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NTRK2 activation cooperates with PTEN deficiency in T-ALL through activation of both the PI3K-AKT and JAK-STAT3 pathways.

ABSTRACT: 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 p110? and p110? 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.

SUBMITTER: Yuzugullu H

PROVIDER: S-EPMC5029543 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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NTRK2 activation cooperates with PTEN deficiency in T-ALL through activation of both the PI3K-AKT and JAK-STAT3 pathways.

Yuzugullu Haluk H Von Thanh T Thorpe Lauren M LM Walker Sarah R SR Roberts Thomas M TM Frank David A DA Zhao Jean J JJ

Cell discovery 20160920

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 transformatio ...[more]

PMID: 27672444

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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.

Project description:The mammalian signalling pathway involving class I PI3K (phosphoinositide 3-kinase), PTEN (phosphatidylinositol 3-phosphatase) and PKB (protein kinase B)/c-Akt has roles in multiple processes, including cell proliferation and apoptosis. To facilitate novel approaches for genetic, molecular and pharmacological analyses of these proteins, we have reconstituted this signalling pathway by heterologous expression in the unicellular eukaryote, Saccharomyces cerevisiae (yeast). High-level expression of the p110 catalytic subunit of mammalian PI3K dramatically inhibits yeast cell growth. This effect depends on PI3K kinase activity and is reversed partially by a PI3K inhibitor (LY294002) and reversed fully by co-expression of catalytically active PTEN (but not its purported yeast orthologue, Tep1). Growth arrest by PI3K correlates with loss of PIP2 (phosphatidylinositol 4,5-bisphosphate) and its conversion into PIP3 (phosphatidylinositol 3,4,5-trisphosphate). PIP2 depletion causes severe rearrangements of actin and septin architecture, defects in secretion and endocytosis, and activation of the mitogen-activated protein kinase, Slt2. In yeast producing PIP3, PKB/c-Akt localizes to the plasma membrane and its phosphorylation is enhanced. Phospho-specific antibodies show that both active and kinase-dead PKB/c-Akt are phosphorylated at Thr308 and Ser473. Thr308 phosphorylation, but not Ser473 phosphorylation, requires the yeast orthologues of mammalian PDK1 (3-phosphoinositide-dependent protein kinase-1): Pkh1 and Pkh2. Elimination of yeast Tor1 and Tor2 function, or of the related kinases (Tel1, Mec1 and Tra1), did not block Ser473 phosphorylation, implicating another kinase(s). Reconstruction of the PI3K/PTEN/Akt pathway in yeast permits incisive study of these enzymes and analysis of their functional interactions in a simplified context, establishes a new tool to screen for novel agonists and antagonists and provides a method to deplete PIP2 uniquely in the yeast cell.

Dataset Information

NTRK2 activation cooperates with PTEN deficiency in T-ALL through activation of both the PI3K-AKT and JAK-STAT3 pathways.

Publications

NTRK2 activation cooperates with PTEN deficiency in T-ALL through activation of both the PI3K-AKT and JAK-STAT3 pathways.

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