Complex intracranial aneurysms: a DELPHI study to define associated characteristics.

PURPOSE: Intracranial aneurysms present significant health risks, as their rupture leads to subarachnoid haemorrhage, which in turn has high morbidity and mortality rates. There are several elements affecting the complexity of an intracranial aneurysm. However, criteria for defining a complex intracranial aneurysm (CIA) in open surgery and endovascular treatment could differ, and actually there is no consensus on the definition of a "complex" aneurysm. This DELPHI study aims to assess consensus on variables defining a CIA. METHODS: An international panel of 50 members, representing various specialties, was recruited to define CIAs through a three-round Delphi process. The panelists participated in surveys with Likert scale responses and open-ended questions. Consensus criteria were established to determine CIA variables, and statistical analysis evaluated consensus and stability. RESULTS: In open surgery, CIAs were defined by fusiform or blister-like shape, dissecting aetiology, giant size (≥ 25 mm), broad neck encasing parent arteries, extensive neck surface, wall calcification, intraluminal thrombus, collateral branch from the sac, location (AICA, SCA, basilar), vasospasm context, and planned bypass (EC-IC or IC-IC). For endovascular treatment, CIAs included giant size, very wide neck (dome/neck ratio ≤ 1:1), and collateral branch from the sac. CONCLUSIONS: The definition of aneurysm complexity varies by treatment modality. Since elements related to complexity differ between open surgery and endovascular treatment, these consensus criteria of CIAs could even guide in selecting the best treatment approach.

A human organoid system that self-organizes to recapitulate growth and differentiation of a benign mammary tumor.

As 3D culture has become central to investigation of tissue biology, mammary epithelial organoids have emerged as powerful tools for investigation of epithelial cell polarization and carcinogenesis. However, most current protocols start from single cells suspended in Matrigel, which can also restrict cell differentiation and behavior. Here, we show that the noncancerous mammary cell line HMT-3522 S1, when allowed to spontaneously form cell aggregates ("spheroids") in medium without Matrigel, switches to a collective growth mode that recapitulates many attributes of "usual ductal hyperplasia" (UDH), a common benign mammary lesion. Interestingly, these spheroids undergo a complex maturation process reminiscent of embryonic development: solid-cell cords form their own basement membrane, grow on the surface of initially homogeneous cell aggregates, and form asymmetric lumina lined by two distinct cell types that express basal and luminal cytokeratins. This sequence of events provides a cellular mechanism that explains how the characteristic crescent-shaped, asymmetrical lumina form in UDH. Our results suggest that HMT-3522 S1 spheroids are useful as an in vitro model system to study UDH biology, glandular lumen formation, and stem cell biology of the mammary gland.

Ferroptosis Involvement in Glioblastoma Treatment.

Glioblastoma multiforme (GBM) is one of the deadliest brain tumors. Current standard therapy includes tumor resection surgery followed by radiotherapy and chemotherapy. Due to the tumors invasive nature, recurrences are almost a certainty, giving the patients after diagnosis only a 12-15 months average survival time. Therefore, there is a dire need of finding new therapies that could potentially improve patient outcomes. Ferroptosis is a newly described form of cell death with several implications in cancer, among which GBM. Agents that target different molecules involved in ferroptosis and that stimulate this process have been described as potentially adjuvant anti-cancer treatment options. In GBM, ferroptosis stimulation inhibits tumor growth, improves patient survival, and increases the efficacy of radiation and chemotherapy. This review provides an overview of the current knowledge regarding ferroptosis modulation in GBM.

Cerebrolysin after moderate to severe traumatic brain injury: prospective meta-analysis of the CAPTAIN trial series.

