Nuclear factor-kappaB activation by the photochemotherapeutic agent verteporfin.
The nuclear factor-kappa B (NF-kappaB) gene transactivator serves in the formation of immune, inflammatory, and stress responses. In quiescent cells, NF-kappaB principally resides within the cytoplasm in association with inhibitory kappa (IkappaB) proteins. The status of IkappaB and NF-kappaB proteins was evaluated for promyelocytic leukemia HL-60 cells treated at different intensities of photodynamic therapy (PDT). The action of the potent photosensitizer, benzoporphyrin derivative monoacid ring A (verteporfin), and visible light irradiation were assessed. At a verteporfin concentration that produced the death of a high proportion of cells after light irradiation, evidence of caspase-3 and caspase-9 processing and of poly(ADP-ribose) polymerase cleavage was present within whole cell lysates. The general caspase inhibitor Z-Val-Ala-Asp-fluoromethylketone (ZVAD.fmk) effectively blocked these apoptosis-related changes. Recent studies indicate that IkappaB proteins may be caspase substrates during apoptosis. However, the level of IkappaBbeta was unchanged for HL-60 cells undergoing PDT-induced apoptosis. IkappaBalpha levels decreased during PDT-induced apoptosis, though ZVAD.fmk did not affect this change. At a less intensive level of photosensitization, cellular IkappaBalpha levels were transiently depressed after PDT. At these times, p50 and RelA NF-kappaB species were increased within nuclear extracts, as revealed by electrophoretic mobility supershift assays. HL-60 cells transiently transfected with a kappaB-luciferase reporter construct exhibited elevated luciferase activity after PDT or treatment with tumor necrosis factor-alpha, a well-characterized NF-kappaB activator. Productive NF-kappaB activation and associated gene transcription may influence the phenotype and behavior of cells exposed to less intensive PDT regimens. However, IkappaBalpha is not subject to caspase-mediated degradation as a component of PDT-induced apoptosis. (Blood. 2000;95:256-262)
Granville
D J
DJ
QLT PhotoTherapeutics Inc, Vancouver, BC, Canada.
Carthy
C M
CM
Jiang
H
H
Levy
J G
JG
McManus
B M
BM
Matroule
J Y
JY
Piette
J
J
Hunt
D W
DW
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D017930:Genes, Reporter; D018922:HL-60 Cells; D006801:Humans; D020672:I-kappa B Proteins; D008027:Light; D008156:Luciferases / Q000235:genetics; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011166:Porphyrins / Q000494:pharmacology*; D014162:Transfection; D000077362:Verteporfin
D000590:Amino Acid Chloromethyl Ketones; D015853:Cysteine Proteinase Inhibitors; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D017319:Photosensitizing Agents; D011166:Porphyrins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D000077362:Verteporfin; D000072000:NF-KappaB Inhibitor alpha; D008156:Luciferases; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases