Inhibitory effect of heat shock protein 70 on apoptosis induced by photodynamic therapy in vitro.
We examined the apoptotic effects of photodynamic therapy (PDT) in leukemia cells (HL60) and lymphoma cells (Raji). Moreover, we also investigated the relationship of apoptosis induced by PDT to heat shock protein (HSP) expression. To induce 80% of cell death by PDT, HL60 cells required 6 microg/mL and Raji cells required 9 microg/mL of Photofrin. PDT induced apoptosis in 77.2% of HL60 and in 0.4% of Raji at lethal dose (LD80) conditions. The cell line in which apoptosis is predisposed may be more susceptible to PDT compared with the cell line in which necrosis is predisposed. Furthermore, HSP-70 was expressed constitutively in Raji cells but not in HL60 cells. Heat treatment of HL60 cells induced expression of HSP-70 and resulted in significant reduction of PDT-mediated apoptosis. From the results of this experiment, it is suggestive that HSP-70 contributes to inhibition of apoptosis mediated by PDT.
Department of Developmental and Reconstructive Medicine, Division of Oral and Maxillofacial Surgery, Nagasaki University, Sakamoto, Nagasaki, Japan. d400018r@stcc.nagasaki-u.ac.jp
Mihoko
M
Nonaka
Hisazumi
H
Ikeda
Tsugio
T
Inokuchi
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D017323:Dihematoporphyrin Ether / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018922:HL-60 Cells; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D006801:Humans; D008954:Models, Biological; D010778:Photochemotherapy; D014407:Tumor Cells, Cultured
D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D018840:HSP70 Heat-Shock Proteins; D017323:Dihematoporphyrin Ether; D020169:Caspases