INTRODUCTION: This prospective meta-analysis summarizes results from the CAPTAIN trial series, evaluating the effects of Cerebrolysin for moderate-severe traumatic brain injury, as an add-on to usual care. MATERIALS AND METHODS: The study included two phase IIIb/IV prospective, randomized, double-blind, placebo-controlled clinical trials. Eligible patients with a Glasgow Coma Score (GCS) between 6 and 12 received study medication (50 mL of Cerebrolysin or physiological saline solution per day for ten days, followed by two additional treatment cycles with 10 mL per day for 10 days) in addition to usual care. The meta-analysis comprises the primary ensembles of efficacy criteria for 90, 30, and 10 days after TBI with a priori ordered hypotheses based on multivariate, directional tests. RESULTS: A total 185 patients underwent meta-analysis (mean admission GCS = 10.3, mean age = 45.3, and mean Baseline Prognostic Risk Score = 2.8). The primary endpoint, a multidimensional ensemble of functional and neuropsychological outcome scales indicated a "small-to-medium" sized effect in favor of Cerebrolysin, statistically significant at Day 30 and at Day 90 (Day 30: MWcombined = 0.60, 95%CI 0.52 to 0.66, p = 0.0156; SMD = 0.31; OR = 1.69; Day 90: MWcombined = 0.60, 95%CI 0.52 to 0.68, p = 0.0146; SMD = 0.34, OR = 1.77). Treatment groups showed comparable safety and tolerability profiles. DISCUSSION: The meta-analysis of the CAPTAIN trials confirms the safety and efficacy of Cerebrolysin after moderate-severe TBI, opening a new horizon for neurorecovery in this field. Integration of Cerebrolysin into existing guidelines should be considered after careful review of internationally applicable criteria.

Efficacy and safety of cerebrolysin in neurorecovery after moderate-severe traumatic brain injury: results from the CAPTAIN II trial.

INTRODUCTION: The objective of this trial was to evaluate the efficacy and safety of Cerebrolysin in treating patients after moderate to severe traumatic brain injury (TBI) as an adjunct to standard care protocols. The trial was designed to investigate the clinical effects of Cerebrolysin in the acute (neuroprotective) stage and during early and long-term recovery as part of a neurorestorative strategy. MATERIALS AND METHODS: The study was a phase IIIb/IV single-center, prospective, randomized, double-blind, placebo-controlled clinical trial. Eligible patients with a Glasgow Coma Score (GCS) between 7 and 12 received study medication (50 ml of Cerebrolysin or physiological saline solution per day for 10 days, followed by two additional treatment cycles with 10 ml per day for 10 days) in addition to standard care. We tested ensembles of efficacy criteria for 90, 30, and 10 days after TBI with a priori ordered hypotheses using a multivariate, directional test, to reflect the global status of patients after TBI. RESULTS: The study enrolled 142 patients, of which 139 underwent formal analysis (mean age = 47.4, mean admission GCS = 10.4, and mean Baseline Prognostic Risk Score = 2.6). The primary endpoint, a multidimensional ensemble of 13 outcome scales, indicated a "small-to-medium"-sized effect in favor of Cerebrolysin, statistically significant at day 90 (MWcombined = 0.59, 95% CI 0.52 to 0.66, P = 0.0119). Safety and tolerability observations were comparable between treatment groups. CONCLUSION: Our trial confirms previous beneficial effects of the multimodal, biological agent Cerebrolysin for overall outcome after moderate to severe TBI, as measured by a multidimensional approach. Study findings must be appraised and aggregated in conjunction with existing literature, as to improve the overall level of insight regarding therapeutic options for TBI patients. The widely used pharmacologic intervention may benefit from a large-scale observational study to map its use and to establish comparative effectiveness in real-world clinical settings.

Proteomic Advances in Glial Tumors through Mass Spectrometry Approaches.

Being the fourth leading cause of cancer-related death, glial tumors are highly diverse tumor entities characterized by important heterogeneity regarding tumor malignancy and prognosis. However, despite the identification of important alterations in the genome of the glial tumors, there remains a gap in understanding the mechanisms involved in glioma malignancy. Previous research focused on decoding the genomic alterations in these tumors, but due to intricate cellular mechanisms, the genomic findings do not correlate with the functional proteins expressed at the cellular level. The development of mass spectrometry (MS) based proteomics allowed researchers to study proteins expressed at the cellular level or in serum that may provide new insights on the proteins involved in the proliferation, invasiveness, metastasis and resistance to therapy in glial tumors. The integration of data provided by genomic and proteomic approaches into clinical practice could allow for the identification of new predictive, diagnostic and prognostic biomarkers that will improve the clinical management of patients with glial tumors. This paper aims to provide an updated review of the recent proteomic findings, possible clinical applications, and future research perspectives in diffuse astrocytic and oligodendroglial tumors, pilocytic astrocytomas, and ependymomas.

In vivo cell-cycle profiling in xenograft tumors by quantitative intravital microscopy.

