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- Ma, Jianhui, et al.
(författare)
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Inhibition of Nuclear PTEN Tyrosine Phosphorylation Enhances Glioma Radiation Sensitivity through Attenuated DNA Repair
- 2019
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Ingår i: Cancer Cell. - : Elsevier BV. - 1535-6108 .- 1878-3686. ; 35:3, s. 504-518.e7
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Tidskriftsartikel (refereegranskat)abstract
- Ionizing radiation (IR) and chemotherapy are standard-of-care treatments for glioblastoma (GBM) patients and both result in DNA damage, however, the clinical efficacy is limited due to therapeutic resistance. We identified a mechanism of such resistance mediated by phosphorylation of PTEN on tyrosine 240 (pY240-PTEN) by FGFR2. pY240-PTEN is rapidly elevated and bound to chromatin through interaction with Ki-67 in response to IR treatment and facilitates the recruitment of RAD51 to promote DNA repair. Blocking Y240 phosphorylation confers radiation sensitivity to tumors and extends survival in GBM preclinical models. Y240F-Pten knockin mice showed radiation sensitivity. These results suggest that FGFR-mediated pY240-PTEN is a key mechanism of radiation resistance and is an actionable target for improving radiotherapy efficacy.
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| 2. |
- Ragu, Sandrine, et al.
(författare)
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Loss of the thioredoxin reductase Trr1 suppresses the genomic instability of peroxiredoxin tsa1 mutants
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:9
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Tidskriftsartikel (refereegranskat)abstract
- The absence of Tsa1, a key peroxiredoxin that scavenges H2O2 in Saccharomyces cerevisiae, causes the accumulation of a broad spectrum of mutations. Deletion of TSA1 also causes synthetic lethality in combination with mutations in RAD51 or several key genes involved in DNA double-strand break repair. In the present study, we propose that the accumulation of reactive oxygen species (ROS) is the primary cause of genome instability of tsa1 Delta cells. In searching for spontaneous suppressors of synthetic lethality of tsa1 Delta rad51 Delta double mutants, we identified that the loss of thioredoxin reductase Trr1 rescues their viability. The trr1 Delta mutant displayed a Can(R) mutation rate 5-fold lower than wild-type cells. Additional deletion of TRR1 in tsa1 Delta mutant reduced substantially the Can(R) mutation rate of tsa1 Delta strain (33-fold), and to a lesser extent, of rad51 Delta strain (4-fold). Loss of Trr1 induced Yap1 nuclear accumulation and over-expression of a set of Yap1-regulated oxidoreductases with antioxidant properties that ultimately re-equilibrate intracellular redox environment, reducing substantially ROS-associated DNA damages. This trr1 Delta -induced effect was largely thioredoxin-dependent, probably mediated by oxidized forms of thioredoxins, the primary substrates of Trr1. Thioredoxin Trx1 and Trx2 were constitutively and strongly oxidized in the absence of Trr1. In trx1 Delta trx2 Delta cells, Yap1 was only moderately activated; consistently, the trx1 Delta trx2 Delta double deletion failed to efficiently rescue the viability of tsa1 Delta rad51 Delta. Finally, we showed that modulation of the dNTP pool size also influences the formation of spontaneous mutation in trr1 Delta and trx1 Delta trx2 Delta strains. We present a tentative model that helps to estimate the respective impact of ROS level and dNTP concentration in the generation of spontaneous mutations.
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| 3. |
- Robinson, Kristina Lagerstedt, et al.
(författare)
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Lynch syndrome (hereditary nonpolyposis colorectal cancer) diagnostics
- 2007
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 1460-2105 .- 0027-8874. ; 99:4, s. 291-299
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Tidskriftsartikel (refereegranskat)abstract
- Background Preventive programs for individuals who have high lifetime risks of colorectal cancer may reduce disease morbidity and mortality. Thus, it is important to identify the factors that are associated with hereditary colorectal cancer and to monitor the effects of tailored surveillance. In particular, patients with Lynch syndrome, hereditary nonpolyposis colorectal cancer (HNPCC), have an increased risk to develop colorectal cancer at an early age. The syndrome is explained by germline mutations in DNA mismatch repair (MMR) genes, and there is a need for diagnostic tools to preselect patients for genetic testing to diagnose those with HNPCC. Methods Patients (n = 112) from 285 families who were counseled between 1990 and 2005 at a clinic for patients at high risk for HNPCC were selected for screening to detect mutations in MMR genes MLH1, MSH2, MSH6, and PMS2 based on family history, microsatellite instability (MSI), and immunohistochemical analysis of MMR protein expression. Tumors were also screened for BRAF V600E mutations; patients with the mutation were considered as non-HNPCC. Results Among the 112 patients who were selected for screening, 69 had germline MMR mutations (58 pathogenic and 11 of unknown biologic relevance). Sixteen of the 69 mutations (23%) were missense mutations. Among patients with MSI-positive tumors, pathogenic MMR mutations were found in 38 of 43 (88%) of patients in families who met Amsterdam criteria and in 13 of 22 (59%) of patients in families who did not. Among patients with MSI-negative tumors, pathogenic MMR mutations were found in 5 of 17 (29%) of families meeting Amsterdam criteria and in 1 of 30 (3%) of non-Amsterdam families with one patient younger than age 50 years. In three patients with MSI-negative tumors who had pathogenic mutations in MLH1 or MSH6, immunohistochemistry showed loss of the mutated protein. Conclusion Our findings suggest that missense MMR gene mutations are common in HNPCC and that germline MMR mutations are also found in patients with IVISI-negative tumors.
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