EZH2 inhibitors restore epigenetically silenced CD58 expression in B-cell lymphomas

Area of Science:

• Oncology
• Immunology
• Epigenetics

Background:

• Loss of CD58 is a key mechanism for tumor immune evasion in lymphoid malignancies.
• CD58 downregulation can result from genetic or non-genetic factors, necessitating exploration of therapeutic restoration.

Purpose of the Study:

• To investigate the potential of restoring CD58 expression in lymphoma cells as a treatment strategy.
• To identify epigenetic mechanisms and therapeutic targets for CD58 re-expression.

Main Methods:

• Screening of B-cell lymphoma lines to identify CD58 downregulation.
• Epigenetic library screening using EZH2 inhibitors (EPZ6438, GSK126) on a lymphoma cell line with epigenetically silenced CD58.
• Analysis of EZH2 inhibitor effects on CD58 expression and T/NK cell activity.
• Chromatin immunoprecipitation to assess H3K27 trimethylation at the CD58 promoter.

Main Results:

• Three out of eleven B-cell lymphoma lines showed decreased CD58 expression.
• EZH2 inhibitors EPZ6438 and GSK126 specifically upregulated CD58 expression in a cell line with epigenetic silencing.
• EZH2 inhibition broadly enhanced CD58 expression across different B-cell lines and boosted T and NK cell-mediated anti-lymphoma activity.
• EZH2 inhibition led to demethylation of H3K27 at the CD58 promoter, activating its transcription.

Conclusions:

• EZH2 plays a role in the epigenetic silencing of CD58 in lymphoma, contributing to immune escape.
• EZH2 inhibitors can restore epigenetically suppressed CD58 expression, enhancing anti-tumor immune responses.
• These findings support the combination of EZH2 inhibitors with immunotherapy for lymphoma treatment.