1. ¹Department of Urology, Urologic Oncology Research Laboratory, Weill Medical College of Cornell University and New York Presbyterian Hospital, New York, NY, USA
2. ²Division of Hematology and Medical Oncology, Department of Medicine, Genitourinary Oncology Research Laboratory, Weill Medical College of Cornell University and New York Presbyterian Hospital, New York, NY, USA
3. ³Department of Physiology, Kanazawa University School of Medicine, Takaramachi, Kanazawa, Japan
4. ⁴Division of Cardiology, Department of Medicine, Weill Medical College of Cornell University and New York Presbyterian Hospital, New York, NY, USA

Correspondence: Dr DM Nanus, Division of Hematology and Medical Oncology, Department of Medicine, Weill Medical College of Cornell University, 525 E. 68th Street, ST-359, New York, NY 10021, USA. E-mail: dnanus@med.cornell.edu

Received 5 January 2006; Revised 3 March 2006; Accepted 6 March 2006; Published online 1 May 2006.

Abstract

The neuropeptides bombesin and endothelin-1 stimulate prostate cancer (PC) cell migration and invasion (J Clin Invest, 2000; 106: 1399–1407). The intracellular signaling pathways that direct this cell movement are not well delineated. The monomeric GTPase RhoA is required for migration in several cell types including neutrophils, monocytes and fibroblasts. We demonstrate that bombesin-stimulated PC cell migration occurs via the heterotrimeric G-protein-coupled receptors (G-protein) G13 subunit leading to activation of RhoA, and Rho-associated coiled-coil forming protein kinase (ROCK). Using siRNA to suppress expression of the three known G-protein -subunit-associated RhoA guanine nucleotide exchange factors (GEFs), we also show that two of these RhoA GEFs, PDZ-RhoGEF and leukemia-associated RhoGEF (LARG), link bombesin receptors to RhoA in a non-redundant manner in PC cells. We next show that focal adhesion kinase, which activates PDZ-RhoGEF and LARG, is required for bombesin-stimulated RhoA activation. Neutral endopeptidase (NEP) is expressed on normal prostate epithelium whereas loss of NEP expression contributes to PC progression. We also demonstrate that NEP inhibits neuropeptide activation of RhoA. Together, these results establish a contiguous signaling pathway from the bombesin receptor to ROCK in PC cells, and they implicate NEP as a major regulator of neuropeptide-stimulated RhoA in these cells. This work also identifies members of this signaling pathway as potential targets for rational pharmacologic manipulation of neuropeptide-stimulated migration of PC cells.