Revealing different roles of the mTOR-targets S6K1 and S6K2 in breast cancer by expression profiling and structural analysis
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE75813 | GEO | 2015/12/09
SECONDARY ACCESSION(S): PRJNA305419
REPOSITORIES: GEO
Similar Datasets
Project description:Expression profiles of ZR751 breast cancer cells after downregulation of S6K1, S6K2 and S6K1+S6K2. Triplicates of control, S6K1siRNA, S6K2siRNA and S6K1+S6K2siRNA, in total twelve samples.
2015-12-09 | E-GEOD-75813 | biostudies-arrayexpress
Project description:BACKGROUND:The AKT/mTORC1/S6K pathway is frequently overstimulated in breast cancer, constituting a promising therapeutic target. The benefit from mTOR inhibitors varies, likely as a consequence of tumour heterogeneity, and upregulation of several compensatory feed-back mechanisms. The mTORC1 downstream effectors S6K1, S6K2, and 4EBP1 are amplified and overexpressed in breast cancer, associated with a poor outcome and divergent endocrine treatment benefit. S6K1 and S6K2 share high sequence homology, but evidence of partly distinct biological functions is emerging. The aim of this work was to explore possible different roles and treatment target potentials of S6K1 and S6K2 in breast cancer. MATERIALS AND METHODS:Whole-genome expression profiles were compared for breast tumours expressing high levels of S6K1, S6K2 or 4EBP1, using public datasets, as well as after in vitro siRNA downregulation of S6K1 and/or S6K2 in ZR751 breast cancer cells. In silico homology modelling of the S6K2 kinase domain was used to evaluate its possible structural divergences to S6K1. RESULTS:Genome expression profiles were highly different in S6K1 and S6K2 high tumours, whereas S6K2 and 4EBP1 profiles showed significant overlaps, both correlated to genes involved in cell cycle progression, among these the master regulator E2F1. S6K2 and 4EBP1 were inversely associated with IGF1 levels, and their prognostic value was shown to be restricted to tumours positive for IGFR and/or HER2. In vitro, S6K1 and S6K2 silencing resulted in upregulation of genes in the mTORC1 and mTORC2 complexes. Isoform-specific silencing also showed distinct patterns, e.g. S6K2 downregulation lead to upregulation of several cell cycle associated genes. Structural analyses of the S6K2 kinase domain showed unique structure patterns, deviating from those of S6K1, facilitating the development of isoform-specific inhibitors. Our data support emerging proposals of distinct biological features of S6K1 and S6K2, suggesting their importance as separate oncogenes and clinical markers, where specific targeting in different breast cancer subtypes could facilitate further individualised therapies.
| S-EPMC4689523 | biostudies-literature
Project description:The mechanistic target of rapamycin (mTOR) is a master regulator of protein translation, metabolism, cell growth and proliferation. It forms two complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2). mTORC1 is frequently deregulated in many cancers, including breast cancer, and is an important target for cancer therapy. The immunosuppressant drug rapamycin and its analogs that inhibit mTOR are currently being evaluated for their potential as anti-cancer agents, albeit with limited efficacy. mTORC1 mediates its function via its downstream targets 40S ribosomal S6 kinases (S6K) and eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). There are two homologs of S6K: S6K1 and S6K2. Most of the earlier studies focused on S6K1 rather than S6K2. Because of their high degree of structural homology, it was generally believed that they behave similarly. Recent studies suggest that while they may share some functions, they may also exhibit distinct or even opposite functions. Both homologs have been implicated in breast cancer, although how they contribute to breast cancer may differ. The purpose of this review article is to compare and contrast the expression, structure, regulation and function of these two S6K homologs in breast cancer.
