Effects of deletion of SAT1, a polyamine-metabolic enzyme, on mouse HeLa xenograft tumor
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PROVIDER: PRJNA1000960 | ENA |
REPOSITORIES: ENA
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Project description:An acidic tumor microenvironment plays a critical role in tumor progression. However, understanding of metabolic reprogramming of tumors in response to acidic extracellular pH has remained elusive. Using comprehensive metabolomic analyses, we demonstrated that acidic extracellular pH (pH 6.8) leads to the accumulation of N1-acetylspermidine, a pro-tumor metabolite, through upregulation of the expression of spermidine/spermine acetyl transferase 1 (SAT1). Inhibition of SAT1 expression suppressed the accumulation of intra- and extracellular N1-acetylspermidine at acidic pH. Conversely, overexpression 3 of SAT1 increased intra- and extracellular N1-acetylspermidine levels, supporting the proposal that SAT1 is responsible for accumulation of N1-acetylspermidine. While inhibition of SAT1 expression only had a minor effect on cancer cell growth in vitro, SAT1 knockdown significantly decreased tumor growth in vivo, supporting a contribution of the SAT1-N1-acetylspermidine axis to pro-tumor immunity. Immune cell profiling revealed that inhibition of SAT1 expression decreased neutrophil recruitment to the tumor, resulting in impaired angiogenesis and tumor growth. We showed that anti-neutrophil neutralizing antibodies suppressed growth in control tumors to a similar extent to that seen in SAT1 knockdown tumors in vivo. Further, a SAT1 signature was found to be correlated with poor patient prognosis. Our findings demonstrate that extracellular acidity stimulates recruitment of pro-tumor neutrophils via the SAT1-N1-acetylspermidine axis, which may represent a novel target for anti-tumor immune therapy.
2023-08-14 | GSE239784 | GEO
Project description:Analysis of differential gene expression in HeLa Parental vs radio-resistant xenograft tumours. The aim is to identify potential genes that are deregulated in radio-resistant tumours.
2021-07-31 | GSE181080 | GEO
Project description:We aimed to identify SAT1 regulated genes in U87MG cell by knockdown of SAT1 with two different shRNAs, and then compared knockdown cells to control cells with shGFP
2021-06-23 | GSE116395 | GEO
Project description:Glioblastoma multiforme (GBM) is the most common and severe form of brain cancer. The median survival time of patients is approximately 12 months due to poor responses to surgery and chemoradiation. To understand the mechanisms involved in radioresistance, we conducted a genetic screen using an shRNA library to identify genes in which inhibition would sensitize cells to radiation. The results were cross-referenced with the Oncomine and Rembrandt databases to focus on genes that are highly expressed in GBM tumors and associated with poor patient outcomes. Spermidine/spermine-N1-acetyltransferase 1 (SAT1), an enzyme involved in polyamine catabolism, was identified as a gene that promotes resistance to ionizing radiation (IR), is overexpressed in brain tumors, and correlates with poor outcomes. Knockdown of SAT1 using shRNA and siRNA approaches in multiple cell and neurosphere lines resulted in sensitization of GBM cells to radiation in colony formation assays and tumors, and decreased tumorigenesis in vivo. Radiosensitization occurred specifically in G2-M and S phases, suggesting a role for SAT1 in homologous recombination (HR) that was confirmed in a DR-GFP reporter system. Mechanistically, we found that SAT1 promotes acetylation of histone H3, suggesting a new role of SAT1 in chromatin remodeling and regulation of gene expression. In particular, SAT1 depletion led to a dramatic reduction in BRCA1 expression, explaining decreased HR capacity. Our findings suggest that the biologic significance of elevated SAT1 expression in GBM lies in its contribution to cell radioresistance and that SAT1 may potentially be a therapeutic target to sensitize GBM to cancer therapies.
| S-EPMC4423404 | biostudies-literature
Project description:BRAF inhibitors are widely employed in the treatment of melanoma with the BRAF V600E mutation. However, the development of resistance greatly compromises their therapeutic efficacy. Here, we elucidate the role of polyamine biosynthesis and its regulatory mechanisms in promoting BRAF inhibitor resistance. Leveraging CRISPR-Cas9 screens, we identify AMD1 (S-adenosylmethionine decarboxylase 1), a critical enzyme for polyamine biosynthesis, as a druggable target whose inhibition reverses vemurafenib resistance. Metabolomic and proteomic analyses reveal that polyamine biosynthesis is upregulated in vemurafenib-resistant cancer, resulting in enhanced EIF5A hypusination, translation of mitochondrial proteins and oxidative phosphorylation. We also identify that sustained c-Myc levels in vemurafenib-resistant cancer are responsible for elevated polyamine biosynthesis. Finally, inhibition of polyamine biosynthesis or c-Myc reversed vemurafenib resistance both in vitro and in vivo in a xenograft model. With the polyamine biosynthesis signature correlated with poor prognosis in BRAF mutant melanoma patients, our findings reveal that the polyamine-hypusination-mitochondrial respiration pathway is an effective therapeutic target that can maximize the therapeutic efficacy of existing BRAF inhibitors.
