Parallel evaluation of cell­based phage display panning strategies: Optimized selection and depletion steps result in AML blast­binding consensus antibodies.

Phage display technology (PD) is a powerful technique for the generation of tumor­targeting antibodies. However, there are a number of different selection methods established in different laboratories around the world. Cell­based PD panning methods using primary tumor cells are particularly heterogeneous between laboratories, which can lead to inconsistent results. Therefore, the present study evaluated different cell­based PD selection methods regarding their potential to generate acute myeloid leukemia (AML) blast­binding antibodies. In addition to this evaluation, the present study improved the PD procedure by optimizing selection as well as depletion strategies. To the best of our knowledge, the current study demonstrated for the first time that antigen diversity during the depletion step is of importance for the enrichment of tumor­targeting phage antibodies. It is demonstrated that medium levels of depletion antigen diversity led to the most promising antibody candidates. In addition, it was determined that purification of blast cells from patients with AML by immunomagnetic separation ameliorated the selection of AML­binding phages during panning. Furthermore, suggesting a common design­related mechanism using a 'single­pot' PD library, such as the well­known Tomlinson single­chain fragment variable (scFv) library, the present study identified specific binding consensus phage particles in independent panning procedures. By means of these optimized strategies, four promising AML blast­binding phage particles were isolated and soluble scFv­Fc (scFv cloned to a fragment crystallizable of an IgG2a mouse antibody) fusion proteins were produced. These scFv­Fc antibodies bound the surface of AML blasts and were successfully internalized into their cytoplasm, indicating that they are potential immunoconjugate candidates for AML immunotherapy.

[Mucoepidermoidcarcinoma - Importance in molecular pathology]. / Das Mukoepidermoidkarzinom ­ Bedeutung der Molekularpathologie.

Mucoepidermoid carcinoma is the most common primary salivary gland malignancy and its tumor grading has an important prognostic significance. The 5 year overall survival rate is significantly higher for low grade mucoepidermoid carcinomas than for intermediate grade and high grade mucoepidermoid carcinomas. The translocation of t(11;19)(q21;p13) with the resulting CRTC1-MAML2 transfusion appears to be of prognostic relevance in patients with mucoepidermoid carcinoma. The translocation is detectable in 38-82 % of all mucoepidermoid carcinomas. Study results have shown a significantly better prognosis for patients with fusion-positive mucoepidermoid carcinomas than fusion-negative mucoepidermoid carcinomas. The t(11;19)(q21;p13) translocation can be found more often in low and intermediate grade mucoepidermoid carcinomas than in high grade tumors of the same entity. Moreover, fusion positive mucoepidermoid carcinoma were found more frequently in younger patients, smaller tumors, lower tumor stages and less frequently lymph node and distant metastases. Up to now, the translocation has not been of therapeutic importance. In selected cases, the lack of t(11;19)(q21;p13) translocation might facilitate the decision towards further escalation of therapy. More studies will be necessary to evaluate the individual prognostic and therapeutic value of CRTC1-MAML2 transfusion.

Genetic alterations in human papillomavirus-associated oropharyngeal squamous cell carcinoma of patients with treatment failure.

OBJECTIVES: Despite improved survival rates of patients with HPV-associated OPSCC, a subset has distant metastasis or develops local recurrence during follow-up. To investigate potential underlying genetic alterations, we analyzed patients with HPV-driven OPSCC who suffered from recurrence in comparison to matching pairs with successful tumor control. MATERIALS AND METHODS: We performed chromosomal copy number analyses and targeted next generation sequencing using a custom panel comprising genes that are frequently mutated in HPV-associated OPSCC. RESULTS: Specific differences regarding chromosomal aberrations were not observed between both groups. In HPV-driven OPSCC from patients with recurrence we found higher mutation rates compared to patients with successful tumor control. Especially mutation rates of HRAS (p ≤ 0.05) PIK3R1, STK11 and TP63 (p ≤ 0.1 each) were statistically significant or trending towards significance. The respective genes can be linked to transcription factors and signaling pathways involved in cell cycle regulation, proliferation and survival. Additionally, combinations of alterations were observed on chromosomes 16 and 19, which might also influence outcome. CONCLUSION: Patients with HPV-driven OPSCC who develop recurrence or have metastasis may be defined by genetic alterations that might be responsible for poor outcome after standard therapy. This might be of importance for stratification in future de-escalation and targeted therapy.

A recurrent activating PLCG1 mutation in cardiac angiosarcomas increases apoptosis resistance and invasiveness of endothelial cells.

