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

2018 ◽  
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.

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

2019 ◽  
Vol 116 (25) ◽  
pp. 12452-12461 ◽  
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.

scholarly journals Inhibition of histone methyltransferase DOT1L silences ERα gene and blocks proliferation of antiestrogen-resistant breast cancer cells

2019 ◽  
Vol 5 (2) ◽  
pp. eaav5590 ◽  
Author(s):  
Giovanni Nassa ◽  
Annamaria Salvati ◽  
Roberta Tarallo ◽  
Valerio Gigantino ◽  
Elena Alexandrova ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Endocrine Therapy ◽  
Gene Transcription ◽  
Apoptotic Cell ◽  
Estrogen Receptor Α ◽  
Cycle Arrest ◽  
H3k79 Methylation ◽  
Target Gene Transcription

Breast cancer (BC) resistance to endocrine therapy results from constitutively active or aberrant estrogen receptor α (ERα) signaling, and ways to block ERα pathway in these tumors are sought after. We identified the H3K79 methyltransferase DOT1L as a novel cofactor of ERα in BC cell chromatin, where the two proteins colocalize to regulate estrogen target gene transcription. DOT1L blockade reduces proliferation of hormone-responsive BC cells in vivo and in vitro, consequent to cell cycle arrest and apoptotic cell death, with widespread effects on ER-dependent gene transcription, including ERα and FOXA1 gene silencing. Antiestrogen-resistant BC cells respond to DOT1L inhibition also in mouse xenografts, with reduction in ERα levels, H3K79 methylation, and tumor growth. These results indicate that DOT1L is an exploitable epigenetic target for treatment of endocrine therapy–resistant ERα-positive BCs.

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

Cancers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2918
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

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.

scholarly journals In Vivo and In Vitro Evaluation of the Protective Effects of Hesperidin in Lipopolysaccharide-Induced Inflammation and Cytotoxicity of Cell

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 478 ◽  
Author(s):  
Rasha Al-Rikabi ◽  
Hanady Al-Shmgani ◽  
Yaser Hassan Dewir ◽  
Salah El-Hendawy
Keyword(s):  
Breast Cancer ◽  
Chromatin Condensation ◽  
Control Group ◽  
Potential Candidate ◽  
Dependent Manner ◽  
Protective Effects ◽  
Mcf7 Cells ◽  
Tnf Α

(1) Background: Plant flavonoids are efficient in preventing and treating various diseases. This study aimed to evaluate the ability of hesperidin, a flavonoid found in citrus fruits, in inhibiting lipopolysaccharide (LPS) induced inflammation, which induced lethal toxicity in vivo, and to evaluate its importance as an antitumor agent in breast cancer. The in vivo experiments revealed the protective effects of hesperidin against the negative LPS effects on the liver and spleen of male mice. (2) Methods: In the liver, the antioxidant activity was measured by estimating the concentration of glutathione (GSH) and catalase (CAT), whereas in spleen, the concentration of cytokines including IL-33 and TNF-α was measured. The in vitro experiments including MTT assay, clonogenity test, and sulforhodamine 101 stain with DAPI (4′, 6-diamidino-2-phenylindole) were used to assess the morphological apoptosis in breast cancer cells. (3) Results: The results of this study revealed a significant increase in the IL-33 and TNF-α cytokine levels in LPS challenged mice along with a considerable elevation in glutathione (GSH); moreover, the catalase (CAT) level was higher compared to that of the control group. Cytotoxicity of the MCF-7 cell line revealed significant differences among the groups treated with different concentrations when compared to the control groups, in a concentration-dependent manner. Hesperidin significantly inhibited the colony formation of MCF7 cells when compared to that of control. Clear changes were observed in the cell shape, including cell shrinkage and chromatin condensation, which were associated with a later apoptotic stage. (4) Conclusion: The results indicate that hesperidin might be a potential candidate in preventing diseases.

scholarly journals Estrogen deprivation triggers an immunosuppressive phenotype in breast cancer cells

2019 ◽  
Author(s):  
Daniela Hühn ◽  
Pablo Martí-Rodrigo ◽  
Silvana Mouron ◽  
Catherine S. Hansel ◽  
Kirsten Tschapalda ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Breast Cancers ◽  
Breast Cancer Patients ◽  
Mcf7 Cells ◽  
Estrogen Deprivation ◽  
Er Positive

ABSTRACTEstrogen receptor (ER)-positive breast tumors are routinely treated with estrogen-depriving therapies. Despite their effectiveness, patients often progress into a more aggressive form of the disease. Through a chemical screen oriented to identify chemicals capable of inducing the expression of the immune-checkpoint ligand PD-L1, we found antiestrogens as hits. Subsequent validations confirmed that estrogen deprivation or ERα depletion induces PD-L1 expression in ER-positive breast cancer cells, both in vitro and in vivo. Likewise, PD-L1 expression is increased in metastasis arising from breast cancer patients receiving adjuvant hormonal therapy for their local disease. Transcriptome analyses indicate that estrogen deprivation triggers a broad immunosuppressive program, not restricted to PD-L1. Accordingly, estrogen deprived MCF7 cells are resistant to T-cell mediated cell killing, in a manner that can be reverted by estradiol. Our study reveals that while antiestrogen therapies effectively limit tumor growth in ER-positive breast cancers, they also trigger a transcriptional program that favors immune evasion.

scholarly journals Fast Fluorine-18 Labeling and Preclinical Evaluation of Novel Mucin1 and its Folate Hybrid Peptide conjugate for Targeting Breast Carcinoma.