| S-EPMC7072743 | biostudies-literature
Project description:Using a retrovirus-mediated cDNA expression cloning approach we identified the grainyhead-like 2 (GRHL2) transcription factor as novel protooncogene. Overexpression of GRHL2 in NIH3T3 cells induced striking morphological changes, an increase in cell proliferation, anchorage-independent growth, and tumor growth in vivo. By combining a microarray analysis and a phylogenetic footprinting analysis with various biochemical assays we identified the epidermal growth factor receptor family member Erbb3 as a novel GRHL2 target gene. In breast cancer cell lines, shRNA-mediated knockdown of GRHL2 expression or functional inactivation of GRHL2 using dominant-negative GRHL2 proteins induce downregulation of ERBB3 gene expression, a striking reduction in cell proliferation and morphological and phenotypical alterations characteristic of an epithelial-to-mesenchymal transition (EMT), thus implying dual roles of GRHL2 in breast carcinogenesis. Interestingly, we could further demonstrate that expression of GRHL2 is directly suppressed by the transcription factor zinc-finger-enhancer binding protein 1 (ZEB1) which in turn is a direct target for repression by GRHL2, suggesting that the EMT transcription factors GRHL2 and ZEB1 form a double negative regulatory feedback loop in breast cancer cells. Finally, a comprehensive immunohistochemical analysis of GRHL2 expression in primary breast cancers showed loss of GRHL2 expression at the invasive front of primary tumors. A pathophysiological relevance of GRHL2 in breast cancer metastasis is further demonstrated by our finding of a statistically significant association between loss of GRHL2 expression in primary breast cancers and lymph-node metastasis. We thus demonstrate a crucial role of GRHL2 in breast carcinogenesis. To evaluate the role of the GRHL2 transcription factor in carcinogenessis we overexpressed the human GRHL2 protein in NIH3T3 cells. Parental NIH3T3 cells do not express the orthologic protein. Alterations in genome-wide transcriptional profiles were determined by microarray analysis.
2013-09-05 | E-GEOD-43610 | biostudies-arrayexpress
Project description:Triple negative breast cancers lack targeted therapies with little side effects and contain higher percentage of cancer stem cells than the other breast cancer subtypes. Genes capturing the features of cancer stem cells of such diseases may serve as potential subtyping marker or therapeutic targets for triple negative breast cancer management. This data descriptor presents a set of transcriptome data from 3 cohorts of cancer stem cells as represented as CD44+/CD24-/low and 2 cohorts of non-cancer stem cells isolated from triple negative breast cancer cells, each having 3 replicates.
2019-06-04 | GSE132083 | GEO
Project description:Using a retrovirus-mediated cDNA expression cloning approach we identified the grainyhead-like 2 (GRHL2) transcription factor as novel protooncogene. Overexpression of GRHL2 in NIH3T3 cells induced striking morphological changes, an increase in cell proliferation, anchorage-independent growth, and tumor growth in vivo. By combining a microarray analysis and a phylogenetic footprinting analysis with various biochemical assays we identified the epidermal growth factor receptor family member Erbb3 as a novel GRHL2 target gene. In breast cancer cell lines, shRNA-mediated knockdown of GRHL2 expression or functional inactivation of GRHL2 using dominant-negative GRHL2 proteins induce downregulation of ERBB3 gene expression, a striking reduction in cell proliferation and morphological and phenotypical alterations characteristic of an epithelial-to-mesenchymal transition (EMT), thus implying dual roles of GRHL2 in breast carcinogenesis. Interestingly, we could further demonstrate that expression of GRHL2 is directly suppressed by the transcription factor zinc-finger-enhancer binding protein 1 (ZEB1) which in turn is a direct target for repression by GRHL2, suggesting that the EMT transcription factors GRHL2 and ZEB1 form a double negative regulatory feedback loop in breast cancer cells. Finally, a comprehensive immunohistochemical analysis of GRHL2 expression in primary breast cancers showed loss of GRHL2 expression at the invasive front of primary tumors. A pathophysiological relevance of GRHL2 in breast cancer metastasis is further demonstrated by our finding of a statistically significant association between loss of GRHL2 expression in primary breast cancers and lymph-node metastasis. We thus demonstrate a crucial role of GRHL2 in breast carcinogenesis.
