POZ-, AT-hook-, and zinc finger-containing protein (PATZ) interacts with human oncogene B cell lymphoma 6 (BCL6) and is required for its negative autoregulation

The PATZ1 gene encoding a POZ/AT-hook/Kruppel zinc finger (PATZ) transcription factor, is considered a cancer-related gene because of its loss or misexpression in human neoplasias. As for other POZ/domain and Kruppel zinc finger (POK) family members, the transcriptional activity of PATZ is due to the POZ-mediated oligomer formation, suggesting that it might be not a typical transactivator but an architectural transcription factor, thus functioning either as activator or as repressor depending on the presence of proteins able to interact with it. Therefore, to better elucidate PATZ function, we searched for its molecular partners. By yeast two-hybrid screenings, we found a specific interaction between PATZ and BCL6, a human oncogene that plays a key role in germinal center (GC) derived neoplasias. We demonstrate that PATZ and BCL6 interact in germinal center-derived B lymphoma cells, through the POZ domain of PATZ. Moreover, we show that PATZ is able to bind the BCL6 regulatory region, where BCL6 itself acts as a negative regulator, and to contribute to negatively modulate its activity. Consistently, disruption of one or both Patz1 alleles in mice causes focal expansion of thymus B cells, in which BCL6 is up-regulated. This phenotype was almost completely rescued by crossing Patz1(+/-) with Bcl6(+/-) mice, indicating a key role for Bcl6 expression in its development. Finally, a significant number of Patz1 knock-out mice (both heterozygous and homozygous) also develop BCL6-expressing lymphomas. Therefore, the disruption of one or both Patz1 alleles may favor lymphomagenesis by activating the BCL6 pathway.

CBX7 is a tumor suppressor in mice and humans

The CBX7 gene encodes a polycomb group protein that is known to be downregulated in many types of human cancers, although the role of this protein in carcinogenesis remains unclear. To shed light on this issue, we generated mice null for Cbx7. Mouse embryonic fibroblasts derived from these mice had a higher growth rate and reduced susceptibility to senescence compared with their WT counterparts. This was associated with upregulated expression of multiple cell cycle components, including cyclin E, which is known to play a key role in lung carcinogenesis in humans. Adult Cbx7-KO mice developed liver and lung adenomas and carcinomas. In in vivo and in vitro experiments, we demonstrated that CBX7 bound to the CCNE1 promoter in a complex that included HDAC2 and negatively regulated CCNE1 expression. Finally, we found that the lack of CBX7 protein expression in human lung carcinomas correlated with CCNE1 overexpression. These data suggest that CBX7 is a tumor suppressor and that its loss plays a key role in the pathogenesis of cancer.

miR-191 down-regulation plays a role in thyroid follicular tumors through CDK6 targeting

CONTEXT

Well-differentiated thyroid carcinomas include papillary (PTC) and follicular (FTC) carcinomas. FTC is usually a more aggressive form of cancer than the more common papillary type. miR-191 expression is frequently altered in several neoplasias, being up-regulated in some cases, such as pancreatic carcinomas, and down-regulated in other carcinomas, such as melanomas.

OBJECTIVE

The objective was to evaluate the expression and the role of miR-191 in thyroid carcinogenesis.

DESIGN

The expression of miR-191 was analyzed in tissues from patients with follicular adenoma (n = 24), FTC (n = 24), PTC (n = 15), anaplastic thyroid carcinoma (n = 8), and the follicular variant of PTC (n = 6) compared with normal thyroid tissues by quantitative RT-PCR. miR-191 expression was restored in the follicular thyroid cell line WRO, and the effects on cell proliferation, migration, and target expression were evaluated.

RESULTS

miR-191 is down-regulated in follicular adenoma, FTC, and follicular variant of PTC. We identified CDK6, a serine-threonine kinase involved in the control of cell cycle progression, as a novel target of miR-191. Restoration of miR-191 expression in WRO cells reduces cell growth and migration rate on vitronectin. CDK6 overexpression, correlated with miR-191 down-regulation, was found in follicular adenoma and FTC, suggesting a role of miR-191 down-regulation in the generation of these neoplasias.

CONCLUSIONS

Our results suggest that miR-191 down-regulation plays a role in thyroid neoplasias of the follicular histotype, likely by targeting CDK6.

