Positive regulation of tumor necrosis factor-alpha by ganglioside GM3 through Akt in mouse melanoma B16 cells.
GM3 has been shown to suppress TNFalpha expression in blood monocytes. However, we found that GM3 and TNFalpha were expressed in parallel in mouse melanoma B16 cells that were transfected with UDP-Gal:glucosylceramide beta-1,4-galactosyltransferase cDNA in a sense or antisense direction or CMP-NeuAc:lactosylceramide alpha-2,3-sialyltransferase siRNA. TNFalpha expression was increased by addition of GM3 to the B16 transfectants and decreased after treatment with D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, an inhibitor of glucosylceramide synthesis. These results clearly indicate that GM3 positively regulates TNFalpha expression in B16 cells. Phosphoinositide 3-kinase inhibitors, wortmannin and LY294,002, suppressed TNFalpha expression and Akt phosphorylation. GM3 was shown to increase phosphorylation of Akt in B16 cells and the B16-derived transfectants. Treatment of B16 cells with siRNA targeted to Akt1/2 resulted in TNFalpha suppression, indicating that Akt plays an important role in regulation of TNFalpha expression. Suppression of Akt1/2 rendered cells insensitive to GM3, suggesting that the GM3 signal may be transduced via Akt.
Wang
Pu
P
Laboratory of Tumor Biology and Glycobiology, P.O. Box 29, Shenyang Pharmaceutical University, 103 WenHua Road, Shenyang 110016, People's Republic of China.
Wu
Peixing
P
Zhang
Jinghai
J
Sato
Toshinori
T
Yamagata
Sadako
S
Yamagata
Tatsuya
T
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002867:Chromones / Q000494:pharmacology; D005679:G(M3) Ganglioside / Q000494:pharmacology*; D008545:Melanoma / Q000473:pathology*; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012878:Skin Neoplasms / Q000473:pathology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*; D000077191:Wortmannin
D000730:Androstadienes; D002867:Chromones; D005679:G(M3) Ganglioside; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010879:Piperazines; D014409:Tumor Necrosis Factor-alpha; C093555:LY 303511; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D051057:Proto-Oncogene Proteins c-akt; D000077191:Wortmannin