Project description:Background Mutations in the POT1 gene explain abnormally long telomeres and multiple tumors including cardiac angiosarcomas (CAS). However, the link between long telomeres and tumorigenesis is poorly understood. Methods and Results Here, we have studied the somatic landscape of 3 different angiosarcoma patients with mutations in the POT1 gene to further investigate this tumorigenesis process. In addition, the genetic landscape of 7 CAS patients without mutations in the POT1 gene has been studied. Patients with CAS and nonfunctional POT1 did not repress ATR (ataxia telangiectasia RAD3-related)-dependent DNA damage signaling and showed a constitutive increase of cell cycle arrest and somatic activating mutations in the VEGF (vascular endothelial growth factor)/angiogenesis pathway (KDR gene). The same observation was made in POT1 mutation carriers with tumors different from CAS and also in CAS patients without mutations in the POT1 gene but with mutations in other genes involved in DNA damage signaling. Conclusions Inhibition of POT1 function and damage-response malfunction activated DNA damage signaling and increased cell cycle arrest as well as interfered with apoptosis, which would permit acquisition of somatic mutations in the VEGF/angiogenesis pathway that drives tumor formation. Therapies based on the inhibition of damage signaling in asymptomatic carriers may diminish defects on cell cycle arrest and thus prevent the apoptosis deregulation that leads to the acquisition of driver mutations.
Project description:Whole Exome sequencing of two patients with Cardiac angiosarcoma in Li-Fraumeni-like families discovers that a mutation in the pot1 gene is responsible for cardiac angiosarcoma in tp53-negative li-fraumeni-like families
Project description:RIL-seq experiment of EPEC hfq-flag mutant, in activating- conditions:growth on DMEM at 37°C to mid exponential growth phase (e.g., OD600=0.3). In these conditions EPEC strongly expresses its major virulence components, T3SS and BFP, mimicking infection. Non-activating conditions: overnight growth of static culture on LB medium at 37°C where virulence factors are not expressed. RIL-seq experiments are designed to reveal the interactions of sRNA and their targets.
Project description:Compared the transcriptome of wild type EPEC with that of an isogenic Δhfq mutant. Comparing activating- conditions:growth on DMEM at 37°C to mid exponential growth phase (e.g., OD600=0.3). In these conditions EPEC strongly expresses its major virulence components, T3SS and BFP, mimicking infection. Non-activating conditions: overnight growth of static culture on LB medium at 37°C where virulence factors are not expressed.
Project description:Telomere protection 1 (POT1) is an important subunit in the shelterin complex, considered the telomere protector. POT1 dysfunction may lead to telomere length dysregulation and genomic instability. Both germline and somatic POT1 mutations have been identified in CLL patients, suggesting the development of the disease. This study aimedto evaluate the occurrence of POT1 mutations throughout CLL's progression and determine their prognostic significance.
Project description:The evolutionarily conserved POT1 protein binds the single stranded G-rich telomeric DNA and has been implicated in telomeric DNA maintenance and the suppression of DNA damage checkpoint signaling. Here, we explore human POT1 function through genetics and proteomics discovering that the complete absence of POT1 leads to severe telomere maintenance defects that had not been anticipated from previous depletion studies. We determine the telomeric proteome upon POT1-loss by implementing an improved telomeric chromatin isolation protocol. Using quantitative proteomics by tandem mass tags (TMT) we identified a large set of proteins involved in nucleic acid metabolism that engage with telomeres upon loss of POT1. Inactivation of the homology directed repair machinery suppresses POT1-loss mediated telomeric DNA defects. Our results unravel as major function of human POT1 the suppression of telomere instability induced by homology directed repair.
