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The receptor tyrosine kinase Alk controls neurofibromin functions in Drosophila growth and learning.

ABSTRACT: Anaplastic Lymphoma Kinase (Alk) is a Receptor Tyrosine Kinase (RTK) activated in several cancers, but with largely unknown physiological functions. We report two unexpected roles for the Drosophila ortholog dAlk, in body size determination and associative learning. Remarkably, reducing neuronal dAlk activity increased body size and enhanced associative learning, suggesting that its activation is inhibitory in both processes. Consistently, dAlk activation reduced body size and caused learning deficits resembling phenotypes of null mutations in dNf1, the Ras GTPase Activating Protein-encoding conserved ortholog of the Neurofibromatosis type 1 (NF1) disease gene. We show that dAlk and dNf1 co-localize extensively and interact functionally in the nervous system. Importantly, genetic or pharmacological inhibition of dAlk rescued the reduced body size, adult learning deficits, and Extracellular-Regulated-Kinase (ERK) overactivation dNf1 mutant phenotypes. These results identify dAlk as an upstream activator of dNf1-regulated Ras signaling responsible for several dNf1 defects, and they implicate human Alk as a potential therapeutic target in NF1.

SUBMITTER: Gouzi JY

PROVIDER: S-EPMC3174217 | biostudies-other | 2011 Sep

REPOSITORIES: biostudies-other

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The receptor tyrosine kinase Alk controls neurofibromin functions in Drosophila growth and learning.

Gouzi Jean Y JY Moressis Anastasios A Walker James A JA Apostolopoulou Anthi A AA Palmer Ruth H RH Bernards André A Skoulakis Efthimios M C EM

PLoS genetics 20110915 9

Anaplastic Lymphoma Kinase (Alk) is a Receptor Tyrosine Kinase (RTK) activated in several cancers, but with largely unknown physiological functions. We report two unexpected roles for the Drosophila ortholog dAlk, in body size determination and associative learning. Remarkably, reducing neuronal dAlk activity increased body size and enhanced associative learning, suggesting that its activation is inhibitory in both processes. Consistently, dAlk activation reduced body size and caused learning de ...[more]

PMID: 21949657

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Project description:Fms-like tyrosine kinase 3 (FLT3) plays an important role in hematopoietic differentiation, and constitutively active FLT3 mutant proteins contribute to the development of acute myeloid leukemia. Little is known about the protein-tyrosine phosphatases (PTP) affecting the signaling activity of FLT3. To identify such PTP, myeloid cells expressing wild type FLT3 were infected with a panel of lentiviral pseudotypes carrying shRNA expression cassettes targeting different PTP. Out of 20 PTP tested, expressed in hematopoietic cells, or presumed to be involved in oncogenesis or tumor suppression, DEP-1 (PTPRJ) was identified as a PTP negatively regulating FLT3 phosphorylation and signaling. Stable 32D myeloid cell lines with strongly reduced DEP-1 levels showed site-selective hyperphosphorylation of FLT3. In particular, the sites pTyr-589, pTyr-591, and pTyr-842 involved in the FLT3 ligand (FL)-mediated activation of FLT3 were hyperphosphorylated the most. Similarly, acute depletion of DEP-1 in the human AML cell line THP-1 caused elevated FLT3 phosphorylation. Direct interaction of DEP-1 and FLT3 was demonstrated by "substrate trapping" experiments showing association of DEP-1 D1205A or C1239S mutant proteins with FLT3 by co-immunoprecipitation. Moreover, activated FLT3 could be dephosphorylated by recombinant DEP-1 in vitro. Enhanced FLT3 phosphorylation in DEP-1-depleted cells was accompanied by enhanced FLT3-dependent activation of ERK and cell proliferation. Stable overexpression of DEP-1 in 32D cells and transient overexpression with FLT3 in HEK293 cells resulted in reduction of FL-mediated FLT3 signaling activity. Furthermore, FL-stimulated colony formation of 32D cells expressing FLT3 in methylcellulose was induced in response to shRNA-mediated DEP-1 knockdown. This transforming effect of DEP-1 knockdown was consistent with a moderately increased activation of STAT5 upon FL stimulation but did not translate into myeloproliferative disease formation in the 32D-C3H/HeJ mouse model. The data indicate that DEP-1 is negatively regulating FLT3 signaling activity and that its loss may contribute to but is not sufficient for leukemogenic cell transformation.

Project description:IntroductionThis study explored the use, safety, and efficacy of initial use of an ALK-inhibiting targeted therapy (ALK tyrosine kinase inhibitor [TKI]) in patients with ALK-rearranged NSCLC in a population-based, real-world clinical population within the province of Alberta, Canada.MethodsDemographic, clinical, treatment, and outcome data of the patients with advanced or metastatic ALK-rearranged NSCLC receiving their first ALK TKI between 2014 and 2019 were included in the analysis.ResultsA total of 92 patients with ALK-rearranged NSCLC treated with ALK TKI (78% crizotinib, 22% alectinib) were identified. In the ALK-rearranged cohort, 1-year survival rate was 73% and median overall survival (OS) and progression-free survival (PFS) were 48.5 months and 17.0 months, respectively. An objective response rate of 49% was observed, and adverse events were reported in 70% of the patients, primarily of low grade (84%). Case-matched comparison to patients with ALK-wildtype disease treated with cytotoxic chemotherapy revealed the benefit of ALK TKI in the context of an ALK rearrangement (ALK-rearranged versus ALK-wildtype) (median post-treatment initiation OS: 46.8 versus 14.2 mo, p < 0.001). Outcomes, measured from the time of ALK TKI initiation, differed by Eastern Cooperative Oncology Group (ECOG) (ECOG < 2 versus ECOG ≥ 2) (median OS: not reached versus 6.8 mo, p < 0.001; median PFS 17.6 versus 7.4 mo, p = 0.02), disease presentation (relapsed versus de novo) (median PFS: 30.8 versus 15.0 mo, p = 0.04), and brain metastasis onset (brain metastases development during ALK TKI versus baseline brain metastases) (not reached versus 12.8 mo, p = 0.04).ConclusionsClinical trials have firmly established that ALK TKIs are safe, well tolerated, and effective; these findings reveal that their impact in a real-world setting is just as profound. The availability and use of ALK TKI therapies contribute to the impressive gains in survival experienced by contemporary patients with ALK-rearranged disease, rendering patients with this oncodriven form of NSCLC among the longest surviving patients with lung cancer.

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The receptor tyrosine kinase Alk controls neurofibromin functions in Drosophila growth and learning.

Publications

The receptor tyrosine kinase Alk controls neurofibromin functions in Drosophila growth and learning.

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