1,721,071 research outputs found
Microbiota-Gut-Brain Axis in Neurological Disorders: From Leaky Barriers Microanatomical Changes to Biochemical Processes
No full textThe gastrointestinal tract and the Central Nervous System are distinct because of evident morpho-functional features. Nonetheless, evidence indicates that these systems are bidirectionally connected through the gut-brain axis, defined as the signaling that takes place between the gastrointestinal tract and Central Nervous System, which plays in concert with the gut microbiota, i.e. the myriad of microorganisms residing in the lumen of the human intestine. In particular, it has been described that gut microbiota abnormalities, referred to as dysbiosis, may affect both Central Nervous System development and physiology
Dual investigation of Myeloid and Lymphoid compartments: role of miRNAs in MDS and HOXA9 in B-ALL
No full textHere we report an exploration of uncommonly investigated molecules in these diseases, microRNA in MDS, and HoxA9 in B-ALL.
miRNAs are small non-coding RNAs that regulate gene expression and are linked to cancer development and progression. MDS with an increased risk of AML progression are managed using hypomethylating agents(azacytidine), alone or in conjunction with other drugs. miRNA expression of 26 high-risk MDS-patients treated with azacytidine and lenalidomide, at baseline and during therapy, were analyzed. miR-192-5p was discovered as differentially expressed during therapy response. Patients were clustered in responder, non-responder, and early losing-response and showed a different expression of this miRNA, as well as of its target BCL2. This investigation also revealed a significant association between miR-192-5p levels during the therapy and extended Overall Survival (OS) and Leukemia-Free Survival (LFS) in responder patients.
On the ALL side, HoxA9 is a member of the Hox-gene family. Dysregulated expression of HoxA9 has been associated with leukemia, where is commonly upregulated. A recent publication revealed a significant downregulation of HoxA9 mRNA levels in leukemic murine samples when compared with normal B-cell precursors. This was highly surprising, because HoxA9 is an oncogene involved in AML, T-ALL, and B-ALL with MLL rearrangement, and led to speculate on tumor suppressive role of this gene in IL7R mutant B-ALL. Proliferation on human cell lines was then assessed and the result was a proliferative disadvantage associated with HoxA9 overexpression. The downregulation mechanism was then investigated, evaluating on mice-derived leukemic cells the effect of SAHA.
The aim of this dual investigation of miRNA in MDS and HoxA9 in B-ALL is to increase the understanding of the intricate web of molecular events that drive these hematological malignancies, ultimately striving for improved patient management and outcome
TiMMing: developing an innovative suite of bioinformatic tools to harmonize and track the origin of copy number alterations in the evolutive history of multiple myeloma
Full text linkMultiple Myeloma (MM) is a hematologic cancer with heterogeneous and complex genomic landscape, where Copy Number Alterations (CNAs) play a key role in the disease's pathogenesis and prognosis. It is of biological and clinical interest to study the temporal occurrence of early alterations, as they play a disease "driver" function by deregulating key tumor pathways.
This study presents an innovative bioinformatic tools suite created for harmonizing and tracing the origin of CNAs throughout the evolutionary history of MM. To this aim, large cohorts of newly-diagnosed MM (NDMM, N=1582) and Smoldering-MM (SMM, N=282) were aggregated.
The tools developed in this study enable the harmonization of CNAs as obtained from different genomic platforms in such a way that a high statistical power can be obtained. By doing so, the high numerosity of those cohorts was harnessed for the identification of novel genes characterized as "driver" (NFKB2, NOTCH2, MAX, EVI5 and MYC-ME2-enhancer), and the generation of an innovative timing model, implemented with a statistical method to introduce confidence intervals in the CNAs-calls.
By applying this model on both NDMM and SMM cohorts, it was possible to identify specific CNAs (1q(CKS1B)amp, 13q(RB1)del, 11q(CCND1)amp and 14q(MAX)del) and categorize them as "early"/ "driver" events. A high level of precision was guaranteed by the narrow confidence intervals in the timing estimates. These CNAs were proposed as critical MM alterations, which play a foundational role in the evolutionary history of both SMM and NDMM. Finally, a multivariate survival model was able to identify the independent genomic alterations with the greatest effect on patients’ survival, including RB1-del, CKS1B-amp, MYC-amp, NOTCH2-amp and TRAF3-del/mut.
In conclusion, the alterations that were identified as both "early-drivers” and correlated with patients’ survival were proposed as biomarkers that, if included in wider survival models, could provide a better disease stratification and an improved prognosis definition
Phospholipase C B1 (PLCB1) and acute myeloid leukemia: correlation study between PLCB1 and the epigenetic mechanisms underlying acute myeloid leukemia
Full text linkLa presente tesi si focalizza sullo studio della relazione tra la via di trasduzione del segnale dalla fosfolipasi C (PLC) β1 e la leucemogenesi, in una linea cellulare umana di Leucemia Mieloide Acuta (LAM) monocitica, identificando alcuni potenziali meccanismi epigenetici implicati nella proliferazione incontrollata dei blasti leucemici nella LAM MLL-AF9.
Numerose evidenze sperimentali hanno ormai stabilito la presenza nel nucleo di fosfoinositidi (PIP) e degli enzimi che li regolano, che insieme partecipano a vie di segnalazione nucleari indipendenti rispetto a quelle citoplasmatiche. Fra questi enzimi nucleari, la PLCβ1 ricopre un ruolo importante nel controllare la proliferazione e il differenziamento cellulare. Recentemente, numerosi studi hanno inoltre dimostrato il potenziale ruolo dei PIP nucleari e dei loro enzimi regolatori nel controllo diretto dei fattori responsabili delle modificazioni dello stato della cromatina.
Nel presente studio, abbiamo dimostrato che la PLCβ1 risulta essere coinvolta nella patogenesi della LAM, attraverso la sua interazione con l’enzima KDM4A, una demetilasi della lisina 9 dell’istone H3. La PLCβ1 regola positivamente l’espressione dei geni HOXA, responsabili della proliferazione neoplastica dei blasti leucemici, modulando l’attività di KDM4A. In particolare, la PLCβ1 favorisce la demetilazione dell’istone H3K9 sul promotore di questi geni, da parte di KDM4A e di conseguenza la trascrizione genica. Esperimenti di microarray hanno permesso di identificare un profilo di espressione genica comune tra i due enzimi, che sembrano partecipare a una via di segnalazione epigenetica comune. Complessivamente, i dati ottenuti mostrano l’esistenza di un meccanismo di controllo da parte dei fosfoinositidi innovativo all’interno della LAM, dimostrando una loro implicazione nella patogenesi di questa malattia. Lo scopo, in futuro, è poter associare un inibitore per la PLCβ1 con nuove combinazioni di inibitori di fattori epigenetici che possano agire in sinergia per invertire questa trascrizione genica disregolata e quindi combattere la progressione del fenotipo leucemico.The current thesis focuses on the study of the relationship between phospholipase C (PLC) β1 signaling and leukemogenesis, in a human Acute Myeloid Leukemia (AML) monocytic cell line, identifying some new potential epigenetic mechanism involved in the leukemic blasts unregulated proliferation in MLL-AF9 driven AML.
Many experimental findings have now established the existence of the phosphoinositides (PIs) and of the enzymes responsible for their metabolism in the nucleus that together participate to nuclear signalling pathways, different and independent from the cytoplasmic counterpart. Among the enzymes of the inositol lipid cycle, PLCβ1 is a key enzyme in nuclear signal transduction, and it controls a wide range of cellular processes including proliferation and differentiation. Lately, many studies have also established the potential role of the nuclear PI and of their regulatory enzymes in the direct control of factors responsible for chromatin remodeling.
In this study, we discovered that PLCβ1 is involved in AML pathogenesis, through its interaction with KDM4A, a H3K9 histone demethylases. PLCβ1 positively regulates the expression of HOXA genes, that are responsible for the neoplastic proliferation of the leukemic blasts, by the modulation of KDM4A activity. In particular, PLCβ1 increases the H3K9 KDM4A mediated demethylation, on the promoter of HOXA genes, resulting in the activation of gene transcription. Gene-array studies allowed to identify a common expression pattern between the two enzymes, that seems to participate to a common epigenetic signalling pathway. Overall, this data shows the existence of an innovative control mechanism from phosphoinositides inside AML, which demonstrates their implication in the pathogenesis of this disease. The future aim is to associate a PLCβ1 specific inhibitor into a new combination of epigenetic factor inhibitor to act in synergy to fight the leukemic phenotype progression
Role of nuclear redox control, intra-population heterogeneity and oxygen tension in human amniotic fluid stem cells aging
Full text linkAmniotic fluid stem cells (hAFSC) are emerging as a potential therapeutic approach for various disorders. The low number of available hAFSC requires their ex vivo expansion prior to clinical use, however, during their in vitro culture, hAFSC quickly reach replicative senescence.
The principal aim of this study was to investigate the aging process occurring during in vitro expansion of hAFSC, focusing on the redox control that has been reported to be affected in premature and physiological aging.
My results show that a strong heterogeneity is present among samples that reflects their different behaviour in culture. I identified three proteins, namely Nox4, prelamin A and PML, which expression increases during hAFSC aging process and could be used as new biomarkers to screen the samples. Furthermore, I found that Nox4 degradation is regulated by sumoylation via proteasome and involves interactions with PML bodies and prelamin A.
Since various studies revealed that donor-dependent differences could be explained by cell-to-cell variation within each patient, I studied in deep this phenomenon.
I showed that the heterogeneity among samples is also accompanied by a strong intra-population heterogeneity. Separation of hAFSC subpopulations from the same donor, using Celector® technology, showed that an enrichment in the last eluted fraction could improve hAFSC application in regenerative medicine.
One of the other problems is that nowadays hAFSC are expanded under atmospheric O2 concentration, which is higher than the O2 tension in their natural niches. This higher O2 concentration might cause environmental stress to the in vitro cultured hAFSCs and accelerate their aging process.
Here, I showed that prolonged low oxygen tension exposure preserves different hAFSC stemness properties.
In conclusion, my study pointed different approaches to improve in vitro hAFSC expansion and manipulation with the purpose to land at stem cell therapy
Nuclear shape instability caused by lamin A deregulation promotes invasiveness in pediatric bone sarcomas: from nucleo-cytoskeleton dynamics to novel therapeutic opportunities
Full text linkOsteosarcoma (OS) and Ewing sarcoma (EWS) are the two most frequent primary bone tumors, in which metastases remain the most relevant adverse prognostic factor. Lamin A is the main constituent of the nuclear lamina, with a fundamental role in maintaining the connection between nucleus and cytoskeleton (through LINC complex proteins interactions), and its alterations can be implicated in tumor progression.
We investigated how nucleo-cytoskeleton dynamics is influenced by lamin A modulation in OS and EWS, demonstrating that both these cancer models had low levels of lamin A, which are linked to a significantly more marked nuclear misshaping. In our in vitro studies, reduced levels of lamin A promoted migratory abilities in these tumors. Moreover, these findings were corroborated by gene expression analyses on EWS patient samples, showing that LMNA levels were significantly lower in metastatic lesions compared to primary tumors and that patients with low LMNA had a significant worse overall survival. We also found that LMNA expression significantly impaired EWS metastases formation in vivo.
We demonstrated that low lamin A expression was linked to a severe mislocalization of LINC complex proteins, thus disrupting nucleo-cytoskeleton interactions, with a corresponding gain in malignant properties, which resulted in increased invasiveness. Lamin A overexpression or its accumulation by a statin-based pharmacological treatment allowed us to reconstitute a functional nucleo-cytoskeleton interplay, which resulted in significant downmodulation of ROCK2 and YAP, two crucial drivers of EWS aggressiveness.
Our study demonstrated that lamin A is a favorable mediator of nuclear shape stability in bone sarcomas, and its modulation rescues LINC complex protein localization and regulates mechano-signaling pathways, thus promoting a less aggressive cancer phenotype. We also identified statins, already employed in clinical practice, as a tool capable to increase lamin A levels, and to reconstitute functional nucleo-cytoskeletal dynamics, resulting in reduced cellular migration
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