Osteosarcoma is the most prevalent primary bone malignancy. Due to its high aggressiveness, novel treatment strategies are urgently required to improve survival of patients with osteosarcoma, especially those with advanced disease. Desmopressin (dDAVP) is a widely used blood-saving agent that has been repurposed as an adjuvant agent for cancer management due to its antiangiogenic and antimetastatic properties. dDAVP acts as a selective agonist of the vasopressin membrane receptor type 2 (AVPR2) present in the microvascular endothelium and in some cancer cells, including breast, lung, colorectal and neuroendocrine tumor cells. Despite the fact that dDAVP has demonstrated its antitumor efficacy in a wide variety of tumor types, exploration of its potential anti-osteosarcoma activity has, to the best of our knowledge, not yet been conducted. Therefore, the aim of the present study was to evaluate the preclinical antitumor activity of dDAVP in osteosarcoma. Human MG-63 and U-2 OS osteosarcoma cell lines were used to assess in vitro and in vivo therapeutic effects of dDAVP. At low micromolar concentrations, dDAVP reduced AVPR2-expressing MG-63 cell growth in a concentration-dependent manner. In contrast, dDAVP exhibited no direct cytostatic effect on AVPR2-negative U-2 OS cells. As it would be expected for canonical AVPR2-activation, dDAVP raised intracellular cAMP levels in osteosarcoma cells, and coincubation with phosphodiesterase-inhibitor rolipram indicated synergistic antiproliferative activity. Cytostatic effects were associated with increased apoptosis, reduced mitotic index and impairment of osteosarcoma cell chemotaxis, as evaluated by TUNEL-labeling, mitotic body count in DAPI-stained cultures and Transwell migration assays. Intravenous administration of dDAVP (12 µg/kg; three times per week) to athymic mice bearing rapidly growing MG-63 xenografts, was indicated to be capable of reducing tumor progression after a 4-week treatment. No major alterations in animal weight, biochemical or hematological parameters were associated with dDAVP treatment, confirming its good tolerability and safety. Finally, AVPR2 expression was detected by immunohistochemistry in 66% of all evaluated chemotherapy-naive human conventional osteosarcoma biopsies. Taking these findings into account, repurposed agent dDAVP may represent an interesting therapeutic tool for the management of osteosarcoma. Further preclinical exploration of dDAVP activity on orthotopic or metastatic osteosarcoma models are required.

No abstract

Osteosarcoma is still associated with limited response to standard-of-care therapy and alarmingly elevated mortality rates, especially in low- and middle-income countries. Despite multiple efforts to repurpose β-blocker propranolol in oncology, its potential application in osteosarcoma management remains largely unexplored. Considering the unsatisfied clinical needs of this aggressive disease, we evaluated the antitumoral activity of propranolol using different in vitro and in vivo osteosarcoma preclinical models, alone or in addition to chemotherapy. Propranolol significantly impaired cellular growth in β2-adrenergic receptor-expressing MG-63 and U-2OS cells, and was capable of blocking growth-stimulating effects triggered by catecholamines. siRNA-mediated ADRB2 knockdown in MG-63 cells was associated with decreased cell survival and a significant attenuation of PPN anti-osteosarcoma activity. Direct cytostatic effects of propranolol were independent of apoptosis induction and were associated with reduced mitosis, G0/G1 cell cycle arrest and a significant down-regulation of cell cycle regulator Cyclin D1. Moreover, colony formation, 3D spheroid growth, cell chemotaxis and capillary-like tube formation were drastically impaired after propranolol treatment. Interestingly, anti-migratory activity of β-blocker was associated with altered actin cytoskeleton dynamics. In vivo, propranolol treatment (10 mg/kg/day i.p.) reduced the early angiogenic response triggered by MG-63 cells in nude mice. Synergistic effects were observed in vitro after combining propranolol with chemotherapeutic agent cisplatin. Sustained administration of propranolol (10 mg/kg/day i.p., five days a week), alone and especially in addition to low-dose metronomic cisplatin (2 mg/kg/day i.p., three times a week), markedly reduced xenograft progression. After histological analysis, propranolol and cisplatin combination resulted in low tumor mitotic index and increased tumor necrosis. β-blockade using propranolol seems to be an achievable and cost-effective therapeutic approach to modulate osteosarcoma aggressiveness. Further translational studies of propranolol repurposing in osteosarcoma are warranted.

Introduction. Osteosarcoma (OS) is the most common malignant primary bone tumor in children and young adults, with alarmingly elevated mortality rates, especially in developing countries. OS patients bear highly invasive and vascularized tumors, with limited response to standard of care (SoC) therapies, and are in urgent need of novel therapeutic strategies. Propranolol (PPN) is a non-selective β-adrenergic receptor (β-AR) antagonist originally used in the treatment of diverse heart diseases. On the other hand, desmopressin (dDAVP) is a hemostatic drug that acts as a selective agonist for the vasopressin type-2 receptor (AVPR2) present in blood microvessels and several tumor types. Given that β-ARs and AVPR2 signalling regulates many cellular processes involved in the initiation and progression of cancer, multiple efforts have been made to repurpose PPN and dDAVP in indications such as breast and colorectal cancer, melanoma and angiosarcoma, among others. Considering the unsatisfied clinical needs of OS, the objective of this work was to evaluate the in vitro/in vivo antitumoral activity of PPN and dDAVP on highly aggressive preclinical models of OS. Materials and methods. The human OS cell lines MG-63 and U2-OS were used for in vitro or in vivo experiments. Target expression was assessed by qPCR and immunohistochemistry. Sensitivity to PPN or dDAVP was evaluated by in vitro 72 h proliferation, 7 d clonogenic growth, 3D spheroid formation, transwell chemotaxis assays and MG-63 xenograft progression in nude mice. In addition, PPN was evaluated as monotherapy or in combination with SoC chemotherapy. Results. PPN (10-100 µM) and dDAVP (0.1-10 µM) drastically reduced clonogenic and 3D growth, migration, mitotic index and proliferation of β-AR and AVPR2-expressing OS cells (p<0.05). Synergistic antitumoral effects were observed after combining PPN with cisplatin or methotrexate, in vitro and in vivo (CI<1). In animals bearing growing OS s.c. xenografts sustained treatment during 4 weeks with PPN (10 mg/kg i.p. daily) or dDAVP (12 µg/kg i.v. three times a week) markedly abrogated tumor progression, exhibiting modulation of local tumor aggressiveness and reducing final tumor burden by 25 or 45%, respectively (p<0.01). Conclusions. Taking into account PPN and dDAVP robust antitumoral effects, β-ARs antagonization or agonist activation of AVPR2 are achievable and interesting therapeutic approaches to modulate OS tumor aggressiveness. Both agents could be proposed as coadyuvant agents for treating OS, not only in combination with chemotherapy but also administered during the perioperative setting. Citation Format: Luisina Solerno, Natasha Sobol, Rocío Rodriguez, Marina Pifano, Giselle Ripoll, Hernan Farina, Liliana Vasquez, Daniel F. Alonso, Juan Garona. Drug repurposing of β-blocker propranolol and hemostatic compound desmopressin in osteosarcoma: Preclinical antitumor activity on 2D and 3D cell growth, chemotaxis and xenograft progression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3062.