Reprogrammed mRNA translation drives resistance to therapeutic targeting of ribosome biogenesis

Area of Science:

• Oncology
• Molecular Biology
• Cancer Therapeutics

Background:

• Elevated ribosome biogenesis is a hallmark of oncogene-driven cancers and a target for cytotoxic drugs.
• CX-5461, a novel RNA polymerase I inhibitor, demonstrated single-agent efficacy in refractory blood cancers but did not cure patients.
• Combination therapy with PI3K/AKT/mTORC1 inhibitors improved CX-5461's in vivo efficacy.

Purpose of the Study:

• To elucidate the molecular mechanisms behind the enhanced efficacy of CX-5461 combined with PI3K/AKT/mTORC1 inhibitors.
• To investigate the mechanisms of acquired resistance to this combination therapy.
• To identify metabolic vulnerabilities for improved Pol I-directed cancer therapies.

Main Methods:

• In vivo efficacy studies of CX-5461 and PI3K/AKT/mTORC1 inhibitors.
• Analysis of mRNA translation suppression.
• Investigation of acquired resistance mechanisms, including translational rewiring and metabolic dysregulation.

Main Results:

• The combination therapy suppressed translation of mRNAs encoding metabolic regulators, explaining improved in vivo efficacy.
• Acquired resistance arose from translational rewiring, leading to metabolic dysregulation.
• A cAMP-dependent pathway was identified as critical for blood cancer survival under resistance conditions.

Conclusions:

• Selective inhibition of ribosome biogenesis by CX-5461 impacts cancer metabolism.
• Translational rewiring and metabolic dysregulation drive resistance to combination therapy.
• Targeting metabolic vulnerabilities and cAMP pathways may enhance Pol I-directed therapies for blood cancers like lymphoma and acute myeloid leukemia.