Signaling Protein Networks as Targets of New Antineoplastic Drugs

In-depth analysis of molecular regulatory networks in cancer holds the promise of improved knowledge of the pathophysiology of tumor cells so that it will become possible to design a detailed molecular tumor taxonomy. This knowledge will also offer new opportunities for the identification and validation of key molecular tumor targets to be exploited for novel therapeutic approaches. Some signaling proteins have already been identified as such, e.g. c-Myc, Cyclin D1, Bcl-XL, kinases and some nuclear receptors. This has led to the successful development of a few function-modulatory drugs (Glivec, SERM, Iressa), providing proof-of-principle of the validity of this approach. Further developments are likely to derive from “-omic” approaches, aimed at the understanding of signaling networks and of the mechanism of action of newfound lead molecules. High-throughput screening of small drug-like molecules from combinatorial chemical libraries or from microbial extracts will identify novel, “intelligent” drug candidates. An additional medicinal chemistry strategy (via 40–50 unit rosary-bead chains) has the potential to be much more effective than small molecules in interfering with protein-protein interactions. This may lead to considerably higher selectivity and effectiveness compared with historical approaches in drug discovery.

Influence of segmental chromosome abnormalities on survival in children over the age of 12 months with unresectable localised peripheral neuroblastic tumours without MYCN amplification

Background:

The prognostic impact of segmental chromosome alterations (SCAs) in children older than 1 year, diagnosed with localised unresectable neuroblastoma (NB) without MYCN amplification enrolled in the European Unresectable Neuroblastoma (EUNB) protocol is still to be clarified, while, for other group of patients, the presence of SCAs is associated with poor prognosis.

Methods:

To understand the role of SCAs we performed multilocus/pangenomic analysis of 98 tumour samples from patients enrolled in the EUNB protocol.

Results:

Age at diagnosis was categorised into two groups using 18 months as the age cutoff. Significant difference in the presence of SCAs was seen in tumours of patients between 12 and 18 months and over 18 months of age at diagnosis, respectively (P=0.04). A significant correlation (P=0.03) was observed between number of SCAs per tumour and age. Event-free (EFS) and overall survival (OS) were calculated in both age groups, according to both the presence and number of SCAs. In older patients, a poorer survival was associated with the presence of SCAs (EFS=46% vs 75%, P=0.023; OS=66.8% vs 100%, P=0.003). Moreover, OS of older patients inversely correlated with number of SCAs (P=0.002). Finally, SCAs provided additional prognostic information beyond histoprognosis, as their presence was associated with poorer OS in patients over 18 months with unfavourable International Neuroblastoma Pathology Classification (INPC) histopathology (P=0.018).

Conclusions:

The presence of SCAs is a negative prognostic marker that impairs outcome of patients over the age of 18 months with localised unresectable NB without MYCN amplification, especially when more than one SCA is present. Moreover, in older patients with unfavourable INPC tumour histoprognosis, the presence of SCAs significantly affects OS.

Risk of non-Hodgkin's lymphoma and residential exposure to air pollution in an industrial area in northern Italy: a case-control study

The aim of this study was to evaluate the risk of non-Hodgkin's lymphoma (NHL) in an adult population residing in an area in northern Italy exposed to industrial air pollution from a big power plant, a coke oven, 2 chemical factories, and some minor plants. The design was a population-based case-control study and information about residential history and the main risk factors for NHL was obtained interviewing 133 cases and 279 controls using a structured questionnaire. Three exposure categories (heavy, moderate, and slight) were defined on the basis of the location of the major facilities with respect to the subject residence. NHL risk was not associated either with location or duration of residence in the heavily polluted area. However, the unavoidable limitations of this study prevent us from drawing definitive conclusions.

