000494:pharmacology*; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects* / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015388:Organelles / Q000187:drug effects* / Q000378:metabolism*; D010641:Phenotype; D010778:Photochemotherapy; D017382:Reactive Oxygen Species / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism
D017382:Reactive Oxygen Species; D019284:Thapsigargin; D017323:Dihematoporphyrin Ether; D020928:Mitogen-Activated Protein Kinases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases