Martin Erdel

Dendritic cells generated from blood precursors of chronic myelogenous leukemia patients carry the Philadelphia translocation and can induce a CML-specific primary cytotoxic T-cell response.

Dendritic cells (DC) are professional antigen‐presenting cells specialized in the initiation of primary immune responses. We were interested to know whether mature DC can be grown in vitro from peripheral blood mononuclear cells (PBMC) of patients with chronic myelogenous leukemia (CML), and whether they carry the Philadelphia (Ph) translocation. Using a method recently described, DC were generated from PBMC precursors of 12 patients with CML using GM‐CSF, IL‐4, and monocyte‐conditioned medium. DC exhibited the typical morphology with thin cytoplasmatic processes and expressed high levels of MHC class II, CD86, and CD83 typical for mature DC. After sorting with the monoclonal antibody CD83, a cell population of more than 95% CD83 positive cells was obtained. The presence of the Ph translocation was analyzed in these cells, in PBMC, lymphoblastoid cell lines (LCL), and in phytohemagglutinin (PHA)‐induced T blasts from the same patients by fluorescence in situ hybridization (FISH). In contrast to all other cells analyzed, the vast majority of DC (95.9 ± 0.7%) displayed the Ph translocation, irrespective of disease stage or therapy. PBMC were predominantly positive for the Ph chromosome (67.6 ± 7.3%), whereas only 11.4 ± 1% of the B cells and 4.4 ± 1.1% of the PHA blasts carried the Ph translocation. Using such leukemic DC as antigen‐presenting cells, a primary CML‐directed cytotoxic immune response in vitro was obtained, as shown by the specific recognition of Ph chromosome positive cells. We conclude that DC can be generated from blood progenitors of CML patients in vitro and exhibit, to a large extent, the Ph translocation. Such DC, which in a preliminary experiment have been able to induce a primary CML‐directed cytotoxic immune response in vitro, might be ideal candidates for adoptive immunotherapy either by direct transfer of DC for in vivo generation of a T‐cell response or by in vitro generation of CML‐specific cytotoxic autologous or HLA‐matched normal T‐cell clones for use in vivo. Genes Chromosomes Cancer 20:215–223, 1997.

Critical role of scavenger receptor-BI-expressing bone marrow-derived endothelial progenitor cells in the attenuation of allograft vasculopathy after human apo A-I transfer.

Allograft vasculopathy is the leading cause of death in patients with heart transplantation. Accelerated endothelial regeneration mediated by enhanced endothelial progenitor cell (EPC) incorporation may attenuate the development of allograft vasculopathy. We investigated the hypothesis that modulation of EPC biology and attenuation of allograft vasculopathy by increased high-density lipoprotein cholesterol after human apo A-I (AdA-I) transfer requires scavenger receptor (SR)-BI expression in bone marrow-derived EPCs. After AdA-I transfer, the number of circulating EPCs increased 2.0-fold (P < .001) at different time points in C57BL/6 mice transplanted with SR-BI(+/+) bone marrow but remained unaltered in mice with SR-BI(-/-) bone marrow. The effect of high-density lipoprotein on EPC migration in vitro requires signaling via SR-BI and extracellular signal-regulated kinases and is dependent on increased nitric oxide (NO) production in EPCs. Human apo A-I transfer 2 weeks before paratopic artery transplantation reduced intimal area at day 21 3.7-fold (P < .001) in mice with SR-BI(+/+) bone marrow but had no effect in mice with SR-BI(-/-) bone marrow. AdA-I transfer potently stimulated EPC incorporation and accelerated endothelial regeneration in chimeric SR-BI(+/+) mice but not in chimeric SR-BI(-/-) mice. In conclusion, human apo A-I transfer accelerates endothelial regeneration mediated via SR-BI expressing bone marrow-derived EPCs, thereby preventing allograft vasculopathy.

