Evaluation of radon exposure risk and lung cancer incidence/mortality in South-eastern Italy.

INTRODUCTION: Radon and its decay products may cause substantial health damage after long-term exposure. The aim of the study was to perform a spatial analysis of radon concentration in the Salento peninsula, province of Lecce (South-eastern Italy) in order to better characterize possible risk for human health, with specific focus on lung cancer. METHODS: Based on previous radon monitoring campaigns carried out in 2006 on behalf of the Local Health Authority (ASL Lecce) involving 419 schools and through the application of kriging estimation method, a radon risk map was obtained for the province of Lecce, in order to determine if areas with higher radon concentrations were overlapping with those characterized by the highest pulmonary cancer incidence and mortality rates. RESULTS: According to our data, areas at higher radon concentrations seem to overlap with those characterized by the highest pulmonary cancer mortality and incidence rates, thus indicating that human exposure to radon could possibly enhance other individual or environmental pro-carcinogenic risk factors (i.e. cigarette smoking, air pollution and other exposures). CONCLUSIONS: The radon risk should be further assessed in the evaluation of the causes resulting in higher mortality and incidence rates for pulmonary cancer in Salento area vs Italian average national data. For these reasons, ASL Lecce in cooperation with ARPA Puglia and CNR-IFC has included the monitoring of individual indoor radon concentrations in the protocol of PROTOS case-control Study, aimed at investigating the role of different personal and environmental risk factors for lung cancer in Salento.

Is less more? Assessing the utility of early clinical and radiographic follow-up for operative supracondylar humerus fractures.

PURPOSE: Postoperative protocols following surgical management of supracondylar humerus fractures (SCFs) are often based upon surgeon preference rather than clinical merit. The purpose of this study is to determine the utility of early clinical and radiographic follow-up. METHODS: A retrospective review of patients who underwent closed reduction and percutaneous pinning (CRPP) for SCF between 2009 and 2015 was performed using a database of prospectively-collected consecutive patient data. Previously undiagnosed neuropathies documented at the first postoperative visit were identified. Unscheduled visits and postoperative complications were compared between patients who were seen at one week and those with delayed first clinic visits. RESULTS: Of 873 patients, 823 (94.3%) were seen within ten days of surgery (early follow-up) and 50 (5.7%) had a delayed first clinic appointment. Among patients seen for early follow-up, 12 (1.5%) had a previously undocumented neuropathy diagnosed but only eight (1%) had an alteration of management secondary to clinical findings. Greater than 90% of patients seen for early follow-up had radiographs performed, but only one had an alteration in management due to radiographic findings. Patients seen for early follow-up had the same rate of unscheduled visits (2.9% versus 4%, p = 0.66) and postoperative complications (1.6% versus 0%, p > 0.99) as those with delayed first appointments. Radiographic parameters were comparable at final follow-up (Baumann's angle 74.5° versus 73.7°, p = 0.40; lateral humeral condylar angle 40.2° versus 41.2°, p = 0.53). CONCLUSION: The early follow-up visit after CRPP of SCF rarely leads to alterations in care and does not reduce unscheduled visits or late complications. LEVEL OF EVIDENCE: Level IV.

Nasal cytology: Methodology with application to clinical practice and research.

Nasal cytology is an easy, cheap, non-invasive and point-of-care method to assess nasal inflammation and disease-specific cellular features. By means of nasal cytology, it is possible to distinguish between different inflammatory patterns that are typically associated with specific diseases (ie, allergic and non-allergic rhinitis). Its use is particularly relevant when other clinical information, such as signs, symptoms, time-course and allergic sensitizations, is not enough to recognize which of the different rhinitis phenotypes is involved; for example, it is only by means of nasal cytology that it is possible to distinguish, among the non-allergic rhinitis, those characterized by eosinophilic (NARES), mast cellular (NARMA), mixed eosinophilic-mast cellular (NARESMA) or neutrophilic (NARNE) inflammation. Despite its clinical usefulness, cheapness, non-invasiveness and easiness, nasal cytology is still underused and this is at least partially due to the fact that, as far as now, there is not a consensus or an official recommendation on its methodological issues. We here review the scientific literature about nasal cytology, giving recommendations on how to perform and interpret nasal cytology.

