C6-ceramide nanoliposome suppresses tumor metastasis by eliciting PI3K and PKCζ tumor-suppressive activities and regulating integrin affinity modulation

Sci Rep. 2015 Mar 20:5:9275. doi: 10.1038/srep09275.

Abstract

Nanoliposomal formulation of C6-ceramide, a proapoptotic sphingolipid metabolite, presents an effective way to treat malignant tumor. Here, we provide evidence that acute treatment (30 min) of melanoma and breast cancer cells with nanoliposomal C6-ceramide (NaL-C6) may suppress cell migration without inducing cell death. By employing a novel flow migration assay, we demonstrated that NaL-C6 decreased tumor extravasation under shear conditions. Compared with ghost nanoliposome, NaL-C6 triggered phosphorylation of PI3K and PKCζ and dephosphorylation of PKCα. Concomitantly, activated PKCζ translocated into cell membrane. siRNA knockdown or pharmacological inhibition of PKCζ or PI3K rescued NaL-C6-mediated suppression of tumor migration. By inducing dephosphorylation of paxillin, PKCζ was responsible for NaL-C6-mediated stress fiber depolymerization and focal adhesion disassembly in the metastatic tumor cells. PKCζ and PI3K regulated cell shear-resistant adhesion in a way that required integrin αvβ3 affinity modulation. In conclusion, we identified a novel role of acute nanoliposomal ceramide treatment in reducing integrin affinity and inhibiting melanoma metastasis by conferring PI3K and PKCζ tumor-suppressive activities.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cell Line, Tumor
  • Ceramides / pharmacology*
  • Humans
  • Integrins / metabolism*
  • Liposomes*
  • Nanostructures*
  • Neoplasm Metastasis / prevention & control*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphorylation
  • Protein Binding
  • Protein Kinase C / metabolism*
  • Protein Transport

Substances

  • Ceramides
  • Integrins
  • Liposomes
  • Phosphatidylinositol 3-Kinases
  • protein kinase C zeta
  • Protein Kinase C