Abstract B001: Beyond DNA damage: What truly drives anthracycline cytotoxicity?

Abstract

Anthracyclines, like doxorubicin, are cornerstone therapies against pediatric sarcomas, and are a first-line treatment for virtually all osteosarcoma patients. While doxorubicin is classified as a topoisomerase II inhibitor whose antineoplastic activity is historically attributed to DNA damage, osteosarcomas are notoriously resistant to both DNA-damaging agents and radiotherapy. This striking paradox suggests doxorubicin’s efficacy is primarily driven by DNA damage-independent mechanisms. Recent work by our group and others has elucidated the non-DNA-damaging properties of anthracyclines, including eviction of chromatin-associated proteins ( “chromatin damage”) and disruption of nucleolar structure. These insights have driven the preclinical development of promising derivatives like dimethyl-doxorubicin, which retains cytotoxic efficacy and chromatin-damaging properties without inducing DNA damage. To understand the specific contributions of these mechanisms, we interrogated a “molecular toolbox” of chemotherapeutics, spanning purely DNA-damaging (etoposide, amrubicin), non-DNA-damaging (dimethyl-doxorubicin), and dual-activity (doxorubicin, epirubicin) agents. By integrating chromatin profiling, transcriptomics, and chromatin compartment-fractionated proteomics with the Broad Institute’s DepMap CRISPR screening and PRISM drug repurposing initiatives, we identified that most anthracyclines drive cytotoxicity primarily through the inhibition of protein translation via disrupted ribosome biogenesis and nucleolar function rather than DNA damage. These findings unify a growing body of literature and fundamentally reframe our understanding of anthracycline mechanisms. Recognizing protein translation inhibition as a major driver of anthracycline cytotoxicity provides a clear mechanistic path for future drug development, effectively decoupling antineoplastic efficacy from traditional DNA-damaging toxicities.