Identification of modulators of the ALT pathway through a native FISH-based optical screen
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Benura Azeroglu1, Simran Khurana2, Shih-Chun Wang3
1Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Abstract:
A significant portion of human cancers utilize a recombination-based pathway, alternative lengthening of telomeres (ALT), to extend telomeres. To gain further insights into this pathway, we developed a high-throughput imaging-based screen named TAILS (telomeric ALT in situ localization screen) to identify genes that either promote or inhibit ALT activity. Screening over 1,000 genes implicated in DNA transactions, TAILS reveals both well-established and putative ALT modulators. Here, we present the validation of factors that promote ALT, such as the nucleosome-remodeling factor CHD4 and the chromatin reader SGF29, as well as factors that suppress ALT, including the RNA helicases DExD-box helicase 39A/B (DDX39A/B), the replication factor TIMELESS, and components of the chromatin assembly factor CAF1. Our data indicate that defects in histone deposition significantly contribute to ALT-associated phenotypes. Based on these findings, we demonstrate that pharmacological treatments can be employed to either exacerbate or suppress ALT-associated phenotypes.
Insights
Many cancers use alternative lengthening of telomeres (ALT) to grow. Researchers developed a screen to find genes that control ALT, revealing new drug targets for cancer therapy.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Alternative lengthening of telomeres (ALT) is a key mechanism for telomere maintenance in a significant fraction of human cancers.
- Understanding the genetic regulation of ALT is crucial for developing targeted cancer therapies.
Purpose of the Study:
- To identify novel genes that modulate the alternative lengthening of telomeres (ALT) pathway using a high-throughput screen.
- To validate identified ALT modulators and explore their therapeutic potential.
Main Methods:
- Development and application of TAILS (telomeric ALT in situ localization screen), a high-throughput imaging-based screen.
- Screening of over 1,000 genes involved in DNA transactions.
- Validation of candidate genes using molecular and cellular assays.
Main Results:
- Identification of both promoters (e.g., CHD4, SGF29) and suppressors (e.g., DDX39A/B, TIMELESS, CAF1) of ALT.
- Demonstration that defects in histone deposition are linked to ALT-associated phenotypes.
- Confirmation that pharmacological agents can modulate ALT activity.
Conclusions:
- The TAILS screen successfully identified key regulators of the ALT pathway.
- Targeting histone deposition and identified ALT modulators offers potential therapeutic strategies for ALT-positive cancers.
- Pharmacological interventions can be used to manipulate ALT activity for cancer treatment.
