Targeting the Hedgehog Signaling Pathway with Small Molecules from Natural Sources.

Natural products drug discovery has allowed the identification of many biologically active compounds from plants, microbial species, and marine organisms. A significant number of these compounds are currently used as drugs in therapeutic protocols, while other naturally occurring chemical entities gave suggestions for designing nonnatural-product derived drugs or have been modified in their structure to have semi-synthetic analogues. In the last decade, experimental evidence that correlated the aberrant activation of the Hedgehog (Hh) signaling pathway with many types of cancer, prompted the researchers to check natural compounds for their ability to modulate this signaling cascade. As a result, many compounds from natural sources showed inhibitory activity toward one or more of the Hh signaling pathway components, such as Smoothened (Smo) and the downstream effectors Gli. On the other hand, only a few natural compounds were able to stimulate the same pathway. This review reports a survey of the compounds extracted from natural sources (especially plants) that showed activity in inhibiting the Hh signaling machinery by interfering with its components.

Recent findings confirm LIM domain kinases as emerging target candidates for cancer therapy.

The two members of the LIM domain kinase family (LIMK1 and LIMK2) represent crucial keys in the signaling pathways that modulate the structure and activity of actin cytoskeleton. They maintain the optimal balance between phosphorylated and unphosphorylated cofilin that in turn acts by severing filamentous actin into globular actin and ensures actin turnover and cytoskeleton regulation. Many macromolecular partners able to regulate LIMK activity (positive and negative regulators) do exist. Proteins that enhance or reduce the nucleocytoplasmic shuttling of LIMK by direct or indirect interaction are also known. Among many LIMK activators, members of the Rho family of small GTPases (i.e., Rho, Rac, and Cdc42) and their downstream effectors (i.e., ROCK, PAK, and MK2) are involved in the progression of various human cancers toward invasive and metastatic stages. As LIMK are centrally positioned in the pathways leading to cytoskeleton dynamics and regulation, they could be considered as valuable targets for actin regulation. Fine modulation of LIMK activity could be a major challenge to inhibit tumor cell invasion mediated by one or a combination of the upstream signaling factors. As LIMK play a critical role in tumor cell invasion, they may be candidate targets for developing novel therapeutic agents toward tumor invasion and metastasis.

Targeting the human DEAD-box polypeptide 3 (DDX3) RNA helicase as a novel strategy to inhibit viral replication.

Compounds currently used for the treatment of HIV-1 Infections are targeted to viral proteins. However, the high intrinsic mutation and replication rates of HIV-1 often lead to the emergence of drug resistant strains and consequent therapeutic failure. On this basis, cellular cofactors represent attractive new targets for HIV-1 chemotherapy, since targeting a cellular factor that is required for viral replication should help to overcome the problem of viral resistance. We and others have recently reported the identification of compounds suppressing HIV-1 replication by targeting the cellular DEAD-box helicase DDX3. These results provide a proof-of-principle for the feasibility of blocking HIV-1 infection by rendering the host cell environment less favorable for the virus. The rationale for such an approach and its implications in potentially overcoming the problem of drug resistance related to drugs targeting viral proteins will be discussed in the context of the known cellular functions of the DEAD-box helicase DDX3.

Enlarging the NSAIDs family: ether, ester and acid derivatives of the 1,5-diarylpyrrole scaffold as novel anti-inflammatory and analgesic agents.

The development of the coxib family has represented a stimulating approach in the treatment of inflammatory disorders, such as arthritis, and for the management of acute pains, in relation to the well-known traditional Non-Steroidal Anti-inflammatory Drugs (t-NSAIDs). Prompted by the pursuit for new cyclooxygenase-2 (COX-2) inhibitors, endowed with fine tuned selectivity and high potency, in the past years we have identified novel classes of ether, ester and acid molecules characterized by the 1,5-diarylpyrrole scaffold as potentially powerful anti-inflammatory molecules (12-66). All compounds proved to exert an in vitro inhibition profile as good as that shown by reference compounds. Compounds bearing a p-methylsulfonylphenyl substituent at C5 displayed the best issues. In particular, ester derivatives proved to perform the best in vitro profile in terms of selectivity and activity toward COX-2. The cell-based assay data showed that an increase of hindrance at the C3 side chain of compounds could translate to activity enhancement. The human whole blood (HWB) test let to highlight that submitted compounds displayed 5-10 fold higher selectivity for COX-2 vs COX-1 which should translate clinically to an acceptable gastrointestinal safety and mitigate the cardiovascular effects highlighted by highly selective COX-2 inhibitors. Finally, to assess in vivo anti-inflammatory and analgesic activity three different tests (rat paw pressure, rat paw oedema and abdominal constriction) were performed. Results showed good in vivo anti-inflammatory and analgesic activities. The issues gained with these classes of compounds represent, nowadays, a potent stimulus for a further enlargement of the NSAIDs family. In this review we describe the results obtained by our research group on this topic.

