studio dei meccanismi d'azione dei bifenili policlorurati non diossino-simili sul sistema immunitario ed endocrino

I PCB 101, PCB 153 e PCB 180 fanno parte del gruppo dei sette “PCB target”, ovvero i congeneri considerati dalla Comunità Scientifica Internazionale come indicatori del grado di contaminazione da PCB e diossine. I policlorobifenili sono inquinanti ampiamente presenti nell’ambiente, essi appartengono insieme alle diossine ed ai furani al gruppo dei Persistent Organic Pollutants (POP). Utilizzando una linea cellulare continua di macrofagi murini J774.A1, combinando tecniche biochimiche e morfologiche, è stato dimostrato che tali composti causano morte delle cellule macrofagiche per apoptosi. I nostri dati dimostrano che l’esposizione a questi inquinanti causa riduzione della vitalità cellulare e induce apoptosi in maniera concentrazione-dipendente, in particolare quando i PCB sono associati ad una concentrazione di per sé sub-citotossica (1 M) si evidenziava un effetto sinergico sulla morte cellulare e un’accelerazione del processo apoptotico. E’ stato dimostrato che l’apoptosi PCB-indotta è mediata dall’attivazione della caspasi-3 e dalla modulazione dell’espressione di proteine antiapoptotiche (in diminuzione di Bcl-2) e proapoptotiche (in aumento di Bax), suggerendo che tale processo fosse mediato dall’attivazione della via intrinseca. E’ noto inoltre che questi composti siano soggetti al bioaccumolo nel tessuto adiposo sia degli animali che dell’uomo. Questa osservazione è coerente con l'idea che i PCB possano essere coinvolti nello sviluppo e nella progressione di patologie endocrine-metaboliche (obesità, diabete, aumento del rischio di patologie cardio-vascolari, sindrome metabolica) e interferire con le normali funzioni endocrine del tessuto adiposo. La tossicità dei PCB è stata valutata considerando tali composti da soli o in associazione per evidenziarne l’eventuale effetto sinergico. In particolare è stata determinato l’effetto di tali inquinanti sulla funzione degli adipociti maturi. Il tessuto adiposo ricopre un ruolo cardine non solo nel deposito e nella mobilizzazione di sostanze ad elevata energia metabolica ma ricoprire un ruolo importante nella regolazione dell’omeostasi energetica dell’intero organismo attraverso la secrezione di specifici ormoni. L’iperleptinemia caratterizza la grande maggioranza degli obesi e molti studi evidenziano che tale ormone abbia un ruolo proaterogeno contribuendo all’insulino-resistenza, alterando la funzione endoteliale, favorendo l’aggregazione piastrinica e la trombosi arteriosa. Negli esperimenti condotti sugli adipociti maturi trattati con i PCB associati a due a due o tutti e tre insieme, si osservava un aumento dell’espressione della leptina in particolare quando si associava il PCB 153 con il 180 ed una concomitante riduzione dell’isoforma recettoriale ad attività biologica. Tale riduzione di Ob-Rb negli adipociti, associata alla elevata produzione dell’ormone, supporta l’insorgenza di una insensibilità all’ormone correlabile alla leptino-resistenza del tessuto adiposo tipica dell’alterazione metabolica periferica dell’obesità Per confermare tale ipotesi, abbiamo investigato come tali inquinanti ambientali modificassero l’espressione di importanti proteine coinvolte nel signaling della leptino-resistenza. In particolare la proteina PTP1B, regolatore negativo del signaling della leptina, che risulta essere aumentata per l’associazione del PCB 153 con il 180 o di tutti i PCB, sostenendo l’ipotesi che tali congeneri possano agire con meccanismo sinergico. Successivamente abbiamo valutato come tali inquinanti modulassero una delle vie di trasduzione del segnale intracellulare specifiche per il recettore Ob-Rb, JAK/STAT. L’effetto indotto dai PCB sulla via di trasduzione del segnale di STAT 3 negli adipociti maturi induce una diminuzione dell’espressione di pSTAT 3 ed un aumento dell’espressione di STAT 3 rispetto alle cellule di controllo che ricevono il veicolo. In particolare dai dati ottenuti si evidenzia una riduzione significativa della ratio pSTAT3/STAT3 nelle cellule trattate con i PCB in associazione (PCB 153+180 e tutti e tre insieme). Successivamente, è stata evidenziata la capacità di tali inquinanti di modulare l’espressione anche dell’adiponectina, dei sui recettori e un aumento dell’espressione della citochine pro- ed anti-infiammatorie IL-6 eTNF e IL-10 sia quando gli adipociti maturi erano trattati con i PCB da soli e ancor più in associazione.. I dati ottenuti appaiono interessanti poiché è noto che la sensibilità degli adipociti umani è generalmente maggiore degli adipociti murini, dimostrando che i PCB in esame, come altri sostanze nocive considerate EDC, possano esercitare affetti additivi e che la contemporanea esposizione dell’uomo a diversi agenti chimici, con più debole attività, possa avere effetti avversi non evidenziati per singola esposizione. Inoltre le concentrazioni studiate in vitro sono comparabili ai livelli dell’esposizione nell’uomo ma si deve considerare che i livelli in vivo possono variare in funzione al legame con le proteine plasmatiche e alla durata dell’esposizione. I dati riportati nella tesi supportano l’ipotesi che tali sostanze possano interferire con le pathway correlate allo sviluppo dell’obesità e delle patologie ad essa correlate

Targeting Interleukin-27 Receptor α in Murine HGSC Cells

https://openworks.mdanderson.org/sumexp23/1119/thumbnail.jp

Anti-tumoral activity of Acetogenins derived from Soursop Fruit (Annona muricata L.) in High Grade Serous Ovarian Cancer

https://openworks.mdanderson.org/sumexp21/1253/thumbnail.jp

Targeting AXL with a Highly Stable Modified Aptamer in Medulloblastoma Cell Lines

https://openworks.mdanderson.org/sumexp22/1081/thumbnail.jp

Effects of a Lactobacillus paracasei B21060 based synbiotic on steatosis, insulin signaling and toll-like receptor expression in rats fed a high-fat diet.

Insulin resistance (IR) has been identified as crucial pathophysiological factor in the development and progression of non-alcoholic fatty liver disease (NAFLD). Although mounting evidence suggests that perturbation of gut microflora exacerbates the severity of chronic liver diseases, therapeutic approaches using synbiotic has remained overlooked. Here, we show that a synbiotic composed by Lactobacillus paracasei B21060 plus arabinogalactan and fructo-oligosaccharides lessens NAFLD progression in a rat model of high fat feeding. IR and steatosis were induced by administration of high fat diet (HFD) for 6 weeks. Steatosis and hepatic inflammation, Toll-like receptor (TLR) pattern, glucose tolerance, insulin signaling and gut permeability were studied. Liver inflammatory markers were down-regulated in rats receiving the synbiotic, along with an increased expression of nuclear peroxisome proliferator-activated receptors and expression of downstream target genes. The synbiotic improved many aspects of IR, such as fasting response, hormonal homeostasis and glycemic control. Indeed it prevented the impairment of hepatic insulin signaling, reducing the phosphorylation of insulin receptor substrate-1 in Ser 307 and down-regulating suppressor of cytokine signaling 3. Gene expression analysis revealed that in the liver the synbiotic reduced cytokines synthesis and restored the HFD-dysregulated TLR 2, 4 and 9 mRNAs toward a physiological level of expression. The synbiotic preserved gut barrier integrity and reduced the relative amount of Gram-negative Enterobacteriales and Escherichia coli in colonic mucosa. Overall, our data indicate that the L. paracasei B21060 based synbiotic is effective in reducing the severity of liver injury and IR associated with high fat intake, suggesting its possible therapeutic/preventive clinical utilization

PRKAR1B-AS2 Long Noncoding RNA Promotes Tumorigenesis, Survival, and Chemoresistance via the PI3K/AKT/mTOR Pathway

Many long noncoding RNAs have been implicated in tumorigenesis and chemoresistance; however, the underlying mechanisms are not well understood. We investigated the role of PRKAR1B-AS2 long noncoding RNA in ovarian cancer (OC) and chemoresistance and identified potential downstream molecular circuitry underlying its action. Analysis of The Cancer Genome Atlas OC dataset, in vitro experiments, proteomic analysis, and a xenograft OC mouse model were implemented. Our findings indicated that overexpression of PRKAR1B-AS2 is negatively correlated with overall survival in OC patients. Furthermore, PRKAR1B-AS2 knockdown-attenuated proliferation, migration, and invasion of OC cells and ameliorated cisplatin and alpelisib resistance in vitro. In proteomic analysis, silencing PRKAR1B-AS2 markedly inhibited protein expression of PI3K-110α and abrogated the phosphorylation of PDK1, AKT, and mTOR, with no significant effect on PTEN. The RNA immunoprecipitation detected a physical interaction between PRKAR1B-AS2 and PI3K-110α. Moreover, PRKAR1B-AS2 knockdown by systemic administration of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine nanoparticles loaded with PRKAR1B-AS2–specific small interfering RNA enhanced cisplatin sensitivity in a xenograft OC mouse model. In conclusion, PRKAR1B-AS2 promotes tumor growth and confers chemoresistance by modulating the PI3K/AKT/mTOR pathway. Thus, targeting PRKAR1B-AS2 may represent a novel therapeutic approach for the treatment of OC patients

Chronic kidney disease, severe arterial and arteriolar sclerosis and kidney neoplasia: on the spectrum of kidney involvement in MELAS syndrome