Quantification of cell-cycle state at a single-cell level is essential to understand fundamental three-dimensional (3D) biological processes such as tissue development and cancer. Analysis of 3D in vivo images, however, is very challenging. Today's best practice, manual annotation of select image events, generates arbitrarily sampled data distributions, which are unsuitable for reliable mechanistic inferences. Here, we present an integrated workflow for quantitative in vivo cell-cycle profiling. It combines image analysis and machine learning methods for automated 3D segmentation and cell-cycle state identification of individual cell-nuclei with widely varying morphologies embedded in complex tumor environments. We applied our workflow to quantify cell-cycle effects of three antimitotic cancer drugs over 8 d in HT-1080 fibrosarcoma xenografts in living mice using a data set of 38,000 cells and compared the induced phenotypes. In contrast to results with 2D culture, observed mitotic arrest was relatively low, suggesting involvement of additional mechanisms in their antitumor effect in vivo.

Alterations in expression levels of deafness dystonia protein 1 affect mitochondrial morphology.

Deafness-Dystonia-Optic Neuropathy (DDON) Syndrome is a rare X-linked progressive neurodegenerative disorder resulting from mutations in the TIMM8A gene encoding for the deafness dystonia protein 1 (DDP1). Despite important progress in identifying and characterizing novel mutations in this gene, little is known about the underlying pathomechanisms. Deficiencies in the biogenesis of hTim23 and consecutive alterations in biogenesis of inner membrane and matrix proteins have been proposed to serve as one possible mechanistic explanation. To shed new light on the role of DDP1 in the biogenesis of mammalian mitochondria, we investigated the effects of reduced or elevated DDP1 levels on mitochondrial dynamics and function. Our results show a reduction in the import of ß-barrel proteins into mitochondria from cells overexpressing DDP1. This effect was not observed when the DDON-related mutant form DDP1-C66W was overexpressed. Live cell microscopy of primary fibroblasts derived from DDON patients and of DDP1 downregulated HeLa cells displayed alterations of mitochondrial morphology with notable extensions in the length of mitochondrial tubules, whereas overexpression of DDP1 induced the formation of hollow spherical mitochondria. Of note, knockdown of the TIMM8A gene by RNA interference did not show an influence on the oxygen respiration rate and the mitochondrial membrane potential. Taken together, these results suggest that alterations in the levels of DDP1 can affect the morphology of mitochondria and thus shed new light on the pathogenic mechanisms of DDON.

Robust detection of clinically relevant features in single-cell RNA profiles of patient-matched fresh and formalin-fixed paraffin-embedded (FFPE) lung cancer tissue.

PURPOSE: Single-cell transcriptional profiling reveals cell heterogeneity and clinically relevant traits in intra-operatively collected patient-derived tissue. So far, single-cell studies have been constrained by the requirement for prospectively collected fresh or cryopreserved tissue. This limitation might be overcome by recent technical developments enabling single-cell analysis of FFPE tissue. METHODS: We benchmark single-cell profiles from patient-matched fresh, cryopreserved and archival FFPE cancer tissue. RESULTS: We find that fresh tissue and FFPE routine blocks can be employed for the robust detection of clinically relevant traits on the single-cell level. Specifically, single-cell maps of fresh patient tissues and corresponding FFPE tissue blocks could be integrated into common low-dimensional representations, and cell subtype clusters showed highly correlated transcriptional strengths of signaling pathway, hallmark, and clinically useful signatures, although expression of single genes varied due to technological differences. FFPE tissue blocks revealed higher cell diversity compared to fresh tissue. In contrast, single-cell profiling of cryopreserved tissue was prone to artifacts in the clinical setting. CONCLUSION: Our analysis highlights the potential of single-cell profiling in the analysis of retrospectively and prospectively collected archival pathology cohorts and increases the applicability in translational research.

Towards a roadmap in brain protection and recovery.

This article briefly reviews some of the mechanisms involved in the pathogenesis of neurological diseases, i.e. damage mechanisms (DM), and their interactions and overlap with protection and reparatory processes (i.e. endogenous defence activities). A relationship between DM and endogenous defence activity (EDA) regarding therapy principles will also be described. Currently, it is difficult to find the correct therapeutic approach for brain protection and recovery, especially because we do not fully understand all of the endogenous neurobiological processes, the complete nature of the pathophysiological mechanisms and the links between these two categories. Moreover, we continue to use a simplistic and reductionist approach in this respect. Endogenous neurobiological processes, such as neurotrophicity, neuroprotection, neuroplasticity and neurogenesis, are central to protection and recovery and represent the background of EDA. The biological reality of the nervous system is far more complex. In fact, there is an endogenous holistic process of neuroprotection and neurorecovery that should be approached therapeutically in an integrated way. The current tendency to exclusively frame drug activity in terms of single mechanisms and single focus effect might distract from other paradigms with greater explanatory power and hinder the development of more effective treatment strategies. A change of concept is required in pharmacological brain protection and recovery. Prospective considerations include an integrated pharmacological approach, focusing on drugs with multimodal activity and pleiotropic neuroprotective effect which are biological drugs, rather than single mechanism drugs, which usually are chemical drugs.

