Characterization of synthetic lethality between MYC activation and splicing inhibition in an immortalized cell line : roles of alternative splicing

Herrero Vicente, Jorge

Characterization of synthetic lethality between MYC activation and splicing inhibition in an immortalized cell line : roles of alternative splicing

Document Type

Doctoral thesis
Published Version

Author

Herrero Vicente, Jorge

Director

Valcarcel, J. (Juan)

Publication Date

2024-02-26

Pages

140 p.

Embargo date

2026-02-26T01:00:00Z

Citation

Herrero Vicente, J. Characterization of synthetic lethality between MYC activation and splicing inhibition in an immortalized cell line : roles of alternative splicing. Universitat Pompeu Fabra; 2024. handle: http://hdl.handle.net/10803/690453

This citation was generated automatically.

Doctoral program

Programa de Doctorat en Biomedicina

Abstract

Cancer cells exhibit a synthetic lethal (SL) phenotype when Myc upregulation is combined with antitumor drugs targeting the splicing factor SF3B1. However, the molecular events and mechanisms responsible for this vulnerability remain poorly understood. We used an immortalized cell line (h-TERT RPE MYC-ER p53KO) which allows inducible MYC activation, and the SF3B1-targeting drug Pladienolide B (PLAD B), to recreate the SL phenotype, scored in viability and clonogenic assays. Our data indicate that apoptosis is a key pathway involved in the SL phenotype. However, contrary to the proposed role of MCL1 alternative splicing as a major mediator of apoptotic effects induced by PLAD B treatment, upregulation of the pro-apoptotic mRNA isoform of MCL1 cannot explain the SL phenotype. We carried out RNA-seq analyses to identify and functionally characterize gene expression and alternative splicing changes potentially associated with the SL phenotype. Importantly, we identified a set of exons known to be essential for cancer cells that, when induced to be skipped using antisense oligonucleotides, are detrimental for cell viability and likely contribute to the SL phenotype.
Las células cancerosas muestran un fenotipo de letalidad sintética (SL) cuando se combina la sobreexpresión de Myc con fármacos anticancerígenos dirigidos contra el factor de splicing SF3B1. Sin embargo, los eventos moleculares responsables de esta vulnerabilidad son poco comprendidos. Usamos una línea celular inmortalizada (h-TERT RPE MYC-ER p53KO) que permite la activación inducida de MYC, y el fármaco dirigido contra SF3B1 Pladienolide B (PLAD B), para recrear el fenotipo SL, medido en ensayos de clonogenicidad y viabilidad. Nuestros datos indican que la apoptosis es una ruta clave en el fenotipo SL. Sin embargo, al contrario del papel propuesto para el splicing alternativo de MCL1 como mediador de los efectos apoptóticos inducidos por tratamiento con PLAD B, el incremento de la isoforma proapoptótica de mRNA de MCL1 no puede explicar el fenotipo SL. No obstante, hemos confirmado que la apoptosis es una ruta clave para conseguir el fenotipo SL. Ejecutamos análisis de RNA-seq para identificar y caracterizar funcionalmente los cambios de expresión génica y splicing alternativo potencialmente asociados a SL. Destacablemente, identificamos un set de exones esenciales para células cancerosas que, al inducir su salto con oligonucleótidos antisentido, son perjudiciales para la viabilidad celular y probablemente contribuyen al fenotipo SL.

Keywords

Alternative splicing, Cancer, MYC, Synthetic lethality, Splicing inhibition, Splicing alternativo, Cáncer, Letalidad sintética, Inhibición de splicing