Recent findings revealed in cancer cells novel stress response pathways, which in response to many chemotherapeutic drugs causing nucleolar stress, will function independently from tumor protein p53 (p53) and still lead to cell cycle arrest and/or apoptosis. Since it is known that most cancers lack functional p53, it is of great interest to explore these emerging molecular mechanisms. Here, we demonstrate that nucleolar stress induced by 5-fluorouracil (5-FU) in colon cancer cells devoid of p53 leads to the activation of ribosomal protein L3 (rpL3) as proapoptotic factor. rpL3, as ribosome-free form, is a negative regulator of cystathionine-β-synthase (CBS) expression at transcriptional level through a molecular mechanism involving Sp1. The rpL3-CBS association affects CBS stability and, in addition, can trigger CBS translocation into mitochondria. Consequently apoptosis will be induced through the mitochondrial apoptotic cell death pathway characterized by an increased ratio of Bax to Bcl-2, cytochrome c release and subsequent caspase activation. It is noteworthy that silencing of CBS is associated to a strong increase of 5-FU-mediated inhibition of cell migration and proliferation. These data reveal a novel mechanism to accomplish p53-independent apoptosis and suggest a potential therapeutic approach aimed at upregulating rpL3 for treating cancers lacking p53.

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Inhaled antivirulence drugs are currently considered a promising therapeutic option to treat Pseudomonas aeruginosa lung infections in cystic fibrosis (CF). We have recently shown that the anthelmintic drug niclosamide (NCL) has strong quorum sensing (QS) inhibiting activity against P. aeruginosa and could be repurposed as an antivirulence drug. In this work, we developed dry powders containing NCL nanoparticles that can be reconstituted in saline solution to produce inhalable nanosuspensions. NCL nanoparticles were produced by high-pressure homogenization (HPH) using polysorbate 20 or polysorbate 80 as stabilizers. After 20 cycles of HPH, all formulations showed similar properties in the form of needle-shape nanocrystals with a hydrodynamic diameter of approximately 450 nm and a zeta potential of -20 mV. Nanosuspensions stabilized with polysorbate 80 at 10% w/w to NCL (T80_10) showed an optimal solubility profile in simulated interstitial lung fluid. T80_10 was successfully dried into mannitol-based dry powder by spray drying. Dry powder (T80_10 DP) was reconstituted in saline solution and showed optimal in vitro aerosol performance. Both T80_10 and T80_10 DP were able to inhibit P. aeruginosa QS at NCL concentrations of 2.5-10 μM. NCL, and these formulations did not significantly affect the viability of CF bronchial epithelial cells in vitro at microbiologically active concentrations (i.e., ≤10 μM). In vivo acute toxicity studies in rats confirmed no observable toxicity of the NCL T80_10 DP formulation upon intratracheal administration at a concentration 100-fold higher than the anti-QS activity concentration. These preliminary results suggest that NCL repurposed in the form of inhalable nanosuspensions has great potential for the local treatment of P. aeruginosa lung infections as in the case of CF patients.

Hydrogen sulfide (H 2 S) is a gaseous mediator synthesized in mammalian tissues by three main enzymes-cystathionine-b-synthase (CBS), cystathionine-g-lyase (CSE), and 3-mercaptopyruvatesulfurtransferase-and its levels increase under inflammatory conditions or sepsis. Since H 2 S and H 2 S-releasing molecules afford inhibitory properties in leukocyte trafficking, we tested whether endogenous annexin A1 (AnxA1), a glucocorticoid-regulated inhibitor of inflammation acting through formylated-peptide receptor 2 (ALX), could display intermediary functions in the anti-inflammatory profile of H 2 S. We first investigated whether endogenous AnxA1 could modulate H 2 S biosynthesis. To this end, a marked increase in CBS and/or CSE gene products was quantified by quantitative real-time polymerase chain reaction in aortas, kidneys, and spleens collected from AnxA1 2/2 mice, as compared with wild-type animals. When lipopolysaccharide-stimulated bone marrow-derived macrophages were studied, H 2 S-donor sodium hydrosulfide (NaHS) counteracted the increased expression of inducible nitric oxide synthase and cyclooxygenase 2 mRNA evoked by the endotoxin, yet it was inactive in macrophages harvested from AnxA1 2/2 mice. Next we studied the effect of in vivo administration of NaHS in a model of interleukin-1b (IL-1b)-induced mesenteric inflammation. AnxA1 1/1 mice treated with NaHS (100 mmol/kg) displayed inhibition of IL-1b-induced leukocyte adhesion/ emigration in the inflamed microcirculation, not observed in AnxA1 2/2 animals. These results were translated by testing human neutrophils, where NaHS (10-100 mM) prompted an intense mobilization (.50%) of AnxA1 from cytosol to cell surface, an event associated with inhibition of cell/endothelium interaction under flow. Taken together, these data strongly indicate the existence of a positive interlink between AnxA1 and H 2 S pathway, with nonredundant functions in the control of experimental inflammation.

