Epigenetic targeting of bromodomain protein BRD4 counteracts cancer cachexia and prolongs survival

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Cancer cachexia is a metabolic syndrome causing significant muscle and adipose tissue loss, contributing to one-third of cancer deaths.
• Current therapies for cancer cachexia are ineffective, and its underlying mechanisms remain poorly understood.
• Bromodomain and extra-terminal domain (BET) proteins, including BRD4, have been identified as epigenetic regulators of muscle mass.

Purpose of the Study:

• To investigate the role of BET proteins in cancer cachexia.
• To evaluate the therapeutic potential of BET inhibitors, specifically (+)-JQ1, in managing cancer cachexia.

Main Methods:

• Utilized a C26 tumor-bearing mouse model.
• Administered the pan-BET inhibitor (+)-JQ1.
• Performed chromatin immunoprecipitation sequencing (ChIP-seq) and chromatin immunoprecipitation (ChIP) analyses.
• Investigated the IL6-dependent AMPK nuclear signaling pathway and its convergence on the FoxO3 transcription factor.

Main Results:

• (+)-JQ1 administration protected tumor-bearing mice from body weight loss and tissue wasting.
• (+)-JQ1 significantly prolonged survival in C26-tumor-bearing mice without impacting tumor growth.
• BET proteins were found to directly promote the muscle atrophy program during cachexia.
• BET proteins are essential for coordinating an IL6-dependent AMPK nuclear signaling pathway involving FoxO3.

Conclusions:

• BET proteins are key regulators of the muscle atrophy program in cancer cachexia.
• Targeting BET proteins with inhibitors like (+)-JQ1 shows promise as a therapeutic strategy for cancer cachexia.
• Further research into BET protein inhibition could lead to novel treatments for this debilitating condition.