1,721,159 research outputs found
MicroRNA coinvolti nello sviluppo del carcinoma epatocellulare. Identificazione delle proteine bersaglio.
No full textIl complesso mosaico dei meccanismi che regolano l’espressione genica si è recentemente arricchito di un nuovo tassello grazie alla scoperta dei microRNA (miRNA). Questo gruppo di piccoli RNA con funzione regolatoria ha catalizzato su di sé l’interesse del mondo scientifico da quando si è visto che questi RNA, della lunghezza di circa 22 nucleotidi, non solo sono altamente conservati tra le diverse specie, segno di una loro origine ancestrale, ma sono anche in grado di influenzare i livelli di espressione di numerose e specifiche proteine che ne costituiscono il bersaglio.
La scoperta dei microRNA avvenne all’inizio degli anni ’90 grazie a studi svolti in C. elegans. In questo nematode, fu scoperto che un piccolo RNA, lin-4, era responsabile dello spegnimento di una proteina che regola lo sviluppo larvale. Gli studi successivi, che si estesero anche ad altri organismi, permisero di capire che i microRNA costituiscono una grande famiglia di molecole in grado di regolare l’espressione genica a livello post-trascrizionale. Il loro ruolo appare molto diffuso e circa il 50% dei geni umani codificanti per proteine potrebbe essere in parte regolato da microRNA. Infatti, ciascun miRNA è in grado di esercitare la sua azione contemporaneamente su molti bersagli tramite l’appaiamento di sequenza con regioni omologhe nel 3’UTR del mRNA: dopo i diversi passaggi maturativi da pri-miRNA a pre-miRNA, il miRNA maturo (miR), lungo 22-25 nucleotidi, si appaia, per omologia di sequenza, con il 3’UTR dei geni bersaglio inducendo o il taglio proteolitico del mRNA o il blocco della traduzione proteica (questo secondo meccanismo è quello più frequente nelle cellule animali). È perciò logico che i microRNA abbiano come bersaglio geni coinvolti in tutte le funzioni cellulari e non solo nello sviluppo.
Pur essendo ancora numerosi gli aspetti da chiarire, a partire per esempio dal numero esatto di miRNA nei diversi organismi, emerge chiaramente l’importanza del ruolo di questi piccoli RNA nella fisiologia cellulare. È pertanto plausibile che alterazioni dei miRNA siano coinvolte in patologie umane. Infatti, accanto a ricerche volte a delucidare i meccanismi d’azione dei microRNA, si sono sviluppati diversi filoni di ricerca aventi lo scopo ultimo di rispondere a questa domanda: se i microRNA hanno un ruolo fisiologico così importante per la cellula, che cosa succede se la loro espressione viene alterata? O ancora, esistono patologie la cui causa sia attribuibile ad alterazioni dell’espressione dei microRNA o nella cui patogenesi siano coinvolte anche alterazioni dei microRNA? Il mio progetto si sviluppa in questo ambito. In particolare, la mia attenzione si rivolgerà allo studio delle eventuali alterazioni dell’espressione dei microRNA in tumori umani e alla messa a punto di sistemi utili per la correzione di queste alterazioni. Vi sono già evidenze che i microRNA siano espressi in modo aberrante in tumori umani. La prima evidenza è venuta dallo studio di caratterizzazione della delezione al cromosoma 13q14 nella leucemia linfatica cronica (LLC), in cui solo i mir-15a e mir-16-1 furono ritrovati nella minima regione di delezione [1]. Successivamente, mir-143 e mir-145 sono stati trovati significativamente sotto-espressi in carcinomi del colon [2], mentre il mir-155 è stato trovato sovra-espresso in linfomi di Burkitt ed altri tipi di linfoma [3, 4]. Infine, la scoperta che let-7, significativamente sottoespresso in tumori del polmone [5], ha come bersagli gli oncogeni K-RAS, N-RAS e H-RAS [6] ha dato supporto all’idea che i microRNA possano agire come oncogeni o come oncosoppressori, suggerendo anche che un’espressione aberrante dei microRNA in cellule tumorali possa identificare microRNA coinvolti nella patogenesi tumorale.
OBIETTIVI E STRATEGIE DI INDAGINE
Partendo da queste considerazioni preliminari, il mio progetto di studio si pone i seguenti obiettivi specifici:
1. Identificare i microRNA differenzialmente espressi in neoplasie umane, in particolare in epatocarcinomi confrontati con la loro controparte normale e con tessuti cirrotici.
2. Identificare il profilo di espressione dei microRNA associati a specifiche caratteristiche clinico-patologiche.
3. Identificare i geni bersaglio dei microRNA la cui espressione sia risultata alterata in HCC.
4. Sviluppare saggi funzionali in vitro ed in vivo con linee cellulari tumorali umane per valutare l’effetto biologico e molecolare dei microRNA la cui espressione sia risultata alterata nelle neoplasie e la validazione dei geni bersaglio tramite saggio dell'attività luciferasica e westrn blot
Progetto triennale AIRC (MFAG 2011). Titolo: Circulating microRNAs as cancer-specific biomarkers
No full textAn important area in cancer research is the identification of tumor markers that might improve the early diagnosis of cancer patients and reduce morbidity and mortality rates associated with the disease. Recently, microRNAs (miRNAs) have been added to the panel of plasma-detected biomarkers thanks to their cancer-specificity, high stability and the availability of assays able to quantify their level.
In addition, recent studies report the association between the deregulated expression of several miRNAs and the response to treatments, prognosis and metastatic potential of malignancies. The determination of miRNAs expression in cancerous tissue, however, requires the availability of tissue specimens which may represent a problem in non surgically treated patients. The availability of blood-circulating markers might overcome the limits of tissue sampling being non invasive and repeatable over time.
Using a microarray technology, we hereby propose to identify different sets of plasma miRNAs whose levels are indeed associated with each of the following cancer types: breast, gastrointestinal (gastric and colorectum), lung, pancreatic, melanoma, thyroid and hepatocellular. Circulating cancer-specific miRNAs will be compared to the miRNA profile of control populations (age-matched healthy subjects or cirrhotic patients for hepatocellular carcinoma). Cancer-associated miRNAs will be validated in an independent population of patients using a quantitative approach; their correlation with clinical-pathological information will be also investigated.
Finally, miRNA levels will be monitored after surgery, according to patients follow-up schedules, in order to verify if they can possibly predict cancer recurrence.
This study aims therefore (i) to assay plasma levels of circulating miRNAs as possible markers of increased risk of cancer development, (ii) to define a profile of circulating miRNAs characterizing cancers at different stages and (iii) to assess a panel of circulating miRNAs as possible early predictors of cancer recurrence after curative treatments.
If this project will be successful, a new panel of sensitive and specific biomarkers for cancer diagnosis and prognostic risk assessment will be available
Micromarkers 2.0: An update on the role of microRNAs in cancer diagnosis and prognosis
No full textThe identification of reliable diagnostic or prognostic biomarkers is one of the most pressing goals in oncological research. MicroRNAs have proven to be very promising cancer biomarkers because they are resistant to degradation in many tissue types (including FFPE specimens and body fluids), easily measured and, most importantly, their amount correlates with the presence of the tumor or with clinically relevant cancer features. In addition, our knowledge of microRNA genetic alterations in familial and sporadic cancer has recently improved. This review presents an update on cancer diagnostic and prognostic microRNAs, discusses novel tools for prognostic microRNAs identification and evaluates the possible translation of these discoveries to the clinic
Micro-markers: microRNAs in cancer diagnosis and prognosis
No full textMolecular diagnostics in cancer should provide the highest specificity and sensitivity in classification, prognostic stratification and early detection. MicroRNAs could contribute to hit the mark, or at least to come nearer, in virtue of their cancer-specific expression and stability. Indeed, differently from other RNA classes, microRNAs can be detected and quantified not only in frozen tissues, but also in formalin fixed paraffin-embedded tissues as well as serum/plasma samples. Thus, microRNA studies have quickly moved from research on the molecular basis of cancer to areas of clinical application. This review summarizes the potential role of microRNAs as molecular markers for cancer classification, prognostic stratification and drug-response prediction. It also summarizes their potential as circulating markers and cancer-predisposing genes. If we consider that studies on microRNAs in cancer therapy have already given important contributions, microRNAs already had an impact in all cancer areas. Whether this will translate into clinical applications is still too early to say. However, in the diagnostic field, microRNAs may already represent an improvement over presently available approaches: for example, their expression profile is effective in the identification of metastasis tissue of origin. In addition, circulating microRNAs are expected to provide improved specificity and/or sensitivity over presently available markers
Quantification of circulating micrornas by droplet digital PCR
No full textMicroRNAs (miRNAs) are released in the blood as cell-free molecules either linked to Ago proteins and LDL or enveloped inside exosomes and microvescicles. The amount of specific circulating microRNAs has been discovered to change accordingly to a disease state and to be potentially used as a disease biomarker. Sensitive and accurate methods for circulating microRNA quantification using probe-based or dye-based digital PCR technology have been developed. With a digital PCR system it is possible to obtain the absolute quantification of specific miRNAs, bypassing several issues related to low abundance targets and miRNA normalization. This chapter addresses the workflow and methods for miRNA assessment in biological fluids using EvaGreen-based droplet digital PCR as well as how to analyze and interpret results
Non-coding RNAs in disease: from mechanisms to therapeutics
Full text linkNon-coding RNAs (ncRNAs) are a heterogeneous group of transcripts that, by definition, are not translated into proteins. Since their discovery, ncRNAs have emerged as important regulators of multiple biological functions across a range of cell types and tissues, and their dysregulation has been implicated in disease. Notably, much research has focused on the link between microRNAs (miRNAs) and human cancers, although other ncRNAs, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), are also emerging as relevant contributors to human disease. In this Review, we summarize our current understanding of the roles of miRNAs, lncRNAs and circRNAs in cancer and other major human diseases, notably cardiovascular, neurological and infectious diseases. Further, we discuss the potential use of ncRNAs as biomarkers of disease and as therapeutic targets.In this Review, the authors describe our current knowledge of the role of microRNAs, long non-coding RNAs and circular RNAs in disease, with a focus on cardiovascular, neurological, infectious diseases and cancer. Further, they discuss the potential use of non-coding RNAs as disease biomarkers and as therapeutic targets
MicroRNAs as biomarker of Parkinson disease? Small but mighty.
No full textComment on
Overexpression of blood microRNAs 103a, 30b, and 29a in L-dopa-treated patients with PD. [Neurology. 2015
Non-Coding RNA Investigations in Cutaneous Melanoma: A Step forward in Discovering Novel Biomarkers
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and Their Role in Cancer
No full textMicroribonucleic acids (miRNAs) are short, noncoding RNAs that act as post-transcription regulators and are able to modulate the expression of hundreds of target genes. In the past few years, they gained a very important role in oncology. Indeed, many of them can be now considered tumour suppressor genes or oncogenes. In cancer, they appeared to have a dysregulated expression due to genetic aberrations, altered methylation or irregular processing that finally lead to an altered modulation of their target genes.
Each cancer type displayed specific alterations of specific miRNAs, and their exceptional stability confer to miRNAs a strong potential as cancer therapeutics. Finally, miRNAs are stable and detectable as circulating molecules in blood of cancer patients. For this reason they are going to become useful biomarkers in cancer diagnostics
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