L. Dalla Via

Synthesis and biological activity of 1,4-dihydrobenzothiopyrano[4,3-c]pyrazole derivatives, novel pro-apoptotic mitochondrial targeted agents.

This study reports the synthesis of a number of 1- and 2-phenyl derivatives of the 1,4-dihydrobenzothiopyrano[4,3-c]pyrazole nucleus, which were obtained by the reaction of the versatile 7-substituted 2,3-dihydro-3-hydroxymethylene-4H-1-benzothiopyran-4-ones with hydrazine and substituted phenylhydrazines. The antiproliferative activity of the synthesized compounds was evaluated by an in vitro assay on human tumor cell lines (HL-60 and HeLa) and showed a significant capacity of the 7-methoxy-substituted benzothiopyrano[4,3-c]pyrazoles 3b-d, carrying the pendant phenyl group in the 1-position, to inhibit cell growth. Investigation of the mechanism of action indicated the induction of the mitochondrial permeability transition (MPT) as the molecular event responsible for the inhibition of cell growth. This phenomenon is related to the ability of the test compounds to cause a rapid Ca2+-dependent and cyclosporin A-sensitive collapse of the transmembrane potential (DeltaPsi) and matrix swelling. All this leads to the release of caspase activators, such as cytochrome c (cyt c) and apoptosis-inducing factor (AIF), which trigger the pro-apoptotic pathway leading to DNA fragmentation.

Correlation between cytosolic Ca2+ concentration, protein phosphorylation and platelet secretion

Addition of the calcium-ionophore ionomycin to acetylsalicylate-treated platelets suspended in a low Ca2+ concentration-containing medium (about 0.1 microM), induced a dose-dependent (range 0.25-3 microM) and transient increase in the cytosolic Ca2+ concentration ([Ca2+]c). Less than 10% of the maximal releasable amount of serotonin was secreted at [Ca2+]c lower than 1 microM, whereas secretion was almost maximal at [Ca2+]c higher than 2 microM. In all cases the secretion stopped after about 1 min even if the [Ca2+]c was kept constant by repeated small additions of CaCl2 (25-40 microM). A rapid phosphorylation of pleckstrin (47 kDa) and myosin light chain (20 kDa) was found in all cases, whereas a weak phosphorylation of a 27 kDa protein occurred at [Ca2+]c lower than 1.5 microM. Addition of 0.2 mM CaCl2 to platelets pretreated for 4 min with 0.5-1 microM ionomycin brought about a serotonin secretion remarkably lower than obtained by the simultaneous addition of CaCl2 and ionophore. Platelets suspended in a low calcium-containing medium and exposed to ionomycin showed a major increase in tyrosine phosphorylation of 60 and 72 kDa proteins and a slight increment in tyrosine phosphorylation of 115 and 130 kDa proteins. Subsequent addition of 0.2 mM CaCl2 induced a widespread phosphotyrosine dephosphorylation, particularly evident in the 60 kDa protein identified as p60c-src kinase. The protein kinase inhibitor genistein caused, together with a marked prevention of the protein tyrosine phosphorylation, a remarkable increase in the ionomycin-elicited secretory activity of platelets All together these results indicate that protein kinase C-dependent pleckstrin phosphorylation is a prerequisite of platelet secretion, but that the latter process is apparently regulated by a network of phosphoproteins, in particular the serine/threonine phosphorylation of 27 and 68 kDa proteins and the tyrosine phosphorylation of the p60c-src were found to be associated with a decrease in the secretory activity.

Electrophoretic polyamine transport in rat liver mitochondria.

SummaryNaturally occurring polyamines (spermidine, putrescine, cadaverine), as the well studied spermine, are transported into rat liver mitochondrial matrix provided that mitochondria are energized and the electrical membrane potential has a value of about 180 mV. This condition is achieved by the presence of inorganic phosphate, or acetate, or nigericin in the incubation medium. Valinomycin plus K+ almost completely blocks polyamine transport.The obtained results clearly show that all naturally occurring polyamines are transported by an electrophoretic mechanism in responce to a high negative inner electrical potential.The distribution ratio of polyamines across the mitochondrial membrane is far from the thermodynamic equilibrium by many orders of magnitude. This result might suggest the existence of a different pathway for polyamine efflux.

