FADD Null Mouse Embryonic Fibroblasts Undergo Apoptosis after Photosensitization with the Silicon Phthalocyanine Pc 4

• Published in: Archives of biochemistry and biophysics 2001-01, Vol.385 (1), p.194-202
• Main Authors: Nagy, Biserka, Yeh, Wen-Chen, Mak, Tak W., Chiu, Song-Mao, Separovic, Duska
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing; Animals; Apoptosis; Carboxylic Acids - pharmacology; Carrier Proteins - genetics; Carrier Proteins - physiology; Caspase 3; Caspases - metabolism; ceramide; Ceramides - metabolism; Cycloheximide - pharmacology; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Enzyme Activation; FADD; Fas-Associated Death Domain Protein; Fibroblasts - pathology; Fumonisins; In Situ Nick-End Labeling; Indoles - pharmacology; Light; Mice; Mice, Knockout; Models, Biological; Organosilicon Compounds - pharmacology; Oxidative Stress; Oxidoreductases - antagonists & inhibitors; Oxygen - metabolism; Pc 4; PDT; Photosensitizing Agents - pharmacology; Protein Synthesis Inhibitors - pharmacology; Silanes; Time Factors; TNF-α; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1006/abbi.2000.2143

Oxidative stress, such as photodynamic therapy with the silicon phthalocyanine Pc 4 (Pc 4-PDT), can induce apoptosis and tumor necrosis factor alpha (TNF) production. TNF receptors, as well as other death receptors, have been implicated in stress-induced apoptosis. To assess directly the role of FADD, a death receptor-associated protein, in induction of apoptosis post-Pc 4-PDT, embryonic fibroblasts from FADD knock out (k/o) and wild-type (wt) mice were used. Pc 4-PDT induced casp-3 activation and apoptosis in both cell types. In the presence of zVAD, a pan-caspase inhibitor, Pc 4-PDT-induced apoptosis was abrogated in both cell lines. Fumonisin B1 (FB), an inhibitor of ceramide synthase, had no effect on apoptosis after Pc 4-PDT in either cell line. Similar to Pc 4-PDT, exogenous C6-ceramide bypassed FADD deficiency and induced zVAD-sensitive apoptosis. In contrast to Pc 4 photosensitization, TNF did not induce either apoptosis or ceramide accumulation in FADD k/o cells. In the absence of FADD deficiency, TNF-induced apoptosis was zVAD-sensitive and FB-insensitive. Induced ceramide levels remained elevated after cotreatment with TNF and zVAD in FADD wt cells. Taken together, these data provide genetic evidence for a lack of FADD requirement in Pc 4-PDT- or C6-ceramide-induced apoptosis. FB-sensitive ceramide production accompanies, but does not suffice, for apoptosis after Pc 4 photosensitization or TNF.