Mechanisms of selective anticancer action of histone deacetylase inhibitors

Area of Science:

• Oncology
• Molecular Biology
• Cancer Genetics

Background:

• Histone deacetylases (HDACs) play a crucial role in gene transcription and are frequently dysregulated in various cancers.
• HDAC inhibitors (HDACIs) demonstrate anti-tumor activity and are well-tolerated, positioning them as a potential cancer therapy strategy.
• While HDACIs are in clinical trials, the precise molecular mechanisms underlying their selective anti-cancer effects remain unclear.

Purpose of the Study:

• To elucidate the molecular basis for the selective anti-tumor activities of HDAC inhibitors.
• To investigate the mechanism by which HDAC inhibitors induce apoptosis in specific cancer cells.

Main Methods:

• Studied leukemias with PML-RAR or AML1-ETO oncogenes.
• Analyzed the effect of HDAC inhibitors on blast-cell apoptosis.
• Investigated the role of the p53 pathway and death receptors (DR5, Fas) and their ligands (TRAIL, FasL) in HDACI-induced apoptosis.

Main Results:

• HDACIs induced massive apoptosis in leukemic blast cells expressing PML-RAR or AML1-ETO oncogenes.
• The pro-apoptotic effect was attributed to the selective upregulation of death receptors DR5 and Fas and their ligands TRAIL and FasL.
• Normal myeloid progenitors were resistant to HDACI-induced apoptosis, and oncogene expression alone did not confer sensitivity.

Conclusions:

• HDACI sensitivity is a characteristic of the fully transformed cellular phenotype, not solely dependent on oncogene expression or p53 pathway modulation.
• The findings suggest that HDACIs could be a viable therapeutic strategy for cancers where HDACs contribute to tumorigenesis.
• Selective upregulation of death receptors is a key mechanism for HDACI-induced anti-tumor activity.