2013-09-05 | GSE43610 | GEO
Project description:The phosphoinositide 3 kinase (PI3K)/Akt/mammalian (or mechanistic) target of rapamycin (mTOR) pathway is a complicated intracellular pathway, which leads to cell growth and tumor proliferation and plays a significant role in endocrine resistance in breast cancer. Multiple compounds targeting this pathway are being evaluated in clinical trials. These agents are generally well tolerated and can be used in combination with targeted therapies, endocrine therapy or cytotoxic agents. The identification of subtypes of tumors more likely to respond to these therapeutics cannot be overemphasized, since breast cancer is a very heterogeneous malignancy. Activation of pathways such as KRAS and MEK can act as escape mechanisms that lead to resistance, thus a combination of agents targeting multiple steps of the intracellular machinery is promising. There is evidence that tumors with PIK3CA mutations are more sensitive to inhibitors of the PI3K pathway but this has yet to be validated. Large clinical trials with correlative studies are necessary to identify reliable biomarkers of efficacy.
| S-EPMC4107712 | biostudies-literature
Project description:BackgroundThe 70 kDa ribosomal protein S6 kinase (RPS6KB1), located at 17q23, is amplified and overexpressed in 10-30% of primary breast cancers and breast cancer cell lines. p70S6K is a serine/threonine kinase regulated by PI3K/mTOR pathway, which plays a crucial role in control of cell cycle, growth and survival. Our aim was to determine p70S6K and PI3K/mTOR/p70S6K pathway dependent gene expression profiles by microarrays using five breast cancer cell lines with predefined gene copy number and gene expression alterations. The p70S6K dependent profiles were determined by siRNA silencing of RPS6KB1 in two breast cancer cell lines overexpressing p70S6K. These profiles were further correlated with gene expression alterations caused by inhibition of PI3K/mTOR pathway with PI3K inhibitor Ly294002 or mTOR inhibitor rapamycin.ResultsAltogether, the silencing of p70S6K altered the expression of 109 and 173 genes in two breast cancer cell lines and 67 genes were altered in both cell lines in addition to RPS6KB1. Furthermore, 17 genes including VTCN1 and CDKN2B showed overlap with genes differentially expressed after PI3K or mTOR inhibition. The gene expression signatures responsive to both PI3K/mTOR pathway and p70S6K inhibitions revealed previously unidentified genes suggesting novel downstream targets for PI3K/mTOR/p70S6K pathway.ConclusionSince p70S6K overexpression is associated with aggressive disease and poor prognosis of breast cancer patients, the potential downstream targets of p70S6K and the whole PI3K/mTOR/p70S6K pathway identified in our study may have diagnostic value.
| S-EPMC2496917 | biostudies-literature
Project description:Response and resistance to anticancer therapies vary due to inter- and intra-tumour heterogeneity. Here, we developed and applied a quantitative chromatin immunoprecipitation sequencing methodology to map differentially enriched G-quadruplex (G4) DNA structure-forming regions (∆G4Rs) in 22 breast cancer patient-derived tumour xenograft (PDTX) models. ∆G4Rs are significantly more associated with the promoter of highly amplified and expressed genes, and with somatic single-nucleotide variant mutations. Specific ∆G4Rs associate with certain patterns of breast cancer TF occupancy, revealing 7 distinct transcription factor programs with differential activities across PDTXs. Collectively, ∆G4Rs report on the genomic, transcriptomic and regulatory architecture of breast cancer. ∆G4R abundance and locations stratify PDTXs into at least three G4-based subtypes. ∆G4Rs of the majority of PDTXs (14/22) associated with more than one distinct breast cancer subtype, which we also call an integrative cluster (IC). This suggests the frequent coexistence of multiple breast cancer states within a PDTX model; the majority, in contrast to expectation, displaying aggressive triple-negative IC10. Short-term cultures of PDTX models with increased ∆G4R levels are more sensitive to small molecules targeting G4 DNA. Thus, G4 DNA structural landscapes revealed additional IC-related intra-tumour heterogeneity in PDTX biopsies, improving their cancer stratification and potentially new treatment strategies.
2020-06-11 | GSE152216 | GEO
Project description:To systematically identify the function of S6K1 and S6K2 in glioblastoma cells, LN229 cells were stably transduced with Cas9, control non-targeting sgRNA (sgNT), or sgRNAs targeting S6K1 or S6K2. The cells were then transiently transfected with non-targeting siRNAs (siNT), or siRNA pools targeting S6K1 or S6K2. RNA sequencing was performed to compare cellular responses to inactivation of single or combination S6 kinases.
2024-08-28 | GSE196591 | GEO