Reciprocal interactions between tumor and endothelial cells: Effects of selective vasopressin V2 receptor peptide agonists

Recent experimental evidence suggested that the synthetic peptide desmopressin (DDAVP) interferes tumor angiogenesis by inducing the formation of angiostatin. It is also known that DDAVP stimulates the endothelial release of von Willebrand factor, a key element in resistance to metastasis. Vasopressin V2 receptor agonists such as DDAVP seem to evoke dual angiostatic and antimetastatic effects, breaking cooperative interactions of tumor and endothelial cells during tumor progression.Fil: Garona, Juan. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Desmopressin in canine mammary carcinoma: Comments on the importance of the administration route

Several years ago, we proposed the haemostatic peptide desmopressin (1-desamino-8-d-arginine vasopressin; dDAVP) as a potential anti-metastatic agent to be used during surgical excision of locally advanced tumours. A prospective randomized study in 28 intact dogs with mammary carcinomas receiving perioperative intravenous dDAVP infusions (1 μg/kg) demonstrated a significant survival benefit in dogs with moderately (grade 2) or poorly differentiated (grade 3) tumours.1 dDAVP is known to exert anti-proliferative and anti-angiogenic effects in laboratory models, by acting on AVPR2 vasopressin receptors present in tumour and endothelial cells. Moreover, dDAVP can induce the release of von Willebrand factor (VWF) from microvascular endothelium into blood circulation. Beyond its critical function in primary haemostasis, VWF plays a protective role against metastatic dissemination. An abrupt increase in VWF blood levels is able to interfere with the arrest of circulating cancer cells at target organs and also to induce apoptosis in micrometastatic foci.2 The article entitled “A prospective randomized trial of desmopressin in canine mammary carcinoma” recently published in Veterinary and Comparative Oncology by Sorenmo et al retested dDAVP as a surgical adjuvant in 24 dogs with mammary carcinomas.3 They reported that few dogs developed metastatic disease in this study, and no significant benefit of perioperative dDAVP administration was observed. We completely agree with the authors in the sense that subgroup comparisons between the high-risk subgroups were very underpowered, since none of the dogs with grade 2 tumours developed metastasis and only one dog with a grade 3 tumour was randomized to receive dDAVP.3 More to the point, all intact dogs underwent ovariohysterectomy as part of their treatment in this study, thus reducing the risk of metastasis and possibly diminishing the impact of perioperative dDAVP on survival. However, it is important to note that Sorenmo et al used a nasal spray formulation of dDAVP administered by the subcutaneous route,3 instead of an intravenous infusion as in our previous study.1 Even though subcutaneous administration is the standard of care in bleeding disorders, it was clearly demonstrated that dDAVP is ineffective by the subcutaneous route in experimental metastasis assays in mice. A clear dose-dependent anti-metastatic action was observed by using the intravenous injection (dDAVP doses ranging from 0.3 to 2 μg/kg), while no significant effects were obtained with similar doses by the subcutaneous route.4 Although a haemostatic factor such as VWF is involved, anti-metastatic effects of dDAVP are not directly associated with the coagulation process.4 VWF is a multifunctional protein and its role in resistance to metastasis is independent of its role in haemostasis,2 probably requiring the rapid peak concentrations associated with high intravenous doses to favour the elimination of early metastatic cells. Finally, we agree with the authors in that a prospective randomized trial in dogs bearing grade 3 mammary tumours should be conducted with the aim of resolving discrepancies between studies. However, in order to confirm the therapeutic benefits of perioperative dDAVP, compound should always be administered using the intravenous route. In this setting, maintenance therapy based on additional postoperative doses of dDAVP, or its synthetic analog with enhanced cytostatic activity [V4Q5]dDAVP,5 could be used to consolidate the effect against dormant metastasis or disseminated tumour cells.Fil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Turic, Esteban. Biogénesis Bagó; ArgentinaFil: Garona, Juan. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Commentary: Arginine vasopressin receptor 1a is a therapeutic target for castration-resistant prostate cancer

