scholarly journals Endocrine Resistance in Breast Cancer: The Role of Estrogen Receptor Stability

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2077
Author(s):  
Sarah A. Jeffreys ◽  
Branka Powter ◽  
Bavanthi Balakrishnar ◽  
Kelly Mok ◽  
Patsy Soon ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Protein Stability ◽  
Posttranslational Modifications ◽  
Endocrine Resistance ◽  
Therapy Resistance ◽  
Disease Recurrence ◽  
Hormone Receptor Positive ◽  
Estrogen Production ◽  
Reported Data

Therapy of hormone receptor positive breast cancer (BCa) generally targets estrogen receptor (ER) function and signaling by reducing estrogen production or by blocking its interaction with the ER. Despite good long-term responses, resistance to treatment remains a significant issue, with approximately 40% of BCa patients developing resistance to ET. Mutations in the gene encoding ERα, ESR1, have been identified in BCa patients and are implicated as drivers of resistance and disease recurrence. Understanding the molecular consequences of these mutations on ER protein levels and its activity, which is tightly regulated, is vital. ER activity is in part controlled via its short protein half-life and therefore changes to its stability, either through mutations or alterations in pathways involved in protein stability, may play a role in therapy resistance. Understanding these connections and how ESR1 alterations could affect protein stability may identify novel biomarkers of resistance. This review explores the current reported data regarding posttranslational modifications (PTMs) of the ER and the potential impact of known resistance associated ESR1 mutations on ER regulation by affecting these PTMs in the context of ET resistance.

scholarly journals The Central Contributions of Breast Cancer Stem Cells in Developing Resistance to Endocrine Therapy in Estrogen Receptor (ER)-Positive Breast Cancer

Cancers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1028 ◽  
Author(s):  
David Rodriguez ◽  
Marc Ramkairsingh ◽  
Xiaozeng Lin ◽  
Anil Kapoor ◽  
Pierre Major ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Estrogen Receptor ◽  
Cancer Stem Cells ◽  
Hormone Therapy ◽  
Endocrine Therapy ◽  
Endocrine Resistance ◽  
Therapy Resistance ◽  
Breast Cancer Stem Cells ◽  
Er Positive

Breast cancer stem cells (BCSC) play critical roles in the acquisition of resistance to endocrine therapy in estrogen receptor (ER)-positive (ER + ve) breast cancer (BC). The resistance results from complex alterations involving ER, growth factor receptors, NOTCH, Wnt/β-catenin, hedgehog, YAP/TAZ, and the tumor microenvironment. These mechanisms are likely converged on regulating BCSCs, which then drive the development of endocrine therapy resistance. In this regard, hormone therapies enrich BCSCs in ER + ve BCs under both pre-clinical and clinical settings along with upregulation of the core components of “stemness” transcriptional factors including SOX2, NANOG, and OCT4. SOX2 initiates a set of reactions involving SOX9, Wnt, FXY3D, and Src tyrosine kinase; these reactions stimulate BCSCs and contribute to endocrine resistance. The central contributions of BCSCs to endocrine resistance regulated by complex mechanisms offer a unified strategy to counter the resistance. ER + ve BCs constitute approximately 75% of BCs to which hormone therapy is the major therapeutic approach. Likewise, resistance to endocrine therapy remains the major challenge in the management of patients with ER + ve BC. In this review we will discuss evidence supporting a central role of BCSCs in developing endocrine resistance and outline the strategy of targeting BCSCs to reduce hormone therapy resistance.

scholarly journals Update on the Role of NFκB in Promoting Aggressive Phenotypes of Estrogen Receptor–Positive Breast Cancer

Endocrinology ◽  
2020 ◽  
Vol 161 (10) ◽  
Author(s):  
Emily Smart ◽  
Svetlana E Semina ◽  
Jonna Frasor
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Endocrine Therapy ◽  
Signaling Pathway ◽  
Endocrine Resistance ◽  
Dimethyl Fumarate ◽  
Therapy Resistance ◽  
Molecular Characteristics ◽  
Breast Cancers ◽  
Estrogen Receptor Positive

