Targeting cancer stem cells in medulloblastoma by inhibiting AMBRA1 dual function in autophagy and STAT3 signalling
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA553789 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR14749811_1.fastq.gz | Fastqsanger.gz | |||
| SRR14749811_2.fastq.gz | Fastqsanger.gz | |||
| SRR14749812_1.fastq.gz | Fastqsanger.gz | |||
| SRR14749812_2.fastq.gz | Fastqsanger.gz | |||
| SRR14749813_1.fastq.gz | Fastqsanger.gz |
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Project description:Medulloblastoma (MB) is a childhood malignant brain tumour comprising four main subgroups characterized by different genetic alterations and rate of mortality. Among MB subgroups, patients with enhanced levels of the c-MYC oncogene (MBGroup3) have the poorest prognosis. Here we identified a previously unrecognized role of the pro-autophagy factor AMBRA1 in regulating MB. We demonstrated that AMBRA1 expression levels strongly depend on c-MYC expression and correlate with patient poor prognosis; also, knockdown of AMBRA1 reduces MB stem potential, growth and migration of MBGroup3 cells in vitro and in vivo. At a molecular level, AMBRA1 mediates these effects by suppressing SOCS3, an inhibitor of STAT3 activation. In turn, active STAT3 increases c-MYC expression that, in a positive feedback loop, sustains AMBRA1 transcription. Importantly, pharmacological inhibition of autophagy profoundly affects stem potential and metastasization of MBGroup3 cells in vitro and in vivo, and a combined anti-autophagy and anti-STAT3 approach impacts MBGroup3 cell survival. Taken together, our data identified the c-MYC/AMBRA1/STAT3 axis as a strong oncogenic signalling pathway with significance for both patient stratification strategies and targeted treatments of MBGroup3.
2021-09-08 | GSE134109 | GEO
Project description:AMBRA1 (Autophagy and Beclin 1 Regulator 1) is a versatile scaffold protein involved in disparate processes including autophagy, cell cycle regulation, and tumorigenesis. While AMBRA1 is primarily recognized as a tumor suppressor, its dual function as a tumor promoter has garnered increasing attention. However, the role of AMBRA1 remains largely unexplored in many malignancies, particularly in brain tumors. Leveraging multiomic analysis of the largest human medulloblastoma (MB) cohort, we identify significantly elevated AMBRA1 protein levels in the Sonic Hedgehog subgroup (MBSHH) compared to other MB variants. Notably, AMBRA1 protein abundance, independent of its mRNA expression, correlates with poor prognosis, positioning AMBRA1 as a biomarker for MBSHH. Mechanistically, AMBRA1 enhances SHH signaling by stabilizing GLI1, the pathway's final effector, by inhibiting the βTrCP-mediated degradation of GLI1. Additionally, AMBRA1 protein stability is modulated by the REN E3 ubiquitin ligase, a tumor suppressor gene and antagonist of the SHH pathway. Genetic inhibition of AMBRA1 significantly blocks MBSHH growth in murine and patient-derived pre-clinical models, highlighting its therapeutic potential. Moreover, combining AMBRA1 knock-down with FDA-approved SHH inhibitors amplifies tumor suppression. These findings uncover the AMBRA1/βTrCP/REN axis as a key regulatory mechanism in SHH signaling, providing actionable insights into targeted therapies for MBSHH.
2026-03-09 | GSE288462 | GEO
Project description:AMBRA1 (Autophagy and Beclin 1 Regulator 1) is a versatile scaffold protein involved in disparate processes including autophagy, cell cycle regulation, and tumorigenesis. While AMBRA1 is primarily recognized as a tumor suppressor, its dual function as a tumor promoter has garnered increasing attention. However, the role of AMBRA1 remains largely unexplored in many malignancies, particularly in brain tumors. Leveraging multiomic analysis of the largest human medulloblastoma (MB) cohort, we identify significantly elevated AMBRA1 protein levels in the Sonic Hedgehog subgroup (MBSHH) compared to other MB variants. Notably, AMBRA1 protein abundance, independent of its mRNA expression, correlates with poor prognosis, positioning AMBRA1 as a biomarker for MBSHH. Mechanistically, AMBRA1 enhances SHH signaling by stabilizing GLI1, the pathway's final effector, by inhibiting the βTrCP-mediated degradation of GLI1. Additionally, AMBRA1 protein stability is modulated by the REN E3 ubiquitin ligase, a tumor suppressor gene and antagonist of the SHH pathway. Genetic inhibition of AMBRA1 significantly blocks MBSHH growth in murine and patient-derived pre-clinical models, highlighting its therapeutic potential. Moreover, combining AMBRA1 knock-down with FDA-approved SHH inhibitors amplifies tumor suppression. These findings uncover the AMBRA1/βTrCP/REN axis as a key regulatory mechanism in SHH signaling, providing actionable insights into targeted therapies for MBSHH.
