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Pooled shRNA Library Screening to Identify Factors that Modulate a Drug Resistance Phenotype
Published on: June 17, 2022
Disrupting tRNA modifications to target mitochondrial vulnerabilities in drug-resistant leukemia cells
Cornelius Pauli1,2,3, Michael Kienhöfer1,2, Maximilian Felix Blank2,3,4
1Division of Mechanisms Regulating Gene Expression, German Cancer Research Center, Heidelberg, Germany.
Abstract:
Dysregulated RNA modifications contribute to cancer progression and therapy resistance, yet the underlying mechanism often remains unknown. Here, we perform CRISPR-based synthetic lethality screens to systematically explore the role of RNA modifications in mediating resistance to antileukemic drugs. We identify the tRNA methyltransferase 5 (TRMT5)-mediated formation of N1-methylguanosine (m1G) in the transfer RNA (tRNA) anticodon loop as essential for mediating drug tolerance to cytarabine and venetoclax (Ven) in acute myeloid leukemia (AML). TRMT5 methylates nearly all mitochondrial and nuclear tRNAs with a guanosine at position 37, but its role in promoting drug tolerance specifically depends on its mitochondrial function. TRMT5 is essential for the dynamic upregulation of mitochondrial messenger RNA translation and oxidative phosphorylation, which are critical for sustaining drug tolerance in leukemia cells. This mitochondrial dependency correlates with therapy outcomes in patients with leukemia: lower expression of electron transport chain genes is linked to poorer outcomes in a cohort of nearly 100 patients with AML undergoing first induction therapy. Finally, we demonstrate that targeted depletion of the TRMT5 protein using a conditional degron, in conjunction with cytarabine and Ven treatment, synergistically induces cell death in drug-tolerant AML cells. Thus, our study reveals TRMT5 as a promising drug target for therapy-resistant leukemia.
Insights
RNA modifications impact cancer drug resistance. Targeting TRMT5, crucial for mitochondrial function and tRNA methylation, can overcome resistance to cytarabine and venetoclax in acute myeloid leukemia.
Area of Science:
- Molecular Biology
- Cancer Research
- Biochemistry
Background:
- Dysregulated RNA modifications are implicated in cancer progression and therapy resistance.
- Mechanisms linking RNA modifications to drug resistance are often poorly understood.
- Systematic exploration is needed to identify RNA modification pathways involved in anti-leukaemic drug resistance.
Purpose of the Study:
- To systematically identify RNA modifications that mediate resistance to anti-leukaemic drugs using CRISPR-based synthetic lethality screens.
- To elucidate the role of TRMT5-mediated N1-methylguanosine (m1G) formation in acute myeloid leukemia (AML) drug tolerance.
- To investigate the mitochondrial dependency of TRMT5 in promoting leukemia cell survival under drug treatment.
Main Methods:
- CRISPR-based synthetic lethality screens were employed to identify genes involved in drug resistance.
- TRMT5 function and its role in tRNA methylation (m1G) were assessed in AML cells.
- Mitochondrial function, mRNA translation, and oxidative phosphorylation (OXPHOS) were analyzed.
- Correlation between gene expression and patient outcomes was examined in a cohort of AML patients.
Main Results:
- TRMT5-mediated m1G formation in tRNA is essential for tolerance to cytarabine and venetoclax in AML.
- TRMT5's role in drug tolerance is dependent on its mitochondrial function, not nuclear.
- TRMT5 dynamically upregulates mitochondrial mRNA translation and OXPHOS, supporting drug-tolerant leukemia cells.
- Lower expression of electron transport chain genes correlates with poorer outcomes in AML patients.
Conclusions:
- TRMT5 is a key mediator of drug tolerance in AML through mitochondrial pathways.
- Targeting TRMT5, particularly its mitochondrial function, offers a potential strategy to overcome therapy resistance.
- TRMT5 represents a promising therapeutic target for treating drug-resistant leukemia.
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