Tissue expression of osteopontin (OPN) and mesothelin (MES) in malignant pleural mesothelioma (MPM). An immunohistochemical study of 70 consecutive cases

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Background: There is still no single test that can reliably identify malignant mesothelial cells. Recently soluble MES and OPN have been proposed as novel serum markers for MPM but a definitive consensus on their use in routine is still lacking. This study aims at 1. analysing the essential pathological features of a series of consecutive MPMs from a single institution and 2. assessing the tumour tissue expression of OPN and MES and speculating about the potential biological role of these molecules in MPM. Methods: All MPMs diagnosed between 1999 and 2008 were retrieved from the archives of the Pathology Unit of Alessandria Hospital. All the diagnoses had been made on the basis of conventional light microscopy features supplemented by a mucin stain (periodic acid-Schiff with and without diastase treatment) and a panel of immunostains (carcinoembryonic antigen, CD15/LeuM1, BerEP4, calretinin and cytokeratin 5). Immunostaining for OPN (polyclonal antibody) and MES (monoclonal antibody, clone 5B2) was performed using the labelled streptavidin-biotin method, and the staining intensity and extent were assessed. Results: The study group consisted of 50 males and 20 females with a mean age at diagnosis of 78.4 years (range 47–92). Histopathology was epithelial, mixed, and sarcomatous in 52, 12, and 6 patients respectively. OPN positivity (percentage of positive tumour cells >10%) was observed in 67 MPMs (96%) mostly in a granular cytoplasmic pattern and with an intensity ranging from weak (25%) to moderate (31%) and strong (44%). MES positivity (percentage of positive tumour cells >10%) was recorded in 60 MPMs (86%), of which 36% exhibited a weak, 36% a moderate and 28% a strong immunostaining in a membrane pattern. MES was positive in 100% of epithelial MPMs, in 67% of mixed and in 0% of sarcomatous. Positivity was restricted to the epithelial component in mixed MPMs. Conclusions: The high expression of OPN in MPM, irrespective of the histotype, seems to point to a role of this molecule as a marker of malignant transformation of mesothelial cells, while the restriction of positive staining for MES to the epithelial phenotype supports a role of MES as a marker of epithelial differentiation in MPM.

No significant financial relationships to disclose.

Small molecules ATP-competitive inhibitors of FLT3: a chemical overview

FLT3 is a tyrosine kinase (TK), member of the class III TK receptor family, normally expressed in hematopoietic, immune and neural systems, also playing an important role in the pathogenesis of acute leukemias, particularly acute myeloid leukemia (AML), where it is present in constitutively activated mutated forms, correlated with poor prognosis, in a notable percentage of patients. For these reasons FLT3 soon appeared as a promising target for the therapeutic intervention for this severe and aggressive malignancy; the recent determination of the crystal structure of the autoinhibited form of FLT3 gave new trend for the design and the synthesis of potent inhibitors. Small molecules tyrosine kinase inhibitors represent one of the largest drug family currently targeted by pharmaceutical companies for the treatment of cancer. Exciting examples of such molecules have reached advanced clinical trials and have been recently approved by FDA for the treatment of different solid or haematological tumors. Usually TK inhibitors share common features, namely two hydrophobic/aromatic regions bearing one or more hydrogen bonding substituents. These two regions can be connected by different spacers and almost all the molecules contain a component resembling the ATP purine structure. This review will deal with FLT3 synthetic inhibitors, reporting not only the most important molecules that are in clinical trials, but also the new compounds that have appeared in literature in the last few years. Our attention will be focused on chemical structures, mechanisms of action and structure-activity relationships.

Cytotoxic effects of a novel pyrazolopyrimidine derivative entrapped in liposomes in anaplastic thyroid cancer cells in vitro and in xenograft tumors in vivo

In this study, we evaluated the activity of two novel pyrazolopyrimidine derivatives (Si 34 and Si 35) against ARO cells, a human anaplastic thyroid cancer cell line. ARO cells exposed to different concentrations of the drugs showed a reduced growth rate and an increase of mortality. After 72 h incubation, doses of 5 and 10 microM Si 34 determined a decrease of cell counts by approximately 25% and approximately 75% compared with those of control cells respectively. Similar findings were observed using Si 35. Treatment with both Si 34 and Si 35 at 10 microM increased cell mortality also ( approximately 29% and approximately 18% respectively). At these concentrations, a decrease in cyclin D1 levels was observed. To improve the biopharmaceutical properties, a liposome formulation was prepared. When entrapped in unilamellar liposomes, Si 34 exerted its cytotoxic effects even at lower doses (maximal inhibition at 5 microM) and after shorter incubation time (48 h) either in ARO or other thyroid cancer cell lines. The effects were associated with weak apoptotic death. Inhibition of epidermal growth factor-stimulated src and ERK phosphorylation, as well as reduction of migration properties of ARO cells was also observed. Moreover, the growth of tumor xenografts induced in severe combined immunodeficiency (SCID) mice was inhibited by i.v. administration of 25-50 mg/kg of the drug liposomal formulation. In conclusion, the liposomal preparation of this novel pyrazolopyrimidine derivative appears to be a promising tool for the treatment of anaplasic thyroid cancer.

Antiangiogenic agents: an update on small molecule VEGFR inhibitors

Angiogenesis is a tightly regulated process that leads to the formation of new blood vessels sprouting from pre-existing microvasculature and occurs in limited physiological conditions or under pathological situations such as retinopathies, arthritis, endometriosis and cancer. Blockade of angiogenesis is an attractive approach for the treatment of such diseases. Particularly in malignancies, antiangiogenic therapy should be less toxic in comparison with conventional treatments such as chemotherapy, as angiogenesis is a process relatively restricted to the growing tumor. Vascular endothelial growth factor (VEGF) is one of the most important inducers of angiogenesis and exerts its cellular effects mainly by interacting with two high-affinity transmembrane tyrosine kinase receptors: VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1). It has been proven that inhibition of VEGF receptor activity reduces angiogenesis. For these reasons, the inhibition of VEGF or its receptor signalling system is an attractive target for therapeutic intervention. The most studied and developed inhibitors are monoclonal antibodies that neutralize VEGF, ribozymes, and small molecule VEGFR kinase inhibitors. Many important reviews dealing with VEGF-induced angiogenesis and its inhibition through the block of VEGF receptors have been reported, especially from a biological point of view. Here, we will review small synthetic VEGFR inhibitors that have appeared in literature in the last few years, focusing our attention on their medicinal chemistry in terms of chemical structure, mechanisms of action and structure-activity relationships. In fact, there have been an increased number of tyrosine kinase inhibitors in the most recent literature reports; their biological profile is extremely interesting and could be of great importance to medicinal chemists working in this area in improving their efficacy.

Phase II study of pemetrexed in combination with carboplatin in patients with malignant pleural mesothelioma (MPM)

BACKGROUND

The aim of this study was to evaluate the activity and toxicity of pemetrexed and carboplatin combination as first-line chemotherapy in malignant pleural mesothelioma (MPM).

PATIENTS AND METHODS

Patients with measurable advanced MPM and a zero to two Eastern Cooperative Oncology Group (ECOG) performance status (PS) were enrolled. The schedule was pemetrexed 500 mg/m(2) in combination with carboplatin area under the curve 5, every 21 days. In all, 76 patients were treated. Median age was 65 years; median ECOG PS was zero.

RESULTS

Grade 3 hematological toxicity according to World Health Organization criteria was seen in 36 (47.3%) patients; grade 4 hematological toxicity in 5 (6.5%) patients. There were 16 (21%) partial responses and 3 (4%) complete responses, for an overall response rate of 19 (25%) [95% confidence interval (CI) 15.3-34.7]. In all, 29 (39%) (95% CI 28-48) patients reported stable disease. The median survival was estimated at 14 months.