Histone demethylating agents as potential S-adenosyl-L-methionine-competitors

Histone H3 methylation on K9 and/or K27 depends on histone lysine methyltransferases (KMTs). EZH2, one of the components of the PRC2 complex, catalyzes the trimethylation of histone H3K27, which is associated with transcriptional repression and tumor development. H3K9me3 mediated gene silencing may result from other KDMs such as G9a/GLP, SUV39H1-2, SETDB1, CCLD8 and RIZ1. Their disturbance leads to defective cell mitosis. It is therefore desirable to find small molecules that are able to decrease H3K9 and K27 tagging to reinitiate gene transcription. Most KDM inhibitors are still based on SAM co-factor competition/modulation. Herein, functional screening of a diversity library proved to be a useful tool for finding new specific KDM inhibitors; the use of SAM-based pharmacophoric models facilitated the understanding of their possible mechanism of action.

Anti-inflammatory and antiproliferative evaluation of 4β-cinnamoyloxy,1β,3α-dihydroxyeudesm-7,8-ene from Verbesina persicifolia and derivatives.

The anti-inflammatory and antiproliferative activities of 4β-cinnamoyloxy,1β,3α-dihydroxyeudesm-7,8-ene (1) and of three derivatives, namely diacetate (2), hydrogenate (3) and diacetate hydrogenate (4) were evaluated. All derivatives exert an anti-inflammatory effect significantly lower than that exerted by 1. Otherwise, both the lead compound and 2-4 showed a comparable antiproliferative activity on human tumor cell lines. The investigation of the mechanism of action accountable for cytotoxicity highlighted the capacity to impair mitochondrial functions through two different pathways, depending on chemical structure. In particular, the lead compound 1 and derivative 3 are able to induce mitochondrial permeability transition, while derivatives 2 and 4 inhibit Complex II in the respiratory chain.

Endocavitary Therapy of Superficial Cancer Bladder: Evaluation of Photobiological Activity of Psoralen Derivatives on in Vitro Reconstituted Bladder Mucosa

The development of high selectivity drugs for urothelial neoplasia is one of the goals in endocavitary therapy of superficial cancer bladder improvement. Photochemotherapy could cover an important role, because it enables to selectively treat the neoplastic lesions thanks to compounds sensitised by light sources specifically addressed. Aims of this study was to evaluate the in vitro biological activity on normal and neoplastic urothelium of a psoralen derivative, 4-Methyl-11-dimethilaminopropoxy-benzopsoralen (G50-E), against 8-methoxypsoralen (8-MOP) reference drug. Both of them are photosensitied by UVA radiations (photochemotherapy PUVA). An experimental model, which reproduces, even if in a simplified manner, the human bladder mucosa and submucosa organization, was in this study adopted. Firstly, we evaluated the antiproliferative activity of these psoralen derivatives on neoplastic and normal origin human urothelial cell lines. For this we determined the relative IC50 by means of cytotoxic test on cellular monolayer with Trypan Blue. In a second phase of this study, we took advantage from reconstitution technique of bladder mucosa proposed by Fujiyama and previously optimized by our group to evaluate on a three-dimensional model the IC50 effects due to both considered compound. Pharmacologically treated neo-bladder and the control ones were evaluated by means of scanning electron microscopy (SEM) observations. The meaningful result appeared in cellular monolayer experimentation was the selectivity exhibited by both tested compounds (particularly G50-E) against the neoplastic origin urothelial cells. Moreover, scanning electron microscopy investigation, carried on neo-bladder, confirmed the G50-E cytotoxic effect. Therefore, these results suggested the benefit of PUVA therapy for superficial bladder cancer. But, we have to remind that the microscopic observations are just a initial approach and further researches are necessary to quantify the functional and sub-microscopic damage on three-dimensional models.