Time-Resolved Profiling Reveals ATF3 as a Novel Mediator of Endocrine Resistance in Breast Cancer

Breast cancer is one of the leading causes of death for women worldwide. Patients whose tumors express Estrogen Receptor α account for around 70% of cases and are mostly treated with targeted endocrine therapy. However, depending on the degree of severity of the disease at diagnosis, 10 to 40% of these tumors eventually relapse due to resistance development. Even though recent novel approaches as the combination with CDK4/6 inhibitors increased the overall survival of relapsing patients, this remains relatively short and there is a urgent need to find alternative targetable pathways. In this study we profiled the early phases of the resistance development process to uncover drivers of this phenomenon. Time-resolved analysis revealed that ATF3, a member of the ATF/CREB family of transcription factors, acts as a novel regulator of the response to therapy via rewiring of central signaling processes towards the adaptation to endocrine treatment. ATF3 was found to be essential in controlling crucial processes such as proliferation, cell cycle, and apoptosis during the early response to treatment through the regulation of MAPK/AKT signaling pathways. Its essential role was confirmed in vivo in a mouse model, and elevated expression of ATF3 was verified in patient datasets, adding clinical relevance to our findings. This study proposes ATF3 as a novel mediator of endocrine resistance development in breast cancer and elucidates its role in the regulation of downstream pathways activities.

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Time-resolved profiling reveals ATF3 as a novel mediator of endocrine resistance in breast cancer

10.1101/2020.06.08.139659 ◽

2020 ◽

Author(s):

Simone Borgoni ◽

Emre Sofyalı ◽

Maryam Soleimani ◽

Heike Wilhelm ◽

Karin Müller-Decker ◽

...

Keyword(s):

Breast Cancer ◽

Endocrine Resistance ◽

Early Response ◽

Estrogen Receptor Α ◽

Response To Therapy ◽

Response To Treatment ◽

Endocrine Treatment ◽

Resistance Development ◽

Time Resolved

AbstractBreast cancer is one of the leading causes of death for women worldwide. Patients whose tumors express Estrogen Receptor α (ERα) account for around 70% of cases and are mostly treated with targeted endocrine therapy. However, 40% of these tumors eventually relapse due to resistance development and further treatment of these patients is highly ineffective. In this study we profiled the early phases of the resistance development process to uncover drivers of this phenomenon. Time-resolved analysis revealed that ATF3, a member of the ATF/CREB family of transcription factors, acts as a novel regulator of the response to therapy via rewiring of central signaling processes towards the adaptation to endocrine treatment. ATF3 was found to be essential in controlling crucial processes such as proliferation, cell cycle and apoptosis during the early response to treatment through the regulation of MAPK/AKT signaling pathways. Its essential role was confirmed in vivo in a mouse model and elevated expression of ATF3 was verified in patient datasets, adding clinical relevance to our findings. This study proposes ATF3 as a novel mediator of endocrine resistance development in breast cancer and elucidates its role in the regulation of downstream pathways activities.

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Hypoxia-induced switch in SNAT2/SLC38A2 regulation generates endocrine resistance in breast cancer

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1818521116 ◽

2019 ◽

Vol 116 (25) ◽

pp. 12452-12461 ◽

Cited By ~ 21

Author(s):

Matteo Morotti ◽

Esther Bridges ◽

Alessandro Valli ◽

Hani Choudhry ◽

Helen Sheldon ◽

...

Keyword(s):

