Involvement of BMPR2 in the protective effect of fluoxetine against monocrotaline-induced endothelial apoptosis in rats

Angiotensin-(1-9) ameliorates pulmonary arterial hypertension via angiotensin type II receptor

Angiotensin-(1-9) [Ang-(1-9)], generated from Ang I by Ang II converting enzyme 2, has been reported to have protective effects on cardiac and vascular remodeling. However, there is no report about the effect of Ang-(1-9) on pulmonary hypertension. The aim of the present study is to investigate whether Ang-(1-9) improves pulmonary vascular remodeling in monocrotaline (MCT)-induced pulmonary hypertensive rats. Sprague-Dawley rats received Ang-(1-9) (576 µg/kg/day) or saline via osmotic mini-pumps for 3 weeks. Three days after implantation of osmotic mini-pumps, 50 mg/kg MCT or vehicle were subcutaneously injected. MCT caused increases in right ventricular weight and systolic pressure, which were reduced by co-administration of Ang-(1-9). Ang-(1-9) also attenuated endothelial damage and medial hypertrophy of pulmonary arterioles as well as pulmonary fibrosis induced by MCT. The protective effects of Ang-(1-9) against pulmonary hypertension were inhibited by Ang type 2 receptor (AT₂R) blocker, but not by Mas receptor blocker. Additionally, the levels of LDH and inflammatory cytokines, such as TNF-α, MCP-1, IL-1β, and IL-6, in plasma were lower in Ang-(1-9) co-treated MCT group than in vehicle-treated MCT group. Changes in expressions of apoptosis-related proteins such as Bax, Bcl-2, Caspase-3 and -9 in the lung tissue of MCT rats were attenuated by the treatment with Ang-(1-9). These results indicate that Ang-(1-9) improves MCT-induced pulmonary hypertension by decreasing apoptosis and inflammatory reaction via AT₂R.

Novel cancer chemotherapy hits by molecular topology: dual Akt and Beta-catenin inhibitors

Background and Purpose

Colorectal and prostate cancers are two of the most common types and cause of a high rate of deaths worldwide. Therefore, any strategy to stop or at least slacken the development and progression of malignant cells is an important therapeutic choice. The aim of the present work is the identification of novel cancer chemotherapy agents. Nowadays, many different drug discovery approaches are available, but this paper focuses on Molecular Topology, which has already demonstrated its extraordinary efficacy in this field, particularly in the identification of new hit and lead compounds against cancer. This methodology uses the graph theoretical formalism to numerically characterize molecular structures through the so called topological indices. Once obtained a specific framework, it allows the construction of complex mathematical models that can be used to predict physical, chemical or biological properties of compounds. In addition, Molecular Topology is highly efficient in selecting and designing new hit and lead drugs. According to the aforementioned, Molecular Topology has been applied here for the construction of specific Akt/mTOR and β-catenin inhibition mathematical models in order to identify and select novel antitumor agents.

Experimental Approach

Based on the results obtained by the selected mathematical models, six novel potential inhibitors of the Akt/mTOR and β-catenin pathways were identified. These compounds were then tested in vitro to confirm their biological activity.

Conclusion and Implications

Five of the selected compounds, CAS n° 256378-54-8 (Inhibitor n°1), 663203-38-1 (Inhibitor n°2), 247079-73-8 (Inhibitor n°3), 689769-86-6 (Inhibitor n°4) and 431925-096 (Inhibitor n°6) gave positive responses and resulted to be active for Akt/mTOR and/or β-catenin inhibition. This study confirms once again the Molecular Topology’s reliability and efficacy to find out novel drugs in the field of cancer.

Fluoxetine induced suicidal erythrocyte death

The antidepressant fluoxetine inhibits ceramide producing acid sphingomyelinase. Ceramide is in turn known to trigger eryptosis the suicidal death of erythrocytes characterized by cell shrinkage and exposure of phosphatidylserine at the erythrocyte surface. Ceramide is effective through sensitizing the erythrocytes to the pro-eryptotic effect of increased cytosolic Ca2+ activity ([Ca2+]i). In nucleated cells, fluoxetine could either inhibit or stimulate suicidal death or apoptosis. The present study tested whether fluoxetine influences eryptosis. To this end cell volume was estimated from forward scatter, phosphatidylserine exposure from annexin V binding, hemolysis from hemoglobin release and [Ca2+]i from Fluo-3 fluorescence intensity. As a result, a 48 h exposure of erythrocytes to fluoxetine (≥25 µM) significantly decreased forward scatter, increased annexin V binding and enhanced [Ca2+]i. The effect on annexin V binding was significantly blunted, but not abolished, in the absence of extracellular Ca2+. In conclusion, fluoxetine stimulates eryptosis, an effect at least in part due to increase of cytosolic Ca2+ activity.

