Galanin decreases proliferation of PC12 cells and induces apoptosis via its subtype 2 receptor (GalR2)

Proc Natl Acad Sci U S A. 2008 Feb 19;105(7):2717-22. doi: 10.1073/pnas.0712300105. Epub 2008 Feb 12.


Galanin is a neuropeptide with a wide range of effects in the nervous and endocrine systems, mediated through three G protein-coupled receptor subtypes (GalR1-3). Interestingly, galanin and its receptors are also expressed in certain tumors. Here we studied the effects of galanin in rat pheochromocytoma (PC12) cells stably transfected with GFP-tagged GalR2. Galanin at 100 nM inhibited cell proliferation in both nontransfected and transfected cells. Conversly, both galanin and the GalR2(R3)-agonist AR-M1896 induced caspase-dependent apoptotic cell death only in GalR2-transfected cells. Western-blot analyses of downstream mediators of the G(q/11)-type G protein showed down-regulation of pAkt and pBad in galanin-exposed transfected cells. Also, the specific PI3 kinase inhibitor LY-294002 increased the level of pBad and decreased activation of caspases. In addition, p21(cip1) levels were up-regulated in galanin-exposed PC12 cells and down-regulated in galanin-exposed GalR2-transfected cells. In agreement, FACS analyses of galanin exposed cells showed occurrence of cell cycle arrest in PC12 cells and cell death in transfected cells. Finally, as shown with real-time PCR, galanin and its receptors were expressed at very high levels in human pheochromocytoma tissues as compared with normal adrenal medulla. These findings point to GalR2 as a possible target for therapeuthic interventions in pheochromocytoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Caspases / metabolism
  • Cell Proliferation / drug effects
  • Enzyme Activation / drug effects
  • Galanin / genetics
  • Galanin / pharmacology*
  • Gene Expression Regulation
  • Humans
  • PC12 Cells
  • Phosphatidylinositol 3-Kinases / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats
  • Receptor, Galanin, Type 1 / genetics
  • Receptor, Galanin, Type 2 / genetics
  • Receptor, Galanin, Type 2 / metabolism*
  • Signal Transduction / drug effects


  • Receptor, Galanin, Type 1
  • Receptor, Galanin, Type 2
  • Galanin
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-akt
  • Caspases