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EIF2Bδ blocks the integrated stress response and maintains eIF2B activity and cancer metastasis by overexpression in breast cancer stem cells.

ABSTRACT: Breast cancer (BC) metastasis involves cancer stem cells (CSCs) and their regulation by micro-RNAs (miRs), but miR targeting of the translation machinery in CSCs is poorly explored. We therefore screened miR expression levels in a range of BC cell lines, comparing non-CSCs to CSCs, and focused on miRs that target translation and protein synthesis factors. We describe a unique translation regulatory axis enacted by reduced expression of miR-183 in breast CSCs, which we show targets the eIF2Bδ subunit of guanine nucleotide exchange factor eIF2B, a regulator of protein synthesis and the integrated stress response (ISR) pathway. We report that reduced expression of miR-183 greatly increases eIF2Bδ protein levels, preventing strong induction of the ISR and eIF2α phosphorylation, by preferential interaction with P-eIF2α. eIF2Bδ overexpression is essential for BC cell invasion, metastasis, maintenance of metastases, and breast CSC expansion in animal models. Increased expression of eIF2Bδ, a site of action of the drug ISRIB that also prevents ISR signaling, is essential for breast CSC maintenance and metastatic capacity.

SUBMITTER: Gupta M

PROVIDER: S-EPMC10104532 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature

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eIF2Bδ blocks the integrated stress response and maintains eIF2B activity and cancer metastasis by overexpression in breast cancer stem cells.

Gupta Malavika M Walters Beth A BA Katsara Olga O Granados Blanco Karol K Geter Phillip A PA Schneider Robert J RJ

Proceedings of the National Academy of Sciences of the United States of America 20230404 15

Breast cancer (BC) metastasis involves cancer stem cells (CSCs) and their regulation by micro-RNAs (miRs), but miR targeting of the translation machinery in CSCs is poorly explored. We therefore screened miR expression levels in a range of BC cell lines, comparing non-CSCs to CSCs, and focused on miRs that target translation and protein synthesis factors. We describe a unique translation regulatory axis enacted by reduced expression of miR-183 in breast CSCs, which we show targets the eIF2Bδ sub ...[more]

PMID: 37014850

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Project description:Vascular endothelial growth factor is a multifunctional cytokine playing important roles in angiogenesis, tumor progression and metastasis. Alternative splicing results in the production of several different isoforms of VEGF. We have previously generated human breast cancer cells overexpressing VEGF165 or VEGF189 isoforms (referred to as the V165 and V189 clones, respectively) and showed that VEGF189-transfected cells were less tumorigenic. In this study, we used bioluminescence imaging to analyze the metastasis capacity of breast cancer cell lines (MDA-MB-321) overexpressing VEGF isoforms in nude mice. V165, V189 and control cV clones were transfected with a luciferase plasmid to generate bioluminescent clones (the V165-B, V189-B and cV clones, respectively). These clones were then injected into the left heart ventricle of nude mice. Analysis of the location of metastases shows that V189-B cells induced fewer metastases in lung and bone than V165-B and cV-B cells. Moreover, there was a delay on metastasis appearance in mice receiving VEGF V189-B clone, consistent with increase survival in these mice. We investigated the possible mechanisms underlying these effects and found that VEGF189 increased adhesion and decreased cell invasion and survival in vitro. In the other side, transcriptomic analyses shown expression of genes, implicated in breast cancer and metastatic dissemination, in VEGF165 overexpressing cells. After in silico analyses of genes differentially expressed between V189 and V165 cells,we used Q-PCR assays to quantify mRNA levels of some gene of interest in 120 breast tumors from patients with or without metastasis and/or specially lung metastasis. We found that genes have prognostical significance and /or showed an influence on relapse-free survival. These data provide the first evidence that different VEGF isoforms have different effects on breast cancer cell line invasion and colonization. Human MDA-MB-231 breast cancer cells were used to generate stable transfected clones overexpressing VEGF165 isoform, VEGF189 isoform, or control vector (referred to as 42ctl8, 13ctl3 and PCIctl3, respectively). Analysis of the metastasis capacity of these clones in nude mice.

Dataset Information

EIF2Bδ blocks the integrated stress response and maintains eIF2B activity and cancer metastasis by overexpression in breast cancer stem cells.

Publications

eIF2Bδ blocks the integrated stress response and maintains eIF2B activity and cancer metastasis by overexpression in breast cancer stem cells.

Similar Datasets

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