Involvement of serotonin mechanism in methamphetamine-induced chronic pulmonary toxicity in rats

The widest distribution and the highest uptake of methamphetamine (MA) in the human body occurred in the lungs, so that more and more attention should be paid to MA-induced pulmonary toxicity. MA induces the release of serotonin, which is an important mediator in pulmonary disease. The purpose of this study is to investigate the chronic response of the lung to MA and its potential mechanism in rats. Models of the chronic toxicity of MA were established with MA of 5 mg/kg and 10 mg/kg (intraperitoneally, twice per day) for 5 weeks. It was found that the high dose of MA induced rat pulmonary toxicity: crowded lung parenchyma, thickened septum, reduced number of alveolar sacs, inflammatory cell infiltration, and pulmonary arteriolar remodeling. In addition, MA resulted in a significant increase in the lung serotonin concentration and the marked upregulation of tryptophan hydroxylase 1, vesicular monoamine transporter 2, serotonin transporter, and downregulation of monoamine oxidase-A. These findings suggest that MA induced chronic pulmonary toxicity, which is concerned with the elevated serotonin concentration in rat lungs by increased synthesis, reduced metabolism, augmented accumulation, and promoted release of serotonin.

VDAC1: from structure to cancer therapy

Here, we review current evidence pointing to the function of VDAC1 in cell life and death, and highlight these functions in relation to cancer. Found at the outer mitochondrial membrane, VDAC1 assumes a crucial position in the cell, controlling the metabolic cross-talk between mitochondria and the rest of the cell. Moreover, its location at the boundary between the mitochondria and the cytosol enables VDAC1 to interact with proteins that mediate and regulate the integration of mitochondrial functions with other cellular activities. As a metabolite transporter, VDAC1 contributes to the metabolic phenotype of cancer cells. This is reflected by VDAC1 over-expression in many cancer types, and by inhibition of tumor development upon silencing VDAC1 expression. Along with regulating cellular energy production and metabolism, VDAC1 is also a key protein in mitochondria-mediated apoptosis, participating in the release of apoptotic proteins and interacting with anti-apoptotic proteins. The involvement of VDAC1 in the release of apoptotic proteins located in the inter-membranal space is discussed, as is VDAC1 oligomerization as an important step in apoptosis induction. VDAC also serves as an anchor point for mitochondria-interacting proteins, some of which are also highly expressed in many cancers, such as hexokinase (HK), Bcl2, and Bcl-xL. By binding to VDAC, HK provides both metabolic benefit and apoptosis-suppressive capacity that offers the cell a proliferative advantage and increases its resistance to chemotherapy. VDAC1-based peptides that bind specifically to HK, Bcl2, or Bcl-xL abolished the cell’s abilities to bypass the apoptotic pathway. Moreover, these peptides promote cell death in a panel of genetically characterized cell lines derived from different human cancers. These and other functions point to VDAC1 as a rational target for the development of a new generation of therapeutics.

Fluoxetine inhibits monocrotaline-induced pulmonary arterial remodeling involved in inhibition of RhoA–Rho kinase and Akt signalling pathways in rats

Activation of the small GTPase Ras homolog gene family member A (RhoA) and Rho-associated kinase (ROCK) are important in the pathogenesis of pulmonary arterial hypertension (PAH). Selective serotonin reuptake inhibitors inhibit activation of RhoA and ROCK in vitro, and ameliorate PAH and pulmonary arterial remodeling in vivo. However, little is known about whether the RhoA–ROCK signalling pathway is involved in the treatment of PAH with fluoxetine in vivo. The aim of the present study was to investigate the involvement of the RhoA–ROCK signalling pathway in the protective effect of the selective serotonin reuptake inhibitor fluoxetine against monocrotaline (MCT)-induced pulmonary arterial remodeling. MCT was applied to establish PAH in male Wistar rats. Fluoxetine was administered by gastric gavage once a day for 21 d. The results showed that MCT induced pulmonary arterial remodeling, raised the serotonylation and membrane translocation of RhoA in the lungs, and increased serotonin transporter (5-HTT), RhoA, and ROCK2 expression, and extracellular signal-regulated kinase (ERK) and Akt phosphorylation in the pulmonary arteries and the lungs. Fluoxetine markedly inhibited these MCT-induced changes. The findings suggest that fluoxetine inhibits MCT-induced pulmonary arterial remodeling in rats by inhibition of the RhoA–ROCK and Akt signalling pathways.