Guanosine-7 tRNA methylation regulates Prostate Cancer progression through protein reprogramming via tRNA-derived fragments biogenesis

• Autores: Raquel García Vílchez
• Directores de la Tesis: Sandra Blanco Benavente (dir. tes.), Mercedes Dosil Castro (tut. tes.)
• Lectura: En la Universidad de Salamanca ( España ) en 2023
• Idioma: inglés
• Tribunal Calificador de la Tesis: Lluís Ribas de Pouplana (presid.), Rogelio González Sarmiento (secret.), Veronica Torrano Moya (voc.)
• Programa de doctorado: Programa de Doctorado en Biociencias: Biología y Clínica del Cáncer y Medicina Traslacional por la Universidad de Salamanca
• Materias:
  • Química
    • Bioquímica
      • Ácidos nucleicos
  • Ciencias de la vida
    • Biología celular
    • Biología molecular
• Enlaces
  • Tesis en acceso abierto en:  TESEO  GREDOS 
• Resumen
  • español

    El cáncer de Próstata (CaP) es el cáncer más común y la tercera causa de muerte por cáncer de hombres en Europa. El objetivo de esta tesis es descifrar el epitranscriptoma del CaP con el fin último de identificar modificadores epitranscriptómicos reguladores de la capacidad proliferativa y de supervivencia de los tumores.

    Análisis "in silico" han demostrado que la metiltransferasa de ARNts METTL1 está sobreexpresada en tumores de próstata primarios y avanzados, existiendo una correlación directa entre mayores niveles de expresión y peor prognosis. Para la caracterización funcional del papel molecular de METTL1, se generaron distintas líneas de CaP con sobreexpresión, silenciamiento o ausencia total de la enzima. En consecuencia, la ausencia de METTL1 produjo una acumulación de fragmentos 5‘TOG derivados de ARNts, lo que no sólo condujo a una inhibición de la síntesis global de proteínas sino también a una alteración del programa traduccional. Como resultado, la deleción de METTL1 dio lugar a una disminución de la capacidad proliferativa tanto "in vivo" como en "in vitro". Además, la deleción de la metiltransferasa produce una desregulación de la autofagia, que conduce a una acumulación de agregados de proteínas, ROS y daño al DNA, lo que se traduce en una hipersensibilidad a condiciones de estrés. En conjunto, esta tesis demuestra que METTL1 regula la capacidad de las células tumorales para responder a los estímulos de estrés y la inhibición de su actividad metiltransferasa conduce en última instancia a un aumento de la sensibilidad a los agentes terapéuticos tradicionales.

  • English

    Prostate Cancer (PCa) is the most common tumour and the third cause of death by cancer in European men. Although important advances have been made in early stages of the disease and most of the tumours respond to hormone deprivation therapy, many patients develop Castration Resistant Prostate Cancer (CRPC) which lacks effective therapeutic options. One of the major drawbacks for PCa treatment is the high intratumoural heterogeneity and the lack of reliable biomarkers of disease progression. During the last years, several studies have highlighted the importance of RNA chemical modifications in the progression and therapy response of several tumours. Thus, manipulation of the epitranscriptome might be a potential therapeutic target to specifically eliminate those cancer cell resistant to conventional treatments. Thereby, this thesis focuses in deciphering the epitranscriptomic landscape of PCa in order to identify altered epitranscriptomic regulators that may control tumour proliferation and survival capacities. In silico analysis demonstrated that the tRNA methyltransferase METTL1 was overexpressed in primary and advanced PCa tumours, being increased expression correlated with poor prognosis. Altered expression of the methyltransferase was confirmed in primary tumours samples from both patients and from PtenKO PCa mouse model. For functional characterization of METTL1 molecular role, cells over-expressing, silenced and knocked out for the methyltransferase were generated in distinct PCa cell lines. In consequence, lack of METTL1 resulted in accumulation of 5’TOG tRNA derived fragments, which lead not only to a global inhibition of protein synthesis but also to an alteration of the translational programme. As a result, METTL1 deletion resulted in impaired cell proliferation and self-renewal capacity in cell cultures and reduced tumour formation and proliferation in both xenografted and PtenKO PCa in vivo murine models. Impaired self-renewal capacity is observed in a human PDXs-derived model upon the enzyme depletion. In addition, cells lacking METTL1 exhibited impaired autophagy termination, which lead to accumulation of protein aggregates, ROS and DNA damage, resulting in an hypersensitivity to stress conditions. Altogether, this thesis demonstrates that METTL1 regulates tumoural cells capacity to respond to stress stimuli and inhibition of its methyltransferase activity ultimately leads to an increase sensitivity to traditional therapeutic agents. This study concludes that METTL1 is overexpressed in PCa and higher expression correlates with poor prognosis. METTL1 is essential for 7-guanine methylation in tRNAs and lack of the methylation results in protein synthesis alterations, which results in a deregulation of essential cellular processes as proliferation and self-renewal. Whether METTL1 can be used as a therapeutical target needs further validation.