Tamoxifen Response at Single Cell Resolution in Estrogen Receptor-Positive Primary Human Breast Tumors

Kim, Hyunsoo; Whitman, Austin A.; Wiśniewska, Kamila; Kakati, Rasha; García-Recio, Susana; Calhoun, Benjamin C.; Franco, Hector L.; Perou, Charles M.; Spanheimer, Philip M.

doi:10.1101/2023.04.01.535159

Cited by 3 publications

(1 citation statement)

References 81 publications

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“…FFPE slides sectioned at 4 microns were obtained from clinical pathology for the primary ER+/HER2-tumor. Immunohistochemistry (IHC) for Ki-67 antigen was performed using the Ki-67 Antibody (MIB-1, Dako) at 1:100 as we have previously described (79). A positive control was included.…”

Section: Primary Human Breast Tumor Cellsmentioning

confidence: 99%

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2− breast tumor cells

Zikry,

Wolff,

Ranek

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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The CDK4/6 inhibitor palbociclib blocks cell cycle progression in Estrogen receptor–positive, human epidermal growth factor 2 receptor–negative (ER+/HER2−) breast tumor cells. Despite the drug’s success in improving patient outcomes, a small percentage of tumor cells continues to divide in the presence of palbociclib—a phenomenon we refer to as fractional resistance. It is critical to understand the cellular mechanisms underlying fractional resistance because the precise percentage of resistant cells in patient tissue is a strong predictor of clinical outcomes. Here, we hypothesize that fractional resistance arises from cell-to-cell differences in core cell cycle regulators that allow a subset of cells to escape CDK4/6 inhibitor therapy. We used multiplex, single-cell imaging to identify fractionally resistant cells in both cultured and primary breast tumor samples resected from patients. Resistant cells showed premature accumulation of multiple G1 regulators including E2F1, retinoblastoma protein, and CDK2, as well as enhanced sensitivity to pharmacological inhibition of CDK2 activity. Using trajectory inference approaches, we show how plasticity among cell cycle regulators gives rise to alternate cell cycle “paths” that allow individual tumor cells to escape palbociclib treatment. Understanding drivers of cell cycle plasticity, and how to eliminate resistant cell cycle paths, could lead to improved cancer therapies targeting fractionally resistant cells to improve patient outcomes.

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Section: Primary Human Breast Tumor Cellsmentioning

confidence: 99%

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2− breast tumor cells

Zikry,

Wolff,

Ranek

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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show abstract

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2- breast tumor cells

Zikry,

Wolff,

Ranek

et al. 2023

Preprint

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The CDK4/6 inhibitor palbociclib blocks cell cycle progression in ER+/HER2− breast tumor cells. Although these drugs have significantly improved patient outcomes in metastatic breast cancers, a small percentage of tumor cells continues to divide in the presence of palbociclib—a phenomenon we refer to as fractional resistance. It is critical to understand the cellular mechanisms underlying fractional resistance because the precise percentage of resistant cells in patient tissue is a strong predictor of clinical outcome. Here, we hypothesize that fractional resistance arises from cell–to–cell differences in core cell cycle regulators that allow a subset of cells to escape CDK4/6 inhibitor therapy. We used multiplex, single–cell imaging to identify fractionally resistant tumor cells both in a cell culture model of ER+/HER2− breast cancer as well as live primary tumor cells resected from a patient. We found that tumor cells capable of proliferating in the presence of palbociclib showed both expected (e.g., CDK2, E2F1) and unexpected (e.g., Cdt1, p21, cyclin B1) shifts in core cell cycle regulators. Notably, resistant cells in both tumor models showed premature enrichment of the G1 regulators E2F1 and CDK2 protein and, unexpectedly, the G2/M regulator cyclin B1 just before cell cycle entry, suggesting that resistant cells may use noncanonical mechanisms to overcome CDK4/6 inhibition. Using computational data integration and trajectory inference approaches, we show how plasticity in cell cycle regulators gives rise to alternate cell cycle "paths" that allow individual ER+/HER2− tumor cells to escape palbociclib treatment. Understanding drivers of cell cycle plasticity, and how to eliminate resistant cell cycle paths, could lead to improved cancer therapies targeting fractionally resistant cells to improve patient outcomes.

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Kinase Plasticity in Response to Vandetanib Enhances Sensitivity to Tamoxifen and Identifies Co-Treatment Strategies in Estrogen Receptor Positive Breast Cancer

Kakati,

Whitman,

Haase

et al. 2024

Preprint

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Resistance to endocrine therapy (ET) is common in estrogen receptor (ER) positive breast cancer. Multiple studies have demonstrated that upregulation of MAPK signaling pathways contributes to ET resistance. Herein we show that vandetanib treatment enhances sensitivity to ET in ET-sensitive and –resistant ER+ breast cancer models. Using a CRISPR knockout model, we demonstrate that vandetanib effects are partially mediated by RET receptor tyrosine kinase. Vandetanib treatment alters the gene expression program of ER+ breast cancer cells resulting in a less proliferative and more estrogen responsive Luminal-A like character. Tyrosine kinase network reprogramming was assessed using multiplexed kinase inhibitor beads-mass spectrometry (MIB/MS) assay to identify adaptive resistance mechanisms to vandetanib treatment, which identified upregulation of HER2 activity. Co-treatment to inhibit HER2 with lapatinib enhanced sensitivity to vandetanib, demonstrating biologic activity of HER2 upregulation. Finally, we use our operating room-to-laboratory assay that measures drug response in individual primary tumor cells in short term cultures to demonstrate conserved gene expression changes, including increased HER2 activity signatures, in vandetanib treated cells, and identify features associated with vandetanib response. These results support future investigation of RET targeting strategies considering reprogrammed networks, such as activated HER2, in patients with ET resistant ER+ breast cancer.

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Tamoxifen Response at Single Cell Resolution in Estrogen Receptor-Positive Primary Human Breast Tumors

Cited by 3 publications

References 81 publications

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2− breast tumor cells

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2− breast tumor cells

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2- breast tumor cells

Kinase Plasticity in Response to Vandetanib Enhances Sensitivity to Tamoxifen and Identifies Co-Treatment Strategies in Estrogen Receptor Positive Breast Cancer

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