2020 ◽  
Author(s):  
ibrahim aljammaz ◽  
Basem Al-Otaibi ◽  
Yousif Al-Malki ◽  
Abdel Abousekhrah ◽  
S. M. Okarvi
Keyword(s):  
Breast Cancer ◽  
Scid Mice ◽  
Tumor Uptake ◽  
Mcf7 Cells ◽  
In Vivo Evaluation ◽  
Synthesis Time ◽  
Radiolabeled Compounds ◽  
Cell Fractions

Abstract Background: There is a need to develop new and more potent radiofluorinated peptide and their hybrid conjugates for multiple-receptors targeting properties that overexpress on many cancers. Methods: We have synthesized MUC1-[18F]SFB and MUC1-FA-[18F]SFB hybrid conjugates using a convenient and one-step nucleophilic displacement reactions. In vitro cell binding and in vivo evaluation in animals were performed to determine the potential of these radiolabeled compounds. Results: Radiochemical yields for MUC1-[18F]SFB and MUC1-FA-[18F]SFB conjugates were greater than 70% in less than 30 min synthesis time. Radiochemical purities were greater than 97% without HPLC purification, which make these approaches amenable for automation. In vitro studies on MCF7 breast cancer cells showed that the significant amounts of the radiofluorinated conjugates were associated with cell fractions and held good affinity and specificity for MCF7 cells. In vivo characterization in Balb/c mice revealed rapid blood clearance with excretion predominantly by urinary as well as hepatobiliary systems for MUC1-[18F]SFB and MUC1-FA-[18F]SFB, respectively. Biodistribution in SCID mice bearing MCF7 xenografts, demonstrated excellent tumor uptake (12% ID/g) and favorable kinetics for MUC1-FA-[18F]SFB over MUC1-[18F]SFB. The tumor uptake was blocked by the excess co-injection of cold peptides suggesting the receptor-mediated process. Conclusion: Initial PET/CT imaging of SCID mice with MCF7 xenografts, confirmed these observations. These results demonstrate that MUC1-FA-[18F]SFB may be useful PET imaging probe for breast cancer detection and monitoring tumor response to the treatment.

scholarly journals High-throughput allelic expression imbalance analyses identify candidate breast cancer risk genes

2019 ◽  
Author(s):  
Mahdi Moradi Marjaneh ◽  
Haran Sivakumaran ◽  
Kristine M Hillman ◽  
Susanne Kaufmann ◽  
Nehal Hussein ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Regulatory Elements ◽  
Normal Breast ◽  
Allelic Expression ◽  
Allelic Expression Imbalance ◽  
Risk Genes ◽  
Causal Variants ◽  
Breast Cells

ABSTRACTFine-mapping of breast cancer GWAS regions has identified 195 high confidence signals containing more than 5,000 credible causal variants (CCVs). The CCVs are predominantly noncoding and enriched in regulatory elements and thus may confer the risk by altering gene expression in cis. We analyzed allelic expression imbalance (AEI) of genes surrounding known breast cancer signals, using normal breast and breast tumor transcriptome data and imputed genotypes. Fourteen genes, including NTN4, were identified whose expression was associated with CCV genotype. We showed that CCVs at this signal were located within an enhancer that physically interacts with the NTN4 promoter. Furthermore, knockdown of NTN4 in breast cells increased cell proliferation in vitro and tumor growth in vivo. Here, we present the most comprehensive AEI analysis of breast cancer CCVs resulting in identification of new candidate risk genes.

scholarly journals Cross-talk between SIM2s and NFκB regulates cyclooxygenase 2 expression in breast cancer

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Garhett L. Wyatt ◽  
Lyndsey S. Crump ◽  
Chloe M. Young ◽  
Veronica M. Wessells ◽  
Cole M. McQueen ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cyclooxygenase 2 ◽  
Luciferase Reporter ◽  
Signaling Proteins ◽  
Dependent Manner ◽  
Mcf7 Cells ◽  
Human Breast Carcinomas ◽  
Cox 2