Histone H3 clipping is a novel signature of human neutrophil extracellular traps.

Neutrophils are critical to host defence, executing diverse strategies to perform their antimicrobial and regulatory functions. One tactic is the production of neutrophil extracellular traps (NETs). In response to certain stimuli, neutrophils decondense their lobulated nucleus and release chromatin into the extracellular space through a process called NETosis. However, NETosis, and the subsequent degradation of NETs, can become dysregulated. NETs are proposed to play a role in infectious as well as many non-infection related diseases including cancer, thrombosis, autoimmunity and neurological disease. Consequently, there is a need to develop specific tools for the study of these structures in disease contexts. In this study, we identified a NET-specific histone H3 cleavage event and harnessed this to develop a cleavage site-specific antibody for the detection of human NETs. By microscopy, this antibody distinguishes NETs from chromatin in purified and mixed cell samples. It also detects NETs in tissue sections. We propose this antibody as a new tool to detect and quantify NETs.

Crowds and power - coordinated in vitro development of a benign breast lesion.

We have discovered an organoid culture approach that recapitulates morphology and coordinated development of a benign breast tumor. This system may be useful to groups investigating normal mammary gland biology and coordination of collective cell behavior in the mammary gland.

High dose vs low dose irradiation of the subventricular zone in patients with glioblastoma-a systematic review and meta-analysis.

PURPOSE: The published data indicate that the irradiation of the subventricular zone (SVZ) might play a role in the treatment of patients with glioblastoma (GBM). We aimed to determine whether radiation treatment doses (high vs low) applied to the SVZ can lead to an increase in progression free survival (PFS) and overall survival (OS). PATIENTS AND METHODS: We undertook a systematic review and meta-analysis according to the PICOS research criteria of patients with glioblastoma which received high doses compared to low doses in order to determine if they have a better survival in observational and experimental studies. RESULTS: Our survey of the literature yielded 2573 unique records. After screening, 17 were assessed for eligibility, and in the end 8 were included in the qualitative and 4 in the quantitative analysis. Subjects who received higher doses of ipsilateral SVZ (iSVZ) irradiation had a statistically significant better PFS than those receiving lower doses (HR 0.58 [95% CI 0.42-0.82], p=0.002). Subjects receiving higher doses of contralateral SVZ (cSVZ) irradiation did not have a statistically significant better PFS than those receiving lower doses (HR =0.89 [95% CI 0.35-2.26], p=0.81). Also for OS the subjects receiving higher doses to the iSVZ did not have a statistically significant better survival than those receiving lower doses (HR =0.75 [95% CI 0.51-1.11], p=0.15). CONCLUSION: The data indicate a possible involvement of the SVZ in the onset and progression of the GBM, as well as a possible role of the SVZ in radiation therapy.

The role of p-Stat3 Y705 immunohistochemistry in glioblastoma prognosis.

BACKGROUND: In spite of the multimodal treatment used today, glioblastoma is still the most aggressive and lethal cerebral tumour. To increase survival in these patients, novel therapeutic targets must be discovered. Signal transducer and activator of transcription 3 (Stat3), a transcription factor that controls normal cell differentiation and survival is also involved in neoplastic celltransformation. In this study we evaluated the immunohistochemical expression of pY705-Stat3 in patients with primary glioblastoma and determined its prognostic role by correlating it with survival. METHODS: This retrospective study included 94 patients diagnosed with glioblastoma. We determined the localization, number of positive cells, and marker intensity for pY705-Stat3 in these patients with the use of immunohistochemistry. The prognostic role was determined by correlating pY705-Stat3 expression on formalin-fixed paraffin-embedded tumour tissues with the patient's survival in univariate and multivariate COX regressions. RESULTS: We found a statistically significant difference in survival between the patients with more than 20% pY705-Stat3 positive cells and those with less than 20% pY705-Stat3 positive cells (8.9 months median survival versus 13.7 months medial survival, p <  0.001). On multivariate analyses with the COX proportional hazards regression model including pY705-Stat3 expression, age and relapse status, pY705-Stat3 status was an independent prognostic factor in glioblastoma (P <  0.001). CONCLUSION: The results obtained show that the immunohistochemical expression of pY705-Stat3 correlates with survival in glioblastoma. This study identifies Stat3 as a possible target for existing or new developed Stat3 inhibitors.