Fluorescence In Situ Hybridization (FISH) on Peripheral Blood Smears for Monitoring Philadelphia Chromosome-Positive Chronic Myeloid Leukemia (CML) During Interferon Treatment: A New Strategy for Remission Assessment

Interferon‐α (IFN‐α) alone or in combination with cytostatic drugs can induce major and durable cytogenetic responses in about 20 to 25% of chronic myeloid leukemia (CML) patients. Since these patients have a significant survival benefit, more frequent follow‐up investigations have become clinically important but require bone marrow (BM) aspirates. The aim of our study was to evaluate interphase fluorescence in situ hybridization (IPF) on peripheral blood (PB) smears as a rapid and reliable method to quantify Ph‐positive myeloid cells. IPF analysis was performed on 49 PB samples from 36 patients in the chronic phase of CML and at different stages of cytogenetic remission. IPF results of 30 PB samples were compared with those from BM aspirates simultaneously obtained from the same patients to evaluate the correlation of Ph‐positive cells. Further, the hypermetaphase FISH (HMF) technique was performed on cultured BM preparations of 31 patients for comparison with IPF results on PB. An excellent correlation was observed between the IPF results obtained on PB and BM samples (r = 0.98, y = x − 0.6, p < 0.0001). The mean difference between HMF from BM, on the one hand, and IPF from PB, on the other hand, was 3.2% (SD = ± 8.4%). Seventy percent of samples were identically classified in one of the four subgroups of cytogenetic response. Thirty percent were classified in neighbouring response groups. We conclude that FISH performed on PB is a rapid and reliable method for assessing the cytogenetic response of CML patients on IFN‐α based therapies, allowing more frequent and less invasive follow‐up investigations although it is not able entirely to replace routine analysis of BM. Genes Chromosomes Cancer 21:90–100, 1998.

Glucocorticoid resistance in two key models of acute lymphoblastic leukemia occurs at the level of the glucocorticoid receptor

Glucocorticoids (GCs) specifically induce apoptosis in malignant lymphoblasts and are thus pivotal in the treatment of acute lymphoblastic leukemia (ALL). However, GC‐resistance is a therapeutic problem with an unclear molecular mechanism. We generated ~70 GC‐resistant sublines from a GC‐sensitive B‐ and a T‐ALL cell line and investigated their mechanisms of resistance. In response to GCs, all GC‐resistant subclones analyzed by real‐time polymerase chain reaction (PCR) showed a deficient up‐regulation of the GC‐receptor (GR) and its downstream target, GC‐induced leucine zipper. This deficiency in GR up‐regulation was confirmed by Western blotting and on retroviral overexpression of GR in resistant subclones GC‐sensitivity was restored. All GC‐resistant subclones were screened for GR mutations using denaturing high‐pressure liquid chromatography (DHPLC), DNA‐fingerprinting, and fluorescence in situ hybridization (FISH). Among the identified mutations were some previously not associated with GC resistance: A484D, P515H, L756N, Y663H, L680P, and R714W. This approach revealed three genotypes, complete loss of functional GR in the mismatch repair deficient T‐ALL model, apparently normal GR genes in B‐ALLs, and heterozygosity in both. In the first genotype, deficiency in GR up‐regulation was fully explained by mutational events, in the second by a putative regulatory defect, and in the third by a combination thereof. In all instances, GC‐resistance occurred at the level of the GR in both models.—Schmidt, S., Irving, J. A. E., Minto, L., Matheson, E., Nicholson, L., Ploner, A., Parson, W., Kofler, A., Amort, M., Erdel, M., Hall, A., Kofler, R. Glucocorticoid resistance in two key models of acute lymphoblastic leukemia occurs at the level of the glucocorticoid receptor. FASEB J. 20, E2087–E2097 (2006)

Cyclin E dysregulation and chromosomal instability in endometrial cancer.

Deregulation of cyclin E, an activator of cyclin-dependent kinase 2 (Cdk2), has been associated with a broad spectrum of human malignancies. Yet the mechanism linking abnormal cyclin E expression to carcinogenesis is largely unknown. The gene encoding the F-box protein hCdc4, a key component of the molecular machinery that targets cyclin E for degradation, is frequently mutated in endometrial cancer, leading to deregulation of cyclin E expression. Here we show that hCDC4 gene mutation and hyperphosphorylation of cyclin E, a parameter that usually correlates with hCDC4 mutation, have a strong statistically significant association with polypoidy and aneuploidy in endometrial cancer. On the contrary, elevated expression of cyclin E by itself was not significantly correlated with polyploidy or aneuploidy when tumors of similar grade are evaluated. These data suggest that impairment of cell cycle regulated proteolysis of cyclin E may be linked to carcinogenesis by promoting genomic instability.

