Nintedanib targets KIT D816V neoplastic cells derived from induced pluripotent stem cells of systemic mastocytosis

The KIT D816V mutation is found in >80% of patients with systemic mastocytosis (SM) and is key to neoplastic mast cell (MC) expansion and accumulation in affected organs. Therefore, KIT D816V represents a prime therapeutic target for SM. Here, we generated a panel of patient-specific KIT D816V induced pluripotent stem cells (iPSCs) from patients with aggressive SM and mast cell leukemia to develop a patient-specific SM disease model for mechanistic and drug-discovery studies. KIT D816V iPSCs differentiated into neoplastic hematopoietic progenitor cells and MCs with patient-specific phenotypic features, thereby reflecting the heterogeneity of the disease. CRISPR/Cas9n-engineered KIT D816V human embryonic stem cells (ESCs), when differentiated into hematopoietic cells, recapitulated the phenotype observed for KIT D816V iPSC hematopoiesis. KIT D816V causes constitutive activation of the KIT tyrosine kinase receptor, and we exploited our iPSCs and ESCs to investigate new tyrosine kinase inhibitors targeting KIT D816V. Our study identified nintedanib, a US Food and Drug Administration-approved angiokinase inhibitor that targets vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and fibroblast growth factor receptor, as a novel KIT D816V inhibitor. Nintedanib selectively reduced the viability of iPSC-derived KIT D816V hematopoietic progenitor cells and MCs in the nanomolar range. Nintedanib was also active on primary samples of KIT D816V SM patients. Molecular docking studies show that nintedanib binds to the adenosine triphosphate binding pocket of inactive KIT D816V. Our results suggest nintedanib as a new drug candidate for KIT D816V-targeted therapy of advanced SM.Peer reviewe

AMN107 (nilotinib): a novel and selective inhibitor of BCR-ABL

Chronic myelogenous leukaemia (CML) and Philadelphia chromosome positive (Ph+) acute lymphoblastic leukaemia (ALL) are caused by the BCR-ABL oncogene. Imatinib inhibits the tyrosine kinase activity of the BCR-ABL protein and is an effective, frontline therapy for chronic-phase CML. However, accelerated or blast-crisis phase CML patients and Ph+ ALL patients often relapse due to drug resistance resulting from the emergence of imatinib-resistant point mutations within the BCR-ABL tyrosine kinase domain. This has stimulated the development of new kinase inhibitors that are able to over-ride resistance to imatinib. The novel, selective BCR-ABL inhibitor, AMN107, was designed to fit into the ATP-binding site of the BCR-ABL protein with higher affinity than imatinib. In addition to being more potent than imatinib (IC50<30 nM) against wild-type BCR-ABL, AMN107 is also significantly active against 32/33 imatinib-resistant BCR-ABL mutants. In preclinical studies, AMN107 demonstrated activity in vitro and in vivo against wild-type and imatinib-resistant BCR-ABL-expressing cells. In phase I/II clinical trials, AMN107 has produced haematological and cytogenetic responses in CML patients, who either did not initially respond to imatinib or developed imatinib resistance. Dasatinib (BMS-354825), which inhibits Abl and Src family kinases, is another promising new clinical candidate for CML that has shown good efficacy in CML patients. In this review, the early characterisation and development of AMN107 is discussed, as is the current status of AMN107 in clinical trials for imatinib-resistant CML and Ph+ ALL. Future trends investigating prediction of mechanisms of resistance to AMN107, and how and where AMN107 is expected to fit into the overall picture for treatment of early-phase CML and imatinib-refractory and late-stage disease are discussed

The Transcription Factor YY1 Is a Substrate for Polo-Like Kinase 1 at the G2/M Transition of the Cell Cycle

Yin-Yang 1 (YY1) is an essential multifunctional zinc-finger protein. It has been shown over the past two decades to be a critical regulator of a vast array of biological processes, including development, cell proliferation and differentiation, DNA repair, and apoptosis. YY1 exerts its functions primarily as a transcription factor that can activate or repress gene expression, dependent on its spatial and temporal context. YY1 regulates a large number of genes involved in cell cycle transitions, many of which are oncogenes and tumor-suppressor genes. YY1 itself has been classified as an oncogene and was found to be upregulated in many cancer types. Unfortunately, our knowledge of what regulates YY1 is very minimal. Although YY1 has been shown to be a phosphoprotein, no kinase has ever been identified for the phosphorylation of YY1. Polo-like kinase 1 (Plk1) has emerged in the past few years as a major cell cycle regulator, particularly for cell division. Plk1 has been shown to play important roles in the G/M transition into mitosis and for the proper execution of cytokinesis, processes that YY1 has been shown to regulate also. Here, we present evidence that Plk1 directly phosphorylates YY1 in vitro and in vivo at threonine 39 in the activation domain. We show that this phosphorylation is cell cycle regulated and peaks at G2/M. This is the first report identifying a kinase for which YY1 is a substrate

