The emerging role of large immunophilin FK506 binding protein 51 in cancer

FK506 binding protein 51 (FKBP51) is an immunophilin physiologically expressed in lymphocytes. Very recently, aberrant expression of this protein was found in melanoma; FKBP51 expression correlates with melanoma aggressiveness and is maximal in metastatic lesions. FKBP51 promotes NF-κB activation and is involved in the resistance to genotoxic agents, including anthracyclines and ionizing radiation. FKBP51 is a cochaperone with peptidyl-prolyl isomerase activity that regulates several biological processes through protein-protein interaction. There is increasing evidence that FKBP51 hyperexpression is associated with cancer and this protein has a relevant role in sustaining cell growth, malignancy, and resistance to therapy. There is also evidence that FKBP ligands are potent anticancer agents, in addition to their immunosuppressant activity. In particular, rapamycin and its analogs have shown antitumor activity across a variety of human cancers in clinical trials. Although, classically, rapamycin actions are ascribed to inhibition of mTOR, recent studies indicate FKBP51 is also an important molecular determinant of the drug's anticancer activity. The aim of this article is to review the functions of FKBP51, especially in view of the recent findings that this protein is a potential oncogene when deregulated and a candidate target for signaling therapies against cancer.

Tissue distribution and metabolism of guanosine in rats following intraperitoneal injection

Guanosine has long been known as an endogenous purine nucleoside deeply involved in the modulation of several intracellular processes, especially G-protein activity. More recently, it has been reported to act as an extracellular signaling molecule released from neurons and, more markedly, from astrocytes either in basal conditions or after different kinds of stimulation including hypoxia. Moreover, in vivo studies have shown that guanosine plays an important role as both a neuroprotective and neurotrophic agent in the central nervous system. Specific high-affinity binding sites for this nucleoside have been found on membrane preparations from rat brain. The present study was undertaken to investigate the distribution and metabolic profiles of guanosine after administering the nucleoside to gain a better understanding of the biological effects of this potential drug candidate. Rats were given an intraperitonal (i.p.) injection of 2, 4, 8 or 16 mg/kg of guanosine combined with 0.05% of [3H]guanosine. Plasma samples were collected 7.5, 15, 30, 60 and 90 min after the guanosine-mixture administration and analyzed by either a liquid scintillation counter or by HPLC connected to a UV and to an on-line radiochemical detector to measure the levels of guanosine and its metabolic products guanine, xanthine and uric acid. The levels of guanosine, guanine and xanthine were also measured in brain, lung, heart, kidney and liver tissue homogenates at the defined time points after the injection of 8 mg/kg of the guanosine-mixture. We found that the levels of radioactivity in plasma increased linearly in a dose- and time-dependent manner. Guanosine was widely distributed in all tissues examined in the present study, at almost twice its usual levels. In addition, guanine levels dramatically increased in all the organs. Interestingly, enzymatic analysis of the plasma samples showed the presence of a soluble purine nucleoside phosphorylase, a key enzyme in the purine salvage pathway and nucleoside catabolism. Since guanosine has been shown to be neuroprotective and astrocytes have been reported to play critical roles in mediating neuronal survival and functions in different neurodegenerative disorders, we also performed uptake and release.

A set of miRNAs participates in the cellular senescence program in human diploid fibroblasts

Here we show that replicative senescence in normal human diploid IMR90 fibroblasts is accompanied by altered expression of a set of microRNAs (miRNAs) (senescence-associated miRNAs), with 14 and 10 miRNAs being either up or downregulated (>2-fold), respectively, in senescent with respect to young cells. The expression of most of these miRNAs was also deregulated upon senescence induced by DNA damage (etoposide) or mild oxidative stress (diethylmaleate). Four downregulated miRNAs were part of miRNA family-17, recently associated to human cell and tissue aging. Moreover, eight upregulated and six downregulated miRNAs mapped in specific chromosomal clusters, suggesting common transcriptional regulation. Upon adoptive overexpression, seven upregulated miRNAs induced the formation of senescence-associated heterochromatin foci and senescence-associated β-galactosidase staining (P<0.05), which was accompanied, in the case of five of them, by reduced cell proliferation. Finally, miR-210, miR-376a(*), miR-486-5p, miR-494, and miR-542-5p induced double-strand DNA breaks and reactive oxygen species accumulation in transfected cells. In conclusion, we have identified a set of human miRNAs induced during replicative and chemically induced senescence that are able to foster the senescent phenotype by prompting DNA damage.

