Ligation of cancer cell surface GRP78 with antibodies directed against its COOH-terminal domain up-regulates p53 activity and promotes apoptosis.

Journal Article

Binding of activated α(2)-macroglobulin to GRP78 on the surface of human prostate cancer cells promotes proliferation by activating signaling cascades. Autoantibodies directed against the activated α(2)-macroglobulin binding site in the NH(2)-terminal domain of GRP78 are receptor agonists, and their presence in the sera of cancer patients is a poor prognostic indicator. We now show that antibodies directed against the GRP78 COOH-terminal domain inhibit [(3)H]thymidine uptake and cellular proliferation while promoting apoptosis as measured by DNA fragmentation, Annexin V assay, and clonogenic assay. These antibodies are receptor antagonists blocking autophosphorylation and activation of GRP78. Using 1-LN and DU145 prostate cancer cell lines and A375 melanoma cells, which express GRP78 on their cell surface, we show that antibodies directed against the COOH-terminal domain of GRP78 up-regulate the tumor suppressor protein p53. By contrast, antibody directed against the NH(2)-terminal domain of GRP78 shows negligible effects on p53 expression. PC-3 prostate cancer cells, which do not express GRP78 on their cell surface, are refractory to the effects of anti-GRP78 antibodies directed against either the COOH- or NH(2)-terminal domains. However, overexpression of GRP78 in PC-3 cells causes translocation of GRP78 to the cell surface and promotes apoptosis when these cells are treated with antibody directed against its COOH-terminal domain. Silencing GRP78 or p53 expression by RNA interference significantly blocked the increase in p53 induced by antibodies. Antibodies directed against the COOH-terminal domain may play a therapeutic role in cancer patients whose tumors trigger the production of autoantibodies directed against the NH(2)-terminal domain of GRP78.

Full Text

Duke Authors

Cited Authors

  • Misra, UK; Mowery, Y; Kaczowka, S; Pizzo, SV

Published Date

  • May 2009

Published In

Volume / Issue

  • 8 / 5

Start / End Page

  • 1350 - 1362

PubMed ID

  • 19417154

Electronic International Standard Serial Number (EISSN)

  • 1538-8514

Digital Object Identifier (DOI)

  • 10.1158/1535-7163.MCT-08-0990

Language

  • eng

Conference Location

  • United States