CONCLUSION

This combination of carboplatin and pemetrexed is moderately active and the toxicity is acceptable.

Growth inhibition of medullary thyroid carcinoma cells by pyrazolo-pyrimidine derivates

There is no effective treatment for recurrent or metastatic medullary thyroid carcinoma (MTC), a tumor arising from thyroid C-cells commonly presenting an inherited or acquired RET mutation. In this study we examined the sensitivity of two human MTC cell lines to novel pyrazolopyrimidine derivates, able to inhibit src-family tyrosine kinase activity. In TT cells [carrying the multiple endocrine neoplasia (MEN)2A Ret mutation Cys 634Trp] and MZ-CRC-1 cells (carrying the MEN2B RET mutation Met891Thr), one of these compounds, namely Si 34, determined a significant growth inhibitory effect (approximately 90% vs control for TT, 80% vs control for MZ-CRC-1) mainly due to enhanced cell mortality after a 6-day incubation. At concentrations that increased cell mortality, neither biochemical or morphological characteristics of apoptosis were detected in TT and MZCRC- 1 cells treated with Si 34. These results, when confirmed in other in vivo preclinical models, suggest that this novel tyrosine kinase inhibitor may be useful for the treatment of MTC.

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.

An approach to address Candida rugosa lipase regioselectivity in the acylation reactions of trytilated glucosides

Candida rugosa lipase crude preparations (CRL) catalyse the regioselective acylation of methyl 6-O-trytil beta-d-glucopyranoside in organic solvents, using vinyl acetate as acyl donor. The ratio of the two products formed, namely methyl 2-O acetyl 6-O-trytil beta-d-glucopyranoside and methyl 3-O acetyl 6-O-trytil beta-d-glucopyranoside was found to be markedly affected by the nature of the reaction medium. In hydrophobic solvents values up to 80% of the monoacetylated product in position C-3 were obtained compared to less than 30% in solvents with low hydrophobicity. Computational studies were carried out to simulate the interactions between methyl 6-O-trytil beta-d-glucopyranoside and both CRL and the solvents, in order to rationalize the experimental results.

Computational Studies of Competitive Inhibitors of Nitric Oxide Synthase (NOS) Enzymes: Towards the Development of Powerful and Isoform-Selective Inhibitors

Crystallographic structures of wild-type and mutant NOS isoforms complexed with substrate, intermediate, inhibitor, cofactor, and cofactor analogs are currently available. However, because of the high level of amino-acid conservation and the consequent similarity in dimeric quaternary structure as well as in the active site of NOS isoforms, structure-based isoform-selective inhibitor design is still a very challenging task. Nevertheless, the comprehension of the structural determinants for selectivity among the isoforms is fundamental for the design of further potent and more selective inhibitors. Computational techniques, based on the knowledge of the tridimensional structure of the isozymes, have been already applied to understand the significant isoform selectivity shown by some compounds. Collectively these structure-based approaches, in combination with SAR studies, have been able to explain the structural reasons of this selectivity.

Pemetrexed (MTA) and carboplatin (CBDCA) in the treatment of advanced pleural mesothelioma (MPM)