Structural comparison of the interaction of tubulin with various ligands affecting microtubule dynamics

Microtubules (MTs), which are highly dynamic assemblies of the protein tubulin, play important and diverse roles in eukaryotic cells. MT dynamics are regulated during the cell cycle by interacting with a large number of endogenous cellular regulators. In addition, many anti-tumour drugs and natural ligands that interact directly with tubulin are able to either stabilise or destabilise MTs and to disrupt the normal dynamics. Herein, we compare the structures of tubulin when complexed with different ligands in order to analyse: (i) various binding-sites of the protein and different positions of ligands within the microtubule (ii) the diverse effect on the microtubule dynamics. The structures and data given are essential for understanding tubulin-ligand interactions and their influence on the regulation of the microtubule system.

Interferon-gamma enhances TNF sensitivity in A172 human glioblastoma cell line

Although human glioblastoma cell line A172 presents tumor necrosis factor (TNF) high affinity receptors, it is resistant to TNF-mediated cytotoxicity. Preincubation of cells with 10 ng/ml interferon (IFN)-gamma for 6 h causes a great increase in TNF receptor numbers (about 477%). IFN-gamma alone is not cytotoxic in A172 cells. Cells preincubated with 10 ng/ml IFN-gamma for 6 h became more sensitive to the TNF cytotoxicity (about 400%). In A172 cells the enhanced TNF receptor expression may contribute to the enhancement of TNF cytotoxicity. This observation may have importance in designing new more effective therapies for human gliomas.

A multi-scale approach to colorectal cancer: from a biochemical- interaction signaling-network level, to multi-cellular dynamics of malignant transformation. Interplay with mutations and onco-protein inhibitor drugs

This review article is part of a special Current Cancer Drug Targets issue devoted to colorectal cancer and molecularly targeted treatments. In our paper we made an attempt to connect more basic aspects with preclinical, pharmacological / therapeutic and clinical aspects. Reconstruction of a Molecular Interaction Map (MIM) comprising an important part of the G0 - G1 - S cell cycle transition, was a major component of our review. Such a MIM serves also as a convenient / organized database of a large set of important molecular events. The frequency of mutated / altered signaling-proteins indicates the importance of this signaling-network region. We have considered problems at different scale levels. Our MIM works at a biochemical-interaction level. We have also touched the multi-cellular dynamics of normal and aberrant colon crypts. Until recently, dynamic simulations at a biochemical or multi-cellular scale level were considered as a sort of esoteric approach. We tried to convince the reader, also on the basis of a rapidly growing literature, mostly published in high quality journals, that suspicion towards simulations should dissipate, as the limitations and advantages of their application are better appreciated, opening the door to their permanent adoption in everyday research. What is really required is a more interdisciplinary mentality and an interdisciplinary approach. The prize is a level of understanding going beyond mere intuition.

Patient-tailored treatments with anti-EGFR monoclonal antibodies in advanced colorectal cancer: KRAS and beyond

Personalized medicine emphasizes the practice of considering individual patient characteristics as opposed to that centered on standards derived from epidemiological studies which, by definition, do not take into account the variability of individuals within a given population. When applied to oncology, personalized medicine is an even more complex concept because it extends the variability beyond the individual patient to the individual tumor. Indeed, the great genotypic and phenotypic variability (both in primary and metastatic sites of cancer) the development of targeted therapies, and the growing availability of biological assays complicate the scenario of personalized medicine in the oncological field. In this paper we review the results of anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) therapy in metastatic colorectal cancer (mCRC) in the context of tumor biology, delineating the future prospects of patient-tailored medicine in this area. In particular, we deal with EGFR inhibition by Cetuximab, a chimeric mouse human IgG1 mAb, and panitumumab, a fully human IgG2 mAb. We discuss the clinical impact of anti-EGFR mAbs on wild-type (WT) KRAS mCRC, also taking into account the feasibility of novel multi-marker approaches to treatment decision-making, aimed at increasing the predictive power of pre-therapy biomarkers. Experimental topics and fields of ongoing research, such as targeting microRNAs (miRNAs) with novel anticancer drugs and epigenetics in CRC are also addressed.

