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Updated: Jan 26, 2026
Pooled shRNA Library Screening to Identify Factors that Modulate a Drug Resistance Phenotype
Published on: June 17, 2022
DECIPHER pooled shRNA library screen identifies PP2A and FGFR signaling as potential therapeutic targets for diffuse
Kathrin Schramm1, Murat Iskar1, Britta Statz1
1Division of Molecular Genetics, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Background:
Diffuse intrinsic pontine gliomas (DIPGs) are highly aggressive pediatric brain tumors that are characterized by a recurrent mutation (K27M) within the histone H3 encoding genes H3F3A and HIST1H3A/B/C. These mutations have been shown to induce a global reduction in the repressive histone modification H3K27me3, which together with widespread changes in DNA methylation patterns results in an extensive transcriptional reprogramming hampering the identification of single therapeutic targets based on a molecular rationale.
Methods:
We applied a large-scale gene knockdown approach using a pooled short hairpin (sh)RNA library in combination with next-generation sequencing in order to identify DIPG-specific vulnerabilities. The therapeutic potential of specific inhibitors of candidate targets was validated in a secondary drug screen.
Results:
We identified fibroblast growth factor receptor (FGFR) signaling and the serine/threonine protein phosphatase 2A (PP2A) as top depleted hits in patient-derived DIPG cell cultures and validated their lethal potential by FGF ligand depletion and genetic knockdown of the PP2A structural subunit PPP2R1A. Further, pharmacological inhibition of FGFR and PP2A signaling through ponatinib and LB-100 treatment, respectively, exhibited strong tumor-specific anti-proliferative and apoptotic activity in cultured DIPG cells.
Conclusions:
Our findings suggest FGFR and PP2A signaling as potential new therapeutic targets for the treatment of DIPGs.
Insights
Researchers identified fibroblast growth factor receptor (FGFR) and protein phosphatase 2A (PP2A) signaling as key vulnerabilities in diffuse intrinsic pontine gliomas (DIPGs). Inhibiting these pathways showed significant anti-tumor effects, suggesting new therapeutic targets for this aggressive pediatric brain cancer.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- Diffuse intrinsic pontine gliomas (DIPGs) are aggressive pediatric brain tumors.
- DIPGs are characterized by K27M mutations in histone H3 genes, leading to reduced H3K27me3 and altered DNA methylation.
- These molecular changes cause extensive transcriptional reprogramming, complicating targeted therapy development.
Purpose of the Study:
- To identify DIPG-specific vulnerabilities using a large-scale genetic screening approach.
- To validate potential therapeutic targets through drug screening and pharmacological inhibition.
Main Methods:
- Utilized a pooled short hairpin (sh)RNA library and next-generation sequencing for large-scale gene knockdown screening.
- Validated candidate targets by assessing the effects of FGF ligand depletion and genetic knockdown of PPP2R1A.
- Performed secondary drug screening with inhibitors of identified targets (FGFR and PP2A).
Main Results:
- Fibroblast growth factor receptor (FGFR) signaling and protein phosphatase 2A (PP2A) were identified as top hits.
- Genetic and ligand depletion validated the essential role of FGFR and PP2A in DIPG cell survival.
- Pharmacological inhibition of FGFR (ponatinib) and PP2A (LB-100) demonstrated potent anti-proliferative and apoptotic activity in DIPG cells.
Conclusions:
- FGFR and PP2A signaling represent promising novel therapeutic targets for DIPGs.
- Targeted inhibition of FGFR and PP2A pathways offers a potential treatment strategy for this pediatric brain tumor.
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