Molecular genetics and structural genomics of the human protein kinase C gene module

BackgroundProtein kinase C (PKC) has become a major focus among cell biologists interested in second-messenger signal transduction and much has been learned about differences in the cellular localization and function of its different isotypes. In this study we systematically address the genomic locations and gene structures of the human PKC gene module.ResultsWe first carried out fine chromosomal mapping of all nine PKC genes by fluorescence in situ hybridization (FISH), using cosmid and BAC probes. The PKC genes are found to be dispersed throughout the genome, and in some positions distinct from those previously reported: PKCα is at 17q24, PKCβ at 16p12, PKCγ at 19q13.4, PKCδ at 3p21.2, PKCε at 2p21, PKCζ at 1p36.3, PKCη at 14q22-23, PKCθ at 10p15 and PKCι at 3q26. For PKCι, an additional FISH signal mapped on Xq21.3 revealed a pseudogene (derived by retrotransposition). PKCγ, ζ, and θ are found to map to the most distal positions on the chromosomes, potentially implicating telomere position effects in their expression. Using the complete human genome draft sequence and bioinformatics tools, we then carried out a systematic analysis of PKC gene structure, including determination of the occurrence of single-nucleotide polymorphisms corresponding to the PKC loci.ConclusionThis resource of genomic information now facilitates investigation of the PKC gene module in structural chromosomal abnormalities and human disease locus mapping studies.

Regulation of transcription factor E2F3a and its clinical relevance in ovarian cancer

Recently we showed an integral epidermal growth factor receptor (EGFR)–E2F3a signaling path, in which E2F3a was found to be essential in EGFR-mediated proliferation in ovarian cancer cells. The present work evaluates the clinical relevance of this novel axis and of E2F3a itself in a large set of 130 ovarian cancer specimens. For this purpose E2F3a and its counterpart, E2F3b, were measured by RT–PCR and activated EGFR was assessed by immunohistochemistry. When compared with healthy control tissue, both E2F3 isoforms were overexpressed in the cancers, but only E2F3a expression correlated with tumor stage (ρ=0.349, P=0.0001) and residual disease (ρ=0.254, P=0.004). Univariate survival analyses showed E2F3a and activated EGFR to be associated with poor PFS and OS. Furthermore, a strong, positive correlation between activated EGFR and E2F3a expression was shown (P=0.0001). We further identified two EGFR-independent mechanisms that regulate E2F3a expression, namely one, acting by promoter methylation of miR-34a, which by its physical interaction with E2F3a transcripts causes their degradation, and the second based on 6p22 gene locus amplification. MiRIDIAN-based knockdown and induction of miR-34a evidenced a direct regulatory link between miR-34a and E2F3a, and the tumor-suppressive character of miR-34a was documented by its association with improved survival. Although, 6p22 gene locus amplification was detected in a significant number of ovarian cancer specimens, 6p22 ploidy was not relevant in predicting survival. In Cox regression analysis, E2F3a, but not activated EGFR or miR-34a expression, retained independent prognostic significance (PFS: hazards ratio 3.785 (1.326–9.840), P=0.013; OS: hazards ratio 4.651 (1.189–15.572), P=0.013). These clinical findings highlight the relevance of E2F3a in the biology of ovarian cancer. Moreover, identification of EGFR-independent mechanisms in E2F3a control can be helpful in explaining the non-responsiveness of therapeutic EGFR targeting in ovarian cancer.