Guanosine protects human neuroblastoma cells from oxidative stress and toxicity induced by Amyloid-beta peptide oligomers

Amyloid-beta (Abeta) peptide aggregation forms such as soluble oligomers (O) have a causal role in neuronal dysfunction and death associated with Alzheimer?s Disease (AD). The main efforts for the development of neuroprotective drugs are therefore focused on preventing Abeta production, aggregation or downstream neurotoxic events. We therefore investigated the effect of guanosine (GUO), a guanine based purine, that exerts neurotrophic and neuroprotective effects. The GUO showed the ability to reduce neuronal death in terms of apoptosis, but not necrosis, elicited by Abeta1-42O in human neuroblastoma SH-SY5Y cells. The neuroprotective effect was recorded only when the GUO was added simultaneously to treatment of the SH-SY5Y cells with Abeta1-42O. By contrast, the GUO treatment of SH-SY5Y cells before and after the appearance of beta1-42O toxicity had no neuroprotective effects. The employment of specific inhibitors showed the involvement of neuronal survival pathways, such as PI3K?Akt and MAPK-ERK for the GUO anti-apoptotic effects observed. In parallel, the SH-SY5Y cells treated with GUO, in experimental conditions similar to those adopted to evaluate neuronal death, showed a marked decrease of the early reactive oxygen species formation induced by Abeta1-42O and pro-oxidant H2O2. In the same neuronal model, GUO was also shown to inhibit the extra- and intra-cellular Abeta1-42 release as well as the beta-secretase activity evoked by H2O2 pro-oxidant action. Based on these findings, GUO and other guanine based purines appear to be a promising class of compounds with neuroprotective properties that may play an important role in the therapy of AD.

Posterior fossa imaging in 158 children with ataxia

OBJECTIFS

To propose a MRI cerebellar algorithm that may be applied to guide genetic/malformative or biochemical investigations for patients with cerebellar ataxia.

PATIENTS AND METHODS

Cerebral MRI of 158 patients with cerebellar ataxia and no supratentorial abnormality were examined according to a new categorization system based on posterior fossa imaging. The clinical and radiological findings were confronted to biochemical and/or genetic results using the MR cerebellar algorithm. Seven groups of cerebellar MRI pattern were described: vermian dysgenesis (n=27), cerebellar hypoplasia (n=15), hemispheric cerebellar dysgenesis (n=6), unilateral hemispheric atrophy (n=5), global cerebellar atrophy (n=84), signal abnormalities (n=11) and normal MRI (n=10). Cerebellar hypoplasia, vermian dysgenesis and hemispheric cerebellar dysgenesis groups were classified as malformative disorders. Global atrophy and signal abnormality groups were classified as metabolic disorders.

RESULTS

In the vermian dysgenesis group, a specific genetic diagnosis was obtained in eight children (8/27) and all of the mutated genes (AHI1 (JBS3), CEP290 (JBS5), TMEM67 (JBS6), and RPGRIP1L (JBS7)) are involved in primary cilia function. In the group of pontocerebellar hypoplasia specific genetic diagnosis was obtained in one patient (PCH2) (1/15). Thus, nine of 42 children classified as malformative disorder had a molecular diagnosis. Global atrophy and signal abnormality groups were classified as metabolic disorders, specific biochemical was obtained in 46/95 children. In global atrophy group, respiratory chain deficiency was diagnosed in 18 children (18/84). In 21 children a congenital disorders of glycosylation type 1a (CDG Ia) was diagnosed (21/84) and infantile neuroaxonale dystrophy (INAD) was diagnosed in one child. In signal abnormalities group, specific biochemical diagnosis was obtained in six out of 11 children, five children with respiratory chain deficiency and one child with sulphite oxidase deficiency. In hemispheric cerebellar dysgenesis and normal MRI groups, no biological diagnosis was found for any of the patients. In the group of unilateral hemispheric atrophy, we hypothesized a clastic prenatal injury.

CONCLUSION

The proposed MR cerebellar algorithm was useful to guide genetic/malformative or biochemical investigations, allowing an etiological diagnosis in 55 children.

Riluzole in cerebellar ataxia: a randomized, double-blind, placebo-controlled pilot trial

BACKGROUND

The pleiotropic effects of riluzole may antagonize common mechanisms underlying chronic cerebellar ataxia, a debilitating and untreatable consequence of various diseases.

METHODS

In a randomized, double-blind, placebo-controlled pilot trial, 40 patients presenting with cerebellar ataxias of different etiologies were randomly assigned to riluzole (100 mg/day) or placebo for 8 weeks. The following outcome measures were compared: proportion of patients with a decrease of at least 5 points in the International Cooperative Ataxia Rating Scale (ICARS) total score after 4 and 8 weeks compared with the baseline score; mean changes from the baseline to posttreatment ICARS (total score and subscores at 8 weeks); and occurrence of adverse events.

