scholarly journals Inhibition of eEF2K synergizes with glutaminase inhibitors or 4EBP1 depletion to suppress growth of triple-negative breast cancer cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
YoungJun Ju ◽  
Yaacov Ben-David ◽  
Daniela Rotin ◽  
Eldad Zacksenhaus
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Translation Initiation ◽  
Triple Negative ◽  
Elongation Factor ◽  
Protein Translation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Related Factors ◽  
Metabolic Conditions

AbstractThe eukaryotic elongation factor-2 kinase, eEF2K, which restricts protein translation elongation, has been identified as a potential therapeutic target for diverse types of malignancies including triple negative breast cancer (TNBC). However, the contexts in which eEF2K inhibition is essential in TNBC and its consequences on the proteome are largely unknown. Here we show that genetic or pharmacological inhibition of eEF2K cooperated with glutamine (Gln) starvation, and synergized with glutaminase (GLS1) inhibitors to suppress growth of diverse TNBC cell lines. eEF2K inhibition also synergized with depletion of eukaryotic translation initiation factor 4E-binding protein 1 (eIF4EBP1; 4EBP1), a suppressor of eukaryotic protein translation initiation factor 4E (eIF4E), to induce c-MYC and Cyclin D1 expression, yet attenuate growth of TNBC cells. Proteomic analysis revealed that whereas eEF2K depletion alone uniquely induced Cyclin Dependent Kinase 1 (CDK1) and 6 (CDK6), combined depletion of eEF2K and 4EBP1 resulted in overlapping effects on the proteome, with the highest impact on the ‘Collagen containing extracellular matrix’ pathway (e.g. COL1A1), as well as the amino-acid transporter, SLC7A5/LAT1, suggesting a regulatory loop via mTORC1. In addition, combined depletion of eEF2K and 4EBP1 indirectly reduced the levels of IFN-dependent innate immune response-related factors. Thus, eEF2K inhibition triggers cell cycle arrest/death under unfavourable metabolic conditions such as Gln-starvation/GLS1 inhibition or 4EBP1 depletion, uncovering new therapeutic avenues for TNBC and underscoring a pressing need for clinically relevant eEF2K inhibitors.

scholarly journals Identification of Cardiac Glycosides as Novel Inhibitors of eIF4A1-Mediated Translation in Triple-Negative Breast Cancer Cells

Cancers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2169
Author(s):  
Cory M. Howard ◽  
Matthew Estrada ◽  
David Terrero ◽  
Amit K. Tiwari ◽  
Dayanidhi Raman
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Cardiac Glycosides ◽  
Triple Negative ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Transcriptional Level ◽  
Fluorescent Intensity ◽  
Translational Initiation ◽  
Core Proteins

The eukaryotic translation initiation factor 4F complex (eIF4F) is a potential chemotherapeutic target in triple-negative breast cancer (TNBC). This complex regulates cap-dependent translational initiation and consists of three core proteins: eIF4E, eIF4G, and eIF4A1. In this study, we focus on repositioning compounds as novel inhibitors of eIF4A1-mediated translation. In order to accomplish this goal, a modified synthetic reporter assay was established. More specifically, a (CGG)4 motif, which confers eIF4A dependency, was incorporated into the 5’-leader region of a luciferase-tdTomato lentiviral reporter construct. The Prestwick Chemical Library was then screened in multiple TNBC cell lines by measuring the tdTomato fluorescent intensity. We identified several cardiac glycosides as potential inhibitors of eIF4A1-mediated translation. Based on our studies, we find that cardiac glycosides inhibit the expression of eIF4A1. To identify a potential mechanism by which this was occurring, we utilized the Integrative Library of Integrated Network-Based Cellular Signatures (iLINCS). Our pursuits led us to the discovery that cardiac glycosides also decrease levels of c-MYC. Quantitative PCR confirmed that decreases in c-MYC and eIF4A were occurring at the transcriptional level. As such, disruption of the eIF4A1-c-MYC axis may be a viable approach in the treatment of TNBC. The novel combination of rocaglamide A and digoxin exhibited synergistic anti-cancer activity against TNBC cells in vitro. The findings in this study and others are important for formulating potential combination chemotherapies against eIF4A1 in vivo. Thus, drug repositioning may be one classical approach to successfully target eIF4A1 in TNBC patients.

scholarly journals Differential expression of eukaryotic translation initiation factor 4E-binding protein 2 in cancers of the breast.

