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.

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.

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.

Adjuvant Endocrine Therapy for Women With Hormone Receptor–Positive Breast Cancer: ASCO Clinical Practice Guideline Focused Update

2019 ◽  
Vol 37 (5) ◽  
pp. 423-438 ◽  
Author(s):  
Harold J. Burstein ◽  
Christina Lacchetti ◽  
Holly Anderson ◽  
Thomas A. Buchholz ◽  
Nancy E. Davidson ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Clinical Practice ◽  
Endocrine Therapy ◽  
Clinical Practice Guideline ◽  
Practice Guideline ◽  
Cancer Recurrence ◽  
Endocrine Treatment ◽  
Breast Cancers ◽  
Node Negative ◽  
Positive Breast Cancer

Purpose To update the ASCO clinical practice guideline on adjuvant endocrine therapy based on emerging data about the optimal duration of aromatase inhibitor (AI) treatment. Methods ASCO conducted a systematic review of randomized clinical trials from 2012 to 2018. Guideline recommendations were based on the Panel’s review of the evidence from six trials. Results The six included studies of AI treatment beyond 5 years of therapy demonstrated that extension of AI treatment was not associated with an overall survival advantage but was significantly associated with lower risks of breast cancer recurrence and contralateral breast cancer compared with placebo. Bone-related toxic effects were more common with extended AI treatment. Recommendations The Panel recommends that women with node-positive breast cancer receive extended therapy, including an AI, for up to a total of 10 years of adjuvant endocrine treatment. Many women with node-negative breast cancer should consider extended therapy for up to a total of 10 years of adjuvant endocrine treatment based on considerations of recurrence risk using established prognostic factors. The Panel noted that the benefits in absolute risk of reduction were modest and that, for lower-risk node-negative or limited node-positive cancers, an individualized approach to treatment duration that is based on considerations of risk reduction and tolerability was appropriate. A substantial portion of the benefit for extended adjuvant AI therapy was derived from prevention of second breast cancers. Shared decision making between clinicians and patients is appropriate for decisions about extended adjuvant endocrine treatment, including discussions about the absolute benefits in the reduction of breast cancer recurrence, the prevention of second breast cancers, and the impact of adverse effects of treatment. Additional information can be found at www.asco.org/breast-cancer-guidelines .

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 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 Estrogen-regulated feedback loop limits the efficacy of estrogen receptor–targeted breast cancer therapy

2018 ◽  
Vol 115 (31) ◽  
pp. 7869-7878 ◽  
Author(s):  
Tengfei Xiao ◽  
Wei Li ◽  
Xiaoqing Wang ◽  
Han Xu ◽  
Jixin Yang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Endocrine Therapy ◽  
Negative Feedback ◽  
Feedback Loop ◽  
Therapy Resistance ◽  
Negative Feedback Loop ◽  
Endocrine Therapy Resistance ◽  
Estrogen Receptor Positive ◽  
Underlying Mechanisms

Endocrine therapy resistance invariably develops in advanced estrogen receptor-positive (ER+) breast cancer, but the underlying mechanisms are largely unknown. We have identified C-terminal SRC kinase (CSK) as a critical node in a previously unappreciated negative feedback loop that limits the efficacy of current ER-targeted therapies. Estrogen directly drives CSK expression in ER+ breast cancer. At low CSK levels, as is the case in patients with ER+ breast cancer resistant to endocrine therapy and with the poorest outcomes, the p21 protein-activated kinase 2 (PAK2) becomes activated and drives estrogen-independent growth. PAK2 overexpression is also associated with endocrine therapy resistance and worse clinical outcome, and the combination of a PAK2 inhibitor with an ER antagonist synergistically suppressed breast tumor growth. Clinical approaches to endocrine therapy-resistant breast cancer must overcome the loss of this estrogen-induced negative feedback loop that normally constrains the growth of ER+ tumors.

scholarly journals Long Non-Coding RNA H19 Acts as an Estrogen Receptor Modulator that is Required for Endocrine Therapy Resistance in ER+ Breast Cancer Cells

2018 ◽  
Vol 51 (4) ◽  
pp. 1518-1532 ◽  
Author(s):  
Pratima Basak ◽  
Sumanta Chatterjee ◽  
Vasudeva Bhat ◽  
Alice Su ◽  
Hyerang Jin ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cancer Cells ◽  
Endocrine Therapy ◽  
Breast Cancer Cells ◽  
Therapy Resistance ◽  
Receptor Signaling ◽  
Met Receptor ◽  
Endocrine Therapy Resistance ◽  
Organoid Cultures

Background/Aims: Blocking estrogen signaling with endocrine therapies (Tamoxifen or Fulverstrant) is an effective treatment for Estrogen Receptor-α positive (ER+) breast cancer tumours. Unfortunately, development of endocrine therapy resistance (ETR) is a frequent event resulting in disease relapse and decreased overall patient survival. The long noncoding RNA, H19, was previously shown to play a significant role in estrogen-induced proliferation of both normal and malignant ER+ breast epithelial cells. We hypothesized that H19 expression is also important for the proliferation and survival of ETR cells. Methods: Here we utilized established ETR cell models; the Tamoxifen (Tam)-resistant LCC2 and the Fulvestrant and Tam cross-resistant LCC9 cells. Gain and loss of H19 function were achieved through lentiviral transduction as well as pharmacological inhibitors of the Notch and c-Met receptor signaling pathways. The effects of altered H19 expression on cell viability and ETR were assessed using three-dimensional (3D) organoid cultures and 2D co-cultures with low passage tumour-associated fbroblasts (TAFs). Results: Here we report that treating ETR cells with Tam or Fulvestrant increases H19 expression and that it’s decreased expression overcomes resistance to Tam and Fulvestrant in these cells. Interestingly, H19 expression is regulated by Notch and HGF signaling in the ETR cells and pharmacological inhibitors of Notch and c-MET signaling together significantly reverse resistance to Tam and Fulvestrant in an H19-dependent manner in these cells. Lastly, we demonstrate that H19 regulates ERα expression at the transcript and protein levels in the ETR cells and that H19 protects ERα against Fulvestrant-mediated downregulation of ERα protein. We also observed that blocking Notch and the c-MET receptor signaling also overcomes Fulvestrant and Tam resistance in 3D organoid cultures by decreasing ERα and H19 expression in the ETR cells. Conclusion: In endocrine therapy resistant breast cancer cells Fulvestrant is ineffective in decreasing ERα levels. Our data suggest that in the ETR cells, H19 expression acts as an ER modulator and that its levels and subsequently ERα levels can be substantially decreased by blocking Notch and c-MET receptor signaling. Consequently, treating ETR cells with these pharmacological inhibitors helps overcome resistance to Fulvestrant and Tamoxifen.

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