Restricted ROC curves are useful tools to evaluate the performance of tumour markers

In Clinical Epidemiology, receiver operating characteristic (ROC) analysis is a standard approach for the evaluation of the performance of diagnostic tests for binary classification based on a tumour marker distribution. The area under a ROC curve is a popular indicator of test accuracy, but its use has been questioned when the curve is asymmetric. This situation often happens when the marker concentrations overlap in the two groups under study in the range of low specificity, corresponding to a subset of values useless for classification purposes (non-informative values). The partial area under the curve at a high specificity threshold has been proposed as an alternative, but a method to identify an optimal cut-off that separates informative from non-informative values is not yet available. In this study, a new statistical approach is proposed to perform this task. Furthermore, a statistical test associated with the area under a ROC curve corresponding to informative values only (restricted ROC curve) is provided and its properties are explored by extensive simulations. Finally, the proposed method is applied to a real data set containing peripheral blood levels of six tumour markers proposed for the diagnosis of neuroblastoma. A new approach to combine couples of markers for classification purposes is also illustrated.

Congenital central hypoventilation syndrome: genotype-phenotype correlation in parents of affected children carrying a PHOX2B expansion mutation

Congenital Central Hypoventilation Syndrome (CCHS) is a rare genetic disorder. Although most CCHS associated PHOX2B mutations occur de novo, about 10% of the cases are inherited from apparently asymptomatic parents, thus confirming variable expressivity and incomplete penetrance of PHOX2B mutations. Three asymptomatic parents of children affected with CCHS, and found to carry the same PHOX2B expansion mutations as their siblings, were studied by overnight polysomnography and somatic mosaicism analysis. In one case, significant sleep breathing control anomalies were detected, while the other two resulted in normal. In tissue-specific allele studies, mosaicism with a comparatively low mutant allele proportion was showed in the two unaffected adult carriers. Accurate polysomnography and assessment of the degree of somatic mosaicism should be conducted in asymptomatic carriers of PHOX2B mutations, as they may unmask subclinical but significant anomalies.

Long-term follow-up of neuroblastoma-associated opsoclonus-myoclonus-ataxia syndrome

OBJECTIVE

The aim of this study is to describe the long-term neurological, neuropsychological and neuroradiological sequelae and to determine prognostic factors for neurological outcome in children with neuroblastoma-associated opsoclonus-myoclonus-ataxia (OMA) syndrome.

METHODS

Data on medical history were collected for the study patients. Examinations with grading of neurological signs, neuropsychological tests and brain magnetic resonance imaging with spectroscopy were performed during a follow-up clinic.

RESULTS

Fourteen subjects entered the study. All had localized neuroblastoma and they were evaluated after a median of 7.8 years. Patients with a chronic/multiphasic neurological course received steroids combined with intravenous immunoglobulins in the majority of cases. 71% presented neurological sequelae and 62% had a full-scale IQ below the normal range. All patients showed at least some deficit in the neuropsychological functions assessed (language, visual-motor integration, memory, attention and motor ability). Long-term deficits were more frequently detected in patients with an interval of more than 2 months between OMA onset and its diagnosis, even if in most comparisons statistical significance was not reached. Cerebellar atrophy, observed in 36% of patients, was not associated with the neurological outcome.

CONCLUSIONS

Persisting disability is present in most children with neuroblastoma-associated OMA. However, our results support the role of an early diagnosis of OMA in reducing sequelae and encourage the use of new immunosuppressive therapies.

PHOX2A and PHOX2B genes are highly co-expressed in human neuroblastoma

The detection of PHOX2B mutations in a small proportion of patients affected with either familial or sporadic neuroblastoma (NB), has arisen interest on the possible pathogenic role of this gene in the disease determination. In this light, we have carried out a quantitative expression analysis of PHOX2B and its paralogue PHOX2A on a panel of NB cell lines and NB tumour samples to identify a possible differential expression between NB cells and their normal counterpart (adrenal medulla cells). Our results revealed that both PHOX2A and PHOX2B are over-expressed in tumour samples and NB cell lines. Particularly, the expression levels of the two genes in NB cell lines show a highly significant correlation, suggesting their possible synergistic role or a coordinated expression regulation. Furthermore, PHOX2 gene over-expression in NB tumours and cell lines suggests these genes may be widely involved in NB development through either a direct mechanism of up-regulation or a failure in maintaining proper transcript levels after embryonic development.

