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The G Protein–Coupled Receptor 87 Is Necessary for p53-Dependent Cell Survival in Response to Genotoxic Stress

Center for Comparative Oncology, Schools of Medicine and Veterinary Medicine, University of California, Davis, California

Requests for reprints: Xinbin Chen, VM: Surgical and Radiological Sciences, University of California, 2128 Tupper Hall, Davis, CA 95616. Phone: 530-754-8404; Fax: 530-752-6042; E-mail: xbchen{at}ucdavis.edu.

Key Words: GPR87 • p53 • DNA damage • growth suppression

p53 regulates an array of target genes, which mediates p53 tumor suppression by inducing cell cycle arrest, apoptosis, and cell survival. G protein–coupled receptors belong to a superfamily of cell surface molecules and are known to regulate cell proliferation, migration, and survival. Here, we found that G protein–coupled receptor 87 (GPR87) was up-regulated by p53 and by DNA damage in a p53-dependent manner. We also found that p53 directly regulated GPR87 potentially via a p53-responsive element in the GPR87 gene. To investigate the role of GPR87 in the p53 pathway, we generated multiple RKO and MCF7 cell lines in that GPR87 can be inducibly overexpressed or knocked down by a tetracycline-inducible system. We found that overexpression of GPR87 had little effect on cell growth. However, GPR87 knockdown sensitized cancer cells to DNA damage–induced growth suppression via enhanced p53 stabilization and activation. Importantly, the prosurvival activity of GPR87 can be reversed by knockdown of p53. Together, our results suggested that GPR87 is essential for p53-dependent cell survival in response to DNA damage. Thus, due to its expression on the cell surface and its role in cell survival, GPR87 may be explored as a novel therapeutic target for cancer treatment and prevention. [Cancer Res 2009;69(15):6049–56]