RESULTS

Riluzole and placebo groups did not differ in baseline characteristics. The number of patients with a 5-point ICARS drop was significantly higher in the riluzole group than in the placebo group after 4 weeks (9/19 vs 1/19; odds ratio [OR] = 16.2; 95% confidence interval [CI ] 1.8-147.1) and 8 weeks (13/19 vs 1/19; OR = 39.0; 95% CI 4.2-364.2). The mean change in the riluzole group ICARS after treatment revealed a decrease (p < 0.001) in the total score (-7.05 [4.96] vs 0.16 [2.65]) and major subscores (-2.11 [2.75] vs 0.68 [1.94] for static function, -4.11 [2.96] vs 0.37 [2.0] for kinetic function, and -0.74 [0.81] vs 0.05 [0.40] for dysarthria). Sporadic, mild adverse events occurred.

CONCLUSIONS

These findings indicate the potential effectiveness of riluzole as symptomatic therapy in diverse forms of cerebellar ataxia.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that riluzole reduces, by at least 5 points, the ICARS score in patients with a wide range of disorders that cause cerebellar ataxia (risk difference 63.2%, 95% CI 33.5%-79.9%).

Expanding CEP290 mutational spectrum in ciliopathies

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Markers of inflammation, thrombosis and endothelial activation correlate with carotid IMT regression in stable coronary disease after atorvastatin treatment

BACKGROUND AND AIMS

MIAMI is a prospective multicenter clinical study designed to investigate the relationship between changes in carotid intima-media thickness (C-IMT) and changes in circulating markers of inflammation, thrombosis and endothelial activation in stable coronary patients treated for 20+/-3.7 months with 20mg/day atorvastatin.

METHODS AND RESULTS

Eighty-five subjects had their C-IMT, blood lipids and soluble markers measured at baseline, at the 12th month and at the end of the study. Almost all soluble markers decreased upon treatment except for high-sensitivity C-reactive protein (hs-CRP), interleukin-18 (IL-18), tissue factor pathway inhibitor-free (TFPI-free) and soluble vascular cell adhesion molecules-1 (sVCAM-1) which did not change significantly, and interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and soluble CD40 ligand (sCD40L) which increased. sCD40L, fibrinogen, tissue factor pathway inhibitor-total (TFPI-total), soluble intercellular adhesion molecules-1 (sICAM-1), sE-selectin, interleukin-8 (IL-8) and von Willebrand factor (vWF) changed significantly even after application of the Bonferroni correction for multiple comparisons. Changes in lipids did not correlate with C-IMT regression either when considered singly or when combined in a lipid score. Changes in soluble markers correlated poorly with C-IMT regression when analyzed singly, but strongly when combined in relevant composite scores (inflammation/coagulation score, endothelial activation score, soluble markers score and total score).

CONCLUSION

In patients with stable coronary artery disease treated with moderate doses of atorvastatin, carotid IMT regression correlated with changes of inflammation, thrombosis and endothelial activation profiles.

The first founder DGUOK mutation associated with hepatocerebral mitochondrial DNA depletion syndrome

Deoxyguanosine kinase (dGK) deficiency is a frequent cause of mitochondrial DNA depletion associated with a hepatocerebral phenotype. In this study, we describe a new splice site mutation in the DGUOK gene and the clinical, radiologic, and genetic features of these DGUOK patients. This new DGUOK homozygous mutation (c.444-62C>A) was identified in three patients from two North-African consanguineous families with combined respiratory chain deficiencies and mitochondrial DNA depletion in the liver. Brain MRIs are normal in DGUOK patients in the literature. Interestingly, we found subtentorial abnormal myelination and moderate hyperintensity in the bilateral pallidi in our patients. This new mutation creates a cryptic splice site in intron 3 (in position -62) and is predicted to result in a larger protein with an in-frame insertion of 20 amino acids. In silico analysis of the putative impact of the insertion shows serious clashes in protein conformation: this insertion disrupts the alpha5 helix of the dGK kinase domain, rendering the protein unable to bind purine deoxyribonucleosides. In addition, a common haplotype that segregated with the disease in both families was detected by haplotype reconstruction with 10 markers (microsatellites and SNPs), which span 4.6 Mb of DNA covering the DGUOK locus. In conclusion, we report a new DGUOK splice site mutation that provide insight into a critical protein domain (dGK kinase domain) and the first founder mutation in a North-African population.