Detection of GD2-positive cells in bone marrow samples and survival of patients with localised neuroblastoma

The impact of bone marrow (BM) GD2-positive cells on survival has been evaluated in 145 Italian children with localised neuroblastoma (NB) evaluated at diagnosis by anti-GD2 immunocytochemistry. Nineteen of these (13.1%) were found to be BM GD2-positive, with the number of positive cells ranging between 1 and 155 out of 1 × 10⁶ total cells analysed. Seven/19 (38.8%) GD2-positive vs 12/126 (9.5%) GD2-negative patients relapsed. The 5-year event-free survival (EFS) and overall survival of the GD2-positive patients was significantly worse than that of the GD2-negative ones (62.2 vs 89.9%, P<0.001; and 74.9 vs 95.9%, P=0.005, respectively). GD2 positivity was not associated to other known risk factors, and in particular to Myc-N amplification and 1p deletion. Among Myc-N-negative patients, the EFS of those negative for both GD2 and 1p deletion was significantly better than in children positive for either one of these two markers (EFS=96.9 vs 66.0%, P<0.001). In conclusion, GD2 positivity may represent a prognostic marker for patients with non-metastatic NB without Myc-N amplification, and its combination with genetic alterations might help identifying patients that require a more careful follow-up.

Internalization via Antennapedia protein transduction domain of an scFv antibody toward c-Myc protein

We constructed a single-chain variable fragment miniantibody (G11-scFv) directed toward the transactivation domain of c-Myc, which is fused with the internalization domain Int of Antennapedia at its carboxyl terminus (a cargo-carrier construct). In ELISA experiments, an EC(50) for binding saturation was achieved at concentrations of G11-scFv-Int(-) of approximately 10(-8) M. Internalization of a fluoresceinated Fl-G11-scFv-Int(+) construct was observed in intact human cultured cells with confocal microscopy. After 5 h of incubation in medium containing 1 microM Fl-G11-scFv-Int(+) or Fl-G11-scFv-Int(-), fluorescence intensity was determined in individual cells, both for cytoplasmic and nuclear compartments: concentration levels of Fl-G11-scFv-Int(+), relative to the extracellular culture medium concentration, were 4-5 times higher in the cytoplasm, 7-8 times higher in the nucleus, and 10 times higher in the nucleoli. In the same experimental conditions, the Fl-G11-scFv-Int(-) construct was 3-4 times more concentrated outside of the cells than inside. Cell membranes kept their integrity after 5 h of incubation. The antiproliferative activity of our miniantibody was studied on HCT116 cells. Incubation with 4 microM G11-scFv-Int(+) for 4 days induced very significant statistical and biological growth inhibition, whereas Int alone was completely inactive. Miniantibodies capable of penetrating cell membranes dramatically broaden the potential for innovative therapeutic agents and attack of new targets.

Inhibition of a protein‐protein interaction between INI1 and c‐Myc by small peptidomimetic molecules inspired by Helix‐1 of c‐Myc: identification of a new target of potential antineoplastic interest

c-Myc is a transcription modulator proto-oncogene. When overexpressed, it becomes an important contributor to the multi-hit process of malignant transformation. In two earlier papers in this journal (see refs. 19 , 20) we reported that retro-inverso peptidomimetic molecules inspired by the Helix-1 of c-Myc motif could be sequence-specific antiproliferative agents active in the low micromolar range. We also found that our peptides were not opening the four-alpha-helix Myc:Max bundle. Their antiproliferative activity in cancer cell lines needs the presence of side chains projecting outside of the bundle in the corresponding native H1 motif. This observation suggested interference with an external partner. In this study we investigated the INI1:Myc interaction. INI1 is a subunit of the SWI/SNF complex (component of the enhanceosome surrounding Myc:Max heterodimer). The INI1:Myc interaction was confirmed via pull down, ELISA, and fluorescence anisotropy assays. According to the length of INI1 fragments used, we calculated Kds ranging between 1.3x10(-6) and 4.8x10(-7) M. The three different techniques applied showed that the INI1:Myc interaction was also the target of our retro-inverso peptidomimetic molecules, which seem to bind specifically at INI1. A Myc binding, 21aa INI1 fragment (minimum interacting sequence), could inspire the synthesis of a new class of more selective c-Myc inhibitors.