Prostate cancer patients managed with androgen-deprivation therapy usually recur after a few years and the disease gradually becomes castration-resistant prostate cancer (CRPC). The role of tumor cell plasticity, including processes such as transdifferentiation and epithelial-mesenchymal transition, is pivotal in the development of androgen receptor (AR)-indifferent tumor variants (1). Cell plasticity may allow CRPC progression and metastasis by favoring reactivation of AR signaling as a result of different mechanisms of transcriptome reprogramming. Interestingly, dissection of such mechanisms can lead to the identification of novel vulnerabilities of aggressive tumor cells that can be targeted therapeutically. The recent work by Zhao et al. (2) identified the vasopressin receptor 1a (AVPR1a) as a critical effector in CRPC expressing the AR coactivator VAV3 and the constitutively active AR variant AR-V7. They demonstrated that ectopic expression of AVPR1a is capable of conferring castration resistance and agonist treatment with the receptor ligand, the natural hormone arginine vasopressin, activates ERK and CREB, signaling molecules known to promote prostate cancer progression. Interestingly, depletion of AVPR1a or inhibition by the selective AVPR1a antagonist relcovaptan resulted in decreased CRPC cell proliferation and reduced bone metastatic growth in vivo. We completely agree with the authors in the sense that AVPR1a can be a potential target for CRPC therapy. We believe that clinical trials with relcovaptan are warranted, particularly in patients with bone-metastatic disease for which therapeutic options are limited. However, we want to point out that these results could be revealing other untapped antitumor properties of the vasopressin system-related drugs against prostate cancer cells. Our team has reported that the vasopressin analog desmopressin, a selective agonist for the vasopressin receptor 2 (AVPR2), significantly reduced tumor cell growth and migration in AR-negative CRPC (3). In vitro exposure to desmopressin also induced a dramatic decrease of the neuroendocrine markers chromogranin and neuron-specific enolase in aggressive CRPC cells (3). In prostate cancer, neuroendocrine transdifferentiation is known to be related with transition toward AR-indifference and metastatic phenotype. Besides, recent studies in orthotopic and heterotopic models of CRPC in athymic nude mice demonstrated an enhanced efficacy of docetaxel in combination with desmopressin (4, 5). Agonist activation of AVPR2 present in various human cancer cell lines has been associated with triggering of antiproliferative signaling pathways involving canonical adenylate cyclase/cAMP/PKA axis activation. cAMP blocks the proliferation of many cell types, both normal and transformed, through multiple downstream effectors. It is known that increased cAMP levels inhibit the Raf/MAPK/ERK signaling pathway in a PKA-dependent manner, but this is not the only mitogenic pathway impaired by cAMP (6). Although cytostatic effect after AVPR2 stimulation is robust, the underlying mechanism is intriguing since AVPR2-mediated cell signaling may eventually lead to phosphorylation of hundreds of PKA substrates granting a complex and seemingly contradictory framework of signaling pathways as evidenced in immortalized epithelial cells after stimulation with desmopressin (7). In this sense, high cAMP levels and PKA activation may eventually lead to phosphorylation and activation of CREB. However, many factors contribute to final cell response. It is known that cAMP can either stimulate or inhibit tumor cell apoptosis, and PKA is able to mediate cAMP-promoted proapoptotic responses depending on the cell type and the cell context (8). In addition, it has been reported a crosstalk of cAMP/PKA that can inhibit RhoA-mediated signaling, thus affecting the aggressive behavior of CRPC cells (9). Taken together, it seems that CREB activation is not prominent after AVPR2 selective agonist action on cancer cells, being favored certain antiproliferative signals. In breast cancer cells expressing AVPR1a and AVPR2, natural vasopressin can activate both receptors but its affinity is higher for AVPR1a and the number of functional AVPR2 tends to be relatively low. Thus, vasopressin elicits AVPR1a-dependent proliferative signals mediated by ERK activation that clearly predominate over AVPR2-dependent antiproliferative signals (10). On the contrary, when AVPR1a is blocked by selective antagonists such as relcovaptan or tumor cells are exposed to specific AVPR2 agonists such as desmopressin, significant antiproliferative effects are achievable in hormone-resistant breast cancer cell lines (10, 11). Desmopressin also contributed to reduce aggressiveness of mammary tumors during chemotherapy in an immunocompetent mouse model (12). We have conducted a Phase 2 dose-escalation clinical trial of desmopressin as a perioperative adjuvant in patients with breast cancer (NCT01606072). Desmopressin appeared safe when administered in two slow infusions before and after surgery, and a rapid postoperative drop in circulating tumor cells was detected after treatment (13). In addition, we documented a reduced intraoperative bleeding associated to the well-known hemostatic effects of the compound (13). From a wider perspective, the stimulating article by Zhao et al. (2) ratifies the relevance of the vasopressin system for searching novel therapeutic targets in hormone-resistant cancer and particularly in CRPC (Figure 1; see also Supplementary Table 1 for preclinical data summary). In this context, repurposing of already-used drugs with a non-oncology primary purpose stands as an interesting strategy to offer effective therapeutic options to cancer patients, allowing faster development and reducing safety concerns (14). The selective AVPR1a antagonist relcovaptan is a small-molecule inhibitor that has been safely and effectively used in clinical trials for Raynaud syndrome, dysmenorrhea and preterm labor. The specific AVPR2 agonist desmopressin is a synthetic peptide compound that has been employed for decades as an antidiuretic in the treatment of diabetic insipidus and enuresis, and as a hemostatic agent for the management of bleeding disorders, with a history of good tolerability and clinical effectiveness. Both compounds constitute promising therapeutic approaches for CRPC that deserve clinical testing either alone or in combination, as well as concurrently with standard chemotherapy regimens.Fil: Ripoll, Giselle Vanina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pifano, Marina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garona, Juan. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Preclinical efficacy of [V 4 Q 5 ]dDAVP, a second generation vasopressin analog, on metastatic spread and tumor-associated angiogenesis in colorectal cancer