SRC inhibitors and angiogenesis.

Angiogenesis is a tightly regulated process that leads to the formation of new blood vessels in limited physiological conditions, and can also occur under pathological situations as retinopathies, arthritis, endometriosis and cancer. Enhanced angiogenesis is present in tumors that need new blood capillaries to grow, remove metabolic waste and transport the cells to locations distal to the primary tumor, facilitating metastasis formation. For these reasons, blockade of angiogenesis is an attractive approach for the treatment of both solid and haematological malignancies. Antiangiogenic therapy should be less toxic in comparison with conventional treatments such as chemotherapy, being angiogenesis a process relatively restricted to the growing tumor. The Src family of tyrosine kinases has been implicated in the intracellular signaling cascade that acts downstream of cell surface receptors to elicit different cellular functions, including growth, proliferation, adhesion and motility. Src kinases are frequently activated in human malignancies, causing tumor progression, metastasis formation and deregulating expression of proangiogenic molecules. This review reports several studies performed by different authors demonstrating the involvement of Src tyrosine kinases in angiogenesis by regulating different signalling pathways. Moreover, we report selective Src inhibitors for which a direct involvement with angiogenesis has been demonstrated, even if every Src inhibitor could potentially possesses also antiangiogenic properties. Biological data, structures and mechanisms of action of selected molecules, in terms of Src protein-inhibitor interactions, are also reported.

Last findings on dual inhibitors of abl and SRC tyrosine-kinases.

Chronic myelogenous leukemia (CML) is a myeloproliferative disease characterized by the presence of the Philadelphia chromosome that expresses the constitutively activated tyrosine kinase Bcr-Abl; this enzyme causes hyperproliferation of the stem cells and the consequent pathology of the disease. Targeted inhibitors of Bcr-Abl have antiproliferative effects on the leukemic cells and induce apoptosis, favouring a regression of the CML chronic phase, but in the successive blast crisis phase cancer cells frequently develop resistance to Bcr-Abl inhibitors. Src is a family of non-receptor tyrosine kinases, fundamental for cell development, growth, replication, adhesion, motility and is overexpressed in a wide number of human cancers. Recently it was demonstrated that Src is increased in hematopoietic cells expressing Bcr-Abl and is involved in the oncogenic pathway that causes CML. For this reason and also for the development of resistance to classical Bcr-Abl inhibitors, various dual Src/Abl inhibitors have been recently synthesized and tested. This mini review will be focused on the latest finding on this matter.

New derivatives of BM212: A class of antimycobacterial compounds based on the pyrrole ring as a scaffold.

During our investigation in the area of antimycobacterial agents, we have identified the 1,5-(4-chlorophenyl)-2-methyl-3-(4-methylpiperazin-1-yl)methyl-1H-pyrrole (BM212) as the lead compound for a new class of antimycobacterial pyrrole derivatives with potent in vitro activity against mycobacteria and with low cytotoxicity. We have also identified the salient structural features of BM212, while structure-activity relationships (SAR) and molecular modeling studies on pyrrole compounds allowed us to design and synthesize additional analogues. Among them, seven compounds revealed a very high activity (better than that of BM212 toward mycobacteria) and a very interesting protection index, comparable to that of reference compounds, such as isoniazid, streptomycin and rifampin.

New pyrazolo[3,4-d]pyrimidines endowed with A431 antiproliferative activity and inhibitory properties of Src phosphorylation.

New 4-aminopyrazolo[3,4-d]pyrimidines bearing various substituents at the position 1 and 6, were synthesized. The new compounds showed antiproliferative activity toward A431 cells, were found to be inhibitors of Src phosphorylation, and induced apoptotic cell death. In particular, 2h was a better inhibitor of Src phosphorylation than the reference compound PP2.

