# Robust-to-fragile transitions of a phase-separated mitotic organelle in triple-negative breast cancer

> **NIH NIH U54** · UNIVERSITY OF VIRGINIA · 2022 · $370,150

## Abstract

PROJECT ABSTRACT/SUMMARY
Aneuploidy and loss of heterozygosity are highly prevalent chromosome aberrations caused by sister-
chromatid segregation errors during mitosis. Aneuploidy is especially common in triple-negative breast
cancers, where outgrowth of aneuploid cells is permitted by the near-universal loss of TP53 that normally
surveils genomic integrity. Prior work from our team has connected the aneuploid phenotype in breast cancer
to network-level abundance changes in genes induced by mitotic transcription factors, which are chronically
elevated in tumors. The target genes of these transcription factors reside upstream and downstream of the
chromosome passenger complex (CPC), a four-protein sensor of proper spindle assembly and a mediator of
repair. The CPC must localize to the inner centromere and auto-activate when microtubules are incorrectly
attached. We recently found that the CPC accumulates during metaphase to a critical concentration causing it
to phase separate as a liquid condensate. CPC phase separation likely confers robustness of function, yet
cancers manage to bypass this checkpoint by changing the abundance of multiple regulators and effectors that
together cause cells to enter a state of chromosome instability. Our objective is to unravel how the complex
abundance imbalances of network regulators found in tumors stress the robust localization of the CPC to the
inner centromere and generate chromosome instability in breast cancers or precursor lesions. The leading
hypothesis is that phase-separated CPC acts as a “phenotypic capacitor” during mitosis by buffering small to
moderate imbalances (storage) and unleashing dramatic rearrangements when a threshold imbalance is
reached (discharge). We will test this hypothesis using biochemical reaction-diffusion models of spatially
regulated CPC phase separation, which will be tailored to primary mammary organoids derived from a mosaic
GEMM of triple-negative mammary cancer and extended to clinical samples through standard diagnostic
assays. The specific aims are to 1) develop and validate a spatial systems model of CPC recruitment that
isolates phase separation and predicts critical network imbalances in cancer-predisposed mammary organoids;
2) test the instability-generating potential of critical network imbalances by quantitatively perturbing triple-
negative mammary premalignancies in vivo; and 3) leverage routine clinical diagnostics to predict druggable
chromosomal instability signatures in any primary breast cancer. Patient-specific, systems-level models of
aneuploidy susceptibility will nominate kinase inhibitors in the network that are predicted to shift cells from
robust to fragile states of segregation fidelity.

## Key facts

- **NIH application ID:** 10525282
- **Project number:** 1U54CA274499-01
- **Recipient organization:** UNIVERSITY OF VIRGINIA
- **Principal Investigator:** P. TODD STUKENBERG
- **Activity code:** U54 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $370,150
- **Award type:** 1
- **Project period:** 2022-09-12 → 2027-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10525282

## Citation

> US National Institutes of Health, RePORTER application 10525282, Robust-to-fragile transitions of a phase-separated mitotic organelle in triple-negative breast cancer (1U54CA274499-01). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10525282. Licensed CC0.

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