Abstract 2321: The novel vasopressin analog [4-valine 5-glutamine] desmopressin inhibits tumor growth and angiogenesis in V2 receptor-expressing breast cancer xenografts
Authors: Garona Juan , Segatori Valeria I. , Iannucci Nancy , Cascone Osvaldo , Gomez Daniel E. , Alonso Daniel F. , Ripoll Giselle V. 
Published: August 2012

Abstract
Desmopressin (dDAVP), a synthetic nonapeptide derivative of arginine vasopressin, is a safe antidiuretic and hemostatic compound that acts as a selective agonist for the vasopressin V2 membrane receptor (V2R). This receptor is expressed in kidney collecting tubes, endothelium and also in some tumor cells. We previously reported that dDAVP can inhibit progression of residual metastatic cells in preclinical models. Among other mechanisms, the compound induces an agonist effect on V2R present in tumor cells. This cyclic nonapeptide was substituted in positions 4 and 5 searching for compounds with improved biological activity (Iannucci et al., Fut. Med. Chem. 2011). Such positions belong to the conformational peptide loop which has a key role in ligand-receptor interaction. In this study, we evaluated the effects of the novel analog [4-valine 5-glutamine] dDAVP ([V4Q5]dDAVP) on cell proliferation and migration in vitro, and tumor growth and angiogenesis in vivo using the MDA-MB-231 triple-negative V2R-expressing human breast cancer cell line. We first examined peptide ability to modify in vitro cell growth of MDA-MB-231 cells by the MTT assay. Incubation with [V4Q5]dDAVP analog (100-1500 nM) during 72 h significantly reduced cell proliferation showing a better performance at high concentrations than the parental compound dDAVP. When studying the effect on cell cycle, flow cytometric analysis showed that a 24-h treatment with [V4Q5]dDAVP resulted in an arrest of MDA-MB-231 cells in G0/G1 phase. Next, we used wound migration and transwell chemotaxis assays to study the ability of [V4Q5]dDAVP to inhibit tumor cell motility. After a 16-h treatment, MDA-MB-231 migration and chemotaxis was impaired by 30-60%. To asses the in vivo effect of the compound on tumor growth, nu/nu mice where implanted s.c. with MDA-MB-231 cells. Three weekly i.v. doses of [V4Q5]dDAVP (0.3 µg/kg/dose) reduced by 40% the subcutaneous tumor volume compared with vehicle-treated controls after a 4- week treatment. Finally, to evaluate the in vivo angiostatic effect, a modified Matrigel plug assay was used. Intravenous administration of [V4Q5]dDAVP (0.3 µg/kg/dose thrice a week) significantly reduced by 18% MDA-MB-231 cell-induced angiogenesis as measured by hemoglobin content in plugs recovered from mice 14 days after tumor cell inoculation. These in vivo effects are probably due to a dual action of [V4Q5]dDAVP involving angiogenesis inhibition mechanisms and direct cytostatic action. In conclusion, this study indicates that the novel peptide compound [V4Q5]dDAVP exerts a remarkable and improved antitumor and antiangiogenic effect in comparison to parental peptide dDAVP. Increased hidrophobicity at the conformational peptide loop by replacing Gln for Val may play a key role on ligand-receptor interaction, thus enhancing agonist effect on V2R present in tumor cells.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2321. doi:1538-7445.AM2012-2321