title: Induction of apoptosis of detached oral squamous cell carcinoma cells by safingol. Possible role of Bim, focal adhesion kinase and endonuclease G.
abstract: The protein kinase C (PKC) inhibitor safingol increased rounding and detachment of human oral squamous cell carcinoma (SCC) cells in monolayer cultures. When dissociated cells were incubated in the presence of safingol, cell adhesion was prevented and cell viability was lost gradually, while most cells survived in the absence of safingol even if their attachment was blocked by coating the culture plates with polyhydroxyethyl methacrylate. Flow cytometric analysis and agarose gel electrophoresis of cellular DNA revealed an increase in the proportion of sub-G(1) cells and DNA fragmentation, indicating that safingol induced apoptosis of dissociated cells. During the induction of apoptosis in cell suspensions by safingol, there was an increase of the pro-apoptotic BH-3 only protein Bim and decrease of pro-survival Bcl-2 family proteins Bcl-xL and mitochondrial pro-apoptogenic factor endonuclease G translocated to the nucleus. The level of phosphorylated focal adhesion kinase (FAK) required for cell survival also rapidly decreased, followed by a decrease in the protein level. The introduction of siRNA against PKCalpha into SAS cells resulted in an increase of Bim, a decrease of Bcl-xL, the translocation of endonuclease G, and a decrease in the phosphorylation of FAK. These results suggest that Bim, Bcl-xL, FAK and endonuclease G are involved in safingol-induced apoptosis of detached oral SCC cells. Safingol can be used to induce apoptosis with cell detachment, anoikis, of oral SCC cells.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Noda
authors.forename: Soichi
authors.initials: S
authors.lastname: Iwai
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hamada
authors.forename: Yusei
authors.initials: Y
authors.lastname: Fujita
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yura
mesh_terms: D023102:Anoikis / Q000502:physiology; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D000072224:Bcl-2-Like Protein 11; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D045304:Cytochromes c / Q000187:drug effects / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004706:Endodeoxyribonucleases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D009062:Mouth Neoplasms / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; D008565:Membrane Proteins; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D045304:Cytochromes c; D051416:Focal Adhesion Protein-Tyrosine Kinases; D004706:Endodeoxyribonucleases; C052391:endonuclease G; D053148:Caspase 3; D013110:Sphingosine; C005682:safingol