Effects of the CD33-targeted drug gemtuzumab ozogamicin (Mylotarg) on growth and mediator secretion in human mast cells and blood basophils.

OBJECTIVE: Mylotarg (gemtuzumab ozogamicin [GO]) has recently been introduced as a novel CD33-targeting drug in clinical hematology. However, despite efficacy, GO produces significant side effects including an infusion syndrome. We have recently shown that mast cells (MCs) and basophils (BAs) express CD33. In the present study, we investigated the effects of GO on growth and mediator secretion in MCs and BAs. METHODS: Growth-inhibitory effects of GO on neoplastic MCs (HMC-1) and BAs (KU812) as well as cord blood-derived MC and BA progenitor cells were determined by counting cell numbers and the numbers of apoptotic cells. The amount of histamine secreted from primary MCs and BAs was measured by radioimmunoassay after incubation of cells with GO alone or GO together with an anti-immunoglobulin E (IgE) antibody. RESULTS: MCs and BAs as well as HMC-1 cells and KU812 cells were found to express CD33 mRNA and the CD33 protein. GO was found to inhibit the growth of HMC-1 cells and KU812 cells as well as stem cell factor-dependent differentiation of MCs and interleukin-3-induced growth of BAs from their cord blood-derived progenitors. The GO-induced inhibition of growth of neoplastic cells was found to be associated with induction of apoptosis. GO neither induced secretion of histamine from MCs or BAs nor upregulated the anti-IgE-induced release of histamine in these cells. CONCLUSIONS: GO counteracts growth of normal and neoplastic MCs and BAs without inducing rapid release of histamine. The exact value of GO as a targeted drug for the treatment of high-grade MC or BA neoplasms remains to be determined.

Detection of vascular endothelial growth factor (VEGF) and VEGF receptors Flt-1 and KDR in canine mastocytoma cells.

Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis and a potential autocrine growth factor for neoplastic cells in various malignancies. In the present study, we have investigated expression of VEGF and VEGF receptors in canine mastocytomas and the canine mastocytoma cell line C2. As assessed by immunostaining of tissue sections and cytospin slides, primary neoplastic mast cells (MC) and C2 cells were found to express the VEGF protein. In Northern blot and RT-PCR experiments, C2 cells expressed VEGF mRNA in a constitutive manner. VEGF mRNA expression in C2 cells was counteracted by LY294002 and rapamycin, suggesting involvement of the PI3-kinase/mTOR pathway. Moreover, C2 cells were found to express VEGF receptor-1 (Flt-1) and VEGF receptor-2 (KDR). However, recombinant VEGF failed to promote (3)H-thymidine uptake in C2 cells, and a neutralizing anti-VEGF antibody (bevacizumab) failed to downregulate spontaneous proliferation in these cells. In addition, rapamycin decreased the expression of VEGF in C2 cells at the mRNA and protein level without suppressing their proliferation. Together, canine mastocytoma cells express VEGF as well as VEGF receptors. However, despite co-expression of VEGF and its receptors, VEGF is not utilized as an autocrine growth regulator by canine mastocytoma cells.

Systemic mastocytosis (SM) associated with chronic eosinophilic leukemia (SM-CEL): detection of FIP1L1/PDGFRalpha, classification by WHO criteria, and response to therapy with imatinib.

Based on generally accepted criteria and the WHO-classification, a subset of patients with systemic mastocytosis (SM) have (or develop) an associated clonal hematologic non-mast cell lineage disease (SM-AHNMD). We describe a case of SM with coexisting chronic eosinophilic leukemia (SM-CEL). The patient, a 51-year-old male, was first seen in 1992 with small-sized infiltrates of spindle-shaped mast cells in his marrow, and marked eosinophilia. Retrospectively, a CHIC2 deletion and the FIP1L1/PDGFRalpha fusion gene-product were demonstrable by FISH analysis and RT-PCR, respectively. SM-associated organopathy or mediator-related symptoms were not recorded. However, the patient developed cardiomyopathy. Therapy with interferon-alpha, hydroxyurea, and corticosteroids were without effects. By contrast, therapy with imatinib was followed by a fast and sustained response with complete and stable regression of eosinophilia, drop in eosinophil cationic protein, and decrease of serum tryptase to normal levels. This case provides further evidence for the potential of co-existence of SM with a primary eosinophilic disorder (CEL) defined by the FIP1L1/PDGFRalpha fusion gene. Because of the availability of a superior targeted drug (imatinib), it is of importance to screen for FIP1L1/PDGFRalpha in suspected CEL with or without co-existing SM.