Cortical lesions in radiologically isolated syndrome

OBJECTIVE

To assess the presence of cortical lesions (CLs) as detected by MRI in subjects with radiologically isolated syndrome (RIS).

METHODS

Fifteen subjects with RIS underwent an MRI examination, including a double inversion recovery sequence for CL assessment. T2-hyperintense white matter (WM) lesion volume (LV) and normalized volumes of brain and cortex were also obtained.

RESULTS

Thirty-four CLs were identified in 6 of 15 (40%) subjects with RIS and predominantly distributed in frontotemporal lobes. CLs were frequent in subjects with RIS with immunoglobulin G oligoclonal bands on CSF, cervical cord lesions, and dissemination in time on brain MRI. WM LV was higher in subjects with CLs than in those without CLs (11.5 ± 10.1 vs 3.9 ± 2.8 cm(3), p = 0.04). Indeed, CL number and volume correlated with WM LV (r = 0.57, p = 0.03 and r = 0.61, p = 0.01). All subjects with CLs were classified in a previous study as having a very high probability of having relapsing-remitting multiple sclerosis (MS) on a logistic regression analysis of quantitative MRI indices.

CONCLUSIONS

We found CLs in subjects with RIS, a condition characterized by the unanticipated MRI finding of WM lesions highly suggestive of MS in the absence of a clinical scenario. CLs were mainly localized to the frontotemporal lobes and were associated with important markers of evolution to MS.

MiR-1 is a tumor suppressor in thyroid carcinogenesis targeting CCND2, CXCR4, and SDF-1alpha

CONTEXT

Micro-RNA have emerged as an important class of short endogenous RNA that act as posttranscriptional regulators of gene expression and are constantly deregulated in human cancer. MiR-1 has been found down-regulated in lung, colon, and prostate cancer.

OBJECTIVES

In this study, we investigated the possible role of miR-1 in thyroid carcinogenesis.

DESIGN

We have analyzed miR-1 expression in a panel of thyroid neoplasias including benign and malignant lesions and searched for miR-1 targets.

RESULTS

Our results show that miR-1 expression is drastically down-regulated in thyroid adenomas and carcinomas in comparison with normal thyroid tissue. Interestingly, miR-1 down-regulation was also found in thyroid hyperproliferative nonneoplastic lesions such as goiters. We identified the CCND2, coding for the cyclin D2 (CCND2) protein that favors the G1/S transition, CXCR4, and SDF-1α genes, coding for the receptor for the stromal cell derived factor-1 (SDF-1)/CXCL12 chemokine and its ligand SDF-1/CXCL12, respectively, as miR-1 targets. An inverse correlation was found between miR-1 expression and CXC chemokine receptor 4 (CXCR4) and SDF-1α protein levels in papillary and anaplastic thyroid carcinomas. Consistent with a role of the CCND2 protein in cell proliferation and CXCR4 and SDF-1α proteins in cell invasion and metastasis, functional studies demonstrate that miR-1 is able to inhibit thyroid carcinoma cell proliferation and migration.

CONCLUSIONS

These results indicate the involvement of miR-1 in thyroid cell proliferation and migration, validating a role of miR-1 down-regulation in thyroid carcinogenesis.

Four novel CYP27A1 mutations in seven Italian patients with CTX

BACKGROUND AND PURPOSE

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disease, because of sterol 27-hydroxylase deficiency. Clinical manifestations of CTX are tendon xanthomas, juvenile cataracts, osteoporosis, diarrhoea and multiple progressive neurological dysfunctions. More than 300 patients with CTX have been reported to date worldwide and about fifty different mutations identified in CYP27A1 gene. This study describes the clinical and laboratory findings of seven new patients.

METHODS

We report the molecular and clinical characterization of seven new Italian patients with CTX carrying four novel mutations.

RESULTS

We identified four novel mutations located in different exons, in particular in the region of exons 2-5 of the CYP27A1 gene. Phenotypical expression did not differ from classical CTX presentation except for absence of tendon xanthomas in two patients.