Breast Cancer ◽

Hypoxia Inducible Factor ◽

Tumor Hypoxia ◽

Endocrine Resistance ◽

Regulatory Elements ◽

Estrogen Receptor Α ◽

Mcf7 Cells ◽

Glutamine Transporter

Tumor hypoxia is associated with poor patient outcomes in estrogen receptor-α–positive (ERα+) breast cancer. Hypoxia is known to affect tumor growth by reprogramming metabolism and regulating amino acid (AA) uptake. Here, we show that the glutamine transporter, SNAT2, is the AA transporter most frequently induced by hypoxia in breast cancer, and is regulated by hypoxia both in vitro and in vivo in xenografts. SNAT2 induction in MCF7 cells was also regulated by ERα, but it became predominantly a hypoxia-inducible factor 1α (HIF-1α)–dependent gene under hypoxia. Relevant to this, binding sites for both HIF-1α and ERα overlap in SNAT2’s cis-regulatory elements. In addition, the down-regulation of SNAT2 by the ER antagonist fulvestrant was reverted in hypoxia. Overexpression of SNAT2 in vitro to recapitulate the levels induced by hypoxia caused enhanced growth, particularly after ERα inhibition, in hypoxia, or when glutamine levels were low. SNAT2 up-regulation in vivo caused complete resistance to antiestrogen and, partially, anti-VEGF therapies. Finally, high SNAT2 expression levels correlated with hypoxia profiles and worse outcome in patients given antiestrogen therapies. Our findings show a switch in the regulation of SNAT2 between ERα and HIF-1α, leading to endocrine resistance in hypoxia. Development of drugs targeting SNAT2 may be of value for a subset of hormone-resistant breast cancer.

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An immune-humanized patient-derived xenograft model of estrogen-independent, hormone receptor positive metastatic breast cancer

Breast Cancer Research ◽

10.1186/s13058-021-01476-x ◽

2021 ◽

Vol 23 (1) ◽

Author(s):

Sandra D. Scherer ◽

Alessandra I. Riggio ◽

Fadi Haroun ◽

Yoko S. DeRose ◽

H. Atakan Ekiz ◽

...

Keyword(s):

Breast Cancer ◽

Metastatic Breast Cancer ◽

Tumor Microenvironment ◽

Endocrine Resistance ◽

Metastatic Breast ◽

Response To Therapy ◽

Model Systems ◽

Hematopoietic Stem ◽

Pdx Model

Abstract Background Metastatic breast cancer (MBC) is incurable, with a 5-year survival rate of 28%. In the USA, more than 42,000 patients die from MBC every year. The most common type of breast cancer is estrogen receptor-positive (ER+), and more patients die from ER+ breast cancer than from any other subtype. ER+ tumors can be successfully treated with hormone therapy, but many tumors acquire endocrine resistance, at which point treatment options are limited. There is an urgent need for model systems that better represent human ER+ MBC in vivo, where tumors can metastasize. Patient-derived xenografts (PDX) made from MBC spontaneously metastasize, but the immunodeficient host is a caveat, given the known role of the immune system in tumor progression and response to therapy. Thus, we attempted to develop an immune-humanized PDX model of ER+ MBC. Methods NSG-SGM3 mice were immune-humanized with CD34+ hematopoietic stem cells, followed by engraftment of human ER+ endocrine resistant MBC tumor fragments. Strategies for exogenous estrogen supplementation were compared, and immune-humanization in blood, bone marrow, spleen, and tumors was assessed by flow cytometry and tissue immunostaining. Characterization of the new model includes assessment of the human tumor microenvironment performed by immunostaining. Results We describe the development of an immune-humanized PDX model of estrogen-independent endocrine resistant ER+ MBC. Importantly, our model harbors a naturally occurring ESR1 mutation, and immune-humanization recapitulates the lymphocyte-excluded and myeloid-rich tumor microenvironment of human ER+ breast tumors. Conclusion This model sets the stage for development of other clinically relevant models of human breast cancer and should allow future studies on mechanisms of endocrine resistance and tumor-immune interactions in an immune-humanized in vivo setting.

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Hypoxia-induced switch in SNAT2/SLC38A2 regulation generates endocrine-resistance in breast cancer

10.1101/384628 ◽

2018 ◽

Cited By ~ 1

Author(s):

Matteo Morotti ◽

Esther Bridges ◽

Alessandro Valli ◽

Hani Choudhry ◽

Helen Sheldon ◽

...

