Ligation of prostate cancer cell surface GRP78 activates a proproliferative and antiapoptotic feedback loop: a role for secreted prostate-specific antigen.

Journal Article

GRP78, a well characterized chaperone in the endoplasmic reticulum, is critical to the unfolded protein response. More recently, it has been identified on the cell surface, where it has many roles. On cancer cells, it functions as a signaling receptor coupled to proproliferative/antiapoptotic and promigratory mechanisms. In the current study, we demonstrate that ligation of prostate cancer cell surface GRP78 by its natural ligand, activated α(2)-macroglobulin (α(2)M*), results in a 2-3-fold up-regulation in the synthesis of prostate-specific antigen (PSA). The PSA is secreted into the medium as an active proteinase, where it binds to native α(2)M. The resultant α(2)M·PSA complexes bind to GRP78, causing a 1.5-2-fold increase in the activation of MEK1/2, ERK1/2, S6K, and Akt, which is coupled with a 2-3-fold increase in DNA and protein synthesis. PSA is a marker for the progression of prostate cancer, but its mechanistic role in the disease is unclear. The present studies suggest that PSA may be involved in a signal transduction-dependent feedback loop, whereby it promotes a more aggressive behavior by human prostate cancer cells.

Full Text

Duke Authors

Cited Authors

  • Misra, UK; Payne, S; Pizzo, SV

Published Date

  • January 14, 2011

Published In

Volume / Issue

  • 286 / 2

Start / End Page

  • 1248 - 1259

PubMed ID

  • 21056970

Electronic International Standard Serial Number (EISSN)

  • 1083-351X

Digital Object Identifier (DOI)

  • 10.1074/jbc.M110.129767

Language

  • eng

Conference Location

  • United States