Purpose Control of metastatic spread of colorectal cancer (CRC) remains as a major therapeutic challenge. [V 4 Q 5 ]dDAVP is a vasopressin peptide analog with previously reported anticancer activity against carcinoma tumors. By acting as a selective agonist of arginine vasopressin type 2 membrane receptor (AVPR2) present in endothelial and tumor cells, [V 4 Q 5 ]dDAVP is able to impair tumor aggressiveness and distant spread. Our aim was to evaluate the potential therapeutic benefits of [V 4 Q 5 ]dDAVP on highly aggressive CRC disease using experimental models with translational relevance. Materials and Methods Murine CT-26 and human Colo-205 AVPR2-expressing CRC cell lines were used to test the preclinical efficacy of [V 4 Q 5 ]dDAVP, both in vitro and in vivo. Results In syngeneic mice surgically implanted with CT-26 cells in the spleen, sustained intravenous treatment with [V 4 Q 5 ]dDAVP (0.3 jg/kg) dramatically impaired metastatic progression to liver without overt signs of toxicity, and also reduced experimental lung colonization. The compound inhibited in vivo angiogenesis driven by Colo-205 cells in athymic mice, as well as in vitro endothelial cell migration and capillary tube formation. [V 4 Q 5 ]dDAVP exerted AVPR2-dependent cytostatic activity in vitro (IC50 1.08 |jM) and addition to 5-fluorouracil resulted in synergistic antiproliferative effects both in CT-26 and Colo-205 cells. Conclusion The present preclinical study establishes for the first time the efficacy of [V 4 Q 5 ]dDAVP on CRC. These encouraging results suggest that the novel second generation vasopressin analog could be used for the management of aggressive CRC as an adjuvant agent during surgery or to complement standard chemotherapy, limiting tumor angiogenesis and metastasis and thus protecting the patient from CRC recurrence.Fil: Garona, Juan. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sobol, Natasha Tatiana. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pifano, Marina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Segatori, Valeria Inés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ripoll, Giselle Vanina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Vasopressin Analog [V4Q5]dDAVP Exerts Cooperative Anticancer Effects in Combination With Low-Dose 5-Fluorouracil on Aggressive Colorectal Cancer Models