Ozone air pollution and daily mortality in Genoa, Italy between 1993 and 1996

The association between ozone (O3) and daily mortality was investigated in Genoa, an Italian city characterized by a Mediterranean climate and a high prevalence of elderly inhabitants. The O3 effect, adjusted for long time trend, seasonality and weather, was assessed using Poisson regression modelling, allowing for overdispersion and autocorrelation, and expressed as mean variation percent of daily mortality per 50 microg/m3 increase (MV). Significant MVs for overall (+4.0%) and cardiovascular (+7.2%) mortality were detected at 1-day lag. The effects were stronger in the warmer season (May-October). Similar estimates were found after restricting the analyses to the elderly (>or=75 years). Furthermore, in this group, higher MVs were observed for total mortality at 2-day lag. A statistically significant synergistic effect between O3 and temperature was observed for cardiovascular mortality, particularly in elderly people, with an evident increase in mortality risk above 26 degrees C (MV +30.0% for the whole population and +40.0% for the elderly, respectively). This investigation highlights the importance of taking local climatic and demographic features into account when comparing different time-series studies, and substantiates the influence of photochemical pollution on mortality trends in small urban areas.

Cis and trans regulatory elements in NPHS2 promoter: implications in proteinuria and progression of renal diseases

Podocin (NPHS2) expression in podocytes is associated with variable degrees of proteinuria and progression to renal failure in different glomerular diseases that suggests different expression profiles in NPHS2 promoter. Three functional polymorphisms in NPHS2 promoter (-51T, -116T, and -535 insCTTTTTT(3)) were found determining strong downregulation (-73, -59, and -82%, respectively) of the reporter gene expression when transfected in podocytes. Electrophoretic mobility shift assay experiments showed that all wild-type variants (-51G, -116C, and -535 insCTTTTTT(2)) formed specific DNA-protein complexes with podocyte nuclear extracts that were abolished by the presence of the rare forms (-51T, -116T, and -535 insCTTTTTT(3)). In the case of -51G, upstream stimulatory factor-1 (USF1) was identified as the specific trans element in accord to binding inhibition experiments and USF1 RNAi silencing. Haplotype analysis of 204 normal controls and 545 patients with renal diseases (308 immunoglobulin (Ig)A nephropathy and 237 focal segmental glomerulosclerosis) evidenced that -116/-51 and -535/P2OL formed two blocks in strong linkage disequilibrium in both normal and pathological cohorts. The high NPHS2 promoter profile -116C/-51G haplotype was more frequent in patients with IgA nephropathy (P-value=0.005) and was associated with a better clinical outcome in terms of proteinuria and creatinine levels. Overall our study describes functional variants of NPHS2 promoter and characterizes trans-acting elements that modulate podocin expression in the kidney. High producer NPHS2 promoter haplotypes seem protective in patients with chronic glomerular diseases.

Glomerular clusterin is associated with PKC-alpha/beta regulation and good outcome of membranous glomerulonephritis in humans

Mechanisms for human membranous glomerulonephritis (MGN) remain elusive. Most up-to-date concepts still rely on the rat model of Passive Heymann Nephritis that derives from an autoimmune response to glomerular megalin, with complement activation and membrane attack complex assembly. Clusterin has been reported as a megalin ligand in immunodeposits, although its role has not been clarified. We studied renal biopsies of 60 MGN patients by immunohistochemistry utilizing antibodies against clusterin, C5b-9, and phosphorylated-protien kinase C (PKC) isoforms (pPKC). In vitro experiments were performed to investigate the role of clusterin during podocyte damage by MGN serum and define clusterin binding to human podocytes, where megalin is known to be absent. Clusterin, C5b-9, and pPKC-alpha/beta showed highly variable glomerular staining, where high clusterin profiles were inversely correlated to C5b-9 and PKC-alpha/beta expression (P=0.029), and co-localized with the low-density lipoprotein receptor (LDL-R). Glomerular clusterin emerged as the single factor influencing proteinuria at multivariate analysis and was associated with a reduction of proteinuria after a follow-up of 1.5 years (-88.1%, P=0.027). Incubation of podocytes with MGN sera determined strong upregulation of pPKC-alpha/beta that was reverted by pre-incubation with clusterin, serum de-complementation, or protein-A treatment. Preliminary in vitro experiments showed podocyte binding of biotinilated clusterin, co-localization with LDL-R and specific binding inhibition with anti-LDL-R antibodies and with specific ligands. These data suggest a central role for glomerular clusterin in MGN as a modulator of inflammation that potentially influences the clinical outcome. Binding of clusterin to the LDL-R might offer an interpretative key for the pathogenesis of MGN in humans.

