Drug-induced inhibition of phosphorylation of STAT5 overrides drug resistance in neoplastic mast cells

Systemic mastocytosis (SM) is a mast cell (MC) neoplasm with complex pathology and a variable clinical course. In aggressive SM (ASM) and MC leukemia (MCL) responses to conventional drugs are poor and the prognosis is dismal. R763 is a multi-kinase inhibitor that blocks the activity of Aurora-kinase-A/B, ABL1, AKT and FLT3. We examined the effects of R763 on proliferation and survival of neoplastic MC. R763 produced dose-dependent inhibition of proliferation in the human MC lines HMC-1.1 (IC₅₀ 5-50 nM), HMC-1.2 (IC₅₀ 1-10 nM), ROSA^{KIT WT} (IC₅₀ 1-10 nM), ROSA^{KIT D816V} (IC₅₀ 50-500 nM) and MCPV-1.1 (IC₅₀ 100-1000 nM). Moreover, R763 induced growth inhibition in primary neoplastic MC in patients with ASM and MCL. Growth-inhibitory effects of R763 were accompanied by signs of apoptosis and a G2/M cell cycle arrest. R763 also inhibited phosphorylation of KIT, BTK, AKT and STAT5 in neoplastic MC. The most sensitive target appeared to be STAT5. In fact, tyrosine phosphorylation of STAT5 was inhibited by R763 at 10 nM. At this low concentration, R763 produced synergistic growth-inhibitory effects on neoplastic MC when combined with midostaurin or dasatinib. Together, R763 is a novel promising multi-kinase inhibitor that blocks STAT5 activation and thereby overrides drug-resistance in neoplastic MC.

Proteome analysis identifies L1CAM/CD171 and DPP4/CD26 as novel markers of human skin mast cells

BACKGROUND

The function of skin mast cells has been well documented in IgE-mediated allergic reactions, whereas other mast cell functions are poorly defined. This study aimed at identifying novel mast cell proteins by proteome analysis of primary human skin mast cells.

METHODS

The proteome of skin mast cells was compared to other cell types and analyzed using bioinformatics. The expression and function of two proteins hitherto not described in skin mast cells was investigated in isolated mast cells as well as in mast cells in situ.

RESULTS

Within the mast cell proteome, we identified 49 highly expressed proteins previously not described in mast cells; 21 of these proteins were found to be selectively expressed in mast cells. Two proteins, the neural cell adhesion molecule L1 and dipeptidyl peptidase 4, were further studied. L1 was found to be highly expressed in mast cells in normal, psoriasis, and mastocytosis skin. Dipeptidyl peptidase 4 was found to be expressed in mast cells in normal, psoriasis, and mastocytosis skin as well as in bone marrow mast cells in patients with systemic mastocytosis. In normal skin, mast cells were identified as a major source of dipeptidyl peptidase 4 and we also found that skin mast cells and fibroblasts secrete an active form of this enzyme.

CONCLUSIONS

In a systematic proteomics approach we identified two novel mast cell proteins potentially relevant to skin homeostasis: neural cell adhesion molecule L1 and dipeptidyl peptidase 4.

[Suicide notes and their importance to suicide research. The representativeness of suicide note writers]

BACKGROUND

Suicide notes provide direct information from suicide victims and often are written shortly before the suicide act. An important question is whether those who write such notes are representative for suicide victims who do not.

METHODS

A consecutive series of suicides investigated at the Department of Forensic Medicine in Vienna from April 2002 to March 2003 was examined for the existence of suicide notes. Note writers were compared with non-note writers according to the variables age, sex, family status, occupational status, psychiatric care, suicide motive, and method.

RESULTS AND CONCLUSIONS

Suicide victims who leave suicide notes do not differ statistically significantly from non-note-leavers in sex, age, family status, psychiatric care, motive, or method. This means they are representative for all suicide victims concerning important demographic factors.

Suizidologie: Abschiedsbriefe und ihre Themen

BACKGROUND

The study of suicide notes has a long tradition. It is important to integrate this study into psychological autopsy and to make contact with the bereaved. For the first time, we present an Austrian-German study and its themes.

MATERIAL AND METHODS

A consecutive series of suicides, investigated at the Department for Forensic Medicine in Vienna from Mai 2002 until April 2005, was examined for the presence of suicide notes. Suicide notes and demographic variables were integrated in an Access databank.

RESULTS

A total of 29% of the those committing suicide left notes, however, the bereaved of only about a quarter allowed these to be studied. The major part was hand written, addressed to the general public or family, and shorter than 150 words. Frequent themes were specific instructions, emotions, themes regarding the environment such as the family, occupation and leisure time, and themes regarding stations of life and illness.

Zur kindlichen Sprachentwicklungsstörung: Verständlichkeit bei der Expressiven Sprachstörung

BACKGROUND

Even in the age of two years toddlers with Expressive Language Impairment (SLI-E) differ regarding their phonetic inventories compared with an age-matched group developing normally.

METHOD AND PATIENTS

PCC-R scores of 19 children with expressive language disorder, aged between four and six years, are compared with age and sex matched controls with normal language acquisition.

RESULTS

There are significant differences between PCC-R scores, children with expressive language disorder show lower scores than children with normal language acquisition. Age, sex and nonverbal intelligence do not influence performance measured with PCC-R. Analysis regarding early, middle and late consonants shows, that expressive language disordered children show bigger problems in aquiring late than early and middle consonants.