scholarly journals 90 YEARS OF PROGESTERONE: Steroid receptors as MAPK signaling sensors in breast cancer: let the fates decide

2020 ◽  
Vol 65 (1) ◽  
pp. T35-T48
Author(s):  
Amy R Dwyer ◽  
Thu H Truong ◽  
Julie H Ostrander ◽  
Carol A Lange

Steroid hormone receptors (SRs) are classically defined as ligand-activated transcription factors that function as master regulators of gene programs important for a wide range of processes governing adult physiology, development, and cell or tissue homeostasis. A second function of SRs includes the ability to activate cytoplasmic signaling pathways. Estrogen (ER), androgen (AR), and progesterone (PR) receptors bind directly to membrane-associated signaling molecules including mitogenic protein kinases (i.e. c-SRC and AKT), G-proteins, and ion channels to mediate context-dependent actions via rapid activation of downstream signaling pathways. In addition to making direct contact with diverse signaling molecules, SRs are further fully integrated with signaling pathways by virtue of their N-terminal phosphorylation sites that act as regulatory hot-spots capable of sensing the signaling milieu. In particular, ER, AR, PR, and closely related glucocorticoid receptors (GR) share the property of accepting (i.e. sensing) ligand-independent phosphorylation events by proline-directed kinases in the MAPK and CDK families. These signaling inputs act as a ‘second ligand’ that dramatically impacts cell fate. In the face of drugs that reliably target SR ligand-binding domains to block uncontrolled cancer growth, ligand-independent post-translational modifications guide changes in cell fate that confer increased survival, EMT, migration/invasion, stemness properties, and therapy resistance of non-proliferating SR+ cancer cell subpopulations. The focus of this review is on MAPK pathways in the regulation of SR+ cancer cell fate. MAPK-dependent phosphorylation of PR (Ser294) and GR (Ser134) will primarily be discussed in light of the need to target changes in breast cancer cell fate as part of modernized combination therapies.

Cancers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2872
Author(s):  
Aaron R. Waddell ◽  
Haojie Huang ◽  
Daiqing Liao

The CREB-binding protein (CBP) and p300 are two paralogous lysine acetyltransferases (KATs) that were discovered in the 1980s–1990s. Since their discovery, CBP/p300 have emerged as important regulatory proteins due to their ability to acetylate histone and non-histone proteins to modulate transcription. Work in the last 20 years has firmly established CBP/p300 as critical regulators for nuclear hormone signaling pathways, which drive tumor growth in several cancer types. Indeed, CBP/p300 are critical co-activators for the androgen receptor (AR) and estrogen receptor (ER) signaling in prostate and breast cancer, respectively. The AR and ER are stimulated by sex hormones and function as transcription factors to regulate genes involved in cell cycle progression, metabolism, and other cellular functions that contribute to oncogenesis. Recent structural studies of the AR/p300 and ER/p300 complexes have provided critical insights into the mechanism by which p300 interacts with and activates AR- and ER-mediated transcription. Breast and prostate cancer rank the first and forth respectively in cancer diagnoses worldwide and effective treatments are urgently needed. Recent efforts have identified specific and potent CBP/p300 inhibitors that target the acetyltransferase activity and the acetytllysine-binding bromodomain (BD) of CBP/p300. These compounds inhibit AR signaling and tumor growth in prostate cancer. CBP/p300 inhibitors may also be applicable for treating breast and other hormone-dependent cancers. Here we provide an in-depth account of the critical roles of CBP/p300 in regulating the AR and ER signaling pathways and discuss the potential of CBP/p300 inhibitors for treating prostate and breast cancer.


2021 ◽  
Author(s):  
Carlos Perez Kerkvliet ◽  
Thu H. Truong ◽  
Julie Hanson Ostrander ◽  
Carol A. Lange

Abstract The classification and treatment of breast cancer is largely defined by the expression of steroid hormone receptors (HRs), namely estrogen receptor (ER) and progesterone receptor (PR), and gene amplification/overexpression of human epidermal growth factor receptor 2 (HER2). More recently, studies of androgen receptor (AR), glucocorticoid receptor (GR), and mineralocorticoid receptor (MR) have revealed that targeting these related HRs may be a promising strategy for a more personalized approach to the treatment of specific subtypes of HR+ breast cancer. For example, GR expression is associated with a good prognosis in ER+ breast cancer, but predicts poor prognosis in triple-negative breast cancer (TNBC). GR, like ER, PRs, and AR, is a ligand-activated transcription factor, but also has significant ligand-independent signaling activities. GR transcriptional activity is classically regulated by circulating glucocorticoids (GCs; ligand-dependent). Recent studies demonstrate that GR transcriptional activity is also regulated by a variety of cellular stress stimuli that input to GR Ser134 phosphorylation via rapid activation of the p38 mitogen activated protein kinase (MAPK) signaling pathway (ligand-independent). Furthermore, ligand-independent GR activation promotes feedforward signaling loops that mediate sustained activation of stress signaling pathways to drive advanced cancer biology (i.e. migration, invasion, chemoresistance, survival, and cellular growth). In this review, we will focus on the role of GR as a key sensor and mediator of physiologic and tumor microenvironment (TME)-derived cellular stress signaling in TNBC and discuss how targeting GR and/or associated signaling pathways may provide a strategy to inhibit deadly TNBC progression.