Differences in the proportions of fluoroquinolone-resistant Gram-negative bacteria isolated from bacteraemic children with cancer in two Italian centres

The proportion of ciprofloxacin-resistant Gram-negative bacteria isolated from the blood of children with cancer (not receiving prophylaxis) was 10% in a paediatric hospital (Genoa) where the use of quinolones was highly restricted, compared with 41% in a department of haematology (Rome) where leukaemic adults, who received fluoroquinolone prophylaxis, were also treated (p < 0.0001). Moreover, simultaneous resistance to ciprofloxacin and ceftazidime, amikacin or imipenem-cilastatin was 11% in Genoa compared with 37% in Rome (p < 0.001). Ciprofloxacin resistance was more frequent in children who shared an environment with adults who were receiving ciprofloxacin prophylaxis.

Central venous catheter-related complications in children with oncological/hematological diseases: an observational study of 418 devices

BACKGROUND

The use of indwelling central venous catheters (CVCs) has become commonplace in the management of children undergoing anticancer treatment. Several types of CVC are available, while information on complications observed in children is scarce. We describe the experience of two tertiary care centers in Italy that prospectively followed up three types of CVC used at both institutions over a 30-month period.

PATIENTS AND METHODS

Between January 2000 and May 2002, double-lumen (DL) or single-lumen (SL) Hickman-Broviac (HB) catheters, and single-lumen pressure-activated safety valve (PASV) catheters were used and prospectively evaluated. Four types of possible complication were defined a priori: mechanical, thrombotic, malfunctioning and infectious.

RESULTS

Four hundred and eighteen CVCs (180 SL-HB, 162 DL-HB and 76 PASV) were inserted in 368 children, for a total of 107 012 catheter days at risk of complication. At least one complication occurred while using 169 of the devices (40%): 46% of the DL-HB, 46% of the PASV and 33% of the SL-HB (P=0.02) catheters. Subjects with hematological malignancies or non-malignant diseases had significantly more complications than those with solid tumors (P <0.0001). Overall, 234 complications were documented: 93 infectious [complication rate per 1000 catheter days at risk (CR)=0.87], 84 malfunctioning (CR=0.78), 48 mechanical (CR=0.45) and nine thrombotic (CR=0.08). SL-HB had statistically fewer infectious complications, while PASV had more mechanical complications. In a multivariate regression model, the most significant risk factors for having a CVC complication were hematological disease [relative risk (RR)=3.0; 95% confidence interval (CI) 1.8-4.8] and age <6 years at CVC insertion (RR=2.5; 95% CI 1.5-4.1). As for the type of CVC, compared with SL-HB, the DL-HB catheter had a statistically significant two-fold increased risk of any complication (RR=2.1; 95% CI 1.2-3.6), while the PASV catheter had a borderline RR of 1.8 (95% CI 1.0-3.6). Analysis by tumor type showed a higher risk of any kind of complication in patients with solid malignancies who had received a DL-HB catheter as compared with an SL-HB catheter (RR=7.2; 95% CI 2.8-18.7).

CONCLUSIONS

CVCs may cause complications in up to 40% of patients, with type of CVC, underlying disease and patient age being the three main factors that affect the incidence of CVC-related complications. SL-HB catheters have the best performance.