2021 ◽  
Author(s):  
Shahan Mamoor
Keyword(s):  
Breast Cancer ◽  
Differential Expression ◽  
Translation Initiation ◽  
Normal Breast ◽  
Translation Initiation Factor ◽  
Differentially Expressed ◽  
Initiation Factor ◽  
Primary Tumors ◽  
Eukaryotic Translation ◽  
Eukaryotic Translation Initiation

Breast cancer affects women at relatively high frequency (1). We mined published microarray datasets (2, 3) to determine in an unbiased fashion and at the systems level genes most differentially expressed in the primary tumors of patients with breast cancer. We report here significant differential expression of the gene encoding eukaryotic translation initiation factor 4E-binding protein 2, EIF4EBP2, when comparing primary tumors of the breast to the tissue of origin, the normal breast. EIF4EBP2 was also differentially expressed in lymph node metastasis in human breast cancer. EIF4EBP2 mRNA was present at significantly lower quantities in tumors of the breast as compared to normal breast tissue. Analysis of human survival data revealed that expression of EIF4EBP2 in primary tumors of the breast was correlated with recurrence-free survival in patients with luminal B and HER2+ subtype cancer, demonstrating a relationship between primary tumor expression of a differentially expressed gene and patient survival outcomes influenced by PAM50 molecular subtype. EIF4EBP2 may be of relevance to initiation, maintenance or progression of cancers of the female breast.

scholarly journals MicroRNA 603 acts as a tumor suppressor and inhibits triple-negative breast cancer tumorigenesis by targeting elongation factor 2 kinase

Oncotarget ◽  
2016 ◽  
Vol 8 (7) ◽  
pp. 11641-11658 ◽  
Author(s):  
Recep Bayraktar ◽  
Martin Pichler ◽  
Pinar Kanlikilicer ◽  
Cristina Ivan ◽  
Emine Bayraktar ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Tumor Suppressor ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Elongation Factor ◽  
Elongation Factor 2

scholarly journals WDHD1 is essential for the survival of PTEN-inactive triple-negative breast cancer

2020 ◽  
Vol 11 (11) ◽  
Author(s):  
Ayse Ertay ◽  
Huiquan Liu ◽  
Dian Liu ◽  
Ping Peng ◽  
Charlotte Hill ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Synthetic Lethality ◽  
Essential Gene ◽  
Growth Factor Receptor ◽  
High Mobility ◽  
Protein Translation ◽  
Sirna Screen ◽  
Potential Biomarker

AbstractTriple-negative breast cancer (TNBC) is the most aggressive type of breast cancer that lacks the oestrogen receptor, progesterone receptor and human epidermal growth factor receptor 2, making it difficult to target therapeutically. Targeting synthetic lethality is an alternative approach for cancer treatment. TNBC shows frequent loss of phosphatase and tensin homologue (PTEN) expression, which is associated with poor prognosis and treatment response. To identify PTEN synthetic lethal interactions, TCGA analysis coupled with a whole-genome siRNA screen in isogenic PTEN-negative and -positive cells were performed. Among the candidate genes essential for the survival of PTEN-inactive TNBC cells, WDHD1 (WD repeat and high-mobility group box DNA-binding protein 1) expression was increased in the low vs. high PTEN TNBC samples. It was also the top hit in the siRNA screen and its knockdown significantly inhibited cell viability in PTEN-negative cells, which was further validated in 2D and 3D cultures. Mechanistically, WDHD1 is important to mediate a high demand of protein translation in PTEN-inactive TNBC. Finally, the importance of WDHD1 in TNBC was confirmed in patient samples obtained from the TCGA and tissue microarrays with clinic-pathological information. Taken together, as an essential gene for the survival of PTEN-inactive TNBC cells, WDHD1 could be a potential biomarker or a therapeutic target for TNBC.