Abstract 2027: CBX7 protein, whose expression is decreased in human carcinomas, positively regulates E-cadherin expression by interacting with the HDAC2 protein

CBX7 is a chromobox family protein encoding a novel Polycomb protein whose expression shows a progressive reduction, well related with the malignant grade of the thyroid neoplasias. Indeed, CBX7 protein levels decreased in an increasing percentage of cases going from benign adenomas to papillary, follicular and anaplastic thyroid carcinomas. To elucidate the function of CBX7 in carcinogenesis, we searched for CBX7 interacting proteins by a proteomic analysis. By this approach, we identified several proteins among which we selected Histone deacetylase 2 that is well known to play a key role in neoplastic cell transformation and to downregulate E-cadherin expression, whose loss is a critical event in the Epithelial-Mesenchymal Transition (EMT). We confirmed by co-immunoprecipitation that CBX7 physically interacts with the Histone deacetylase 2 protein and is able to inhibit its activity. Then, we showed that both these proteins bind the E-cadherin promoter, and that CBX7 is able to upregulate E-cadherin expression. Consistent with these data we found a positive statistical correlation between CBX7 and E-cadherin expression in human thyroid carcinomas. Finally, we demonstrated that the expression of CBX7 increases the acetylation status of the histones H3 and H4 on the E-cadherin promoter. Therefore, the ability of CBX7 to positively regulate E-cadherin expression by interacting with Histone deacetylase 2 and inhibiting its activity on the E-cadherin promoter would account for the correlation between the loss of CBX7 expression and a highly malignant phenotype in thyroid cancer patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2027. doi:10.1158/1538-7445.AM2011-2027

Chronic cerebro-spinal venous insufficiency (CCSVI) and multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS caused by the interplay of genetic and environmental factors. In the last years, it has been suggested that an abnormal venous drainage due to stenosis or malformation of the internal jugular and/or azygous veins may play a major pathogenetic role in MS. This abnormality called chronic cerebro-spinal venous insufficiency (CCSVI) could result in increased permeability of blood brain barrier, local iron deposition and secondary multifocal inflammation. In the present paper, literature data in favour and against this hypothesis are reported. A great variability of CCSVI has been found in both MS patients (ranging from 0 to 100%) and in control subjects (from 0 to 23%). This large variability is explained by methodological aspects, problems in assessing CCSVI, and differences among clinical series. It is urgent to perform appropriate epidemiological studies to define the possible relationship between CCSVI and MS.

Clinical relevance and neurophysiological correlates of spasticity in cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX) is a rare neurometabolic disease due to defective activity of sterol 27-hydroxylase, with plasma and tissue cholestanol storage. Clinical phenotype is characterized by both systemic manifestations and neurological signs. Therapy with chenodeoxycholic acid (CDCA) suppresses abnormal bile acid synthesis. The purpose of the study was to assess the frequency and clinical relevance of spasticity in the CTX phenotype and to study the usefulness of transcranial magnetic stimulation (TMS) in detecting corticospinal tract damage and monitoring the effects of replacement therapy. Twenty-four CTX patients underwent clinical evaluation including general disability scores, pyramidal and cerebellar function scales, assessment of serum cholestanol and TMS. Nine patients who started CDCA therapy at baseline received clinical and neurophysiological follow up. All patients showed signs of pyramidal damage which were relevant for clinical disability in 18 out of 24 cases (75%), resulting in spastic paraparesis. TMS revealed corticospinal alterations even in subjects with mild clinical signs of corticospinal tract involvement. After CDCA treatment, serum cholestanol decreased to normal concentrations in all patients. Clinical picture was unchanged in seven out of nine cases; in two others pyramidal signs disappeared. A reduction in abnormal neurophysiological parameters was found. Spastic paraparesis is the most frequent and relevant neurological feature in CTX patients. Replacement treatment with CDCA can prevent the progression of pyramidal damage, especially if started early in the course of the disease. TMS represents a sensitive indicator of corticospinal tract dysfunction and subclinical improvements in pyramidal function after CDCA therapy.

Clinical relevance of brain volume changes in patients with cerebrotendinous xanthomatosis

OBJECTIVE

To quantify total and regional brain damage in subjects with cerebrotendinous xanthomatosis (CTX) using MR based quantitative measures.

BACKGROUND

CTX is a rare inherited disorder characterised by progressive neurological impairment. Appropriate therapy can slow disease progression. Measures of brain volume changes have been used in several neurological disorders due to their value in assessing disease outcome and monitoring patients' evolution.

METHODS

24 CTX patients underwent conventional MRI to measure total and regional brain volumes. In five CTX patients who started therapy at baseline, clinical and MRI examinations were repeated after 2 years. Clinical disability, overall cognitive performance and cerebellar function were evaluated using the modified Rankin Scale (RS), Mini Mental Status Examination (MMSE) and cerebellar functional system score (CB-FSS).