2020 ◽  
Vol 98 (3) ◽  
pp. 131-138 ◽  
Author(s):  
Aysegul Hanikoglu ◽  
Ertan Kucuksayan ◽  
Ferhat Hanikoglu ◽  
Tomris Ozben ◽  
Georgia Menounou ◽  
...  

Breast cancer is a worldwide commonly found malignancy in women and effective treatment is regarded as a huge clinical challenge even in the presence of several treatment options. Extensive literature is available demonstrating polyphenols as phytopharmaceutical anticancer agents. Among the polyphenols, quercetin and curcumin have been reported to have a strong potential against breast cancer. However, so far, no comprehensive study has been performed to demonstrate the anticarcinogenic effects of curcumin, quercetin, and their combinations with somatostatin on the fatty acid profile of breast cancer cell membranes. We used MCF-7 and MDA-MB231 breast cancer cells incubated with curcumin and quercetin for 24 h, in the absence and presence of somatostatin, at their EC50 concentrations to evaluate membrane fatty acid based functional lipidomics together with the followup of EGFR and MAPK signaling pathways. The two cell lines gave different membrane free fatty acid reorganization. In MCF-7 cells, the following changes were observed: an increase of ω6 linoleic acid in the cells incubated with somatostatin + quercetin and quercetin and a decrease of ω3 acids in the cells incubated with somatostatin + curcumin compared to somatostatin and significant increases of monounsaturated fatty acid (MUFA), mono-trans arachidonic acid levels and docosapentaenoic acid for the cells incubated with somatostatin + quercetin compared to the control cells. In MDA-MB231 cells, incubations with curcumin, quercetin, and somatostatin + quercetin induced the most significant membrane remodeling with the increase of stearic acid, diminution of ω6 linoleic, arachidonic acids, and ω3 (docosapentaenoic and docosahexaenoic acids). Distinct signaling pathway changes were found for these cell lines. In MCF-7 cells, separate or combined incubations with somatostatin and quercetin, significantly decreased EGFR and incubation with curcumin decreased MAPK signaling. In MDA-MB231 cells, incubation with curcumin decreased AKT1 and p-AKT1 (Thr308) levels. Incubation with curcumin and quercetin decreased the EGFR levels. Our results showed that cytostatic and antioxidant treatments can be combined to induce membrane fatty acid changes, including lipid isomerization as specific free radical driven process, and to influence signaling pathways. This study aimed to contribute to the literature on these antioxidants in the treatment of breast cancer to clarify the effects and mechanisms in combination with somatostatin.


2016 ◽  
Vol 56 (3) ◽  
pp. R99-R114 ◽  
Author(s):  
Katherine A Leehy ◽  
Tarah M Regan Anderson ◽  
Andrea R Daniel ◽  
Carol A Lange ◽  
Julie H Ostrander

Steroid hormone receptors (SRs) are heavily posttranslationally modified by the reversible addition of a variety of molecular moieties, including phosphorylation, acetylation, methylation, SUMOylation, and ubiquitination. These rapid and dynamic modifications may be combinatorial and interact (i.e. may be sequential, complement, or oppose each other), creating a vast array of uniquely modified receptor subspecies that allow for diverse receptor behaviors that enable highly sensitive and context-dependent hormone action. For example, in response to hormone or growth factor membrane-initiated signaling events, posttranslational modifications (PTMs) to SRs alter protein–protein interactions that govern the complex process of promoter or gene-set selection coupled to transcriptional repression or activation. Unique phosphorylation events allow SRs to associate or disassociate with specific cofactors that may include pioneer factors and other tethering partners, which specify the resulting transcriptome and ultimately change cell fate. The impact of PTMs on SR action is particularly profound in the context of breast tumorigenesis, in which frequent alterations in growth factor-initiated signaling pathways occur early and act as drivers of breast cancer progression toward endocrine resistance. In this article, with primary focus on breast cancer relevance, we review the mechanisms by which PTMs, including reversible phosphorylation events, regulate the closely related SRs, glucocorticoid receptor and progesterone receptor, allowing for precise biological responses to ever-changing hormonal stimuli.


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