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Background: Aim of this study was to evaluate the activity and toxicity of MTA and CBDCA combination as first line chemotherapy in advanced MPM. Methods: Chemonaive patients (pts) with histologically proven, an ECOG performance status (PS) 0–2, and measurable advanced MPM were considered. The schedule of administration was: pemetrexed 500 mg/m2 in combination with CBDA AUC 5, once every 21 days for 8 cycles. Results: From July 2003 to March 2005 76 pts (54 male and 22 female) have been treated with this combination chemotherapy. Median age was 62.7 years (range 40–70); median PS 0 (range 0–3); epithelial histologic findings were in 57 (75%), mixed in 13 (17.1%), sarcomatous in 3 (3.9%), and unspecified in 3 (3.9%) pts. A total of 537 cycles was administered (median 7, range 1 to 13). Grade 3 hematologic toxicity according to WHO criteria was seen in 43 (56.6%) pts (neutropenia in 30, thrombocytopenia in 8, and anemia in 5); grade 4 hematologic toxicity in 5 (6.6%) pts. The most common nonhematologic events were grade 3 nausea/vomiting in 10 (13.1%), and fever in 4 (5.3%) pts. 74 pts were evaluable for clinical response. There were 16 (21.%) partial responses (PR) and 3 (3.9%) complete responses (CR), for an overall response rate of 23.9%. 29 (38.2%) pts reported stable disease (SD). The overall survival was considered from date of diagnosis to date of death from any cause or to date of last follow-up. The median survival time for the entire group was estimated at 23 months. Conclusions: The results of this phase II study indicate that, at this dose and schedule, the combination of CBDCA and MTA is moderately active and that the profile of toxicity is acceptable in pts with advanced MPM.

No significant financial relationships to disclose.

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.

Variable selection and specification of robust QSAR models from multicollinear data: arylpiperazinyl derivatives with affinity and selectivity for ?2-adrenoceptors

Two QSAR models have been identified that predict the affinity and selectivity of arylpiperazinyl derivatives for alpha1 and alpha2 adrenoceptors (ARs). The models have been specified and validated using 108 compounds whose structures and inhibition constants (Ki) are available in the literature [Barbaro et al., J. Med. Chem., 44 (2001) 2118; Betti et al., J. Med. Chem., 45 (2002) 3603; Barbaro et al., Bioorg. Med. Chem., 10 (2002) 361; Betti et al., J. Med. Chem., 46 (2003) 3555]. One hundred and forty-seven predictors have been calculated using the Cerius 2 software available from Accelrys. This set of variables exhibited redundancy and severe multicollinearity, which had to be identified and removed as appropriate in order to obtain robust regression models free of inflated errors for the beta estimates - so-called bouncing betas. Those predictors that contained information relevant to the alpha2 response were identified on the basis of their pairwise linear correlations with affinity (-log Ki) for alpha2 adrenoceptors; the remaining variables were discarded. Subsequent variable selection made use of Factor Analysis (FA) and Unsupervised Variable Selection (UzFS). The data was divided into test and training sets using cluster analysis. These two sets were characterised by similar and consistent distributions of compounds in a high dimensional, but relevant predictor space. Multiple regression was then used to determine a subset of predictors from which to determine QSAR models for affinity to alpha2-ARs. Two multivariate procedures, Continuum Regression (the Portsmouth formulation) and Canonical Correlation Analysis (CCA), have been used to specify models for affinity and selectivity, respectively. Reasonable predictions were obtained using these in silico screening tools.

RRE: a tool for the extraction of non-coding regions surrounding annotated genes from genomic datasets

RRE allows the extraction of non-coding regions surrounding a coding sequence [i.e. gene upstream region, 5'-untranslated region (5'-UTR), introns, 3'-UTR, downstream region] from annotated genomic datasets available at NCBI.

AVAILABILITY

RRE parser and web-based interface are accessible at http://www.bioinformatica.unito.it/bioinformatics/rre/rre.html

Structure-activity analysis of guanidine group in agmatine for brain agmatinase

To identify a selective inhibitor of mammalian agmatinase, screening was performed on four analogues of agmatine with modifications directly to the guanidine group, six analogues with modifications to the carbon-amine chain, and one analogue with modifications at both ends of the molecule. Control compounds were aminoguanidine and 7-nitroindazole, known inhibitors of the three isoforms (i, e, n) of nitric oxide synthase (NOS), and arcaine, a known inhibitor of the glutamate NMDA receptor. These compounds were compared for inhibition of rat agmatinase and arginine decarboxylase (ADC) activities. Results were studied by ab initio Hartee-Fock descriptors based on optimized geometries and van der Waals radii. Linear correlations were obtained using various geometric and electronic descriptors of the carbon (C), nitrogen (N), and hydrogen (H) atoms in the guanidine moiety. The best fit equation for percent activity remaining of rat agmatinase was = 0.3225 D + 72.76 D1916 + 64.97 D1920 - 192.58 H21 - 253.09 (r = 0.89), where D is the calculated dipole moment, D1916 and D1920 are the N19-N16 and N19-N20 distances, respectively, and H21 is the charge on H21. This agmatinase equation is distinct from the equations fit for ADC, the three NOS isoforms, and inhibition of NMDA receptor binding.