Arylpiperazines with affinity toward alpha(1)-adrenergic receptors.

In the last years, alpha(1) adrenoceptors (alpha(1)-AR) have been the subject of intense research, in part because receptor-binding studies and molecular biology have opened up new aspects of understanding but also because of the potential to find new drugs possibly acting toward pathophysiological processes where alpha(1)-AR are involved, such as benign prostatic hyperplasia (BPH) or hypertension. At present, arylpiperazines represent one of the most studied classes of molecules with affinity at alpha(1)-AR. In fact, a large amount of work has been done and reported, describing synthetic procedures, biological evaluation at both alpha(1)-AR and the corresponding subtypes, and structure-activity relationships (SARs). In this paper, a review based on a literature survey aimed at focusing on the structural properties that a compound should possess to show affinity toward alpha(1)-AR is presented. Moreover, the identification and optimization of the structural features of a hit compound derived from a pharmacophore-based database search, leading to a new class of arylpiperazinylalkyl pyridazinone derivatives with alpha(1)-AR affinity is reported.

Synthesis, biological evaluation, and pharmacophore generation of uracil, 4(3H)-pyrimidinone, and uridine derivatives as potent and selective inhibitors of parainfluenza 1 (Sendai) virus.

Several new 6-oxiranyl-, 6-oxiranylmethyluracils, and pyrimidinone derivatives, synthesized by lithiation-alkylation sequence of 1,3,6-trimethyluracil, 1,3-dimethyl-6-chloromethyluracil, and 2-alkoxy-6-methyl-4(3H)-pyrimidinones, showed a potent and selective antiviral activity against Sendai virus (SV) replication. To gain insight into the structural features required for SV inhibition activity, the new compounds were submitted to a pharmacophore generation procedure using the program Catalyst. The resulting pharmacophore model showed high correlation and predictive power. It also rationalized the relationships between structural properties and biological data of these inhibitors of SV replication.

Synthesis, biological evaluation, and pharmacophore generation of new pyridazinone derivatives with affinity toward alpha(1)- and alpha(2)-adrenoceptors.

A series of new pyridazin-3(2H)-one derivatives (3 and 4) were evaluated for their in vitro affinity toward both alpha(1)- and alpha(2)-adrenoceptors by radioligand receptor binding assays. All target compounds showed good affinities for the alpha(1)-adrenoceptor, with K(i) values in the low nanomolar range. The polymethylene chain constituting the spacer between the furoylpiperazinyl pyridazinone and the arylpiperazine moiety was shown to influence the affinity and selectivity of these compounds. Particularly, a gradual increase in affinity was observed by lengthening the polymethylene chain up to a maximum of seven carbon atoms. In addition, compound 3k, characterized by a very interesting alpha(1)-AR affinity (1.9 nM), was also shown to be a highly selective alpha(1)-AR antagonist, the affinity ratio for alpha(2)- and alpha(1)-adrenoceptors being 274. To gain insight into the structural features required for alpha(1) antagonist activity, the pyridazinone derivatives were submitted to a pharmacophore generation procedure using the program Catalyst. The resulting pharmacophore model showed high correlation and predictive power. It also rationalized the relationships between structural properties and biological data of, and external to, the pyridazinone class.

Access to medical care for individuals with workers' compensation claims.

Experience at a publically funded occupational health clinical center in New York State suggests that patients with work-related illnesses often have great difficulty accessing diagnostic and treatment services. A study was designed to more quantitatively investigate the extent and nature of barriers to medical services for patients with Workers' Compensation claims. Medical practices from 13 selected medical specialties were identified from telephone directories. The directories covered six areas encompassing almost all of a 15-county region. All practices from each selected specialty were contacted by phone and asked a set of standardized questions regarding patient acceptance policies. A number of barriers were identified by the survey including practices closed to new patients and practices closed specifically to patients with Workers' Compensation claims. Barriers also were found to be widespread among practices that did accept Workers' Compensation claims, primarily related to requiring a guarantee of payment prior to seeing the patient. The results were compared by medical specialty and geographic area. While the study showed some of the difficulties patients with occupational illnesses face attempting to access medical services, it most likely underestimated the extent of the problem. Attitudes and practices that impede access, but were not measurable, create additional barriers. Our study strongly suggests that policies that improve access to medical care for individuals with Workers' Compensation claims are necessary to better serve the needs of workers with occupational illnesses.

