title: Autophagy modulators sensitize prostate epithelial cancer cell lines to TNF-alpha-dependent apoptosis.
abstract: TNF-alpha levels in prostate cancer correlate with the extent of disease and are significantly elevated in the metastatic stage. TNF receptor superfamily controls two distinct signalling cascades, leading to opposite effects, i.e. apoptosis and survival; in prostate cancer TNF-alpha-mediated signalling induces cell survival and resistance to therapy. The apoptosis of prostate epithelial cancer cells LNCaP and PC3 was investigated upon treatment with the autophagy inhibitor 3-methyladenine and the autophagy inducer rapamycin, in combination with TNF-alpha. Cells were exposed to these molecules for 18, 24 and 48 h. Autophagy was assessed via LC3 Western blot analysis; propidium iodide and TUNEL stainings followed by flow cytometry or caspase-8 and caspase-3 activation assays were performed to evaluate apoptosis. TNF-alpha-induced apoptosis was potentiated by 3-methyladenine in the androgen-responsive LNCaP cells, whereas no effect was observed in the androgen-insensitive PC3 cells. Interestingly such pro-apoptosis effect in LNCaP cells was associated with reduced c-Flip levels through proteasomal degradation via increased reactive oxygen species production and p38 activation; such c-Flip reduction was reversed in the presence of either the proteasome inhibitor MG132 or the reactive oxygen species scavenger N-acetyl-cysteine. Conversely in PC3 but not in LNCaP cells, rapamycin stimulated TNF-alpha-dependent apoptosis; such effect was associated with reduced c-Flip promoter activity and FoxO3a activation. We conclude that TNF-alpha-induced apoptosis may be potentiated, in prostate cancer epithelial cells, through autophagy modulators. Increased sensitivity to TNF-alpha-dependent apoptosis correlates with reduced c-Flip levels which are consequent to a post-transcriptional and a transcriptional mechanism in LNCaP and PC3 cells respectively.
authors.affiliation: Department of Anatomy, Histology, Forensic Medicine and Orthopedics-Section of Histology and Medical Embryology, Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Via A. Scarpa, 14, 00161 Rome, Italy. claudia.giampietri@uniroma1.it
authors.forename: Claudia
authors.initials: C
authors.lastname: Giampietri
authors.forename: Simonetta
authors.initials: S
authors.lastname: Petrungaro
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Padula
authors.forename: Alessio
authors.initials: A
authors.lastname: D'Alessio
authors.forename: Elettra Sara
authors.initials: ES
authors.lastname: Marini
authors.forename: Antonio
authors.initials: A
authors.lastname: Facchiano
authors.forename: Antonio
authors.initials: A
authors.lastname: Filippini
authors.forename: Elio
authors.initials: E
authors.lastname: Ziparo
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D015153:Blotting, Western; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004354:Drug Screening Assays, Antitumor; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006801:Humans; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000473:pathology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors / Q000494:pharmacology; D059748:Proteolysis / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D061988:Proteasome Inhibitors; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; C025946:3-methyladenine; D051057:Proto-Oncogene Proteins c-akt; D048051:p38 Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex; D000225:Adenine; D020123:Sirolimus