(Epi)genotype-phenotype correlations in Beckwith-Wiedemann syndrome: a paradigm for genomic medicine.

Beckwith-Wiedemann syndrome (BWS) is the commonest overgrowth cancer predisposition disorder and represents a model for human imprinting dysregulation and tumorigenesis. BWS features can variably combine and present a widely variable range of severity in the phenotypic expression. This wide spectrum is paralleled at molecular level by complex (epi)genetic defects on chromosome 11p15.5 leading to disrupted expression of imprinted genes controlling growth and cellular proliferation. In this review, we outline the spectrum of clinical manifestations of BWS analyzing their (epi)genotype-phenotype correlations. The differences observed in the phenotypic profiles of BWS molecular subtypes allow a composite view of this syndrome with implications on clinical care, diagnosis, follow-up, and management, and provide directions for future disease monitoring.

CXCR4 and CXCR7 transduce through mTOR in human renal cancer cells.

Treatment of metastatic renal cell carcinoma (mRCC) has improved significantly with the advent of agents targeting the mTOR pathway, such as temsirolimus and everolimus. However, their efficacy is thought to be limited by feedback loops and crosstalk with other pathways leading to the development of drug resistance. As CXCR4-CXCL12-CXCR7 axis has been described to have a crucial role in renal cancer; the crosstalk between the mTOR pathway and the CXCR4-CXCL12-CXCR7 chemokine receptor axis has been investigated in human renal cancer cells. In SN12C and A498, the common CXCR4-CXCR7 ligand, CXCL12, and the exclusive CXCR7 ligand, CXCL11, activated mTOR through P70S6K and 4EBP1 targets. The mTOR activation was specifically inhibited by CXCR4 antagonists (AMD3100, anti-CXCR4-12G5 and Peptide R, a newly developed CXCR4 antagonist) and CXCR7 antagonists (anti-CXCR7-12G8 and CCX771, CXCR7 inhibitor). To investigate the functional role of CXCR4, CXCR7 and mTOR in human renal cancer cells, both migration and wound healing were evaluated. SN12C and A498 cells migrated toward CXCL12 and CXCL11; CXCR4 and CXCR7 inhibitors impaired migration and treatment with mTOR inhibitor, RAD001, further inhibited it. Moreover, CXCL12 and CXCL11 induced wound healing while was impaired by AMD3100, the anti CXCR7 and RAD001. In SN12C and A498 cells, CXCL12 and CXCL11 promoted actin reorganization characterized by thin spikes at the cell periphery, whereas AMD3100 and anti-CXCR7 impaired CXCL12/CXCL11-induced actin polymerization, and RAD001 treatment further reduced it. In addition, when cell growth was evaluated in the presence of CXCL12, CXCL11 and mTOR inhibitors, an additive effect was demonstrated with the CXCR4, CXCR7 antagonists and RAD001. RAD001-resistant SN12C and A498 cells recovered RAD001 sensitivity in the presence of CXCR4 and CXCR7 antagonists. In conclusion, the entire axis CXCR4-CXCL12-CXCR7 regulates mTOR signaling in renal cancer cells offering new therapeutic opportunities and targets to overcome resistance to mTOR inhibitors.

Montelukast effects on inflammation in allergic rhinitis: a double blind placebo controlled pilot study.