Abstract Background Breast cancer is a leading cause of cancer-related death for women in the USA. Thus, there is an increasing need to investigate novel prognostic markers and therapeutic methods. Inflammation raises challenges in treating and preventing the spread of breast cancer. Specifically, the nuclear factor kappa b (NFκB) pathway contributes to cancer progression by stimulating proliferation and preventing apoptosis. One target gene of this pathway is PTGS2, which encodes for cyclooxygenase 2 (COX-2) and is upregulated in 40% of human breast carcinomas. COX-2 is an enzyme involved in the production of prostaglandins, which mediate inflammation. Here, we investigate the effect of Singleminded-2s (SIM2s), a transcriptional tumor suppressor that is implicated in inhibition of tumor growth and metastasis, in regulating NFκB signaling and COX-2. Methods For in vitro experiments, reporter luciferase assays were utilized in MCF7 cells to investigate promoter activity of NFκB and SIM2. Real-time PCR, immunoblotting, immunohistochemistry, and chromatin immunoprecipitation assays were performed in SUM159 and MCF7 cells. For in vivo experiments, MCF10DCIS.COM cells stably expressing SIM2s-FLAG or shPTGS2 were injected into SCID mice and subsequent tumors harvested for immunostaining and analysis. Results Our results reveal that SIM2 attenuates the activation of NFκB as measured using NFκB-luciferase reporter assay. Furthermore, immunostaining of lysates from breast cancer cells overexpressing SIM2s showed reduction in various NFκB signaling proteins, as well as pAkt, whereas knockdown of SIM2 revealed increases in NFκB signaling proteins and pAkt. Additionally, we show that NFκB signaling can act in a reciprocal manner to decrease expression of SIM2s. Likewise, suppressing NFκB translocation in DCIS.COM cells increased SIM2s expression. We also found that NFκB/p65 represses SIM2 in a dose-dependent manner, and when NFκB is suppressed, the effect on the SIM2 is negated. Additionally, our ChIP analysis confirms that NFκB/p65 binds directly to SIM2 promoter site and that the NFκB sites in the SIM2 promoter are required for NFκB-mediated suppression of SIM2s. Finally, overexpression of SIM2s decreases PTGS2 in vitro, and COX-2 staining in vivo while decreasing PTGS2 and/or COX-2 activity results in re-expression of SIM2. Conclusion Our findings identify a novel role for SIM2s in NFκB signaling and COX-2 expression.

scholarly journals Activating transcription factor-2 (ATF2) is a key determinant of resistance to endocrine treatment in an in vitro model of breast cancer

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Athina Giannoudis ◽  
Mohammed Imad Malki ◽  
Bharath Rudraraju ◽  
Hisham Mohhamed ◽  
Suraj Menon ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Gene Expression ◽  
Transcription Factor ◽  
Endocrine Resistance ◽  
Endocrine Treatment ◽  
Mcf7 Cells ◽  
Microarray Gene Expression ◽  
Mcf7 Cell Line ◽  
Activating Transcription Factor

Abstract Background Activating transcription factor-2 (ATF2), a member of the leucine zipper family of DNA binding proteins, has been implicated as a tumour suppressor in breast cancer. However, its exact role in breast cancer endocrine resistance is still unclear. We have previously shown that silencing of ATF2 leads to a loss in the growth-inhibitory effects of tamoxifen in the oestrogen receptor (ER)-positive, tamoxifen-sensitive MCF7 cell line and highlighted that this multi-faceted transcription factor is key to the effects of tamoxifen in an endocrine sensitive model. In this work, we explored further the in vitro role of ATF2 in defining the resistance to endocrine treatment. Materials and methods We knocked down ATF2 in TAMR, LCC2 and LCC9 tamoxifen-resistant breast cancer cell lines as well as the parental tamoxifen sensitive MCF7 cell line and investigated the effects on growth, colony formation and cell migration. We also performed a microarray gene expression profiling (Illumina Human HT12_v4) to explore alterations in gene expression between MCF7 and TAMRs after ATF2 silencing and confirmed gene expression changes by quantitative RT-PCR. Results By silencing ATF2, we observed a significant growth reduction of TAMR, LCC2 and LCC9 with no such effect observed with the parental MCF7 cells. ATF2 silencing was also associated with a significant inhibition of TAMR, LCC2 and LCC9 cell migration and colony formation. Interestingly, knockdown of ATF2 enhanced the levels of ER and ER-regulated genes, TFF1, GREB1, NCOA3 and PGR, in TAMR cells both at RNA and protein levels. Microarray gene expression identified a number of genes known to mediate tamoxifen resistance, to be differentially regulated by ATF2 in TAMR in relation to the parental MCF7 cells. Moreover, differential pathway analysis confirmed enhanced ER activity after ATF2 knockdown in TAMR cells. Conclusion These data demonstrate that ATF2 silencing may overcome endocrine resistance and highlights further the dual role of this transcription factor that can mediate endocrine sensitivity and resistance by modulating ER expression and activity.

Sign in / Sign up

Export Citation Format

Share Document