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Catalytically distinct IDH1 mutants tune phenotype severity in tumor models
Mowaffaq Adam Ahmed Adam1,2, Mikella Robinson3,2, Ashley V Schwartz4,2
1Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182, USA.
Biorxiv : the Preprint Server for Biology
|May 7, 2024
Summary
Isocitrate dehydrogenase 1 (IDH1) mutations produce D-2-hydroxyglutarate (D2HG), a molecule linked to cancer. The IDH1 R132Q mutation generates more D2HG than R132H, correlating with more aggressive tumor characteristics.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Mutations in isocitrate dehydrogenase 1 (IDH1) are implicated in tumorigenesis.
- IDH1 mutations create a neomorphic enzyme activity producing D-2-hydroxyglutarate (D2HG).
- D2HG is known to inhibit DNA demethylases, contributing to cancer development.
Purpose of the Study:
- To compare the catalytic efficiency of D2HG production between different IDH1 mutations (R132Q vs. R132H).
- To investigate the distinct epigenetic and transcriptomic consequences of IDH1 R132Q and R132H mutations.
- To correlate D2HG levels with tumor aggressiveness.
Main Methods:
- In vitro analysis of catalytic efficiency for D2HG production by IDH1 mutants.
- Expression of IDH1 mutants in cellular and xenograft models.
- Quantification of D2HG levels in cells, tumors, and sera.
- DNA methylation analysis.
- Transcriptome analysis (RNA sequencing).
Main Results:
- IDH1 R132Q mutants exhibit greater catalytic efficiency for D2HG production compared to R132H mutants.
- Expression of IDH1 R132Q leads to higher D2HG concentrations in vivo and in vitro.
- IDH1 R132Q expression is associated with more pronounced DNA hypomethylation and increased expression of pro-tumor pathways (e.g., EGFR, PI3K) compared to R132H.
- Higher D2HG levels correlate with more aggressive tumor phenotypes.
Conclusions:
- IDH1 mutations modulate D2HG levels through altered catalysis, leading to distinct epigenetic and transcriptomic profiles.
- The IDH1 R132Q mutation, with its higher D2HG production, is associated with more aggressive tumor characteristics.
- D2HG levels serve as a potential biomarker for tumor aggressiveness in IDH1-mutated cancers.
