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The IGF1R/IRS1 signaling is activated in acute lymphoblastic leukemia (ALL) and can be targeted by the pharmacological inhibitors NT157 (IGF1R-IRS1/2 inhibitor) and OSI-906 (IGF1R/IR inhibitor). Here we investigate the cellular and molecular effects of NT157 and OSI-906 in ALL cells. NT157 and OSI-906 treatment reduced viability, proliferation and cell cycle progression in ALL cell lines. Similarly, in primary samples of patients with ALL, both OSI-906 and NT157 reduced viability, but only NT157 induced apoptosis. NT157 and OSI-906 did not show cytotoxicity in primary samples from healthy donor. NT157 and OSI-906 significantly decreased Jurkat cell migration, but did not modulate Namalwa migration. Consistent with the more potent effect of NT157 on cells, NT157 significantly modulated expression of 25 genes related to the MAPK signaling pathway in Jurkat cells, including oncogenes and tumor suppressor genes. Both compounds inhibited mTOR and p70S6K activity, but only NT157 inhibited AKT and 4-EBP1 activation. In summary, in ALL cells, NT157 has cytotoxic activity, whereas OSI-906 is cytostatic. NT157 has a stronger effect on ALL cells, and thus the direct inhibition of IRS1 may be a potential therapeutic target in ALL., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The insulin receptor substrate (IRS) proteins are a family of cytoplasmic proteins that integrate and coordinate the transmission of signals from the extracellular to the intracellular environment via transmembrane receptors, thus regulating cell growth, metabolism, survival and proliferation. The PI3K/AKT/mTOR and MAPK signaling pathways are the best-characterized downstream signaling pathways activated by IRS signaling (canonical pathways). However, novel signaling axes involving IRS proteins (noncanonical pathways) have recently been identified in solid tumor and hematologic neoplasm models. Insulin receptor substrate-1 (IRS1) and insulin receptor substrate-2 (IRS2) are the best-characterized IRS proteins in hematologic-related processes. IRS2 binds to important cellular receptors involved in normal hematopoiesis (EPOR, MPL and IGF1R). Moreover, the identification of IRS1/ABL1 and IRS2/JAK2V617F interactions and their functional consequences has opened a new frontier for investigating the roles of the IRS protein family in malignant hematopoiesis. Insulin receptor substrate-4 (IRS4) is absent in normal hematopoietic tissues but may be expressed under abnormal conditions. Moreover, insulin receptor substrate-5 (DOK4) and insulin receptor substrate-6 (DOK5) are linked to lymphocyte regulation. An improved understanding of the signaling pathways mediated by IRS proteins in hematopoiesis-related processes, along with the increased development of agonists and antagonists of these signaling axes, may generate new therapeutic approaches for hematological diseases. The scope of this review is to recapitulate and review the evidence for the functions of IRS proteins in normal and malignant hematopoiesis.

Insulin-like growth factor 1 (IGF1) and its receptor IGF1R regulate normal cell growth and contribute to cell transformation through activation of downstream signaling pathways. In fibroblast cells, insulin receptor substrate 1 (IRS1), through IGF1 signaling, was found to be the key protein for nuclear translocation of β-catenin and MYC transcription activation. We herein investigated the IRS1/β-catenin axis in acute lymphoblastic leukemia (ALL) cells. Samples were obtained from 45 patients with ALL and 13 healthy donors. ALL cell lines were used. Gene expression was measured by quantitative PCR. Protein expression, associations, and cellular localization were evaluated by immunoprecipitation, subcellular fractionation, and confocal microscopy. Cells were submitted to IGF1 stimulation and/or IGF1R pharmacological inhibition (OSI-906). IRS1, β-catenin, and MYC mRNA expression were significantly elevated in ALL patients, compared to normal controls. MYC mRNA expression positively correlated with β-catenin and IRS1. Increased age and MYC expression negatively affected overall survival by univariate analysis. Total and phospho-IGF1R and IRS1, MYC and β-catenin protein expression were higher in ALL cells, compared to normal peripheral blood mononuclear cells (PBMC). IRS1 and β-catenin were found to be colocalized in the nuclei and the cytoplasm of ALL cell lines, whereas both proteins were only slightly detected in the cytoplasm of normal PBMC. In Jurkat cells, a constitutive IRS1 and β-catenin protein interaction were observed; OSI-906 treatment decreased IGF1R tyrosine phosphorylation, IRS1 expression and phosphorylation, nuclear translocation of β-catenin, IRS1 and β-catenin association, and MYC protein expression. In conclusion, the IRS1/β-catenin axis is activated in ALL cells. J. Cell. Biochem. 118: 1774-1781, 2017. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)