Chronic myeloid leukemia (CML) is a hematopoietic neoplasm characterized by the Philadelphia chromosome and the related BCR-ABL1 oncoprotein. Acceleration of CML is usually accompanied by basophilia. Several proangiogenic molecules have been implicated in disease acceleration, including the hepatocyte growth factor (HGF). However, little is known so far about the cellular distribution and function of HGF in CML. We here report that HGF is expressed abundantly in purified CML basophils and in the basophil-committed CML line KU812, whereas all other cell types examined expressed only trace amounts of HGF or no HGF. Interleukin 3, a major regulator of human basophils, was found to promote HGF expression in CML basophils. By contrast, BCR-ABL1 failed to induce HGF synthesis in CML cells, and imatinib failed to inhibit expression of HGF in these cells. Recombinant HGF as well as basophil-derived HGF induced endothelial cell migration in a scratch wound assay, and these effects of HGF were reverted by an anti-HGF antibody as well as by pharmacologic c-Met inhibitors. In addition, anti-HGF and c-Met inhibitors were found to suppress the spontaneous growth of KU812 cells, suggesting autocrine growth regulation. Together, HGF is a BCR-ABL1-independent angiogenic and autocrine growth regulator in CML. Basophils are a unique source of HGF in these patients and may play a more active role in disease-associated angiogenesis and disease progression than has so far been assumed. Our data also suggest that HGF and c-Met are potential therapeutic targets in CML.

Background-Recent data obtained in mouse models have initiated a controversy whether basophils are the key antigen-presenting cells (APCs) in allergy. Here, we investigate whether basophils are of importance for the presentation of allergen and the induction of T cell proliferation in allergic patients.

IntroductionSystemic mastocytosis (SM) is a myeloid neoplasm characterized by pathologic accumulation of mast cells (MCs) in one or more extracutaneous organs. 1,2 Indolent and aggressive variants of SM have been described. [1][2][3][4][5] In most patients, the transforming KIT mutation D816V is detectable independent of the category of SM. [6][7][8] Patients with indolent SM (ISM) have an excellent prognosis with normal or near-normal life expectancy. [1][2][3][4][5]9,10 In patients with aggressive SM (ASM) and mast cell leukemia (MCL), the prognosis is grave, [1][2][3][4][5]9,10 and responses to conventional drugs and most targeted drugs are poor. [1][2][3][4]9,[11][12][13][14][15] During the past few years, several attempts have been made to define new molecular targets in neoplastic MCs and to establish new treatment concepts for these patients. 16,17 Abnormal DNA methylation and histone-acetylation are frequently observed in various neoplasms and supposedly contribute to disease evolution and drug resistance. [18][19][20] In hematologic malignancies, epigenetic abnormalities have been reported in acute and chronic leukemias as well as in myelodysplastic syndromes (MDS). [21][22][23] Especially in patients with MDS, abnormal methylation of the genome has been described. 21,22 Correspondingly, epigenetically active drugs such as 5-azacytidine and 5-aza2Јdeoxycytidine (decitabine) reportedly act as antineoplastic agents in these patients. [23][24][25] More recent data suggest that demethylating agents also exert beneficial effects in patients in whom neoplastic cells exhibit myeloproliferative and myelodysplastic features, such as chronic myelomonocytic leukemia (CMML), and sometimes even in patients with advanced myeloproliferative neoplasms (MPN). 26,27 Advanced SM is a myeloid neoplasm that often presents with myeloproliferative features and sometimes with bone marrow (BM) dysplasia. [1][2][3][4][5] In addition, advanced SM may coexist with MDS (SM-MDS), CMML, or a JAK2-mutated MPN. 28 However, so far, no data on the effects of demethylating agents on neoplastic cells in advanced SM or SM-AHNMD are available. In addition, little is known about methylation patterns in neoplastic MCs. We explored the effects of 2 widely used demethylating agents, 5-azacytidine and decitabine, on growth and survival of neoplastic MCs, and examined the mechanism(s) of action of these drugs. MethodsDrugs, monoclonal antibodies, and other reagents PKC412 (midostaurin) was kindly provided by Dr J. Roesel and Dr P. W. Manley (Novartis). 5-azacytidine, decitabine, recombinant human FASligand, and propidium iodide (PI) were purchased from Sigma-Aldrich, Submitted September 27, 2011; accepted February 29, 2012. Prepublished online as Blood First Edition paper, March 21, 2012; DOI 10.1182 DOI 10. /blood-2011 The online version of this article contains a data supplement.The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked ''advertis...

The phosphoinositide 3-kinase (PI3-kinase) and the mammalian target of rapamycin (mTOR) are two major signaling molecules involved in growth and activation of mast cells (MC) and basophils (BA). We examined the effects of the dual PI3-kinase/mTOR blocker NVP-BEZ235 on growth of normal and neoplastic BA and MC as well as immunoglobulin E (IgE)-dependent cell activation. Growth of MC and BA were determined by measuring 3H-thymidine uptake and apoptosis. Cell activation was determined in histamine release experiments and by measuring upregulation of CD63 and CD203c after challenging with IgE plus anti-IgE or allergen. We found that NVP-BEZ235 exerts profound inhibitory effects on growth of primary and cloned neoplastic MC. In the MC leukemia cell line HMC-1, NVP-BEZ235 showed similar IC50 values in the HMC-1.1 subclone lacking KIT D816V (0.025 µM) and the HMC-1.2 subclone expressing KIT D816V (0.005 µM). Moreover, NVP-BEZ235 was found to exert strong growth-inhibitory effects on neoplastic MC in a xenotransplant-mouse model employing NMR1-Foxn1nu mice. NVP-BEZ235 also exerted inhibitory effects on cytokine-dependent differentiation of normal BA and MC, but did not induce growth inhibition or apoptosis in mature MC or normal bone marrow cells. Finally, NVP-BEZ235 was found to inhibit IgE-dependent histamine release in BA and MC (IC50 0.5–1 µM) as well as anti-IgE-induced upregulation of CD203c in BA and IgE-dependent upregulation of CD63 in MC. In summary, NVP-BEZ235 produces growth-inhibitory effects in immature neoplastic MC and inhibits IgE-dependent activation of mature BA and MC. Whether these potentially beneficial drug effects have clinical implications is currently under investigation.

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