Identification of mTOR as a novel bifunctional target in chronic myeloid leukemia: dissection of growth-inhibitory and VEGF-suppressive effects of rapamycin in leukemic cells.

The mammalian target of rapamycin (mTOR) has recently been described to be constitutively activated in Bcr-Abl-transformed cells and to mediate rapamycin-induced inhibition of growth in respective cell lines. We have recently shown that rapamycin down-regulates expression of vascular endothelial growth factor (VEGF), a mediator of leukemia-associated angiogenesis, in primary CML cells. In the present study, we analyzed growth-inhibitory in vitro and in vivo effects of rapamycin on primary CML cells and asked whether rapamycin-induced suppression of VEGF in leukemic cells is related to growth inhibition. Rapamycin dose dependently inhibited growth of primary CML cells obtained from patients with imatinib-responsive or imatinib-resistant disease as well as growth of Bcr-Abl-transformed imatinib-resistant cell lines. Moreover, we observed potent cytoreductive effects of rapamycin in a patient with imatinib-resistant Bcr-Abl+ leukemia. The growth-inhibitory effects of rapamycin on CML cells were found to be associated with G1 cell cycle arrest and with induction of apoptosis. In all cell types tested, rapamycin was found to down-regulate expression of VEGF. However, exogenously added VEGF did not counteract the rapamycin-induced decrease in proliferation. In conclusion, rapamycin inhibits growth of CML cells in vitro and in vivo and, in addition, down-regulates expression of VEGF. Both effects may contribute to the antileukemic activity of the drug in CML.

Detection of molecular targets on the surface of CD34+/CD38-- stem cells in various myeloid malignancies.

Recent data suggest that myeloid neoplasms are organized hierarchically in terms of self-renewal and maturation of early progenitor cells, similar to normal myelopoiesis. In acute myeloid leukemia (AML), the NOD/SCID mouse-repopulating leukemic stem cells usually co-express CD123 with CD34, but lack CD38. So far, however, little is known about expression of other markers and targets on these progenitors. In the present study, expression of target antigens on CD34+/CD38- cells was analysed by multi-color flow cytometry in patients with AML (n = 18), myelodysplastic syndromes (MDS, n = 6), chronic myeloid leukemia (CML, n = 8) and systemic mastocytosis (SM, n = 9). The IL-3Ralpha chain (CD123) was found to be expressed on CD34+/CD38- cells in a majority of the patients in all disease categories. Independent of the type of disease, the vast majority of these stem cells co-expressed aminopeptidase-N (CD13) and CD44 in all patients. By contrast, the CD34+/CD38- progenitor cells expressed variable amounts of the target receptor CD33, c-kit (CD117) and AC133 (CD133). In conclusion, neoplastic stem cells in various myeloid neoplasms appear to express a similar phenotype including target antigens such as CD13, CD33 and CD44. Since many of these targets are not expressed on all stem cells in all patients, the elimination of the entire clone may require combinations of targeted antibodies or use of additional drugs.

Evaluation of biologic activity of tryptase secreted from blast cells in acute myeloid leukemia.

A number of autocrine and paracrine growth regulators are considered to be involved in the survival and proliferation of blast cells in acute myeloid leukemia (AML). We have recently shown that blast cells in a group of patients with AML produce and secrete the mitogenic enzyme tryptase. In the present study, we examined functional effects of tryptase in the context of AML. As assessed by 3H-thymidine uptake experiments, tryptase-containing serum from patients with AML as well as heparin-complexed recombinant tryptase were found to promote the proliferation of cultured bone marrow- and lung fibroblasts in a dose-dependent manner. A neutralizing antibody against human beta-tryptase was found to diminish these growth-stimulatory effects of serum-tryptase in all patients examined. Tryptase also induced the expression of mRNA for GM-CSF and SCF, two cytokines known to promote growth of AML cells, in cultured bone marrow fibroblasts. Neither recombinant tryptase nor tryptase-rich serum of AML patients, showed an effect on the growth of leukemic blast cells irrespective of the FAB category or expression of protease-activated receptor (PAR)-2, a putative molecular target of tryptase. Together, tryptase is secreted from AML blasts as a biologically active molecule that may exhibit paracrine rather than autocrine effects in AML.