Keyword(s):

Breast Cancer ◽

Tumor Hypoxia ◽

Endocrine Resistance ◽

Estrogen Therapy ◽

Regulatory Elements ◽

Estrogen Receptor Α ◽

Mcf7 Cells ◽

Glutamine Transporter

AbstractTumor hypoxia is associated with poor patient outcomes in estrogen receptor-α (ERα) positive breast cancer. Hypoxia is known to affect tumor growth by reprogramming metabolism and regulating amino acid (AA) uptake. Here we show that the glutamine transporter, SNAT2, is the AA transporter most frequently induced by hypoxia in breast cancer and it is regulated by HIF1α bothin-vitroandin-vivoin xenografts. SNAT2 induction in MCF7 cells was also regulated by ERα but it became predominantly a HIF-1α-dependent gene under hypoxia. Relevant to this, binding sites for both HIF-1α and ERα overlap in SNAT2’s cis-regulatory elements. In addition, the downregulation of SNAT2 by the ER antagonist fulvestrant was reverted in hypoxia.Overexpression of SNAT2in-vitroto recapitulate the levels induced by hypoxia caused enhanced growth, particularly after ERα inhibition, in hypoxia, or when glutamine levels were low. SNAT2 upregulationin-vivocaused complete resistance to anti-estrogen and, partially, anti-VEGF therapies. Finally, high SNAT2 expression levels correlate with HIF-1α and worse outcome in patients given anti-estrogen therapy. Our findings show a switch in regulation of SNAT2 between ERα and HIF-1α, leading to endocrine resistance in hypoxia. Development of drugs targeting SNAT2 may be of value for a subset of hormone-resistant breast cancer.

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MCM3 upregulation confers endocrine resistance in breast cancer and is a predictive marker of diminished tamoxifen benefit

npj Breast Cancer ◽

10.1038/s41523-020-00210-8 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Sanne Løkkegaard ◽

Daniel Elias ◽

Carla L. Alves ◽

Martin V. Bennetzen ◽

Anne-Vibeke Lænkholm ◽

...

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Cancer Patients ◽

Endocrine Therapy ◽

Endocrine Resistance ◽

Predictive Marker ◽

Endocrine Treatment ◽

Breast Cancer Patients ◽

Minichromosome Maintenance ◽

Primary Tumors

AbstractResistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer is a major clinical problem with poorly understood mechanisms. There is an unmet need for prognostic and predictive biomarkers to allow appropriate therapeutic targeting. We evaluated the mechanism by which minichromosome maintenance protein 3 (MCM3) influences endocrine resistance and its predictive/prognostic potential in ER+ breast cancer. We discovered that ER+ breast cancer cells survive tamoxifen and letrozole treatments through upregulation of minichromosome maintenance proteins (MCMs), including MCM3, which are key molecules in the cell cycle and DNA replication. Lowering MCM3 expression in endocrine-resistant cells restored drug sensitivity and altered phosphorylation of cell cycle regulators, including p53(Ser315,33), CHK1(Ser317), and cdc25b(Ser323), suggesting that the interaction of MCM3 with cell cycle proteins is an important mechanism of overcoming replicative stress and anti-proliferative effects of endocrine treatments. Interestingly, the MCM3 levels did not affect the efficacy of growth inhibitory by CDK4/6 inhibitors. Evaluation of MCM3 levels in primary tumors from four independent cohorts of breast cancer patients receiving adjuvant tamoxifen mono-therapy or no adjuvant treatment, including the Stockholm tamoxifen (STO-3) trial, showed MCM3 to be an independent prognostic marker adding information beyond Ki67. In addition, MCM3 was shown to be a predictive marker of response to endocrine treatment. Our study reveals a coordinated signaling network centered around MCM3 that limits response to endocrine therapy in ER+ breast cancer and identifies MCM3 as a clinically useful prognostic and predictive biomarker that allows personalized treatment of ER+ breast cancer patients.