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Homocysteine is metabolized to methionine by the action of 5,10methylenetetrahydrofolate reductase (MTHFR). Alternatively, by thetransulfuration pathway, homocysteine is transformed to hydrogen sulphide (H2S),through multiple steps involving cystathionine beta-synthase and cystathioninegamma-lyase. Here we have evaluated the involvement of H2S in the thromboticevents associated with hyperhomocysteinemia. To this purpose we have usedplatelets harvested from healthy volunteers or patients newly diagnosed withhyperhomocysteinemia with a C677T polymorphism of the MTHFR gene (MTHFR++). NaHS(0.1-100 microM) or l-cysteine (0.1-100 microM) significantly increased plateletaggregation harvested from healthy volunteers induced by thrombin receptoractivator peptide-6 amide (2 microM) in a concentration-dependent manner. Thisincrease was significantly potentiated in platelets harvested from MTHFR++carriers, and it was reversed by the inhibition of either cystathioninebeta-synthase or cystathionine gamma-lyase. Similarly, in MTHFR++ carriers, thecontent of H2S was significantly higher in either platelets or plasma comparedwith healthy volunteers. Interestingly, thromboxane A2 production was markedlyincreased in response to both NaHS or l-cysteine in platelets of healthyvolunteers. The inhibition of phospholipase A2, cyclooxygenase, or blockade ofthe thromboxane receptor markedly reduced the effects of H2S. Finally,phosphorylated-phospholipase A2 expression was significantly higher in MTHFR++carriers compared with healthy volunteers. In conclusion, the H2S pathway isinvolved in the prothrombotic events occurring in hyperhomocysteinemic patients

The urothelium modulates detrusor activity through releasing factors whose nature has not been clearly defined. Here we have investigated the involvement of H2S as possible mediator released downstream following muscarinic (M) activation, by using human bladder and urothelial T24 cell line. Carbachol stimulation enhances H2S production and in turn cGMP in human urothelium or in T24 cells. This effect is reversed by cysthationine-β-synthase (CBS) inhibition. The blockade of M1 and M3 receptors reverses the increase in H2S production in human urothelium. In T24 cells, the blockade of M1 receptor significantly reduces carbachol-induced H2S production. In the functional studies, the urothelium removal from human bladder strips leads to an increase in carbachol-induced contraction that is mimicked by CBS inhibition. Instead, the CSE blockade does not significantly affect carbachol-induced contraction. The increase in H2S production and in turn of cGMP is driven by CBS-cGMP/PKG-dependent phosphorylation at Ser227 following carbachol stimulation. The finding of the presence of this crosstalk between the cGMP/PKG and H2S pathway downstream to the M1/M3 receptor in the human urothelium further implies a key role for H2S in bladder physiopathology. Thus, the modulation of the H2S pathway can represent a feasible therapeutic target to develop drugs for bladder disorders.

Linagliptin, by interfering with the protein-protein interaction CAV-1/eNOS, led to an increased eNOS availability, thus enhancing NO production. This mechanism accounts for the vascular effect of linagliptin that is independent from glucose control and GLP-1/GLP-1R interaction.