It has been demonstrated that Leukotriene modifiers reduce rhinitis symptoms, but montelukast preventive effect on inflammatory cells pattern in intranasal challenge studies has not been already assessed. This pilot study has been designed to explore the montelukast effects in preventing early/late inflammatory cells response to specific allergen challenge in persistent rhinitis. After a 4 week wash-out period, patients were randomised to receive montelukast/placebo for 4 weeks. Pre-post treatment nasal washing and scraping before and after specific nasal challenge were performed. No difference in baseline inflammatory cells count before and after treatment was shown between groups. Despite at a basal level a decrease of inflammatory cells in active group after treatment was observed, the statistical significance was not reached. The generalised mixed model showed that, after therapeutic interventions, the inflammatory cells increased 30' and 6 hour after challenge but, only in the active group the cells amounting was less for eosinophils (-34%), macrophages (-56%), lymphocytes (-45%) and neutrophils (-46%; p = 0.001). The longitudinal generalised linear model with just one time variable showed a decrease of all inflammatory cellular types although a significant relevance was reached only for macrophages (p = 0.038) and neutrophils (p = 0.001). The modulatory effect on neutrophils and macrophages could lead to montelukast still unexplored effects. Specific trials, sized according to the results of this pilot exploratory study, could add relevant evidences concerning the leukotrienes receptors antagonist treatment of specific rhinitis and asthma phenotypes.

Omalizumab modulates bronchial reticular basement membrane thickness and eosinophil infiltration in severe persistent allergic asthma patients.

Severe persistent asthma causes a substantial morbidity and mortality burden and is frequently not well controlled, despite intensive guideline-based therapy. The unique monoclonal antibody approved for patients with severe allergic asthma is omalizumab: a recombinant humanised murine against IgE antibodies. The aim of the present study is to investigate the effect of long-term anti-IgE on the thickening of the reticular basement membrane (RBM) and eosinophil infiltration in bronchial biopsies from patients with severe persistent allergic asthma. Biopsies were obtained from 11 patients with severe persistent allergic asthma before and after (12 months) treatment with omalizumab. RBM thickness and eosinophils were measured by using light microscope image analysis. A significant mean reduction in RBM thickness and eosinophil infiltration were measured after one-year omalizumab treatment. No correlation between eosinophil reduction and RBM thickness reduction was found. No correlation between each of the previous two parameters and clinical parameters was detected. In conclusion, our study showed that a substantial proportion of severe asthmatics reduced the original bronchial RBM thickness and eosinophil infiltration after one-year treatment with anti-IgE, thus emphasizing the possible role of omalizumab in affecting airway remodeling in severe persistent allergic asthma.

Similar serum levels of IL-6 and its soluble receptors in patients with HCV-related arthritis and rheumatoid arthritis: a pilot study.

The high serum levels of Interleukin-6 (IL-6) and its soluble receptors (sIL-6r and sgp130), described in the course of Rheumatoid Arthritis (RA), have been linked to the enhanced activity of this cytokine in this disorder. In this study, the serum concentrations of IL-6 and its soluble receptors were determined in a group of patients with HCV-related arthritis (HCVrA), a condition resembling RA in several aspects, and then compared to those found in a sample of subjects affected by RA. Twenty-one patients with HCVrA, 24 patients with RA and 20 healthy subjects (control group) were examined. Different ELISA methods were used for determination of serum concentrations of IL-6, sIL-6r and sgp130. Increased IL-6 serum levels were found in 15 (71 %) of the patients with HCVrA and in 16 (62 %) of those with RA. Eight (38 %) of the patients with HCVrA and 11 (46%) of those with RA denoted high levels of sIL-6r, while sgp130 levels were elevated in 21 (76%) of the patients with HCVrA and in 16 (69%) of those with RA. A significant difference between the median values of sIL-6r and sgp130 levels in the two groups of patients versus controls was found. A mild correlation of these parameters with RF levels was detected in the RA group. Furthermore, in HCVrA patients the serum levels of IL-6, sIL-6r and sgp130 appeared unrelated to HCV viraemia and to levels of transaminases. The enhanced serum levels of IL-6 in HCVra patients indicate an increased synthesis and hyperactivity of this cytokine in HCVrA, and the substantial similarity of the behaviour of IL-6 and its serum receptors in the two groups of patients suggests common mechanisms with RA, in which the function of I L-6 is central.

Effect of statins on fibroblasts from human nasal polyps and turbinates.

