Abstract
BET inhibitors are promising therapeutic agents for the treatment of triple-negative breast cancer (TNBC), but the rapid emergence of resistance necessitates investigation of combination therapies and their effects on tumor evolution. Here, we show that palbociclib, a CDK4/6 inhibitor, and paclitaxel, a microtubule inhibitor, synergize with the BET inhibitor JQ1 in TNBC lines. High-complexity DNA barcoding and mathematical modeling indicate a high rate of de novo acquired resistance to these drugs relative to pre-existing resistance. We demonstrate that the combination of JQ1 and palbociclib induces cell division errors, which can increase the chance of developing aneuploidy. Characterizing acquired resistance to combination treatment at a single cell level shows heterogeneous mechanisms including activation of G1-S and senescence pathways. Our results establish a rationale for further investigation of combined BET and CDK4/6 inhibition in TNBC and suggest novel mechanisms of action for these drugs and new vulnerabilities in cells after emergence of resistance.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Animals
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Azepines / pharmacology
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Cell Cycle Checkpoints / drug effects
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Cell Proliferation / drug effects
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Clone Cells
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Cyclin-Dependent Kinase 4 / antagonists & inhibitors*
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Cyclin-Dependent Kinase 4 / metabolism
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Cyclin-Dependent Kinase 6 / antagonists & inhibitors*
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Cyclin-Dependent Kinase 6 / metabolism
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DNA, Neoplasm / metabolism
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Drug Resistance, Neoplasm* / drug effects
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Drug Synergism
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Female
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Gene Expression Regulation, Neoplastic / drug effects
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Mice
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Models, Biological
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Mutation / genetics
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Paclitaxel / pharmacology
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Piperazines / pharmacology
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Ploidies
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Proteins / antagonists & inhibitors*
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Proteins / metabolism
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Pyridines / pharmacology
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Retinoblastoma Protein / genetics
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Retinoblastoma Protein / metabolism
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Treatment Outcome
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Triazoles / pharmacology
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Triple Negative Breast Neoplasms / drug therapy*
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Triple Negative Breast Neoplasms / genetics
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Up-Regulation / drug effects
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Up-Regulation / genetics
Substances
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(+)-JQ1 compound
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Azepines
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DNA, Neoplasm
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Piperazines
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Proteins
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Pyridines
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Retinoblastoma Protein
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Triazoles
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bromodomain and extra-terminal domain protein, human
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Cyclin-Dependent Kinase 4
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Cyclin-Dependent Kinase 6
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palbociclib
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Paclitaxel