<p>Abstract</p> <p>Background</p> <p>MELAS syndrome (MIM ID#540000), an acronym for Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-like episodes, is a genetically heterogeneous mitochondrial disorder with protean manifestations and occasional kidney involvement. Interest in the latter is rising due to the identification of cases with predominant kidney involvement and to the hypothesis of a link between mitochondrial DNA and kidney neoplasia.</p> <p>Case presentation</p> <p>We report the case of a 41-year-old male with full blown MELAS syndrome, with lactic acidosis and neurological impairment, affected by the "classic" 3243A > G mutation of mitochondrial DNA, with kidney cancer. After unilateral nephrectomy, he rapidly developed severe kidney functional impairment, with nephrotic proteinuria. Analysis of the kidney tissue at a distance from the two tumor lesions, sampled at the time of nephrectomy was performed in the context of normal blood pressure, recent onset of diabetes and before the appearance of proteinuria. The morphological examination revealed a widespread interstitial fibrosis with dense inflammatory infiltrate and tubular atrophy, mostly with thyroidization pattern. Vascular lesions were prominent: large vessels displayed marked intimal fibrosis and arterioles had hyaline deposits typical of hyaline arteriolosclerosis. These severe vascular lesions explained the different glomerular alterations including ischemic and obsolescent glomeruli, as is commonly observed in the so-called "benign" arteriolonephrosclerosis. Some rare glomeruli showed focal segmental glomerulosclerosis; as the patient subsequently developed nephrotic syndrome, these lesions suggest that silent ischemic changes may result in the development of focal segmental glomerulosclerosis secondary to nephron loss.</p> <p>Conclusions</p> <p>Nephron loss may trigger glomerular sclerosis, at least in some cases of MELAS-related nephropathy. Thus the incidence of kidney disease in the "survivors" of MELAS syndrome may increase as the support therapy of these patients improves.</p

Extra-Visual Functional and Structural Connection Abnormalities in Leber's Hereditary Optic Neuropathy

We assessed abnormalities within the principal brain resting state networks (RSNs) in patients with Leber's hereditary optic neuropathy (LHON) to define whether functional abnormalities in this disease are limited to the visual system or, conversely, tend to be more diffuse. We also defined the structural substrates of fMRI changes using a connectivity-based analysis of diffusion tensor (DT) MRI data. Neuro-ophthalmologic assessment, DT MRI and RS fMRI data were acquired from 13 LHON patients and 13 healthy controls. RS fMRI data were analyzed using independent component analysis and SPM5. A DT MRI connectivity-based parcellation analysis was performed using the primary visual and auditory cortices, bilaterally, as seed regions. Compared to controls, LHON patients had a significant increase of RS fluctuations in the primary visual and auditory cortices, bilaterally. They also showed decreased RS fluctuations in the right lateral occipital cortex and right temporal occipital fusiform cortex. Abnormalities of RS fluctuations were correlated significantly with retinal damage and disease duration. The DT MRI connectivity-based parcellation identified a higher number of clusters in the right auditory cortex in LHON vs. controls. Differences of cluster-centroid profiles were found between the two groups for all the four seeds analyzed. For three of these areas, a correspondence was found between abnormalities of functional and structural connectivities. These results suggest that functional and structural abnormalities extend beyond the visual network in LHON patients. Such abnormalities also involve the auditory network, thus corroborating the notion of a cross-modal plasticity between these sensory modalities in patients with severe visual deficits

Schizophrenia-associated somatic copy-number variants from 12,834 cases reveal recurrent NRXN1 and ABCB11 disruptions

While germline copy-number variants (CNVs) contribute to schizophrenia (SCZ) risk, the contribution of somatic CNVs (sCNVs)—present in some but not all cells—remains unknown. We identified sCNVs using blood-derived genotype arrays from 12,834 SCZ cases and 11,648 controls, filtering sCNVs at loci recurrently mutated in clonal blood disorders. Likely early-developmental sCNVs were more common in cases (0.91%) than controls (0.51%, p = 2.68e−4), with recurrent somatic deletions of exons 1–5 of the NRXN1 gene in five SCZ cases. Hi-C maps revealed ectopic, allele-specific loops forming between a potential cryptic promoter and non-coding cis-regulatory elements upon 5′ deletions in NRXN1. We also observed recurrent intragenic deletions of ABCB11, encoding a transporter implicated in anti-psychotic response, in five treatment-resistant SCZ cases and showed that ABCB11 is specifically enriched in neurons forming mesocortical and mesolimbic dopaminergic projections. Our results indicate potential roles of sCNVs in SCZ risk

Aptamers: Novel Therapeutics and Potential Role in Neuro-Oncology

A relatively new paradigm in cancer therapeutics is the use of cancer cell&ndash;specific aptamers, both as therapeutic agents and for targeted delivery of anticancer drugs. After the first therapeutic aptamer was described nearly 25 years ago, and the subsequent first aptamer drug approved, many efforts have been made to translate preclinical research into clinical oncology settings. Studies of aptamer-based technology have unveiled the vast potential of aptamers in therapeutic and diagnostic applications. Among pediatric solid cancers, brain tumors are the leading cause of death. Although a few aptamer-related translational studies have been performed in adult glioblastoma, the use of aptamers in pediatric neuro-oncology remains unexplored. This review will discuss the biology of aptamers, including mechanisms of targeting cell surface proteins, various modifications of aptamer structure to enhance therapeutic efficacy, the current state and challenges of aptamer use in neuro-oncology, and the potential therapeutic role of aptamers in pediatric brain tumors