BACKGROUND: Statins are serum cholesterol-lowering agents used for the prevention and treatment of atherosclerotic vascular disease. There is, however, growing evidence that statins have immunomodulatory and anti-inflammatory activities and may prove invaluable in the treatment of immunological and inflammatory disorders. OBJECTIVE: On these basis we evaluated the effect of statins on the proliferation of fibroblasts derived from human nasal polyps and turbinates and determined their ability to modulate airway remodelling. METHODS: Fluvastatin (0.01-0.1-1 microM), Atorvastatin (0.1-1-10 microM) and Simvastatin (0.1-1-10 microM) were tested on cultured fibroblasts derived from human nasal polyps and turbinates stimulated or not with Fibroblast Growth Factor beta (10 ng/ml). All cultures were treated with 3H-Thymidine (1 microCi/ml) to test cell proliferation. RESULTS: Our results show that proliferation of turbinate-derived fibroblasts is significantly inhibited by the three statins. Fluvastatin is already effective at the lowest dose (0.01 microM), whereas Atorvastatin and Simvastatin act at the plasmatic peak concentration (1 microM). No significant effect was found on fibroblasts derived from nasal polyps, except for Simvastatin which was effective after 144 hours of stimulation. CONCLUSIONS: These drugs show a remarkable antiprolhferative effect and their different outcome depending on the different kind of fibroblasts in vitro is prompting news in the studies about statin use for the treatment of chronic inflammatory diseases.

HCV infection and chronic arthritis: Does viral replication matter?

BACKGROUND: HCV infection beside chronic hepatitis can induce immunological disorders with different clinical expressions such as chronic arthritis. AIM: To study the prevalence of arthritis in HCV-Ab positive patients and verify possible correlation with viral replication, hepatic damage and autoimmunity imbalance. STUDY DESIGN: Three hundred and eighty patients (196 M and 184 F) affected by HCV infection were examined and 38 (10%) were selected according to the presence of arthritis. Eight of them were excluded because arthritis raised before HCV infection. Each patient, once undergone liver biopsy, was evaluated for: clinical examination (articular evolution), Rx examination, serum expression of hepatic damage (mainly ALT), viral replication, and involvement of autoimmunity (ANA, RF, crioglobulins, AKA, CCP). RESULTS: Data from patients [Lamprecht P, Gause A, Gross WL. Cryoglobulinemic vasculitis. Arthritis Rheum 1999; 42:2507-16.] with AKA and CCP positivity were not considered for statistical examination because the clear correlation between rheumatoid arthritis and these parameters. The remaining 20 patients showed hepatic damage 47%, viral replication in 74%, RF 42%, ANA 16%, crioglobulins 42% (RF positive). No correlation was evident between ANA serum concentrations and viral replication; furthermore a significant negative correlation between RF positivity and viral replication only in a subgroup of patients with serologic expression of hepatic damage was found. CONCLUSIONS: These data support hypothesis that the onset of arthritis and presence of autoimmunity parameters ANA, RF are not related to the viral replication but others mechanism immunological induced by HCV might be considered.

Different intrathyroid expression of intercellular adhesion molecule-1 (ICAM-1) in Hashimoto's thyroiditis and Graves' disease: analysis at mRNA level and association with B7.1 costimulatory molecule.

Cultured thyroid epithelial cells can be induced to express intercellular adhesion molecule-1 (ICAM-1, or CD54). However, constitutive follicular expression of ICAM-1 has been reported only in thyroid autoimmunity. We evaluated the expression of ICAM-1 mRNA and protein on thyroid tissue from different autoimmune thyroid diseases, and its relationship with other immunologically relevant surface markers, namely costimulatory molecules of B7 family. Thyroid tissue sections were obtained by surgically removed thyroid glands from 6 patients with Hashimoto's thyroiditis (HT), 6 with Graves' disease (GD) and 3 with multinodular nontoxic goiter. We used in situ hybridization to localize ICAM-1 mRNA, and immunohistochemical analysis by alkaline phosphatase anti-alkaline phosphatase (APAAP) method. We showed a clear hybridization pattern, localized in follicular cells, in sections of glands with HT. The hybridization pattern was far less pronounced in GD: no staining was apparent on follicular cells. These results were strictly consistent with those obtained by means of immunohistochemistry. Moreover, double-staining experiments demonstrated colocalization of ICAM-1 and B7.1 molecules in HT, whereas no B7.1 expression was observed in Graves' or in non-autoimmune thyroid diseases. These data agree with the hypothesis of distinct immunoregulatory phenomena and effector mechanisms in the 2 main autoimmune thyroid diseases.

