GM3 suppresses anchorage-independent growth via Rho GDP dissociation inhibitor beta in melanoma B16 cells

Pu Wang, Su Xu, Yinan Wang, Peixing Wu, Jinghai Zhang, Toshinori Sato, Sadako Yamagata, Tatsuya Yamagata

Research output: Contribution to journalArticle

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Abstract

Ly-GDI, Rho GTPase dissociation inhibitor beta, was found to be expressed parallel to the GM3 level in mouse B16 cells whose GM3 contents were modified by B4galt6 sense, B4galt6 antisense cDNA, or St3galt5 siRNA transfection. Ly-GDI expression was increased on GM3 addition to these cells and decreased with D-PDMP treatment, a glucosylceramide synthesis inhibitor. Suppression of GM3 or Ly-GDI by RNAi was concomitantly associated with an increase in anchorage-independent growth in soft agar. These results clearly indicate that GM3 suppresses anchorage-independent growth through Ly-GDI. GM3 signals regulating Ly-GDI expression was inhibited by LY294002, siRNA against Akt1 and Akt2 and rapamycin, showing that GM3 signals are transduced via the PI3K/Akt/mTOR pathway. Either siRNA towards Rictor or Raptor suppressed Ly-GDI expression. The Raptor siRNA suppressed the effects of GM3 on Ly-GDI expression and Akt phosphorylation at Thr308, suggesting GM3 signals to be transduced to mTOR-Raptor and Akt-Thr308, leading to Ly-GDI stimulation. siRNA targeting Pdpk1 reduced Akt phosphorylation at Thr308 and rendered the cells insensitive to GM3 stimulation, indicating that Akt-Thr308 plays a critical role in the pathway. The components aligned in this pathway showed similar effects on anchorage-independent growth as GM3 and Ly-GDI. Taken together, GM3 signals are transduced in B16 cells through PI3K, Pdpk1, AktThr308 and the mTOR/Raptor pathway, leading to enhanced expression of Ly-GDI mRNA, which in turn suppresses anchorage-independent growth in melanoma B16 cells.

Original languageEnglish
Pages (from-to)1476-1485
Number of pages10
JournalCancer Science
Volume102
Issue number8
DOIs
Publication statusPublished - 2011 Aug

Fingerprint

rho Guanine Nucleotide Dissociation Inhibitor beta
Guanine Nucleotide Dissociation Inhibitors
Experimental Melanomas
Raptors
Growth
Small Interfering RNA
Phosphatidylinositol 3-Kinases
Phosphorylation
Glucosylceramides
rho GTP-Binding Proteins
2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
Sirolimus
RNA Interference

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

GM3 suppresses anchorage-independent growth via Rho GDP dissociation inhibitor beta in melanoma B16 cells. / Wang, Pu; Xu, Su; Wang, Yinan; Wu, Peixing; Zhang, Jinghai; Sato, Toshinori; Yamagata, Sadako; Yamagata, Tatsuya.

In: Cancer Science, Vol. 102, No. 8, 08.2011, p. 1476-1485.

Research output: Contribution to journalArticle

Wang, Pu ; Xu, Su ; Wang, Yinan ; Wu, Peixing ; Zhang, Jinghai ; Sato, Toshinori ; Yamagata, Sadako ; Yamagata, Tatsuya. / GM3 suppresses anchorage-independent growth via Rho GDP dissociation inhibitor beta in melanoma B16 cells. In: Cancer Science. 2011 ; Vol. 102, No. 8. pp. 1476-1485.
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