EMBR-20_Alberto Delaidelli


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Alberto Delaidelli1, Gian Luca Negri1, Que Xi Wang1, Albert Huang1, Simran Sidhu1, Joyce Zhang1, Yue Zhou Huang1, Betty Yao1, Sofya Langman1, Andrii Vislovukh1, Volker Hovestadt2, Michael Taylor3, Gabriel Leprivier4, Poul Sorensen1;

1BC Cancer Research Centre, Vancouver, BC, Canada. 2Massachusetts General Hospital, Boston, MA, USA. 3Arthur and Sonia Labatt Brain Tumor Research Centre, Toronto, ON, Canada. 4Heinrich Heine University, Duesseldorf, Germany

Medulloblastoma (MB) is the most common pediatric intracranial tumor and leading cause of childhood related cancer deaths. Group 3 affiliation and genetic amplifications of the MYC oncogene are predictors of adverse outcome in MB, underscoring a dire need for novel and more effective therapeutic approaches. The let-7 family of small non-coding RNAs (miRNAs) is known to inhibit tumor progression and regulate metabolism by targeting and degrading several cellular mRNAs, including MYC. Indeed, let-7 miRNAs are frequently repressed in several cancer types, including in MYC-driven MB.
We previously reported that the mRNA translation elongation regulator eukaryotic Elongation Factor-2 Kinase (eEF2K) is a pivotal mediator of cancer cell adaptation to nutrient deprivation. In the current work, we identified a potential binding site for let-7 miRNAs on the eEF2K 3’ untranslated region (UTR). In addition, eEF2K mRNA and let-7 miRNA expressions negatively correlate in MB, suggesting a potential regulation of the former by the latter. Let-7 miRNAs transfection decreases eEF2K mRNA and protein levels (by ~40-50%). Down-regulation of luciferase activity by let-7 miRNAs is impaired upon mutation of the let-7 binding site on the eEF2K 3’UTR. Inhibition of eEF2K significantly reduces survival of MYC-amplified MB cell lines under nutrient deprivation, altering their mRNA translation rates. Knockout of eEF2K increases survival of MYC-amplified MB xenografts when mice are kept under calorie restricted diets. We conclude that let-7 miRNAs degrade the eEF2K mRNA by binding to its 3'UTR, indicating that let-7 repression in MYC-driven MB is partially responsible for increased eEF2K levels. Moreover, the let-7-eEF2K axis constitutes a critical mechanism for MYC-driven MB adaptation to acute metabolic stress, representing a promising therapeutic target. Future therapeutic studies will aim to combine eEF2K inhibition with caloric restriction mimetic drugs, as eEF2K activity appears critical under metabolic stress conditions.

Duration: 05:22

Posted: Sunday, June 6, 2021

Video tags: 2021 SNO Pediatric Meeting