Antitumor activity of a small-molecule inhibitor of the histone kinase Haspin

The approval of histone deacetylase inhibitors for treatment of lymphoma subtypes has positioned histone modifications as potential targets for the development of new classes of anticancer drugs. Histones also undergo phosphorylation events, and Haspin is a protein kinase the only known target of which is phosphorylation of histone H3 at Thr3 residue (H3T3ph), which is necessary for mitosis progression. Mitotic kinases can be blocked by small drugs and several clinical trials are underway with these agents. As occurs with Aurora kinase inhibitors, Haspin might be an optimal candidate for the pharmacological development of these compounds. A high-throughput screening for Haspin inhibitors identified the CHR-6494 compound as being one promising such agent. We demonstrate that CHR-6494 reduces H3T3ph levels in a dose-dependent manner and causes a mitotic catastrophe characterized by metaphase misalignment, spindle abnormalities and centrosome amplification. From the cellular standpoint, the identified small-molecule Haspin inhibitor causes arrest in G2/M and subsequently apoptosis. Importantly, ex vivo assays also demonstrate its anti-angiogenetic features; in vivo, it shows antitumor potential in xenografted nude mice without any observed toxicity. Thus, CHR-6494 is a first-in-class Haspin inhibitor with a wide spectrum of anticancer effects that merits further preclinical research as a new member of the family of mitotic kinase inhibitors

The Tumor-Immune Microenvironment and Response to Radiation Therapy

Chemotherapy and radiation therapy (RT) are standard therapeutic modalities for patients with cancer, including breast cancer. Historic studies examining tissue and cellular responses to RT have predominantly focused on damage caused to proliferating malignant cells leading to their death. However, there is increasing evidence that RT also leads to significant alterations in the tumor microenvironment, particularly with respect to effects on immune cells infiltrating tumors. This review focuses on tumor-associated immune cell responses following RT and discusses how immune responses may be modified to enhance durability and efficacy of RT

A novel canine histiocytic sarcoma cell line:initial characterization and utilization for drug screening studies

In order to be responsible stewards of other people’s data, cloud providers must be accountable for their data handling practices. The potential long provider chains in cloud computing introduces additional accountability challenges, and this paper examines requirements which must be fulfilled to achieve an accountability-based approach.acceptedVersio

A novel canine histiocytic sarcoma cell line:initial characterization and utilization for drug screening studies

Abstract Background Histiocytic sarcoma is a rare disorder in humans, however it is seen with appreciable frequency in certain breeds of dogs, such as Bernese mountain dog. The purpose of this study was to fully characterize a novel canine histiocytic sarcoma cell line, and utilize it as a tool to screen for potential therapeutic drugs. Methods The histiocytic sarcoma cell line was characterized by expression of cellular markers as determined by immunohistochemistry and flow cytometry techniques. The neoplastic cells were also evaluated for their capability of phagocytizing beads particles, and their potential to grow as xenograft in an immunodeficient mouse. We investigated the in vitro cytotoxic activity of a panel of thirteen compounds using the MTS proliferation assay. Inhibitory effects of different drugs were compared using one-way ANOVA, and multiple means were compared using Tukey’s test. Results Neoplastic cells expressed CD11c, CD14, CD18, CD45, CD172a, CD204, MHC I, and vimentin. Expression of MHC II was upregulated after exposure to LPS. Furthermore, the established cell line clearly demonstrated phagocytic activity similar to positive controls of macrophage cell line. The xenograft mouse developed a palpable subcutaneous soft tissue mass after 29 days of inoculation, which histologically resembled the primary neoplasm. Dasatinib, a tyrosine kinase pan-inhibitor, significantly inhibited the growth of the cells in vitro within a clinically achievable and tolerable plasma concentration. The inhibitory response to dasatinib was augmented when combined with doxorubicin. Conclusions In the present study we demonstrated that a novel canine histiocytic sarcoma cell line presents a valuable tool to evaluate novel treatment approaches. The neoplastic cell line favorably responded to dasatinib, which represents a promising anticancer strategy for the treatment of this malignancy in dogs and similar disorders in humans

Integrative mRNA profiling comparing cultured primary cells with clinical samples reveals PLK1 and C20orf20 as therapeutic targets in cutaneous squamous cell carcinoma

This work was funded by DebRA, the dystrophic epidermolysis bullosa research association (http:// www.debra.org.uk