2024-07-10 | GSE243344 | GEO
Project description:The full complement of molecular pathways contributing to Parkinson’s disease (PD) pathogenesis remains unknown. Here, to address this issue, we began by using a high-resolution variant of functional magnetic resonance imaging (fMRI) to pinpoint brainstem regions differentially affected by, and resistant to, the disease. Then, relying on the imaging information as a guide, we profiled gene expression levels of postmortem brain samples and used a factorial statistical model to identify a disease related decrease in the expression of the polyamine enzyme spermidine/spermine N1-acetyltransferase 1 (SAT1). Next, a series of studies were performed to confirm the pathogenic relevance of this finding. First, to test for a causal link between polyamines and α-synuclein toxicity, we investigated a yeast model expressing α-synuclein. Polyamines were found to enhance the toxicity of α-synuclein, and an unbiased genome-wide screen for modifiers of α-synuclein toxicity identified Tpo4, a member of a family of proteins responsible for polyamine transport. Second, to test for a causal link between SAT1 activity and PD histopathology we investigated a mouse model expressing α-synuclein. DENSPM (N1, N11-diethylnorspermine), a polyamine analog that increases SAT1 activity, was found to reduce PD histopathology, while Berenil (diminazene aceturate), a pharmacological agent that reduces SAT1 activity, worsened the histopathology. Third, we genotyped PD patients and controls and isolated a rare but novel variant in the SAT1 gene, although the functional significance of this genetic variant was not identified. Taken together, the results suggest that the polyamine pathway contributes to PD pathogenesis.
2010-08-19 | GSE19587 | GEO
Project description:Microarray analysis of HeLa Parental vs HeLa radio-resistant tumour xenograft in mice
| PRJNA750651 | ENA
Project description:Performed gene expression profiling of U87MG cells with two different shRNAs to SAT1 using Affymetrix microarrays covering 67,528 gene transcripts. Accordingly, we infected U87MG cells with lentiviruses expressing shRNAs to either the green fluorescent protein (GFP) or SAT1, performed a drug selection to ensure stable expression of the shRNAs, and expanded the cells for RNA harvest within 7 days of infection. RNA was reverse transcribed into cDNA, labelled with biotin and hybridized onto the arrays for analyses. Hierarchical clustering of duplicate experiments correctly segregated samples according to sample identity (i.e. shGFP clustered together, shSAT1-1 clustered together, and shSAT1-2 clustered together; with the latter two separately branching from shGFP)
2019-09-18 | E-MTAB-7270 | biostudies-arrayexpress
Project description:Non-small cell lung cancer (NSCLC) is the most lethal and prevalent type of lung cancer. In almost all types of cancer, the levels of polyamines (putrescine, spermidine, and spermine) are increased, playing a pivotal role in tumor proliferation. Indomethacin, a non-steroidal anti-inflammatory drug, increases the abundance of an enzyme termed spermidine/spermine-N1-acetyltransferase (SSAT) encoded by the SAT1 gene. This enzyme is a key player in the export of polyamines from the cell. The aim of this study was to compare the effect of indomethacin on two NSCLC cell lines, and their combinatory potential with polyamine-inhibitor drugs in NSCLC cell lines. A549 and H1299 NSCLC cells were exposed to indomethacin and evaluations included SAT1 expression, SSAT levels, and the metabolic status of cells. Moreover, the difference in polyamine synthesis enzymes among these cell lines as well as the synergistic effect of indomethacin and chemical inhibitors of the polyamine pathway enzymes on cell viability were investigated. Indomethacin increased the expression of SAT1 and levels of SSAT in both cell lines. In A549 cells, it significantly reduced the levels of putrescine and spermidine. However, in H1299 cells, the impact of treatment on the polyamine pathway was insignificant. Also, the metabolic features upstream of the polyamine pathway (i.e., ornithine and methionine) were increased. In A549 cells, the increase of ornithine correlated with the increase of several metabolites involved in the urea cycle. Evaluation of the levels of the polyamine synthesis enzymes showed that ornithine decarboxylase is increased in A549 cells, whereas S-adenosylmethionine-decarboxylase and polyamine oxidase are increased in H1299 cells. This observation correlated with relative resistance to polyamine synthesis inhibitors eflornithine and SAM486 (inhibitors of ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase, respectively), and MDL72527 (inhibitor of polyamine oxidase and spermine oxidase). Finally, indomethacin demonstrated a synergistic effect with MDL72527 in A549 cells and SAM486 in H1299 cells. Collectively, these results indicate that indomethacin alters polyamine metabolism in NSCLC cells and enhances the effect of polyamine synthesis inhibitors, such as MDL72527 or SAM486. However, this effect varies depending on the basal metabolic fingerprint of each type of cancer cell.
2021-02-08 | MTBLS873 | MetaboLights
Project description:Streptomyces sp. SAT1 Genome sequencing and assembly
| PRJNA321638 | ENA