Background: Colorectal cancer (CRC) is a leading cause of cancerassociated mortality worldwide. Despite being an essential component of systemic chemotherapy for advanced CRC, 5-fluorouracil (5-FU) clinical use has severe limitations, such as high toxicity, low selectivity and drug resistance. [V4Q5]dDAVP (1-deamino-4-valine-5-glutamine- 8-D-arginine vasopressin) is a peptide vasopressin analog and a selective agonist of the arginine vasopressin type 2 membrane receptor (AVPR2), expressed in microvascular and tumor tissue. This synthetic compound has well-proven antitumor and antimetastatic activity in different tumor types, including metastatic CRC. The objective of this work was to assess the potential combinational benefits in preclinical CRC models after [V4Q5]dDAVP addition to 5-FU. Methods: Effects on cellular viability, cell cycle progression, apoptosis and molecular mechanisms associated to [V4Q5]dDAVP treatment in combination with 5-FU were evaluated in murine CT-26 and human COLO-205 cell lines. In vivo, impact of dual therapy was explored on CRC tumor growth and metastatic spread. Results: In CRC cells, [V4Q5]dDAVP (1 μM) addition to sub-IC50 5-FU concentrations resulted in the enhancement of cytostatic effects induced by chemotherapy. Reduction of cell viability after combined treatment was associated with cell cycle arrest in the G0/G1 phase, induction of apoptosis and increased gene expression of the cyclindependent kinase inhibitor p21 (CDKN1A) and the tumor suppressor p53 (TP53) in malignant cells, as assessed by flow cytometry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL), and quantitative reverse transcription polymerase chain reaction (qRT-PCR), respectively. In vivo, intravenous administration of [V4Q5]dDAVP (0.3 μg/kg) in combination with safe low doses of 5-FU (50 or 80 mg/kg for CT-26 or COLO-205 tumor models, respectively) effectively abrogated CRC growth, reducing aggressiveness of primary lesions and increasing survival of tumor-bearing mice. In addition, concomitant administration of [V4Q5]dDAVP and 5-FU inhibited pulmonary metastasis formation by CT-26 cells in immunocompetent mice, especially reducing macrometastatic disease. Conclusions: [V4Q5]dDAVP seems to enhance the efficacy of 5-FUbased chemotherapy in CRC by modulating tumor progression, as well as metastatic dissemination, suggesting its potential role as a safe and cost-effective co-adjuvant agent for the management of advanced CRC.Fil: Sobol, Natasha Tatiana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentina. Gobierno de la Provincia de Buenos Aires. Hospital El Cruce Doctor Néstor Carlos Kirchner. Centro de Medicina Traslacional; ArgentinaFil: Solernó, Luisina María. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentina. Gobierno de la Provincia de Buenos Aires. Hospital El Cruce Doctor Néstor Carlos Kirchner. Centro de Medicina Traslacional; ArgentinaFil: Llavona, Candela. Universidad Nacional de Quilmes; Argentina. Gobierno de la Provincia de Buenos Aires. Hospital El Cruce Doctor Néstor Carlos Kirchner. Centro de Medicina Traslacional; ArgentinaFil: Alonso, Daniel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentina. Gobierno de la Provincia de Buenos Aires. Hospital El Cruce Doctor Néstor Carlos Kirchner. Centro de Medicina Traslacional; ArgentinaFil: Garona, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentina. Gobierno de la Provincia de Buenos Aires. Hospital El Cruce Doctor Néstor Carlos Kirchner. Centro de Medicina Traslacional; Argentin

Effects of the synthetic vasopressin analog desmopressin in a mouse model of colon cancer