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Project description:Previously, we reported that Ambra1 is a core component of a cytoplasmic trafficking network, acting as a spatial rheostat to control active Src and FAK levels in addition to its critical roles in autophagy during neurogenesis. Here we identify a novel nuclear scaffolding function for Ambra1 that controls gene expression. Ambra1 binds to nuclear pore proteins, to other adaptor proteins like FAK and Akap8 in the nucleus, as well as to chromatin modifiers and transcriptional regulators such as Brg1, Cdk9 and the cAMP-regulated transcription factor Atf2. Ambra1 contributes to their association with chromatin and we identified genes whose transcription is regulated by Ambra1 complexes, likely via histone modifications and phospho-Atf2-dependent transcription. Therefore, Ambra1 scaffolds protein complexes at chromatin, regulating transcriptional signalling in the nucleus; in particular, it recruits chromatin modifiers and transcriptional regulators to control expression of genes such as Angpt1, Tgfb2, Tgfb3, Itga8 and Itgb7 that likely contribute to the role of Ambra1 in cancer cell invasion.
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Project description:The initiation of cell division integrates a large number of intra- and extracellular inputs. D-type cyclins (hereafter, cyclin D) couple these inputs to the initiation of DNA replication1. Increased levels of cyclin D promote cell division by activating cyclin-dependent kinases 4 and 6 (hereafter, CDK4/6), which in turn phosphorylate and inactivate the retinoblastoma tumour suppressor. Accordingly, increased levels and activity of cyclin D-CDK4/6 complexes are strongly linked to unchecked cell proliferation and cancer2,3. However, the mechanisms that regulate levels of cyclin D are incompletely understood4,5. Here we show that autophagy and beclin 1 regulator 1 (AMBRA1) is the main regulator of the degradation of cyclin D. We identified AMBRA1 in a genome-wide screen to investigate the genetic basis of the response to CDK4/6 inhibition. Loss of AMBRA1 results in high levels of cyclin D in cells and in mice, which promotes proliferation and decreases sensitivity to CDK4/6 inhibition. Mechanistically, AMBRA1 mediates ubiquitylation and proteasomal degradation of cyclin D as a substrate receptor for the cullin 4 E3 ligase complex. Loss of AMBRA1 enhances the growth of lung adenocarcinoma in a mouse model, and low levels of AMBRA1 correlate with worse survival in patients with lung adenocarcinoma. Thus, AMBRA1 regulates cellular levels of cyclin D, and contributes to cancer development and the response of cancer cells to CDK4/6 inhibitors.
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Project description:Melanoma is the most deadly type of skin cancers and, there is a continuous need to develop early biomarkers as well as treatments to improve the survivability of patients. Ambra1 is an essential regulator in autophagy and it has been recently shown to have a role in cell proliferation. We used microarrays to analyse the transcriptomic changesi n A375 melanoma cell lines following Ambra1 differential expression
2021-05-23 | GSE175361 | GEO
Project description:Glioblastoma (GBM) is a devastating disease and the most common primary brain malignancy of adults with a median survival barely exceeding one year. Recent findings suggest that the antipsychotic drug pimozide triggers an autophagy-dependent, lysosomal type of cell death in GBM cells with possible implications for GBM therapy. One oncoprotein that is often overactivated in these tumors and associated with a particularly dismal prognosis is Signal Transducer and Activator of Transcription 3 (STAT3). Here, we used isogenic human GBM knockout cell lines, advanced fluorescence microscopy, transcriptomic analysis and FACS-based assessment of cell viability to show that STAT3 has an underappreciated, context-dependent role in drug-induced cell death. Specifically, we demonstrate that depletion of STAT3 significantly enhances cell survival after treatment with pimozide, suggesting that STAT3 confers a particular vulnerability to GBM. Furthermore, we show that active STAT3 has no major influence on the early steps of the autophagy pathway, but exacerbates drug-induced lysosomal membrane permeabilisation (LMP) and release of cathepsins into the cytosol. Collectively, our findings support the concept of exploiting the pro-death functions of autophagy and LMP for GBM therapy and to further determine whether STAT3 can be employed as a treatment predictor for highly apoptosis-resistant, but autophagy-proficient cancers.
2022-01-13 | GSE162429 | GEO
Project description:AMBRA1 as a novel positive regulator of the SHH pathway in medulloblastoma [RNA-Seq]
| PRJNA1217801 | ENA
Project description:AMBRA1 as a novel positive regulator of the SHH pathway in medulloblastoma [scRNA-seq]
| PRJNA1217811 | ENA