Identifying the transcriptional drivers of dormancy in luminal A breast cancer
File(s)
Author(s)
Dewhurst, Hannah Faith
Type
Thesis
Abstract
Recurrence of ERα+ breast cancer (BC) can originate from dormant single cells or micro-metastases that persist during adjuvant endocrine therapy (ET). Up to 50% of patients initially deemed ‘disease-free’ experience terminal, metastatic relapse. Dormancy is characterized by G0-G1 cell cycle arrest, allowing disseminated cells to survive for decades. Multi-omics analyses from our group indicate that adaptation to ET involves non-genetic cell state transitions, including transcriptional reprogramming and chromatin remodeling, preceding ET resistance. However, endpoint analyses miss critical dynamics of dormant persister lineages, limiting therapeutic insights.
This work describes a workflow combining time-lapse imaging of an engineered ET-treated cell cycle reporter line with lineage tracking to examine persister cells at single-cell resolution. Classifying cell lineages as ‘apoptotic,’ ‘persister,’ or ‘active’ revealed that the mother cell's initial cell cycle state influences lineage fate, with prolonged cell cycle durations enhancing survival. Tamoxifen-treated MCF7 cells demonstrated extended G0/G1 and G2/M phases, with G2/M arrest prominent at later treatment stages. Enriching for G2/M-phase cells increased their vulnerability to aromatase inhibitors (AI) and CDK7 inhibitors (CDK7i), highlighting a potential combination strategy to synchronise and target susceptible cell cycle states within residual disease. To explore mechanisms of dormancy, an in vitro CRISPR screen identified 26 transcription factors and chromatin modifiers linked to the transcriptionally repressive heterochromatin state of dormant BC cells. Follow-up targeting of NFAT5, a candidate dormancy mediator, with inhibitor KRN5 impaired survival during oestrogen deprivation. These findings suggest NFAT5 and other screen candidates could be targeted in combination therapies to eliminate dormant cells, reducing metastatic relapse risk.
This work describes a workflow combining time-lapse imaging of an engineered ET-treated cell cycle reporter line with lineage tracking to examine persister cells at single-cell resolution. Classifying cell lineages as ‘apoptotic,’ ‘persister,’ or ‘active’ revealed that the mother cell's initial cell cycle state influences lineage fate, with prolonged cell cycle durations enhancing survival. Tamoxifen-treated MCF7 cells demonstrated extended G0/G1 and G2/M phases, with G2/M arrest prominent at later treatment stages. Enriching for G2/M-phase cells increased their vulnerability to aromatase inhibitors (AI) and CDK7 inhibitors (CDK7i), highlighting a potential combination strategy to synchronise and target susceptible cell cycle states within residual disease. To explore mechanisms of dormancy, an in vitro CRISPR screen identified 26 transcription factors and chromatin modifiers linked to the transcriptionally repressive heterochromatin state of dormant BC cells. Follow-up targeting of NFAT5, a candidate dormancy mediator, with inhibitor KRN5 impaired survival during oestrogen deprivation. These findings suggest NFAT5 and other screen candidates could be targeted in combination therapies to eliminate dormant cells, reducing metastatic relapse risk.
Version
Open Access
Date Issued
2024-08-01
Date Awarded
01/12/2024
License URL
Advisor
Magnani, Luca
Thomas, Philipp
Sponsor
Medical Research Council (Great Britain)
Publisher Department
Department of Surgery & Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)