Experimental and clinical data indicated that perioperative administration of the hemostatic peptide desmopressin (DDAVP) can inhibit progression of residual metastatic cells. The compound seems to act by inducing an agonist effect on specific V2 vasopressin membrane receptors present in both tumor cells and endothelial cells. Here we explored the antitumor effects of DDAVP in cultured colon carcinoma cells and in a syngeneic Balb/c mouse model. Both human Colo-205 and mouse CT-26 colon carcinoma cell lines expressed the V2 receptor, as revealed by immunofluorescence. DDAVP (at doses ranging from 100 ng/ml to 1 μg/ml) exerted a modest but significant antiproliferative effect on cultured CT26 and Colo-205 cells. In vivo, DDAVP (2 intravenous doses of 2 μg/kg) reduced accumulation of ascites and formation of intestinal tumor nodules in mice intraperitoneally inoculated with CT-26 cells. Perioperative administration of DDAVP significantly inhibited tumor progression in animals surgically implanted in the spleen with CT-26 cells, and caused some reduction in liver metastasis. Although DDAVP and 5- fluorouracil demonstrated additive cytostatic effects in vitro, no antitumor effects were observed in this study in mice receiving a single cycle of chemotherapy (25 mg/kg) in combination with the peptide. Our data suggest that DDAVP may be potentially used to minimize spread or survival of residual malignant cells during surgical procedures for colon and other gastrointestinal tumors.Fil: Ripoll, Giselle Vanina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garona, Juan. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hermo, Guillermo Adrian. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Effects of the synthetic vasopressin analog desmopressin in a mouse model of colon cancer

Experimental and clinical data indicated that perioperative administration of the hemostatic peptide desmopressin (DDAVP) can inhibit progression of residual metastatic cells. The compound seems to act by inducing an agonist effect on specific V2 vasopressin membrane receptors present in both tumor cells and endothelial cells. Here we explored the antitumor effects of DDAVP in cultured colon carcinoma cells and in a syngeneic Balb/c mouse model. Both human Colo-205 and mouse CT-26 colon carcinoma cell lines expressed the V2 receptor, as revealed by immunofluorescence. DDAVP (at doses ranging from 100 ng/ml to 1 μg/ml) exerted a modest but significant antiproliferative effect on cultured CT26 and Colo-205 cells. In vivo, DDAVP (2 intravenous doses of 2 μg/kg) reduced accumulation of ascites and formation of intestinal tumor nodules in mice intraperitoneally inoculated with CT-26 cells. Perioperative administration of DDAVP significantly inhibited tumor progression in animals surgically implanted in the spleen with CT-26 cells, and caused some reduction in liver metastasis. Although DDAVP and 5- fluorouracil demonstrated additive cytostatic effects in vitro, no antitumor effects were observed in this study in mice receiving a single cycle of chemotherapy (25 mg/kg) in combination with the peptide. Our data suggest that DDAVP may be potentially used to minimize spread or survival of residual malignant cells during surgical procedures for colon and other gastrointestinal tumors.Fil: Ripoll, Giselle Vanina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garona, Juan. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hermo, Guillermo Adrian. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Insight into the effect of the vasopressin analog desmopressin on lung colonization by mammary carcinoma cells in BALB/c mice

Background/Aim: Desmopressin (dDAVP) is a synthetic peptide analog of vasopressin with antidiuretic and hemostatic properties. Recent experimental evidence suggested that dDAVP can inhibit metastasis formation by agonist action on V2 vasopressin receptors present in both tumor and endothelial cells. We have examined the kinetics of dDAVP effect during metastatic colonization and its potential association with hemostasis. Materials and Methods: The experimental metastasis assay was performed by injecting F3II mammary carcinoma cells into the lateral tail vein of syngeneic female BALB/c mice. Results: Clinically relevant doses of dDAVP (0.3 to 2 μg/kg intravenously (i.v.)) produced a dose-dependent inhibition in the formation of lung nodules when administered during the first 24 hours after F3II tumor cell injection. The hemostatic agent tranexamic acid (10 mg/kg, i.v.) had not effect on metastasis formation in the same experimental conditions, while the anticoagulant enoxaparin (1 mg/kg, subcutaneously (s.c.)) did not modify the antimetastatic action of dDAVP. In vitro, dDAVP had a strong inhibitory effect on F3II cell colony formation. Conclusion: dDAVP interferes with early metastatic disease, and direct association of this effect with hemostatic mechanisms is unlikely.Fil: Garona, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Pifano, Marina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Scursoni, Alejandra Marcela. Municipalidad de Quilmes (buenos Aires). Hospital Zonal General de Agudos Doctor Isidoro Iriarte.; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Ripoll, Giselle Vanina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentin

Peptide Agonists of Vasopressin V2 Receptor Reduce Expression of Neuroendocrine Markers and Tumor Growth in Human Lung and Prostate Tumor Cells

Neuroendocrine tumors (NETs) comprise a heterogeneous group of malignancies that express neuropeptides as synaptophysin, chromogranin A (CgA), and specific neuronal enolase (NSE), among others. Vasopressin (AVP) is a neuropeptide with an endocrine, paracrine, and autocrine effect in normal and pathological tissues. AVP receptors are present in human lung, breast, pancreatic, colorectal, and gastrointestinal tumors. While AVP V1 receptors are associated with stimulation of cellular proliferation, AVP V2 receptor (V2r) is related to antiproliferative effects. Desmopressin (dDAVP) is a synthetic analog of AVP that acts as a selective agonist for the V2r, which shows antitumor properties in breast and colorectal cancer models. Recently, we developed a derivative of dDAVP named [V4Q5]dDAVP, which presents higher antitumor effects in a breast cancer model compared to the parental compound. The goal of present work was to explore the antitumor properties of the V2r agonist dDAVP and its novel analog [V4Q5]dDAVP on aggressive human lung (NCI-H82) and prostate cancer (PC-3) cell lines with neuroendocrine (NE) characteristics. We study the presence of specific NE markers (CgA and NSE) and V2r expression in NCI-H82 and PC-3. Both cell lines express high levels of NE markers NSE and CgA but then incubation with dDAVP diminished expression levels of both markers. DDAVP and [V4Q5]dDAVP significantly reduced proliferation, doubling time, and migration in both tumor cell cultures. [V4Q5]dDAVP analog showed a higher cytostatic effect than dDAVP, on cellular proliferation in the NCI-H82 cell line. Silencing of V2r using small interfering RNA significantly attenuated the inhibitory effects of [V4Q5]dDAVP on NCI-H82 cell proliferation. We, preliminarily, explored the in vivo effect of dDAVP and [V4Q5]dDAVP on NCI-H82 small cell lung cancer xenografts. Treated tumors (0.3 μg kg−1, thrice a week) grew slower in comparison to vehicle-treated animals. In this work, we demonstrated that the specific agonists of V2r, dDAVP, and [V4Q5]dDAVP displays antitumor capacity on different human models of lung and prostate cancers with NE features, showing their potential therapeutic benefits in the treatment of these aggressive tumors.Fil: Pifano, Marina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garona, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Capobianco, Carla Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: González, Nazareno. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Alonso, Daniel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Ripoll, Giselle Vanina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentin

Anticancer activity of repurposed hemostatic agent desmopressin on AVPR2‑expressing human osteosarcoma

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.Fil: Sobol, Natasha Tatiana. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Solernó, Luisina María. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Beltrán, Brady. Universidad San Martín de Porres. Facultad de Medicina Humana. Centro de Investigación de Medicina de Precisión; PerúFil: Vásquez, Liliana. Universidad San Martín de Porres. Facultad de Medicina Humana. Centro de Investigación de Medicina de Precisión; PerúFil: Ripoll, Giselle Vanina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Inmunogenética; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Garona, Juan. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Inmunogenética; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; ArgentinaFil: Alonso, Daniel Fernando. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín. Laboratorio de Inmunogenética; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentin