Please use this identifier to cite or link to this item:
Title: Epigenetic Regulation of tRNA Biology in Cancer
Author: Rosselló Tortella, Margalida
Director/Tutor: Esteller, Manel
Keywords: Càncer
Issue Date: 9-Dec-2021
Publisher: Universitat de Barcelona
Abstract: [eng] Transfer RNAs (tRNAs) are essential molecules that allow the translation of the genetic code into amino acids. Extensive research during the last 50 years have revealed that, despite their apparently simple structure and function, tRNAs are more than simple adaptors in protein synthesis –they are of high importance in normal cell functions. Reinforcing this, tRNA levels are tightly regulated to match the codon usage patterns of a given cell type or cellular status to meet the cellular specific needs and adapt to stress. Moreover, tRNA nucleoside modifications are critical for their function at multiple levels, such as translation efficiency and fidelity, wobbling and fragmentation. The relevance of tRNA regulation in cell physiology is emphasized by the recent discovery that these molecules and their derived fragments are deregulated in cancer. Not only tRNA biology imbalance is associated to malignant transformation, but it also actively participates in it. These alterations occur at multiple levels of tRNA biology, such as expression, nucleoside modification and fragmentation, but many open questions remain unanswered. Cancer- specific tRNA deregulation is a very new and still unexplored discipline, and further studies are required to fully understand the molecular mechanisms that account for these alterations and their relevance in tumor biology. Because alterations in DNA methylation constitute a frequent mechanism by which transformed cells acquire their malignant characteristics, the cornerstone of this thesis is the description of epigenetic lesions that support the cancer-associated tRNA deregulation. To this end, we have designed and performed two independent studies to unveil the epigenetic regulation of tRNA biology in cancer. In the first study, we highlighted the tumor-specific epigenetic silencing of TYW2 as a mechanism to induce tRNAPhe hypomodification at position 37, a phenomenon that was observed for the first time more than forty years ago but whose cause and consequences have remained obscure. Our results established the connection between this epigenetic defect and a phenotype that enhances -1 ribosome frameshifting events to ultimately confer increased migratory capacities and mesenchymal features to the transformed colon cells. In the second study, we established a founded connection between cancer-associated DNA methylation defects with alterations in the expression of specific tRNAs. Our analyses also revealed that the oncogenic tRNA-Arg-TCT-4-1 overexpression in endometrial cancer was guided by DNA hypomethylation. Most importantly from the clinical perspective, the epigenetic alterations identified in both studies can anticipate the patients’ outcome, for which they may serve as biomarkers to allow the identification of high-risk patients that may benefit from a more comprehensive surveillance or complementary therapeutic strategies.
[cat] Els ARN de transferència (tRNAs) són d’una importància clau en la regulació de la síntesi proteica i l’expressió gènica. La seva rellevància en la fisiologia cel·lular es veu reforçada pel descobriment que aquestes molècules i els seus derivats estan alterats en patologies com el càncer, on contribueixen activament. Les alteracions dels tRNAs en càncer suposen una nova disciplina d’estudi on encara moltes preguntes romanen obertes per tal d’arribar a comprendre quines són les causes d’aquestes defectes i quin impacte tenen sobre la malaltia. Aquesta tesi té com objectiu identificar i caracteritzar alteracions en la metilació de l’ADN subjacents als desequilibris en la biologia dels tRNAs de les cèl·lules tumorals. En el primer estudi, hem descobert el silenciament epigenètic de l’enzim TYW2 en càncer colorectal com a causa de la hipomodificació del tRNAPhe, un fenomen que va ser descrit per primer cop fa més de quaranta anys però les causes i conseqüències del qual no van ser mai estudiades. Els nostres resultats estableixen una clara connexió entre aquest defecte epigenètic i un fenotip que és propens a potencial el frameshift dels ribosomes, cosa que augmenta la capacitat migratòria de les cèl·lules de càncer de colon. El segon estudi ha servit per caracteritzar la relació entre els canvis en la metilació de l’ADN i les alteracions en l’expressió dels tRNAs en càncer. Els nostres resultats han revelat que l’expressió de tRNA-Arg-TCT-4-1 augmenta en càncer d’endometri arrel de la hipometilació del seu gen. Més enllà d’aquests dos mecanismes epigenètics per modular la biologia dels tRNAs, els nostres estudis estableixen una connexió entre aquestes lesions epigenètiques i la prognosi dels pacients amb certs tipus de tumor, per la qual cosa podrien proposar-se com biomarcadors per identificar pacients de risc.
Appears in Collections:Tesis Doctorals - Facultat - Medicina

Files in This Item:
File Description SizeFormat 
MRT_PhD_THESIS.pdf17.14 MBAdobe PDFView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.