Fibroblast growth factors and their inhibitors.

Fibroblast growth factors (FGFs) are members of a family of polypeptides synthesized by a variety of cell types during the processes of embryonic development and in adult tissues. FGFs have been detected in normal and malignant cells and show a biological profile that includes mitogenic and angiogenic activity with a consequent crucial role in cell differentiation and development. To activate signal transduction pathways, FGFs use a dual receptor system based on tyrosine kinases and heparan sulfate (HS) proteoglycans. Based on these considerations, a variety of inhibitors able to block the interactions between FGFs and their receptors have been designed and investigated for their biological properties related to antiangiogenesis and antitumor activity. In this paper, in addition to an extensive description of the FGF family members, we report several compounds acting as FGF inhibitors by direct interaction with the growth factors. Suramin and other diverse polyanionic polysulfated and polysulfonated compounds are described, with a particular focus on suradistas. For this class of molecules, by means of molecular modeling procedures, a binding model to FGF-2 has been proposed and the structure-activity relationships of suradistas have been analyzed on the basis of the computational model described.

Design and realization of a tailor-made enzyme to modify the molecular recognition of 2-arylpropionic esters by Candida rugosa lipase.

Within a research project aimed at probing the substrate specificity and the enantioselectivity of Candida rugosa lipase (CRL), computer modeling studies of the interactions between CRL and methyl (+/-)-2-(3-benzoylphenyl)propionate (Ketoprofen methyl ester) have been carried out in order to identify which amino acids are essential to the enzyme/substrate interaction. Different binding models of the substrate enantiomers to the active site of CRL were investigated by applying a computational protocol based on molecular docking, conformational analysis, and energy minimization procedures. The structural models of the computer generated complexes between CRL and the substrates enabled us to propose that Phe344 and Phe345, in addition to the residues constituting the catalytic triad and the oxyanion hole, are the amino acids mainly involved in the enzyme-ligand interactions. To test the importance of these residues for the enzymatic activity, site-directed mutagenesis of the selected amino acids has been performed, and the mutated enzymes have been evaluated for their conversion and selectivity capabilities toward different substrates. The experimental results obtained in these biotransformation reactions indicate that Phe344 and especially Phe345 influence CRL activity, supporting the findings of our theoretical simulations.

Research on anti-HIV-1 agents. Investigation on the CD4-Suradista binding mode through docking experiments.

Sulfonated distamycin (Suradista) derivatives exhibit anti-HIV-1 activity by inhibiting the binding of the viral envelope glycoprotein gp120 to its receptor (CD4). With the aim to propose a possible binding mode between Suradistas and the CD4 macromolecule, molecular docking experiments, followed by energy minimization of the complexes thus obtained, were performed. Computational results show that ligand binding at the CD4 surface involves two or three positively charged regions of the macromolecule, in agreement with the results of X-ray crystallographic analysis of a ternary complex (CD4/gp120/neutralizing antibody) recently reported in the literature. Our findings account well for the structure-activity relationship found for Suradista compounds.

Building a pharmacophore model for a novel class of antitubercular compounds.

Starting from a set of 32 antitubercular compounds, for the first time a three-dimensional pharmacophore model has been derived through a computational approach based on CATALYST software. The model proved to be able to identify compounds belonging to classes of molecules already reported as antitubercular agents.

[Assessment of potential exposure risk for radiotherapy staff working with lineal accelerators]. / Valutazione del rischio da esposizioni potenziali per il personale operante con acceleratori lineari per radioterapia.