Abstract The majority of breast cancers are diagnosed as estrogen receptor–positive (ER+) and respond well to ER-targeted endocrine therapy. Despite the initial treatability of ER+ breast cancer, this subtype still accounts for the majority of deaths. This is partly due to the changing molecular characteristics of tumors as they progress to aggressive, metastatic, and frequently therapy resistant disease. In these advanced tumors, targeting ER alone is often less effective, as other signaling pathways become active, and ER takes on a redundant or divergent role. One signaling pathway whose crosstalk with ER has been widely studied is the nuclear factor kappa B (NFκB) signaling pathway. NFκB is frequently implicated in ER+ tumor progression to an aggressive disease state. Although ER and NFκB frequently co-repress each other, it has emerged that the 2 pathways can positively converge to play a role in promoting endocrine resistance, metastasis, and disease relapse. This will be reviewed here, paying particular attention to new developments in the field. Ultimately, finding targeted therapies that remain effective as tumors progress remains one of the biggest challenges for the successful treatment of ER+ breast cancer. Although early attempts to therapeutically block NFκB activity frequently resulted in systemic toxicity, there are some effective options. The drugs parthenolide and dimethyl fumarate have both been shown to effectively inhibit NFκB, reducing tumor aggressiveness and reversing endocrine therapy resistance. This highlights the need to revisit targeting NFκB in the clinic to potentially improve outcome for patients with ER+ breast cancer.

scholarly journals Oral Selective Estrogen Receptor Degraders (SERDs) as a Novel Breast Cancer Therapy: Present and Future from a Clinical Perspective

2021 ◽  
Vol 22 (15) ◽  
pp. 7812
Author(s):  
Cristina Hernando ◽  
Belén Ortega-Morillo ◽  
Marta Tapia ◽  
Santiago Moragón ◽  
María Teresa Martínez ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Endocrine Resistance ◽  
Tamoxifen Resistance ◽  
Gene Mutations ◽  
Treatment Resistance ◽  
Progression Free Survival ◽  
Endocrine Treatment ◽  
Estrogen Production ◽  
Underlying Mechanisms

Estrogen receptor-positive (ER+) is the most common subtype of breast cancer. Endocrine therapy is the fundamental treatment against this entity, by directly or indirectly modifying estrogen production. Recent advances in novel compounds, such as cyclin-dependent kinase 4/6 inhibitors (CDK4/6i), or phosphoinositide 3-kinase (PI3K) inhibitors have improved progression-free survival and overall survival in these patients. However, some patients still develop endocrine resistance after or during endocrine treatment. Different underlying mechanisms have been identified as responsible for endocrine treatment resistance, where ESR1 gene mutations are one of the most studied, outstanding from others such as somatic alterations, microenvironment involvement and epigenetic changes. In this scenario, selective estrogen receptor degraders/downregulators (SERD) are one of the weapons currently in research and development against aromatase inhibitor- or tamoxifen-resistance. The first SERD to be developed and approved for ER+ breast cancer was fulvestrant, demonstrating also interesting activity in ESR1 mutated patients in the second line treatment setting. Recent investigational advances have allowed the development of new oral bioavailable SERDs. This review describes the evolution and ongoing studies in SERDs and new molecules against ER, with the hope that these novel drugs may improve our patients’ future landscape.

scholarly journals Epigenetic activation of the prostaglandin receptor EP4 promotes resistance to endocrine therapy for breast cancer

2016 ◽  
Author(s):  
Jeffrey F. Hiken ◽  
James I. McDonald ◽  
Keith F. Decker ◽  
Cesar Sanchez ◽  
Jeremy Hoog ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Methylation ◽  
Estrogen Receptor ◽  
Endocrine Therapy ◽  
Cancer Recurrence ◽  
Therapy Resistance ◽  
Epigenetic Mechanism ◽  
Prostaglandin E ◽  
Breast Cancers ◽  
Estrogen Production

AbstractApproximately 75% of breast cancers express estrogen receptor α (ERα) and depend on estrogen signals for continued growth. Aromatase inhibitors (AIs) prevent estrogen production and inhibit estrogen receptor signaling, resulting in decreased cancer recurrence and mortality. Advanced tumors treated with AIs almost always develop resistance to these drugs via the up-regulation of alternative growth signals. The mechanisms that drive this resistance—especially epigenetic events that alter gene expression—are however not well understood. Genome-wide DNA methylation and expression analysis of cell line models of acquired aromatase inhibitor resistance indicated that prostaglandin E2 receptor 4 (PTGER4) is up-regulated after demethylation in resistant cells. Knockdown and inhibitor studies demonstrate that PTGER4 is essential for estrogen independent growth. Analysis of downstream signaling indicates that PTGER4 likely promotes AI resistance via ligand independent activation of the ERα-cofactor CARM1. We believe that we have discovered a novel epigenetic mechanism for altering cell signaling and acquiring endocrine therapy resistance. Our findings indicate that PTGER4 is a potential drug target in AI resistant cancers. Additionally, the epigenetic component of PTGER4 regulation suggests that further study of PTGER4 may yield valuable insights into how DNA methylation-targeted diagnoses and treatments can improve AI resistant breast cancer treatment.