RESULTS

Measures of normalised brain, cortical and cerebellar volumes were lower in CTX patients than in healthy controls (p<0.01). Instead, there were no differences in normalised white matter volumes between the two groups (p=0.1). At regional analysis, a significant volume decrease was found in each cortical region (p<0.01 for all regions). Normalised cortical volumes correlated closely with age (r=-0.9, p<0.0001), RS (r=-0.65, p<0.001) and MMSE (r=-0.60, p<0.01). Normalised cerebellar volumes correlated closely with CB-FSS scores (r=-0.58, p<0.01). In the five CTX patients followed over time, the annual brain volume decrease was -1.1 ± 0.2%.

CONCLUSIONS

Cortical volume, rather than white matter volume, is diffusely decreased in CTX patients and correlates closely with the patient's clinical status. These data provide evidence for the presence of clinically relevant neuronal-axonal damage in the brains of CTX patients.

Ataxia with vitamin E deficiency: update of molecular diagnosis

Ataxia with vitamin E deficiency (AVED) is a rare autosomal recessive neurodegenerative disease, due to mutations in TTPA gene (Arita et al. in Biochem J 306(Pt. 2):437-443, 1995; Hentati et al. in Ann Neurol 39:295-300, 1996), which encodes for alpha-TTP, a cytosolic liver protein that is presumed to function in the intracellular transport of alpha-tocopherol. This disease is characterized clinically by symptoms with often striking resemblance to those of Friedreich ataxia. The neurological symptoms include ataxia, dysarthria, hyporeflexia, and decreased vibration sense, sometimes associated with cardiomyopathy and retinitis pigmentosa (Mariotti et al. in Neurol Sci 25:130-137, 2004). Vitamin E supplementation improves symptoms and prevents disease progress (Doria-Lamba et al. in Eur J Pediatr 165(7):494-495, 2006). Over 20 mutations have been identified in patients with AVED. In the present paper we summarize the recent findings on molecular genetic of this disease including the list of the known mutations.

Four novel CYP27A1 mutations in seven Italian patients with CTX

BACKGROUND AND PURPOSE

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disease, because of sterol 27-hydroxylase deficiency. Clinical manifestations of CTX are tendon xanthomas, juvenile cataracts, osteoporosis, diarrhoea and multiple progressive neurological dysfunctions. More than 300 patients with CTX have been reported to date worldwide and about fifty different mutations identified in CYP27A1 gene. This study describes the clinical and laboratory findings of seven new patients.

METHODS

We report the molecular and clinical characterization of seven new Italian patients with CTX carrying four novel mutations.

RESULTS

We identified four novel mutations located in different exons, in particular in the region of exons 2-5 of the CYP27A1 gene. Phenotypical expression did not differ from classical CTX presentation except for absence of tendon xanthomas in two patients.

Loss of the CBX7 protein expression correlates with a more aggressive phenotype in pancreatic cancer

Polycomb group (PcG) proteins function as multiprotein complexes and are part of a gene regulatory mechanism that determines cell fate during normal and pathogenic development. Several studies have implicated the deregulation of different PcG proteins in neoplastic progression. Pancreatic ductal adenocarcinoma is an aggressive neoplasm that follows a multistep model of progression through precursor lesions called pancreatic intraepithelial neoplasia (PanIN). Aim of this study was to investigate the role of PcG protein CBX7 in pancreatic carcinogenesis and to evaluate its possible diagnostic and prognostic significance. We analysed by immunohistochemistry the expression of CBX7 in 210 ductal pancreatic adenocarcinomas from resection specimens, combined on a tissue microarray (TMA) including additional 40 PanIN cases and 40 normal controls. The results were evaluated by using receiver operating characteristic (ROC) curve analysis for the selection of cut-off scores and correlated to the clinicopathological parameters of the tumours and the outcome of the patients. Expression of E-cadherin, a protein positively regulated by CBX7, was also assessed. A significantly differential, and progressively decreasing CBX7 protein expression was found between normal pancreatic tissue, PanINs and invasive ductal adenocarcinoma. Loss of CBX7 expression was associated with increasing malignancy grade in pancreatic adenocarcinoma, whereas the maintenance of CBX7 expression showed a trend toward a longer survival. Moreover, loss of E-cadherin expression was associated with loss of CBX7 and with a trend towards worse patient survival. These results suggest that CBX7 plays a role in pancreatic carcinogenesis and that its loss of expression correlates to a more aggressive phenotype.