Structural variations across the lanthanide series of macrocyclic DOTA complexes: insights into the design of contrast agents for magnetic resonance imaging

It was early shown that the macrocyclic Ln(DOTA) complexes (DOTA = 1,4,7,10-tetra-azacyclododecane-N,N',N' ',N' "-tetraacetic acid) exists in solution as a mixture of two enantiomeric pairs of diastereoisomers differing in the ligand conformation, namely, square antiprismatic (SA) and twisted square antiprismatic (TSA) geometries, respectively. Later, extensive (1)H NMR investigations suggested that a coordination change may be superimposed on this conformational equilibrium involving two additional structures in which the metal ion possesses a coordination number of eight (CN 8). It was predicted that these two species, lacking the apical coordinated water molecule, would maintain the SA and TSA coordination geometries, and therefore, they have been labeled as SA' and TSA', respectively. In this work we report the X-ray solid-state crystal structure determination of six Ln(DOTA) complexes representative of all four coordination geometry typologies deduced from NMR solution studies. A distinctive structural feature that discriminates SA (and SA') and TSA (and TSA') structures is represented by the twist angle between the two square planes of the antiprism, the basal four nitrogen, and the apical four oxygen planes. [Ce(DOTA)(H(2)O)](-) displays a TSA structural typology with a twist angle of 25 degrees and a Ce-O(water) distance of 2.59 A. The SA-type structure has been found in the case of complexes with Pr(III), Nd(III), and Dy(III), where the twist angle is 39, 39, and 38 degrees, respectively, and the metal-water oxygen distance varies significantly (Pr-O(w) 2.529 A; Nd-O(w) 2.508 A; and Dy-O(w) 2.474 A). [Tm(DOTA)](-) displays a TSA'-type structure with a twist angle of 24 degrees. As compared with the TSA structure of the corresponding Ce(III) complex, the Tm(III) complex shows an overall marked shrinkage of all metal-nitrogen and metal-oxygen distances (ca. 0.2 A), which reflects the contraction of the metal ionic radius across the series but also the effect associated with the decrease of the CN from 9 to 8. In [Sc(DOTA)](-), the even smaller ionic radius of Sc(III) shifts the geometry of the coordination cage to the more compact SA' typology with a twist angle of 41 degrees, a value very similar to that found in the SA structures of lanthanide(III) ions with CN 9. Finally, an investigation was made into the hydration spheres of the complexes with SA and TSA geometries to account for the experimental evidence of a markedly different rate of water exchange for the two isomeric structures. This is of fundamental importance to the understanding of the corresponding Gd(III) complexes as MRI contrast agents.

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.

Dexamethazone-induced acute tumor lysis syndrome in a T-cell malignant lymphoma

We report a case of steroid-induced acute tumor lysis syndrome and review the literature. A 60-year-old woman was started on steroid therapy for dyspnea due to bilateral pleural effusion and a large mass involving the anterior mediastinum. The final diagnosis was precursor T-lymphoblastic lymphoma-leukemia. Following steroid therapy, the patient developed acute renal failure and laboratory evidence of metabolic changes induced by massive cytolysis. She received vigorous hydration, diuretic and allopurinol therapy, and haemodialysis. Her diuresis, renal function and laboratory data returned to normal within 2 weeks. A review of the medical literature on T-cell lymphoma revealed only one similar case of steroid-induced acute tumor lysis syndrome, a life-threatening metabolic emergency. This risk should be kept into account in the management of patients with lymphoproliferative disorders.