Inflammatory and mechanical factors of allergen-induced bronchoconstriction in mild asthma and rhinitis.

We studied whether different bronchial responses to allergen in asthma and rhinitis are associated with different bronchial inflammation and remodeling or airway mechanics. Nine subjects with mild asthma and eight with rhinitis alone underwent methacholine and allergen inhalation challenges. The latter was preceded and followed by bronchoalveolar lavage and bronchial biopsy. The response to methacholine was positive in all asthmatic but in only two rhinitic subjects. The response to allergen was positive in all asthmatic and most, i.e., five, rhinitic subjects. No significant differences between groups were found in airway inflammatory cells or basement membrane thickness either at baseline or after allergen. The ability of deep inhalation to dilate methacholine-constricted airways was greater in rhinitis than in asthma, but it was progressively reduced in rhinitis during allergen challenge. We conclude that 1) rhinitic subjects may develop similar airway inflammation and remodeling as the asthmatic subjects do and 2) the difference in bronchial response to allergen between asthma and rhinitis is associated with different airway mechanics.

Preliminary evidence for 'aberrant' expression of the leukocyte integrin LFA-1 (CD11a/CD18) on conjunctival epithelial cells of patients with mite allergy.

BACKGROUND: We have previously shown aberrant expression of the 'leukocyte' integrin LFA-1 on epithelial cells in chronic autoimmune thyroiditis. In the present study we investigated whether conjunctival epithelial cells, which bear the adhesion molecule ICAM-1 on their surface during allergic inflammation, may also aberrantly express its natural ligand, the 'leukocyte' integrin LFA-1. METHODS: We studied 13 patients with rhinoconjunctivitis allergic to mites, chronically exposed to the allergen, 11 patients allergic to pollen tested out of the pollen season and 8 normal volunteers. Single and double immunocytochemical staining of conjunctival smears was employed. RESULTS: LFA-1 staining on epithelial cells was demonstrated in 12/13 patients allergic to mites and not in normal controls or in patients allergic to pollen tested out of the pollen season. The epithelial localization of LFA-1 was confirmed by double staining with anti-LFA-1 and anti-cytokeratin antibodies (both immunocytochemical and immunofluorescence). CONCLUSIONS: Coexpression of LFA-1 and ICAM-1 during persistent allergen stimulation may be relevant for interaction between epithelial cells and activated effector cells, such as eosinophils, which bear on their surface both ICAM-1 and its beta2 integrin ligands.

Nasal endoscopy in asthmatic children: assessment of rhinosinusitis and adenoiditis incidence, correlations with cytology and microbiology.

BACKGROUND: Upper respiratory airway diseases may induce a worsening of asthma. Sinusitis represents one of the most common chronic diseases. The association of asthma and sinusitis varies greatly in different studies, depending on diagnostic procedures. OBJECTIVE: The aims were: (i) to demonstrate that nasal endoscopy may be easily feasible in asthma at paediatric age; (ii) to evaluate the incidence of rhinosinusitis and adenoiditis in children with asthma by nasal endoscopy; (iii) to correlate inflammatory parameters such as cytology and microbiological cultures with nasal endoscopy findings. SUBJECTS AND METHODS: One hundred and forty-five asthmatic children were evaluated, 48 males and 97 females, with an average age of 7.27 years. Evaluated parameters were the incidence of rhinosinusal infections in asthmatic children, and the role of: (i) nasal endoscopy, (ii) nasal cytology, and (iii) nasal microbiology in their diagnoses. RESULTS: Nasal endoscopy was successfully performed on 128 patients. Twenty-six children had endoscopic rhinosinusitis alone, 10 had adenoiditis alone, and 35 showed endoscopic rhinosinusitis associated with adenoiditis. There were significant correlations between endoscopic rhinosinusitis and adenoiditis (P < 0.001), between clinical and endoscopic rhinosinusitis (P < 0.001), between endoscopic rhinosinusitis and adenoiditis and microbiology (P < 0.05 and P < 0.0001, respectively), and between microbiology and cytology (P < 0.05). CONCLUSION: This study shows that rhinosinusal infections are common in asthmatic children. Moreover, nasal endoscopy might represent a fruitful tool in the management of asthmatic children.