Alcoholic beverages and gastric epithelial cell viability: effect on oxidative stress-induced damage

Alcohol is known to cause damage to the gastric epithelium independently of gastric acid secretion. Different alcoholic beverages exert different damaging effects in the stomach. However, this has not been systematically evaluated. Moreover, it is not known whether the non-alcoholic components of alcoholic beverages also play a role in the pathogenesis of gastric epithelial cell damage. Therefore, this study was designed to evaluate whether different alcoholic beverages, at a similar ethanol concentration, exerted different damaging effect in gastric epithelial cells in vitro. Moreover, we evaluated whether pre-treatment of gastric epithelial cells with alcoholic beverages prevented oxidative stress-induced damage to gastric cells. Cell damage was assessed, in MKN-28 gastric epithelial cells, by MTT assay. Oxidative stress was induced by incubating cells with xanthine and xanthine oxidase. Gastric cell viability was assessed following 30, 60, and 120 minutes incubation with ethanol 17.5-125 mg/ml(-1) or different alcoholic beverages (i.e., beer, white wine, red wine, spirits) at comparable ethanol concentration. Finally, we assessed whether pre-incubation with red wine (with or without ethanol) prevented oxidative stress-induced cell damage. Red wine caused less damage to gastric epithelial cells in vitro compared with other alcoholic beverages at comparable ethanol concentration. Pre-treatment with red wine, but not with dealcoholate red wine, significantly and time-dependently prevented oxidative stress-induced cell damage.

CONCLUSIONS

1) red wine is less harmful to gastric epithelial cells than other alcoholic beverages; 2) this seems related to the non-alcoholic components of red wine, because other alcoholic beverages with comparable ethanol concentration exerted more damage than red wine; 3) red wine prevents oxidative stress-induced cell damage and this seems to be related to its ethanol content.

Evaluation of brain apoptosis in a CADASIL postmortem case

OBJECTIVE

To evaluate the role of apoptosis in the pathogenesis of brain lesions in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a hereditary microangiopathy leading to cognitive decline and dementia, caused by mutations in the NOTCH3 gene.

MATERIALS AND METHODS

Detection of apoptotic nuclei in temporal lobe, brain stem, medulla oblongata, hippocampus and basal ganglia from one young CADASIL patient was performed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL).

RESULTS

Our results showed a great involvement of glial cells in apoptotic cell death in the majority of the brain regions examined; neuronal apoptosis was significantly present only in the brain stem region.

CONCLUSIONS

We hypothesized that in the early stages of the disease neuronal involvement of apoptosis is limited to the cells of the brain stem, sparing the cortical area which is involved in neuronal apoptosis and cognitive decline later.

Chromobox protein homologue 7 protein, with decreased expression in human carcinomas, positively regulates E-cadherin expression by interacting with the histone deacetylase 2 protein

Chromobox protein homologue 7 (CBX7) is a chromobox family protein encoding a novel polycomb protein, the expression of which shows a progressive reduction, well related with the malignant grade of the thyroid neoplasias. Indeed, CBX7 protein levels decreased in an increasing percentage of cases going from benign adenomas to papillary, follicular, and anaplastic thyroid carcinomas. To elucidate the function of CBX7 in carcinogenesis, we searched for CBX7 interacting proteins by a proteomic analysis. By this approach, we identified several proteins. Among these proteins, we selected histone deacetylase 2 (HDAC2), which is well known to play a key role in neoplastic cell transformation and down-regulation of E-cadherin expression, the loss of which is a critical event in the epithelial-to-mesenchymal transition. We confirmed by coimmunoprecipitation that CBX7 physically interacts with the HDAC2 protein and is able to inhibit its activity. Then, we showed that both these proteins bind the E-cadherin promoter and that CBX7 up-regulates E-cadherin expression. Consistent with these data, we found a positive statistical correlation between CBX7 and E-cadherin expression in human thyroid carcinomas. Finally, we showed that the expression of CBX7 increases the acetylation status of the histones H3 and H4 on the E-cadherin promoter. Therefore, the ability of CBX7 to positively regulate E-cadherin expression by interacting with HDAC2 and inhibiting its activity on the E-cadherin promoter would account for the correlation between the loss of CBX7 expression and a highly malignant phenotype.