Elevated protein kinase D3 (PKD3) expression supports proliferation of triple-negative breast cancer cells and contributes to mTORC1-S6K1 pathway activation

J Biol Chem. 2014 Feb 7;289(6):3138-47. doi: 10.1074/jbc.M113.502633. Epub 2013 Dec 11.

Abstract

Here, we show that the expression of the Golgi-localized serine-threonine kinase protein kinase D3 (PKD3) is elevated in triple-negative breast cancer (TNBC). Using an antibody array, we identified PKD3 to trigger the activation of S6 kinase 1 (S6K1), a main downstream target of the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway. Accordingly, PKD3 knockdown in TNBC cells led to reduced S6K1 phosphorylation, which was associated with impaired activation of mTORC1 at endolysosomal membranes, the accumulation of the mannose 6-phosphate receptor in and the recruitment of the autophagy marker light chain 3 to enlarged acidic vesicles. We further show that PKD3 depletion strongly inhibited cell spreading and proliferation of TNBC cells, identifying this kinase as a potential novel molecular therapeutic target in TNBC. Together, our data suggest that PKD3 in TNBC cells provides a molecular connection between the Golgi and endolysosomal compartments to enhance proliferative mTORC1-S6K1 signaling.

Keywords: Autophagy; Breast Cancer; Endosomes; Golgi; Lysosomes; Protein Kinase D (PKD); S6 Kinase; mTOR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • Breast Neoplasms / therapy
  • Cell Line, Tumor
  • Cell Proliferation*
  • Endosomes / genetics
  • Endosomes / metabolism
  • Endosomes / pathology
  • Female
  • Gene Knockdown Techniques
  • Golgi Apparatus / genetics
  • Golgi Apparatus / metabolism
  • Golgi Apparatus / pathology
  • Humans
  • Lysosomes / genetics
  • Lysosomes / metabolism
  • Lysosomes / pathology
  • Mechanistic Target of Rapamycin Complex 1
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism*
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • Protein Kinase C / biosynthesis*
  • Protein Kinase C / genetics
  • Ribosomal Protein S6 Kinases, 70-kDa / genetics
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism*
  • Signal Transduction*
  • TOR Serine-Threonine Kinases / genetics
  • TOR Serine-Threonine Kinases / metabolism*

Substances

  • Multiprotein Complexes
  • Neoplasm Proteins
  • protein kinase C nu
  • Mechanistic Target of Rapamycin Complex 1
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases
  • ribosomal protein S6 kinase, 70kD, polypeptide 1
  • Protein Kinase C