Endocrine Treatment of Breast Cancer: Current Perspectives, Future Directions

2017 ◽  
Vol 8 (03) ◽  
Author(s):  
Tazia Irfan ◽  
Mainul Haque ◽  
Sayeeda Rahman ◽  
Russell Kabir ◽  
Nuzhat Rahman ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Endocrine Therapy ◽  
Ovarian Function ◽  
Premenopausal Women ◽  
New Drugs ◽  
Effective Control ◽  
Endocrine Treatment ◽  
Estrogen Production ◽  
Hormone Sensitive

Breast cancer remains one of the major causes of death in women, and endocrine treatment is currently one of the mainstay of treatment in patients with estrogen receptor positive breast cancer. Endocrine therapy either slows down or stops the growth of hormone-sensitive tumors by blocking the body’s capability to yield hormones or by interfering with hormone action. In this paper, we intended to review various approaches of endocrine treatments for breast cancer highlighting successes and limitations. There are three settings where endocrine treatment of breast cancer can be used: neoadjuvant, adjuvant, or metastatic. Several strategies have also been developed to treat hormone-sensitive breast cancer which include ovarian ablation, blocking estrogen production, and stopping estrogen effects. Selective estrogen-receptor modulators (SERMs) (e.g. tamoxifen and raloxifene), aromatase inhibitors (AIs) (e.g. anastrozole, letrozole and exemestane), gonadotropin-releasing hormone agonists (GnRH) (e.g. goserelin), and selective estrogen receptor downregulators (SERDs) (e.g. fulvestrant) are currently used drugs to treat breast cancer. Tamoxifen is probably the first targeted therapy widely used in breast cancer treatment which is considered to be very effective as first line endocrine treatment in previously untreated patients and also can be used after other endocrine therapy and chemotherapy. AIs inhibit the action of enzyme aromatase which ultimately decrease the production of estrogen to stimulate the growth of ER+ breast cancer cells. GnRH agonists suppress ovarian function, inducing artificial menopause in premenopausal women. Endocrine treatments are cheap, well-tolerated and have a fixed single daily dose for all ages, heights and weights of patients. Endocrine treatments are not nearly as toxic as chemotherapy and frequent hospitalization can be avoided. New drugs in preliminary trials demonstrated the potential for improvement of the efficacy of endocrine therapy including overcoming resistance. However, the overall goals for breast cancer including endocrine therapy should focus on effective control of cancer, design personalized medical therapeutic approach, increase survival time and quality of life, and improve supportive and palliative care for end-stage disease.

scholarly journals The Emerging Role of Extracellular Vesicles in Endocrine Resistant Breast Cancer

Cancers ◽  
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.

scholarly journals Mismatch repair-deficient hormone receptor-positive breast cancers: Biology and pathological characterization

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Elham Sajjadi ◽  
Konstantinos Venetis ◽  
Roberto Piciotti ◽  
Marco Invernizzi ◽  
Elena Guerini-Rocco ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Mismatch Repair ◽  
Hormone Receptor ◽  
Therapy Resistance ◽  
Genetic Alterations ◽  
Diagnostic Tools ◽  
Breast Cancers ◽  
Comprehensive Overview ◽  
Hormone Receptor Positive ◽  
Status Assessment

AbstractThe clinical outcome of patients with a diagnosis of hormone receptor (HR)+ breast cancer has improved remarkably since the arrival of endocrine therapy. Yet, resistance to standard treatments is a major clinical challenge for breast cancer specialists and a life-threatening condition for the patients. In breast cancer, mismatch repair (MMR) status assessment has been demonstrated to be clinically relevant not only in terms of screening for inherited conditions such as Lynch syndrome, but also for prognostication, selection for immunotherapy, and early identification of therapy resistance. Peculiar traits characterize the MMR biology in HR+ breast cancers compared to other cancer types. In these tumors, MMR genetic alterations are relatively rare, occurring in ~3 % of cases. On the other hand, modifications at the protein level can be observed also in the absence of gene alterations and vice versa. In HR+ breast cancers, the prognostic role of MMR deficiency has been confirmed by several studies, but its predictive value remains a matter of controversy. The characterization of MMR status in these patients is troubled by the lack of tumor-specific guidelines and/or companion diagnostic tests. For this reason, precise identification of MMR-deficient breast cancers can be problematic. A deeper understanding of the MMR biology and clinical actionability in HR+ breast cancer may light the path to effective tumor-specific diagnostic tools. For a precise MMR status profiling, the specific strengths and limitations of the available technologies should be taken into consideration. This article aims at providing a comprehensive overview of the current state of knowledge of MMR alterations in HR+ breast cancer. The available armamentarium for MMR testing in these tumors is also examined along with possible strategies for a tailored pathological characterization.

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