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Updated: Dec 4, 2025
Dual CRISPR-Interference Strategy for Targeting Synthetic Lethal Interactions Between Non-Coding RNAs in Cancer Cells
Published on: May 30, 2025
Targeted CRISPR screening identifies PRMT5 as synthetic lethality combinatorial target with gemcitabine in pancreatic
Xiaolong Wei1, Jiekun Yang1, Sara J Adair2
1Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22903.
Abstract:
Pancreatic ductal adenocarcinoma (PDAC) remains one of the most challenging cancers to treat. Due to the asymptomatic nature of the disease and lack of curative treatment modalities, the 5-y survival rate of PDAC patients is one of the lowest of any cancer type. The recurrent genetic alterations in PDAC are yet to be targeted. Therefore, identification of effective drug combinations is desperately needed. Here, we performed an in vivo CRISPR screen in an orthotopic patient-derived xenograft (PDX) model to identify gene targets whose inhibition creates synergistic tumor growth inhibition with gemcitabine (Gem), a first- or second-line chemotherapeutic agent for PDAC treatment. The approach revealed protein arginine methyltransferase gene 5 (PRMT5) as an effective druggable candidate whose inhibition creates synergistic vulnerability of PDAC cells to Gem. Genetic depletion and pharmacological inhibition indicate that loss of PRMT5 activity synergistically enhances Gem cytotoxicity due to the accumulation of excessive DNA damage. At the molecular level, we show that inhibition of PRMT5 results in RPA depletion and impaired homology-directed DNA repair (HDR) activity. The combination (Gem + PRMT5 inhibition) creates conditional lethality and synergistic reduction of PDAC tumors in vivo. The findings demonstrate that unbiased genetic screenings combined with a clinically relevant model system is a practical approach in identifying synthetic lethal drug combinations for cancer treatment.
Insights
Pancreatic cancer (PDAC) treatment needs new strategies. Inhibiting PRMT5 enhances gemcitabine effectiveness by increasing DNA damage, offering a promising combination therapy for PDAC.
Area of Science:
- Oncology
- Cancer Genetics
- Drug Discovery
Background:
- Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis due to late diagnosis and limited treatment options.
- Effective drug combinations are crucial for improving PDAC patient survival rates.
- Targeting recurrent genetic alterations in PDAC is an unmet clinical need.
Purpose of the Study:
- To identify gene targets that synergize with gemcitabine (Gem) for PDAC treatment using an in vivo CRISPR screen.
- To evaluate protein arginine methyltransferase 5 (PRMT5) as a druggable target for PDAC therapy.
- To elucidate the molecular mechanisms underlying the synergistic effect of PRMT5 inhibition and Gem.
Main Methods:
- Conducted an in vivo CRISPR screen in a patient-derived xenograft (PDX) model of PDAC.
- Utilized gemcitabine (Gem) as a standard chemotherapeutic agent.
- Employed genetic depletion and pharmacological inhibition of PRMT5.
- Assessed DNA damage and homology-directed DNA repair (HDR) activity.
Main Results:
- Identified PRMT5 as a key target whose inhibition synergizes with Gem in PDAC.
- PRMT5 inhibition enhances Gem cytotoxicity by inducing excessive DNA damage.
- Loss of PRMT5 leads to RPA depletion and impaired HDR.
- The combination of Gem and PRMT5 inhibition resulted in synergistic tumor growth inhibition in vivo.
Conclusions:
- Unbiased genetic screening in a clinically relevant PDX model can identify effective synthetic lethal drug combinations.
- PRMT5 inhibition represents a promising therapeutic strategy to enhance gemcitabine efficacy in PDAC.
- Targeting PRMT5 and exploiting DNA repair pathways offers a novel approach for PDAC treatment.
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