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Combination therapies to inhibit LCK tyrosine kinase and mTOR signaling in T-cell Acute Lymphoblastic Leukemia

ABSTRACT: Relapse and refractory T cell acute lymphoblastic leukemia (T-ALL) has a poor prognosis and new combination therapies are sorely needed. This work uncovered potent drug synergies between AKT/mTORC1 inhibitors and the general tyrosine kinase-inhibitor, dasatinib. The combination effectively curbed T-ALL growth in human cell lines and primary human T-ALL samples, and was well tolerated and effective in suppressing leukemia growth in patient-derived xenografts grown in mice. Mechanistically, dasatinib inhibited phosphorylation and activation of the lymphocyte-specific protein tyrosine kinase (LCK) to blunt the T-cell receptor (TCR) signaling pathway and when complexed with mTORC1 inhibition, induced potent T-ALL cell killing through reducing MCL-1 protein expression. Analysis of responses across T-ALL subtypes and association with specific genetic mutations or expression patterns failed to identify any obvious biomarkers or correlations in predicting therapy responses, although there appeared to be a trend toward higher TCR/LCK pathway activity in samples that exhibited synergistic therapy responses.

PROVIDER: EGAS00001005945 | EGA |

REPOSITORIES: EGA

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Project description:Introduction: Mammalian target of rapamycin (mTOR) represents a key downstream intermediate for a myriad of oncogenic receptor tyrosine kinases. In the case of the insulin-like growth factor (IGF) pathway, the mTOR complex (mTORC1) mediates IGF-1 receptor (IGF-1R)-induced estrogen receptor alpha (ERÎ±) phosphorylation/activation and leads to increased proliferation and growth in breast cancer cells. As a result, the prevalence of mTOR inhibitors combined with hormonal therapy has increased in recent years. Conversely, activated mTORC1 provides negative feedback regulation of IGF signaling via insulin receptor substrate (IRS)-1/2 serine phosphorylation and subsequent proteasomal degradation. Thus, the IGF pathway may provide escape (e.g. de novo or acquired resistance) from mTORC1 inhibitors. It is therefore plausible that combined inhibition of mTORC1 and IGF-1R for select subsets of ER-positive breast cancer patients presents as a viable therapeutic option. Methods: Using hormone-sensitive breast cancer cells stably transfected with the aromatase gene (MCF-7/AC-1), works presented herein describe the in vitro and in vivo antitumor efficacy of the following compounds: dalotuzumab (DALO; âMK-0646â; anti-IGF-1R antibody), ridaforolimus (RIDA; âMK-8669â; mTORC1 small molecule inhibitor) and letrozole (âLETâ, aromatase inhibitor). Results: With the exception of MK-0646, all single agent and combination treatment arms effectively inhibited xenograft tumor growth, albeit to varying degrees. Correlative tissue analyses revealed MK-0646 alone and in combination with LET induced insulin receptor alpha A (InsR-A) isoform upregulation (both mRNA and protein expression), thereby further supporting a triple therapy approach. Conclusion: These data provide preclinical rationalization towards the combined triple therapy of LET plus MK-0646 plus MK-8669 as an efficacious anti-tumor strategy for ER-positive breast tumors. 46 samples, 28 days post treatment

Project description:Canine mast cell tumour proliferation depends to a large extent on the activity of KIT, a tyrosine kinase receptor. Inhibitors of the KIT tyrosine kinase have recently been introduced and successfully applied as a therapeutic agent for this tumour type. However, little is known on the downstream target genes of this signalling pathway and molecular changes after inhibition. Transcriptome analysis of the canine mast cell tumour cell line C2 treated for up to 72 hours with the tyrosine kinase inhibitor masitinib identified significant changes in the expression levels of approximately 3500 genes representing 16% of the canine genome. Approximately 40% of these genes had increased mRNA expression levels including genes associated with the pro-proliferative pathways of B- and T-cell receptors, chemokine receptors, steroid hormone receptors and EPO-, RAS and MAP kinase signalling. Proteome analysis of C2 cells treated for 72 hours identified 24 proteins with changed expression levels, most of which being involved in gene transcription, e.g. EIA3, EIA4, TARDBP, protein folding, e.g. HSP90, UCHL3, PDIA3 and protection from oxidative stress, GSTT3, SELENBP1. Transcriptome and proteome analysis of neoplastic canine mast cells treated with masitinib confirmed the strong important and complex role of KIT in these cells. Approximately 16% of the total canine genome and thus the majority of the active genes were significantly transcriptionally regulated. Most of these changes were associated with reduced proliferation and metabolism of treated cells. Interestingly, several pro-proliferative pathways were up-regulated which may represent attempts of masitinib treated cells to activate alternative pro-proliferative pathways. These pathways may contain hypothetical targets for a combination therapy with masitinib to further improve its therapeutic effect. The present study aimed at identifying the transcriptional and translational responses of neoplastic canine mast cells to the tyrosine kinase inhibitor masitinib. To this end, C2 cells, a cell line with a tandem duplication in the juxtamembrane unit and thus constitutively activated KIT, were treated with masitinib and changes in the global mRNA and protein expression levels were characterized.

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Combination therapies to inhibit LCK tyrosine kinase and mTOR signaling in T-cell Acute Lymphoblastic Leukemia

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