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  • AML  (1)
  • CELL-CYCLE ARREST  (1)
  • 1
    Keywords: NF-KAPPA-B ; BREAST-CANCER ; TARGET ; MUTATIONS ; HEMATOPOIETIC STEM-CELLS ; ACUTE MYELOGENOUS LEUKEMIA ; RAPAMYCIN ; AML ; MEK INHIBITION ; CONSTITUTIVE PHOSPHORYLATION
    Abstract: In acute myeloid leukemia (AML), several signaling pathways such as the phosphatidylinositol-3-kinase/AKT and the mammalian target of rapamycin (PI3K/AKT/mTOR) pathway are deregulated and constitutively activated as a consequence of genetic and cytogenetic abnormalities. We tested the effectiveness of PI3K/AKT/mTOR-targeting therapies and tried to identify alterations that associate with treatment sensitivity. By analyzing primary samples and cell lines, we observed a wide range of cytotoxic activity for inhibition of AKT (MK-2206), mTORC1 (rapamycin) and PI3K/mTORC1/2 (BEZ-235) with a high sensitivity of cells carrying an MLL rearrangement. In vivo PI3K/mTOR inhibition delayed tumor progression, reduced tumor load and prolonged survival in an MLL-AF9(+)/FLT3-ITD+ xenograft mouse model. By performing targeted amplicon sequencing in 38 MLL-AF9(+) and 125 cytogenetically normal AML patient samples, we found a high additional mutation rate for genes involved in growth factor signaling in 79% of all MLL-AF9(+) samples, which could lead to a possible benefit of this cohort. PI3K/mTOR inhibition for 24 h led to the cross-activation of the ERK pathway. Further in vitro studies combining PI3K/mTOR and ERK pathway inhibition revealed highly synergistic effects in apoptosis assays. Our data implicate a possible therapeutic benefit of PI3K/mTOR inhibition in the MLL-mutated subgroup. Inhibiting rescue pathways could improve the therapeutic efficacy of PI3K-targeted therapies in AML.
    Type of Publication: Journal article published
    PubMed ID: 25322685
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  • 2
    Keywords: APOPTOSIS ; IN-VITRO ; TUMOR-CELLS ; BREAST-CANCER ; p53 ; DNA-DAMAGE ; CANCER-THERAPY ; CELL-CYCLE ARREST ; ARRIVE GUIDELINES ; DRUG-COMBINATIONS
    Abstract: BACKGROUND AND PURPOSE: In polychemotherapy protocols, that is for treatment of neuroblastoma and Ewing sarcoma, Vinca alkaloids and cell cycle-arresting drugs are usually administered on the same day. Here we studied whether this combination enables the optimal antitumour effects of Vinca alkaloids to be manifested. EXPERIMENTAL APPROACH: Vinca alkaloids were tested in a preclinical mouse model in vivo and in vitro in combination with cell cycle-arresting drugs. Signalling pathways were characterized using RNA interference. KEY RESULTS: In vitro, knockdown of cyclins significantly inhibited vincristine-induced cell death indicating, in accordance with previous findings, Vinca alkaloids require active cell cycling and M-phase transition for induction of cell death. In contrast, anthracyclines, irradiation and dexamethasone arrested the cell cycle and acted like cytostatic drugs. The combination of Vinca alkaloids with cytostatic therapeutics resulted in diminished cell death in 31 of 36 (86%) tumour cell lines. In a preclinical tumour model, anthracyclines significantly inhibited the antitumour effect of Vinca alkaloids in vivo. Antitumour effects of Vinca alkaloids in the presence of cytostatic drugs were restored by caffeine, which maintained active cell cycling, or by knockdown of p53, which prevented drug-induced cell cycle arrest. Therapeutically most important, optimal antitumour effects were obtained in vivo upon separating the application of Vinca alkaloids from cytostatic therapeutics. CONCLUSION AND IMPLICATIONS: Clinical trials are required to prove whether Vinca alkaloids act more efficiently in cancer patients if they are applied uncoupled from cytostatic therapies. On a conceptual level, our data suggest the implementation of polychemotherapy protocols based on molecular mechanisms of drug-drug interactions. LINKED ARTICLE: This article is commented on by Solary, pp 1555-1557 of this issue. To view this commentary visit http://dx.doi.org/10.1111/bph.12101.
    Type of Publication: Journal article published
    PubMed ID: 23186127
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