Pre- and postnatal findings in trisomy 17 mosaicism†‡

Trisomy 17 mosaicism is one of the rarest autosomal trisomies in humans. Thus far, only 23 cases have been described, most of them detected prenatally. In only five instances has mosaicism been demonstrated in lymphocytes and/or fibroblasts postnatally, and only in these have multiple congenital anomalies (MCA), facial dysmorphisms, and mental retardation been reported. Patients with trisomy 17 mosaicism at amniocentesis and a normal karyotype in blood and fibroblasts (n = 17) were always healthy. Here, we report on pre‐ and postnatal clinical, cytogenetic, molecular‐cytogenetic, and molecular findings in four patients with trisomy 17 mosaicism. The first case was detected in cultured but not in short‐term chorionic villi and amniocytes. Due to MCA on prenatal ultrasound examination the pregnancy was terminated. The second patient is a 13‐month‐old healthy boy, in whom low level trisomy 17 mosaicism was detected in cultured chorionic villi only. The third patient is a 2‐year‐old girl with growth retardation, developmental delay, MCA, and trisomy 17 mosaicism in amniocytes, fibroblasts, and placenta, but not in blood and buccal smear. The fourth patient is a 9‐year‐old boy with growth and mental retardation, sensoneurinal hearing loss, and MCA. Cytogenetic analyses showed trisomy 17 mosaicism in amniocytes, skin fibroblasts, and urinary sediment cells, whereas in blood and buccal smear a 46,XY karyotype was found. Molecular investigations in all four cases indicated biparental inheritance of chromosome 17. Formation of trisomy was most likely due to a maternal meiosis I error in Patient 1 and a postzygotic non‐disjunction of the paternal chromosome 17 in Patient 4. Cerebellar malformations, reported in two cases from the literature and in two reported here may be a specific feature of trisomy 17 mosaicism. Since the aberration has rarely been reported in lymphocytes, chordocentesis is not indicated in prenatal diagnosis. Prenatal genetic counseling for trisomy 17 mosaicism in chorionic villi or amniocytes should consider that the clinical significance remains uncertain.

The elastin gene is disrupted in a family with a balanced translocation t(7;16)(q11.23;q13) associated with a variable expression of the Williams-Beuren syndrome

The Williams-Beuren syndrome (WBS) is a complex developmental disorder with multisystemic manifestations including supravalvular aortic stenosis (SVAS), a so-called elfin face, a hoarse voice, and a specific cognitive phenotype. Most WBS patients have a >1 Mb deletion on one of their chromosomes 7 in q11 but except for elastin, whose haploinsufficiency causes the cardiovascular malformations, it is unknown which genes in the deletion area contribute to the phenotype. We have investigated a family with a cytogenetically balanced translocation t(7;16)(q11.23;q13) in which affected individuals manifested a broad spectrum of clinical phenotypes ranging from a hoarse voice as the only feature to the full WBS phenotype. Molecular cytogenetic and DNA sequence analyses of the translocation breakpoint showed that the cytogenetic rearrangement disrupts the elastin gene locus within intron 5 in the exact same manner in all translocation carriers. The recently described large inversion of the 7q11.23 region was not present in this family. Our data demonstrate that disruption of the elastin gene by a translocation breakpoint may cause classical WBS, atypical WBS, SVAS, or no recognisable phenotype, and provide a clear example for extensive phenotypic variability associated with a position effect in humans.

Mapping of the human protein kinase C-θ (PRKCQ) gene locus to the short arm of chromosome 10 (10p15) by FISH ☆

Members of the protein kinase C (PKC) family of serine/threonine kinases play critical roles in the regulation of cellular differentiation and proliferation of diverse cell types. In an attempt to find PKC isoforms that are involved in growth control and/or activation of T lymphocytes, we have used a human peripheral blood lymphocyte-derived cDNA library to identify a novel PKC isoform, termed PKC-{theta}. The human PKC-{theta} cDNA (human gene symbol PRKCQ) was characterized and found to encode an {approximately} 80-kDa protein, expressed predominantly in lymphoid tissues and hematopoietic cell lines, in particular T cells. A murine homolog gene derived from skin cDNA library was found to be expressed predominantly in skeletal muscle. Molecular cloning and biochemical studies identified PKC enzymes as members of a distinct family that constitutes, at the gene level, nine mammalian members, i.e., {alpha}, {beta}, {gamma}, {delta}, {epsilon}, {zeta}, {theta}, and {lambda}, of which three have already been assigned to individual human chromosomes. Thus, PKC-{alpha} was mapped to H17q22-q24, PKC-{Beta} to H16p12-q11.1, and PKC-{gamma} to H19q13.4. The chromosomal location of other members is yet unknown. 13 refs., 1 fig.