Elevated H3K27me3 levels sensitize osteosarcoma to cisplatin

Area of Science:

• Epigenetics
• Cancer Biology
• Pharmacology

Background:

• Chemotherapy resistance in osteosarcoma (OS) significantly contributes to patient mortality.
• The underlying mechanisms of drug resistance in OS are not fully understood, hindering effective treatment.
• This study investigates the role of dynamic histone modifications in cisplatin resistance in OS.

Purpose of the Study:

• To explore the relationship between histone changes and cisplatin efficacy in osteosarcoma.
• To identify specific histone modifications and related enzymes involved in chemoresistance.
• To evaluate the potential of targeting epigenetic modifications to overcome cisplatin resistance in OS.

Main Methods:

• Analysis of histone demethylases KDM6A and KDM6B in relation to H3K27me3 levels after cisplatin treatment.
• In vitro and in vivo experiments involving inhibition of EZH2 (methyltransferase) and KDM6A/KDM6B (demethylases) in OS cells.
• RNA sequencing (RNAseq) to elucidate downstream molecular mechanisms, including PRKCA, MCL1, and the RAF/ERK/MAPK pathway.

Main Results:

• Histone demethylases KDM6A and KDM6B were upregulated post-cisplatin treatment, correlating with decreased H3K27me3 levels in resistant OS specimens.
• Inhibition of EZH2 reduced H3K27me3 and induced cisplatin resistance, while inhibiting KDM6A/KDM6B increased H3K27me3 and reversed resistance.
• RNAseq identified PRKCA and MCL1 as key players, with altered H3K27me3 on their loci affecting RAF/ERK/MAPK signaling and BCL2 phosphorylation.

Conclusions:

• A novel epigenetic mechanism underlying OS cisplatin resistance involving H3K27me3 dynamics was uncovered.
• Elevated H3K27me3 levels demonstrate the capacity to sensitize osteosarcoma to cisplatin.
• Targeting H3K27me3 levels presents a promising therapeutic strategy for overcoming chemotherapy resistance in OS.