INTRODUCTION: Radiation exposure to the radiotherapy staff operating with linear accelerators comes from both normal exposure, which can be easily quantified by direct measurement, and potential exposure, whose evaluation is made difficult by its stochastic character. International guidelines recommend that risk be of the same order of magnitude for both types of exposure. We evaluated the health risk associated with potential exposure following the fault-tree approach suggested by the International Commission on Radiological Protection (IRCP) in its Publication 76. MATERIAL AND METHODS: Considering a typical radiotherapy installation we identified four possible staff irradiation scenarios, namely: 1) entry into the treatment room after a high-energy photon beam treatment, when induced radioactivity from photonuclear reactions has not decayed; 2) unintentional entry into the treatment room when the radiation beam is on; 3) beam failing to turn off at the end of treatment, and subsequent entry into the treatment room; 4) treatment room door inadvertently left ajar, and subsequent entry when the radiation beam is on. Each scenario depends on a particular set of parameters which are related to failure probabilities and workload. Average absorbed dose, exposure probability and related risk have been evaluated for each scenario. RESULTS: Under standard parameter set-up, the overall risk did not exceed the IRCP threshold (i.e., .0002) by more than four orders of magnitude. Two main sources of potential exposure have been identified, that is early entry into the treatment room before safe decay of activation products and unintentional entry during treatment. By varying the parameters within reasonable ranges, risk has been shown to correlate with personnel training, workload, installation characteristics and operational procedures. To optimize protection, quantitative limitations have been set for human error probability, daily workload, number and quality of safety devices and waiting time before entry after a treatment with high-energy radiations. CONCLUSIONS: Although the potential exposure risk for a typical radiotherapy department with standard safety devices is well below international recommended values, our results indicate that risk can be further decreased by improving personnel training, in particular relative to minimum time to entry after a high-energy treatment, to respecting warning signs and being skilled in emergency procedures. In addition, failing to install some safety devices or removing them after a failure may result in rapidly exceeding IRCP thresholds.

Recognizing occupational disease--taking an effective occupational history.

Occupational exposures contribute to the morbidity and mortality of many diseases. However, occupational diseases continue to be underrecognized even though they are responsible for an estimated 860,000 illnesses and 60,300 deaths each year. Family physicians can play an important role in improving the recognition of occupational disease, preventing progressive illness and disability in their own patients, and contributing to the protection of other workers similarly exposed. This role can be maximized if physicians raise their level of suspicion for workplace disease, develop skills in taking occupational histories and establish routine access to occupational health resources.

Synthesis and binding mode of heterocyclic analogues of suramin inhibiting the human basic fibroblast growth factor.

The design, synthesis, and biological evaluation of a series of pyrrole and pyrazole congeners 2 of suramin, directed toward the development and identification of new ligands that complex the human fibroblast growth factor (bFGF), thereby inhibiting tumor-promoted angiogenesis, is reported. Compounds 2 were evaluated for their ability to inhibit binding of bFGF to its receptor, in vivo bFGF-induced angiogenesis, and neovascularization of the chorioallantoic membrane in comparison with suramin. These assays showed that ligands 2 exhibit moderate to good activity, comparable to that of suramin, and are less toxic than suramin itself. In this study, affinity data of ligands in combination with the crystal structure of bFGF were used to explain structure-affinity relationships and to gain an insight into the possible mode of ligand-protein interaction. Due to the lack of experimental structural data on the ligand-bFGF complexes, molecular mechanics techniques were used to obtain putative bioactive conformations and to generate docked complexes with the three-dimensional structure of bFGF. These experiments led to suggest that compounds 2 give rise to 1:1 complexes with bFGF through an unprecedented, bidentate attachment of their naphthylsulfonate groups to two main domains, commonly referred to as the heparin binding site and the receptor binding site, on bFGF, thus preventing the interaction of the growth factor with its receptor.

[Automated procedures for radiation protection and quality controls in conventional diagnostic radiology]. / Automatizzazione delle procedure per i controlli di qualità e radioprotezionistici nella radiodiagnostica tradizionale.

To comply with regulations on radiation protection and quality controls is a difficult task when operating in large hospitals. This leads to the need of defining more efficient protocols and of making procedures as automated as possible. The procedure described in this paper is based on a multimeter controlled by a portable PC, and on a spreadsheet program for data processing. Multimeter data are automatically imported and processed, in order to assess the compliance of measured parameters with the reference regulations (IEC recommendations, radiation safety rules, etc.). The spreadsheet is permanently linked to a data base. It is therefore possible to perform the controls and to store the corresponding results in a shorter time (one hour per machine, approximately). By using a properly chosen quality index, monitoring the efficiency of the diagnostic equipment is also possible, which allows to prevent the onset of severe failures.