Investigation of the substrate spectrum of the human mismatch-specific DNA N-glycosylase MED1 (MBD4): fundamental role of the catalytic domain.

The human DNA repair protein MED1 (also known as MBD4) was isolated as an interactor of the mismatch repair protein MLH1 in a yeast two-hybrid screening. MED1 has a tripartite structure with an N-terminal 5-methylcytosine binding domain (MBD), a central region, and a C-terminal catalytic domain with homology to bacterial DNA damage-specific glycosylases/lyases. Indeed, MED1 acts as a mismatch-specific DNA N-glycosylase active on thymine, uracil, and 5-fluorouracil paired with guanine. The glycosylase activity of MED1 preferentially targets G:T mismatches in the context of CpG sites; this indicates that MED1 is involved in the repair of deaminated 5-methylcytosine. Interestingly, frameshift mutations of the MED1 gene have been reported in human colorectal, endometrial, and pancreatic cancers. For its putative role in maintaining genomic fidelity at CpG sites, it is important to characterize the biochemical properties and the substrate spectrum of MED1. Here we show that MED1 works under a wide range of temperature and pH, and has a limited optimum range of ionic strength. MED1 has a weak glycosylase activity on the mutagenic adduct 3,N(4)-ethenocytosine, a metabolite of vinyl chloride and ethyl carbamate. The differences in glycosylase activity on G:U and G:T substrates are not related to differences in substrate binding and likely result from intrinsic differences in the chemical step. Finally, the isolated catalytic domain of MED1 retains the preference for G:T and G:U substrates in the context of methylated or unmethylated CpG sites. This suggests that the catalytic domain is fundamental, and the 5-methylcytosine binding domain dispensable, in determining the substrate spectrum of MED1.

Biphasic kinetics of the human DNA repair protein MED1 (MBD4), a mismatch-specific DNA N-glycosylase.

The human protein MED1 (also known as MBD4) was previously isolated in a two-hybrid screening using the mismatch repair protein MLH1 as a bait, and shown to have homology to bacterial base excision repair DNA N-glycosylases/lyases. To define the mechanisms of action of MED1, we implemented a sensitive glycosylase assay amenable to kinetic analysis. We show that MED1 functions as a mismatch-specific DNA N-glycosylase active on thymine, uracil, and 5-fluorouracil when these bases are opposite to guanine. MED1 lacks uracil glycosylase activity on single-strand DNA and abasic site lyase activity. The glycosylase activity of MED1 prefers substrates containing a G:T mismatch within methylated or unmethylated CpG sites; since G:T mismatches can originate via deamination of 5-methylcytosine to thymine, MED1 may act as a caretaker of genomic fidelity at CpG sites. A kinetic analysis revealed that MED1 displays a fast first cleavage reaction followed by slower subsequent reactions, resulting in biphasic time course; this is due to the tight binding of MED1 to the abasic site reaction product rather than a consequence of enzyme inactivation. Comparison of kinetic profiles revealed that the MED1 5-methylcytosine binding domain and methylation of the mismatched CpG site are not required for efficient catalysis.

Relaxation of insulin-like growth factor 2 imprinting and discordant methylation at KvDMR1 in two first cousins affected by Beckwith-Wiedemann and Klippel-Trenaunay-Weber syndromes.