Abstract 2461: Targeting eIF4A3 as a multifunctional translation initiation factor for breast cancer therapy

2020 ◽  
Author(s):  
Jun Ling ◽  
Allen Huang ◽  
Ai Ohno ◽  
Joe Chen ◽  
Maria Cavataio
Keyword(s):  
Breast Cancer ◽  
Cancer Therapy ◽  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Breast Cancer Therapy

The Translation Initiation Factor eIF4E Is Overexpressed in Multiple Myeloma and Is Critical for Myeloma Cell Proliferation and Survival

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1853-1853 ◽  
Author(s):  
Shirong Li ◽  
MeiHua Jin ◽  
Ailing Liu ◽  
Markus Y. Mapara ◽  
Suzanne Lentzsch
Keyword(s):  
Multiple Myeloma ◽  
Protein Synthesis ◽  
Translation Initiation ◽  
Clinical Care ◽  
Protein Translation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Mrna Levels ◽  
Myeloma Cells ◽  
Rpmi 8226

Abstract Abstract 1853 Methods: The translation initiation factor eIF4E is central to protein synthesis in general, and overexpression and/or activation of eIF4E is associated with a malignant phenotype by regulating oncogenic protein translation. Several previous publications indicate that aberrant control of protein synthesis contributes to lymphoma genesis but the exact role of protein translation in multiple myeloma (MM) is less clear. Therefore, understanding the mechanisms that control protein synthesis is an emerging new research area in MM with significant potential for developing innovative therapies. The goal of this study was to determine the role and regulation of eIF4E, as well as the effects of protein translation controlling drugs in MM. Results: By western blot analysis as well as RT-PCR we found that eIF4E protein and mRNA levels are significantly elevated (up to 20 fold) in MM cell lines (H929, RPMI-8226, MM.1S and OPM2) and primary myeloma cells compared to normal plasma cells. Silencing of eIF4E gene expression in RPMI-8226 MM cells by a stable and inducible shRNA system significantly decreased viability of myeloma cells (by ∼ 43%) but not of HEK 293 suggesting a higher dependency of MM cells to protein translation. Next we evaluated different drugs including pomalidomide, rapamycin, pp242, 4EGI-1 and ribavirin, that are known to inhibit protein synthesis for their effects on protein translation in MM. By m7GTP pull down assays we evaluated the effects of the different drugs on eIF4E expression and activity. Rapamycin blocked the phosphorylation of 4EBP1 and eIF4E release, and subsequently inhibited eIF4G binding. The compound 4EGI-1 decreased the interaction between eIF4E and eIF4G. Pomalidomide decreased eIF4E protein expression. All drugs inhibited MM cell DNA synthesis measured by 3H-Thymidine incorporation. Treatment with pomalidomide (10uM), rapamycin (40nM), pp242 (10uM), 4EGI1 (50uM) or ribavirin (50uM) for 48h significantly decreased (p<0.05) proliferation by 43–62% indicating that drugs controlling protein translation inhibit MM growth. We also found that all drugs decreased expression of eIF4E dependent targets such as cyclin D1 and c-myc. Conclusion: Here we show that eIF4E, a key player in translational control, is highly expressed in MM cells and critical for MM growth and survival. Therefore our study helps to understand the function and regulatory mechanism of eIF4E in MM. Further the evaluation of drugs targeting protein translation provides the basis for the optimization of current MM treatment or to open up new strategies such as targeting protein translation in future MM therapy. Disclosures: Lentzsch: Celgene Corp: Consultancy, Research Funding; Onyx: Consultancy; Genzyme: Consultancy; prIME Oncology: Honoraria; Imedex: Honoraria; Clinical Care Options: Honoraria.

Sign in / Sign up

Export Citation Format

Share Document