PARK2 Depletion Connects Energy and Oxidative Stress to PI3K/Akt Activation via PTEN S-Nitrosylation.
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ABSTRACT:
SUBMITTER: Gupta A
PROVIDER: S-EPMC5426642 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The present study aimed to investigate the effects of microRNA (miR)?21 on osteoclastogenesis and its underlying molecular mechanisms. The expression levels of tartrate?resistant acid phosphatase (TRAP) and miR?21 were detected during osteoclastogenesis in receptor activator of NF??B ligand (RANKL)?induced RAW264.7 cells via reverse transcription?quantitative PCR. Bioinformatics and dual luciferase reporter assays were performed to analyze the association between miR?21 and Pten. RANKL?induced RAW264.7 cells were divided into the following groups: MiR?negative control (NC), miR?21 mimic, miR?21 inhibitor and miR?21 mimic + LY294002. The effects of miR?21 on osteoclastogenesis and bone resorption were then detected using TRAP staining and a bone resorption assay. Pten, phosphorylated?Akt and nuclear factor of activated T cell (NFATc1) expression levels were measured by western blotting to analyze the effects of miR?21 on the PI3K/Akt signaling pathway. The present study revealed that miR?21 was upregulated during osteoclastogenesis in RANKL?induced RAW264.7 cells. Furthermore, miR?21 negatively regulated Pten. Compared with the miR?negative control (NC) group, the number of osteoclasts and the percentage of bone resorption were increased in the miR?21 mimic group, whereas they were decreased in the miR?21 inhibitor group. The number of osteoclasts and the percentage of bone resorption in the miR?21 mimic + LY294002 group were lower than in the miR?21 mimic group. Compared with the miR?NC group, the protein expression levels of Pten were decreased, whereas p?Akt and NFATc1 were increased in the miR?21 mimic group. Conversely, Pten protein expression was increased, whereas p?Akt and NFATc1 were decreased in the miR?21 inhibitor group. In the miR?21 mimic + LY294002 group, Pten protein expression was higher, and p?Akt and NFATc1 were lower than in the miR?21 mimic group. In conclusion, miR?21 is upregulated during osteoclastogenesis, and may promote osteoclastogenesis and bone resorption through activating the PI3K/Akt signaling pathway via targeting Pten.
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Project description:Loss of PTEN, a negative regulator of the phosphoinositide 3-kinase signaling pathway, is a frequent event in T-cell acute lymphoblastic leukemia, suggesting the importance of phosphoinositide 3-kinase activity in this disease. Indeed, hyperactivation of the phosphoinositide 3-kinase pathway is associated with the disease aggressiveness, poor prognosis and resistance to current therapies. To identify a molecular pathway capable of cooperating with PTEN deficiency to drive oncogenic transformation of leukocytes, we performed an unbiased transformation screen with a library of tyrosine kinases. We found that activation of NTRK2 is able to confer a full growth phenotype of Ba/F3 cells in an IL3-independent manner in the PTEN-null setting. NTRK2 activation cooperates with PTEN deficiency through engaging both phosphoinositide3-kinase/AKT and JAK/STAT3 pathway activation in leukocytes. Notably, pharmacological inhibition demonstrated that p110α and p110δ are the major isoforms mediating the phosphoinositide 3-kinase/AKT signaling driven by NTRK2 activation in PTEN-deficient leukemia cells. Furthermore, combined inhibition of phosphoinositide 3-kinase and STAT3 significantly suppressed proliferation of PTEN-mutant T-cell acute lymphoblastic leukemia both in culture and in mouse xenografts. Together, our data suggest that a unique conjunction of PTEN deficiency and NTRK2 activation in T-cell acute lymphoblastic leukemia, and combined pharmacologic inhibition of phosphoinositide 3-kinase and STAT3 signaling may serve as an effective and durable therapeutic strategy for T-cell acute lymphoblastic leukemia.
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Project description:The PI3K/AKT/mTOR signaling pathway is constitutively active in PTEN-deficient cancer cells, and its targeted inhibition has significant anti-tumor effects. However, the efficacy of targeted therapies is often limited due to drug resistance. The relevant signaling pathways in PTEN-deficient cancer cells treated with the PI3K/mTOR inhibitor BEZ235 were screened using a phosphokinase array, and further validated following treatment with multiple PI3K/AKT/mTOR inhibitors or AKT knockdown. The correlation between PTEN expression levels and STAT3 kinase phosphorylation in the tissue microarrays of gastric cancer patients was analyzed by immunohistochemistry. Cell proliferation and clonogenic assays were performed on the suitably treated PTEN-deficient cancer cells. Cytokine arrays, small molecule inhibition and knockdown assays were performed to identify related factors. PTEN-deficient tumor xenografts were established in nude mice that were treated with PI3K/AKT/mTOR and/or STAT3 inhibitors. PTEN deficiency was positively correlated with low STAT3 activity. PI3K/mTOR inhibitors increased the expression and secretion of macrophage migration inhibitory factor (MIF) and activated the JAK1/STAT3 signaling pathway. Both cancer cells and in vivo tumor xenografts showed that the combined inhibition of PI3K/AKT/mTOR and STAT3 activity enhanced the inhibitory effect of BEZ235 on the proliferation of PTEN-deficient cancer cells. Our findings provide a scientific basis for a novel treatment strategy in cancer patients with PTEN deficiency.
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2016-12-01 | E-MTAB-5286 | biostudies-arrayexpress
Project description:Notoginsenoside R7 was isolated from Panax notoginseng, a plant used commonly in traditional Chinese medicine. We investigated the anti-cancer effects of R7 in HeLa cells in vitro and in vivo, and explored the underlying mechanisms of action. R7 dose-dependently inhibited HeLa cell proliferation and induced apoptosis in vitro, In silico docking-based screening assays showed that R7 can directly bind Akt. Pretreatment with the Akt inhibitor LY294002 synergistically enhanced the R7 anti-proliferation and anti-apoptosis effects in HeLa cells, confirming that R7 acts through the PI3K/Akt pathway. Consistent with the in vitro findings, R7 exerted anti-tumor effects in a mouse xenograft model by targeting PI3K (PTEN) and Akt, activating the pro-apoptotic Bcl-2 family and, subsequently, caspase family members. R7 treatment activated PTEN and downregulated mTOR phosphorylation without affecting mTOR expression, though regulatory-associated protein of mTOR (raptor) expression declined. Our study suggests that R7 is a promising chemotherapeutic agent for the treatment of cervical cancer and other PI3K/PTEN/Akt/mTOR signaling-associated tumors.
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