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Identification and Roles of miR-29b-1-3p and miR29a-3p-Regulated and Non-Regulated lncRNAs in Endocrine-Sensitive and Resistant Breast Cancer Cells

Cancers ◽

10.3390/cancers13143530 ◽

2021 ◽

Vol 13 (14) ◽

pp. 3530

Author(s):

Penn Muluhngwi ◽

Carolyn M. Klinge

Keyword(s):

Breast Cancer ◽

Cancer Survival ◽

Expression Patterns ◽

Endocrine Resistance ◽

Estrogen Receptor Α ◽

Resistant Cell ◽

Differentially Expressed ◽

Primary Tumors ◽

Non Coding Rnas ◽

Mcf 7

Despite improvements in the treatment of endocrine-resistant metastatic disease using combination therapies in patients with estrogen receptor α (ERα) primary tumors, the mechanisms underlying endocrine resistance remain to be elucidated. Non-coding RNAs (ncRNAs), including microRNAs (miRNA) and long non-coding RNAs (lncRNA), are targets and regulators of cell signaling pathways and their exosomal transport may contribute to metastasis. Previous studies have shown that a low expression of miR-29a-3p and miR-29b-3p is associated with lower overall breast cancer survival before 150 mos. Transient, modest overexpression of miR-29b1-3p or miR-29a-3p inhibited MCF-7 tamoxifen-sensitive and LCC9 tamoxifen-resistant cell proliferation. Here, we identify miR-29b-1/a-regulated and non-regulated differentially expressed lncRNAs in MCF-7 and LCC9 cells using next-generation RNA seq. More lncRNAs were miR-29b-1/a-regulated in LCC9 cells than in MCF-7 cells, including DANCR, GAS5, DSCAM-AS1, SNHG5, and CRND. We examined the roles of miR-29-regulated and differentially expressed lncRNAs in endocrine-resistant breast cancer, including putative and proven targets and expression patterns in survival analysis using the KM Plotter and TCGA databases. This study provides new insights into lncRNAs in endocrine-resistant breast cancer.

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The Emerging Role of Extracellular Vesicles in Endocrine Resistant Breast Cancer

Cancers ◽

10.3390/cancers13051160 ◽

2021 ◽

Vol 13 (5) ◽

pp. 1160

Author(s):

Giusi La Camera ◽

Luca Gelsomino ◽

Amanda Caruso ◽

Salvatore Panza ◽

Ines Barone ◽

...

Keyword(s):

Breast Cancer ◽

Endocrine Therapy ◽

Extracellular Vesicles ◽

Molecular Mechanisms ◽

Endocrine Resistance ◽

Disease Recurrence ◽

Estrogen Receptor Α ◽

Research Area ◽

Tumor Evolution

Breast cancer is the most common solid malignancy diagnosed in females worldwide, and approximately 70% of these tumors express estrogen receptor α (ERα), the main biomarker of endocrine therapy. Unfortunately, despite the use of long-term anti-hormone adjuvant treatment, which has significantly reduced patient mortality, resistance to the endocrine treatments often develops, leading to disease recurrence and limiting clinical benefits. Emerging evidence indicates that extracellular vesicles (EVs), nanosized particles that are released by all cell types and responsible for local and systemic intercellular communications, might represent a newly identified mechanism underlying endocrine resistance. Unraveling the role of EVs, released by transformed cells during the tumor evolution under endocrine therapy, is still an open question in the cancer research area and the molecular mechanisms involved should be better defined to discover alternative therapeutic approaches to overcome resistance. In this review, we will provide an overview of recent findings on the involvement of EVs in sustaining hormonal resistance in breast cancer and discuss opportunities for their potential use as biomarkers to monitor the therapeutic response and disease progression.

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FOXA1 overexpression mediates endocrine resistance by altering the ER transcriptome and IL-8 expression in ER-positive breast cancer

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1612835113 ◽

2016 ◽

Vol 113 (43) ◽

pp. E6600-E6609 ◽

Cited By ~ 61

Author(s):

Xiaoyong Fu ◽

Rinath Jeselsohn ◽

Resel Pereira ◽

Emporia F. Hollingsworth ◽

Chad J. Creighton ◽

...