Beckwith-Wiedeman syndrome (BWS) and Klippel-Trenaunay-Weber syndrome (KTWS) are different human disorders characterized, among other features, by tissue overgrowth. Deregulation of one or more imprinted genes located at chromosome 11p15.5, of which insulin-like growth factor 2 (IGF2) is the most likely candidate, is believed to cause BWS, whereas the etiology of KTWS is completely obscure. We report a case of BWS and a case of KTWS in a single family. The probands, sons of two sisters, showed relaxation of the maternal IGF2 imprinting, although they inherited different 11p15.5 alleles from their mothers and did not show any chromosome rearrangement. The patient with BWS also displayed hypomethylation at KvDMR1, a maternally methylated CpG island within an intron of the KvLQT1 gene. The unaffected brother of the BWS proband shared the same maternal and paternal 11p15.5 haplotype with his brother, but the KvDMR1 locus was normally methylated. Methylation of the H19 gene was normal in both the BWS and KTWS probands. Linkage between the insulin-like growth factor 2 receptor (IGF2R) gene and the tissue overgrowth was also excluded. These results raise the possibility that a defective modifier or regulatory gene unlinked to 11p15.5 caused a spectrum of epigenetic alterations in the germ line or early development of both cousins, ranging from the relaxation of IGF2 imprinting in the KTWS proband to disruption of both the imprinted expression of IGF2 and the imprinted methylation of KvDMR1 in the BWS proband. Analysis of these data also indicates that loss of IGF2 imprinting is not necessarily linked to alteration of methylation at the KvDMR1 or H19 loci and supports the notion that IGF2 overexpression is involved in the etiology of the tissue hypertrophy observed in different overgrowth disorders, including KTWS.

The H19 endodermal enhancer is required for Igf2 activation and tumor formation in experimental liver carcinogenesis.

The expression of the linked but reciprocally imprinted Igf2 and H19 genes is activated in adult liver in the course of tumor development. By in situ hybridization analysis we have shown that both the Igf2 and H19 RNAs are expressed in the majority of the neoplastic nodules, and that hepatocellular carcinomas are developed in an experimental model of liver carcinogenesis. H19 is also highly activated in smaller and less distinct hyperplastic regions. The few neoplastic areas showing Igf2 but no H19 RNA display loss of the maternally inherited allele at the Igf2/H19 locus. These data are compatible with the existence of a common activation mechanism of these two genes during liver carcinogenesis and with a stronger H19 induction in the pre-neoplastic lesions. By using mice carrying a deletion of the H19 endodermal enhancer, we show that this regulatory element is necessary for the activation of the Igf2 and H19 genes upon induction of liver carcinogenesis. Furthermore, multiple sites of the H19 endodermal enhancer region become hypersensitive to DNase I when the carcinogenesis process is induced. Lastly, liver tumors developed in mice paternally inheriting the H19 enhancer deletion are found to have marked growth delays, increased frequency of apoptotic nuclei, and lack of Igf2 mRNA expression, thus indicating that this regulatory element plays a major role in the progression of liver carcinogenesis, since it is required for the activation of the anti-apoptotic Igf2 gene.

Mediation by a CREB family transcription factor of NGF-dependent survival of sympathetic neurons.

Nerve growth factor (NGF) and other neurotrophins support survival of neurons through processes that are incompletely understood. The transcription factor CREB is a critical mediator of NGF-dependent gene expression, but whether CREB family transcription factors regulate expression of genes that contribute to NGF-dependent survival of sympathetic neurons is unknown. CREB-mediated gene expression was both necessary for NGF-dependent survival and sufficient on its own to promote survival of sympathetic neurons. Moreover, expression of Bcl-2 was activated by NGF and other neurotrophins by a CREB-dependent transcriptional mechanism. Overexpression of Bcl-2 reduced the death-promoting effects of CREB inhibition. Together, these data support a model in which neurotrophins promote survival of neurons, in part through a mechanism involving CREB family transcription factor-dependent expression of genes encoding prosurvival factors.