Protein kinase C θ (PKCθ) expression as a potential diagnostic marker for KIT-negative GIST

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Background: Currently, GIST is differentiated from other mesenchymal tumors based on morphologic characteristics and immunohistochemical detection of KIT. Nevertheless, 5% of tumors with clinicopathologic features of GIST lack KIT expression (KIT-negative GIST). A precise diagnosis of GIST is crucial due to the therapeutic efficacy of tyrosine kinase inhibitors. Our goal was to characterize mutational status of tyrosine kinase receptors (KIT and PDGFRA) and to evaluate the value of PKCθ as a diagnostic marker in KIT-negative GISTs. Methods: KIT-negative GISTs (n=22) were analyzed in a retrospective manner. As controls, we included KIT-positive GISTs (n=46), mesenchymal non-GIST tumors (n=28) and KIT-positive non-GIST tumors (n=32). PKCθ and diagnostic markers including CD34, S-100 and desmin were analyzed by immunohistochemistry using a tissue microarray. The χ2test was used to compare the presence of PKCθ among the tumors included. Further, PDGFRA gene (exons 12, 14, 18) and KIT gene (exons 9, 11) were examined in KIT-negative GISTs (n=14) by sequencing. Results: PKCθ expression was detected in 63.6% (14/22) of KIT-negative GISTs and this was significantly higher than the frequency of non-GIST tumors (23.3%; 14/60) (p=0.001). PKCθ was detected in 83.7% of KIT-positive GISTs. We found no significant difference between expression rates for PKCθ in KIT-negative and KIT positive GISTs (p=0.069). However, expression rates for PKCθ was higher among all GISTs, regardless KIT expression, when compared to non-GISTs tumors (p<0.001). In addition, among KIT-negative GISTs, CD34 was detected in 59.1% and desmin in 13.6%. None expressed S-100. PDGFRA mutations were found in 5/14 (35.7%) (exon 18, 33.3%; exon 12, 33.3%; exon 14, 16.7%). KIT mutation was found in 1/14 (16.7%; exon 9) tumors analyzed. Conclusions: In contrast to previous reports, there was no predominance of PDGFRA exon 18 mutations in our KIT-negative GISTs. Further, mutation frequency was lower in these tumors than those reported for KIT-positive GISTs. The diagnostic and pathogenic relevance of both PDGFRA and KIT mutations should be better explored. In this study, PKCθ could differentiate GIST, regardless KIT expression, from non-GIST tumors and emerged as a potential diagnostic biomarker for KIT-negative GISTs.

No significant financial relationships to disclose.

Multiple OXPHOS deficiency in the liver of a patient with CblA methylmalonic aciduria sensitive to vitamin B(12)

An adult patient with methylmalonic aciduria due to defective cobalamin synthesis (CblA) responsive to vitamin B(12) presented suddenly with severe visual impairment ascribed to optic atrophy followed by a fatal multiorgan failure and lactic acidosis but low methylmalonic acid in plasma and urine. Multiple deficiency of oxidative phosphorylation was found in the patient's liver. We suggest that patients with B(12)-sensitive methylmalonic aciduria who have a milder clinical course should be carefully monitored for long-term complications.

Differentiated thyroid carcinoma (DTC) in a young woman with Peutz-Jeghers syndrome: are these two conditions associated?

AIMS

Peutz-Jeghers Syndrome (PJS) is a rare dominantly inherited disease characterized by hamartomatous small bowel polyposis, mucocutaneous hyperpigmentation, and increased risk of cancer. Differentiated thyroid cancers (DTCs) present mainly as sporadic, but they may have also a familial component. We present a case of PJS in a caucasian 25 years-old woman, who developed a DTC.

METHODS

The patient had a palpable nodule in the right side of the thyroid region and an endocrinological evaluation, including hormonal assays, neck ultrasound (US) and fine needle aspiration (FNAB) of the nodule was performed.

RESULTS

US confirmed a single nodular lesion in the right thyroid lobe (14 mm). Cytological analysis at FNAB revealed a pattern compatible with papillary thyroid carcinoma. The histological analysis after total thyroidectomy confirmed the diagnosis of a Hurtle cell variant of papillary thyroid carcinoma, with follicular architecture.

CONCLUSION

Even though rare, the association between PJS and DTC can be possible. In clinical practice it must be borne in mind that the wide spectrum of possible cancer diseases occurring in PJS could also include DTC, that the latter can occur earlier in life in PJS population and with a more aggressive histological pattern. Furthermore, in patients with PJS, US of the thyroid should be performed whenever thyroid disease is suspected at physical examination or based on patient's medical history. Due to lack of established data allowing for a real esteem of the association between PJS and DTC, US of the thyroid, should not be recommended as a routine screening for all subjects with PJS.