Keyword(s):

Breast Cancer ◽

Endocrine Resistance ◽

Cancer Cell Line ◽

Estrogen Receptor Α ◽

Resistant Cell ◽

Transcriptional Reprogramming ◽

Er Positive ◽

Integrated Omics ◽

And Function

Forkhead box protein A1 (FOXA1) is a pioneer factor of estrogen receptor α (ER)–chromatin binding and function, yet its aberration in endocrine-resistant (Endo-R) breast cancer is unknown. Here, we report preclinical evidence for a role of FOXA1 in Endo-R breast cancer as well as evidence for its clinical significance. FOXA1 is gene-amplified and/or overexpressed in Endo-R derivatives of several breast cancer cell line models. Induced FOXA1 triggers oncogenic gene signatures and proteomic profiles highly associated with endocrine resistance. Integrated omics data reveal IL8 as one of the most perturbed genes regulated by FOXA1 and ER transcriptional reprogramming in Endo-R cells. IL-8 knockdown inhibits tamoxifen-resistant cell growth and invasion and partially attenuates the effect of overexpressed FOXA1. Our study highlights a role of FOXA1 via IL-8 signaling as a potential therapeutic target in FOXA1-overexpressing ER-positive tumors.

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Nuclear Mechanisms Involved in Endocrine Resistance

Frontiers in Oncology ◽

10.3389/fonc.2021.736597 ◽

2021 ◽

Vol 11 ◽

Author(s):

Jürgen Dittmer

Keyword(s):

Breast Cancer ◽

Estrogen Receptor ◽

Endocrine Therapy ◽

Standard Treatment ◽

Current Knowledge ◽

Endocrine Resistance ◽

Estrogen Receptor Α ◽

Cyclin Dependent Kinase ◽

Druggable Targets ◽

Positive Breast Cancer

Endocrine therapy is a standard treatment offered to patients with ERα (estrogen receptor α)-positive breast cancer. In endocrine therapy, ERα is either directly targeted by anti-estrogens or indirectly by aromatase inhibitors which cause estrogen deficiency. Resistance to these drugs (endocrine resistance) compromises the efficiency of this treatment and requires additional measures. Endocrine resistance is often caused by deregulation of the PI3K/AKT/mTOR pathway and/or cyclin-dependent kinase 4 and 6 activities allowing inhibitors of these factors to be used clinically to counteract endocrine resistance. The nuclear mechanisms involved in endocrine resistance are beginning to emerge. Exploring these mechanisms may reveal additional druggable targets, which could help to further improve patients’ outcome in an endocrine resistance setting. This review intends to summarize our current knowledge on the nuclear mechanisms linked to endocrine resistance.

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New insights in the interaction of FGF/FGFR and steroid receptor signaling in breast cancer

Endocrinology ◽

10.1210/endocr/bqab265 ◽

2022 ◽

Author(s):

Cecilia Pérez Piñero ◽

Sebastián Giulianelli ◽

Caroline A Lamb ◽

Claudia Lanari

Keyword(s):

Breast Cancer ◽

Hormone Receptors ◽

Endocrine Resistance ◽

Short Review ◽

Experimental Models ◽

Luminal Breast Cancer ◽

Tumor Subtypes ◽

Stromal Tissue ◽

The Many

Abstract Luminal breast cancer (BrCa) has a favorable prognosis compared to other tumor subtypes. However, with time tumors may evolve and lead to disease progression. Thus, there is a great interest in unraveling the mechanisms that drive tumor metastasis and endocrine resistance. In this review we focused in one of the many pathways that have been involved in tumor progression, the FGF/FGFR axis. We emphasized in data obtained from in vivo experimental models since we believe that in luminal BrCa, tumor growth relies in a crosstalk with the stromal tissue. We revisited the studies that illustrate the interaction between hormone receptors and FGFR. We also highlighted the most frequent alterations found in BrCa cell lines and we provide a short review on the trials that use FGFR inhibitors in combination with endocrine therapies. The analysis of this data suggests that there are many players involved in this pathway that might be also targeted to decrease FGF signaling in addition to specific FGFR inhibitors that may be exploited to increase their efficacy.

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