Inhibition of protein kinase A (PKA) promotes estrogen-dependent growth of MCF7 breast cancer cells, although the mechanisms by which PKA regulates estrogen receptor (ER) function remain unclear. In this study elevation of cAMP by forskolin/3-isobutyl-1-methylxanthine (F/I) suppressed estradiol-dependent MCF7 and T47D breast cancer cell growth but not tamoxifen-resistant MCF7-LCC2 cells. Although F/I induced ligand independent activation of ERalpha, F/I also decreased estradiol-dependent reporter gene transcription. Overexpression of PKA or PKA inhibitor (PKI) demonstrated that F/I effects on repression of estradiol action occurred through the PKA pathway. 8CPT-2Me-cAMP, a selective inducer of non-PKA signaling, did not alter ER-dependent transcription. In contrast to F/I effects on reporter genes, F/I exhibited gene-specific effects on endogenous, ER-regulated genes. F/I enhanced estradiol induction of pS2 and cMyc but repressed estradiol induction of cyclin D1 mRNA and protein in MCF7 cells. To explore likely mechanisms by which F/I regulated ER, experiments examined estradiol binding, Hsp90 interaction, promoter recruitment, and ERalpha phosphorylation. F/I decreased estradiol binding and increased Hsp90 association with ERalpha. Chromatin immunoprecipitation revealed that F/I recruited ERalpha to both pS2 and cMyc promoters at earlier times than estradiol, and F/I shifted estradiol recruitment of ERalpha to earlier time points. F/I induced a unique ERalpha phosphorylation profile (increase in serine 305 and decrease in serine 118 phosphorylation) that was distinct from estradiol and estradiol + F/I. Taken together, F/I signaling through PKA selectively regulates estradiol-dependent genes in breast cancer, which is associated with reduced ligand binding and changes in promoter interaction and ERalpha phosphorylation.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1210/me.2006-0059 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
CXCR4 promotes tumor stemness maintenance and CDK4/6 inhibitors resistance in ER-positive breast cancer.
Breast Cancer Res
January 2025
Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, China.
Background: CDK4/6 inhibitors have significantly improved the survival of patients with HR-positive/HER2-negative breast cancer, becoming a first-line treatment option. However, the development of resistance to these inhibitors is inevitable. To address this challenge, novel strategies are required to overcome resistance, necessitating a deeper understanding of its mechanisms.
View Article and Find Full Text PDFFactors influencing role preferences in decision-making of healthy women with BRCA1/2 pathogenic variants: subanalysis from a randomised controlled decision coaching trial.
BMC Cancer
January 2025
Faculty of Medicine, University of Cologne and Institute for Health Economics and Clinical Epidemiology, University Hospital Cologne, Cologne, Germany.
Background: Patients who actively engage in their medical decision-making processes can experience better health outcomes. This exploratory study aimed to identify predictors of preferred and actual roles in decision-making in healthy women with BRCA1/2 pathogenic variants (PVs).
Methods: Women with BRCA1/2 PVs without a history of breast and/or ovarian cancer were recruited in six centres across Germany.
Targeting MYC for the treatment of breast cancer: use of the novel MYC-GSPT1 degrader, GT19630.
Invest New Drugs
January 2025
UCD School of Medicine, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland.
Background: Since MYC is one of the most frequently altered driver genes involved in cancer formation, it is a potential target for new anti-cancer therapies. Historically, however, MYC has proved difficult to target due to the absence of a suitable crevice for binding potential low molecular weight drugs.
Objective: The aim of this study was to evaluate a novel molecular glue, dubbed GT19630, which degrades both MYC and GSPT1, for the treatment of breast cancer.
F-FDG PET/CT radiomic analysis and artificial intelligence to predict pathological complete response after neoadjuvant chemotherapy in breast cancer patients.
Radiol Med
January 2025
Department of Translational Medicine, University of Ferrara, Ferrara, Italy.
Purpose: Build machine learning (ML) models able to predict pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) in breast cancer (BC) patients based on conventional and radiomic signatures extracted from baseline [F]FDG PET/CT.
Material And Methods: Primary tumor and the most significant lymph node metastasis were manually segmented in baseline [F]FDG PET/CT of 52 newly diagnosed BC patients. Clinical parameters, NAC and conventional semiquantitative PET parameters were collected.
Micropeptide hSPAR regulates glutamine levels and suppresses mammary tumor growth via a TRIM21-P27KIP1-mTOR axis.
EMBO J
January 2025
Department of Geriatrics, Gerontology Institute of Anhui Province, Centre for Leading Medicine and Advanced Technologies of IHM, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China.
mTOR plays a pivotal role in cancer growth control upon amino acid response. Recently, CDK inhibitor P27KIP1 has been reported as a noncanonical inhibitor of mTOR signaling in MEFs, via unclear mechanisms. Here, we find that P27KIP1 degradation via E3 ligase TRIM21 is inhibited by human micropeptide hSPAR through its C-terminus (hSPAR-C), causing P27KIP1's cytoplasmic accumulation in breast cancer cells.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!