Project description:Angiosarcomas are highly aggressive tumors of endothelial origin, which carry a poor prognosis. Fenofibrate is a hypolipidemic drug, which acts by activating the transcription factor PPARα. It has also been widely reported to have 'anti-cancer' activity. The current study investigated its effect in a murine VEGF-dependent angiosarcoma cell-line, MS1 VEGF. The study utilised assays to monitor cell proliferation and viability, apoptosis, cell cycle progression, mitochondrial membrane potential, changes in protein expression, and changes in miRNA expression using microarrays. Fenofibrate showed potent anti-proliferative action in MS1 VEGF angiosarcoma cells, without inducing apoptosis. It enriched cells in G2/M cell cycle phase and hyperpolarised mitochondria. Other PPARα activators failed to mimic fenofibrate action. Inhibitors of PPARα and NFκB failed to reverse the inhibitory effect of fenofibrate and their combination with fenofibrate was cytotoxic. Fenofibrate downregulated the expression of key VEGF-effector proteins, including Akt, ERK, Bcl-2 and survivin, and a chemical inhibitor screen discovered relevance of these proteins to cell proliferation. A miRNA microarray revealed that fenofibrate differentially regulated cellular miRNAs with known roles in cancer and angiogenesis. The data raise the possibility that fenofibrate could be useful in angiosarcoma therapy, especially considering its well-established clinical safety and tolerability profile.
Project description:The vascular endothelium plays an essential role in vascular disease and cardiovascular diseases. The effects and underlying mechanisms of sevoflurane on vascular endothelial growth factor (VEGF) in human endothelial cells have not been elucidated. The MTT colorimetric assay was used to determine HUVEC activity at different concentrations (1 and 3%, respectively) of sevoflurane for different time-points (12, 24 and 48 h, respectively). The regulation of sevoflurane on the mRNA levels of VEGFa, VEGFb, VEGFc and VEGFR1, 2, 3 was analyzed by real-time PCR. When VEGFR2 was inhibited by axitinib, VEGFR2 protein expression was determined by western blotting, and the cell viability was assessed by MTT analysis. The results revealed that sevoflurane increased cell viability in a dose- and time-dependent manner. Sevoflurane significantly upregulated VEGFA mRNA expression only. In addition, sevoflurane increased the expression of VEGFR2 at the mRNA and protein levels, whereas sevoflurane did not modulate the mRNA expression of VEGFR1 and VEGFR3. Furthermore, sevoflurane failed to increase the mRNA and protein expression of VEGFR2 when VEGFR2 was inhibited by axitinib, an inhibitor of VEGF receptors. In conclusion, sevoflurane may be a promising agent against endothelium dysfunction-caused vascular disease by activating the VEGF-A/VEGFR2 signaling pathway.
Project description:BackgroundScalp angiosarcomas (SA) are rare, representing <1% of soft tissue sarcomas. The optimal management of these tumors is unknown, with management based on small case series. We sought to assess the impact of different therapies on overall survival (OS), the practice patterns nationally, and identify factors associated with OS for non-metastatic scalp angiosarcomas.MethodsA prospectively maintained database was used to identify non-metastatic scalp angiosarcomas who received some form of definitive therapy. Logistics regression, Kaplan-Meier, and Cox proportional-hazard models were utilized.ResultsA total of 589 patients met study entry criteria with a median follow-up of 4.2 years. The majority (482 patients, 81.8%) had upfront definitive resection and an additional 317 patients (65.8%) received postoperative radiation. Of the 107 patients who didn't have surgery, the majority (65 patients, 60.7%) received definitive radiation and 42 patients (39.3%) received radiation and chemotherapy. One-year and five-year survival estimates for patients not receiving definitive surgery were 68.0% (95%CI: 57.5-76.4) and 18.0% (95%CI: 10.2-27.5) respectively compared to 78.2% (95%CI: 74.0-81.9) and 34.1% (95%CI: 28.9-39.3) for patients receiving definitive surgery (p < 0.01). On multivariable analysis, age ≥65 years, tumor size ≥5 cm, and not receiving definitive surgery was associated with worse OS.ConclusionsThe majority of patients with non-metastatic scalp angiosarcomas had upfront definitive surgery, with a subsequent improvement in OS, including when accounting for other patient and tumor factors. Postoperative radiation was frequently given. Our large series confirmed age and tumor size as prognostic factors for this rare disease.