Primary cardiac angiosarcomas are rare tumors with unfavorable prognosis. Pathogenic driver mutations are largely unknown. We therefore analyzed a collection of cases for genomic aberrations using SNP arrays and targeted next-generation sequencing (tNGS) of oncogenes and tumor-suppressor genes. Recurrent gains of chromosome 1q and a small region of chromosome 4 encompassing KDR and KIT were identified by SNP array analysis. Repeatedly mutated genes identified by tNGS were KDR with different nonsynonymous mutations, MLL2 with different nonsense mutations, and PLCG1 with a recurrent nonsynonymous mutation (R707Q) in the highly conserved autoinhibitory SH2 domain in three of 10 cases. PLCγ1 is usually activated by Y783 phosphorylation and activates protein kinase C and Ca(2+)-dependent second messengers, with effects on cellular proliferation, migration, and invasiveness. Ectopic expression of the PLCγ1-R707Q mutant in endothelial cells revealed reduced PLCγ1-Y783 phosphorylation with concomitant increased c-RAF/MEK/ERK1/2 phosphorylation, increased IP3 amounts, and increased Ca(2+)-dependent calcineurin activation compared with ectopic expressed PLCγ1-wild-type. Furthermore, cofilin, whose activation is associated with actin skeleton reorganization, showed decreased phosphorylation, and thus activation after expression of PLCγ1-R707Q compared with PLCγ1-wild-type. At the cellular level, expression of PLCγ1-R707Q in endothelial cells had no influence on proliferation rate, but increased apoptosis resistance and migration and invasiveness in in vitro assays. Together, these findings indicate that the PLCγ1-R707Q mutation causes constitutive activation of PLCγ1 and may represent an alternative way of activation of KDR/PLCγ1 signaling besides KDR activation in angiosarcomas, with implications for VEGF/KDR targeted therapies.

Detection of an activated JAK3 variant and a Xq26.3 microdeletion causing loss of PHF6 and miR-424 expression in myelodysplastic syndromes by combined targeted next generation sequencing and SNP array analysis.

Myelodysplastic syndromes (MDS) are hematopoietic disorders characterized by ineffective hematopoiesis and progression to acute leukemia. In patients ineligible for hematopoietic stem cell transplantation, azacitidine is the only treatment shown to prolong survival. However, with the availability of a growing compendium of cancer biomarkers and related drugs, analysis of relevant genetic alterations for individual MDS patients might become part of routine evaluation. Therefore and in order to cover the entire bone marrow microenvironment involved in the pathogenesis of MDS, SNP array analysis and targeted next generation sequencing (tNGS) for the mostly therapy relevant 46 onco- and tumor-suppressor genes were performed on bone marrow biopsies from 29 MDS patients. In addition to the detection of mutations known to be associated with MDS in NRAS, KRAS, MPL, NPM1, IDH1, PTPN11, APC and MET, single nucleotide variants so far unrelated to MDS in STK11 (n=1), KDR (n=3), ATM (n=1) and JAK3 (n=2) were identified. Moreover, a recurrent microdeletion was detected in Xq26.3 (n=2), causing loss of PHF6 expression, a potential tumor suppressor gene, and the miR-424, which is involved in the development of acute myeloid leukemia. Finally, combined genetic aberrations affecting the VEGF/VEGFR pathway were found in the majority of cases demonstrating the diversity of mutations affecting different nodes of a particular signaling network as an intrinsic feature in MDS patients. We conclude that combined SNP array analyses and tNGS can identify established and novel therapy relevant genomic aberrations in MDS patients and track them in a clinical setting for individual therapy selection.

Patient with three euchromatic supernumerary marker chromosomes derived from chromosomes 1, 12, and 18: characterization and evaluation of the aberrations.

The genetic relevance of small supernumerary marker chromosomes (sSMCs) depends on their content of euchromatin. In case of mosaicism, the phenotype of the carrier furthermore is influenced by the distribution of the marker in the body. In the majority of reported cases no correlation of the degree of mosaicism in the tissue(s) analyzed and the phenotype could be detected. In particular, non-acrocentric derived sSMCs show a strong tendency to appear in mosaic state irrespective of the clinical picture. We present a patient with cognitive disability and mild craniofacial dysmorphisms with mosaicism of three different autosomal marker chromosomes. The extra chromosomes were analyzed by a combination of SNP array and a variety of fluorescence in situ hybridization (FISH) probes. All three markers were identified as ring chromosomes containing different amounts of euchromatic material derived from chromosome 1 (1p12 → q21), 12 (12p13.1 → q13.11) and 18 (18p11.21 → q11.2). The size and the frequency of the sSMCs were strikingly different, besides, we observed an unequal combination of the three derivates.

Duplication 3q13.11q23: Longitudinal study in a patient over a period of more than 7 years and refinements of the breakpoints.

In 2006, we reported the first case with a pure duplication of proximal 3q. In these rare aberrations, detailed clinical and developmental investigations at different ages are required to provide sufficient phenotypic documentation. Clinical and psychological differences were therefore regularly documented in our case. Supplemental genetic investigations comprised conventional karyotyping, fluorescence in-situ hybridization, single nucleotide polymorphism array analysis, and microsatellite typing. Thus, the exact position and extension of the duplication (3q13.11q23), the size (35.6 Mb), and the paternal origin could be determined. The development of our patient was followed up in detail over a period of 7.5 yr and thus enabled specific characterization of the phenotype of the patient.

Rare interstitial deletion 9q31.2 to q33.1 de novo: longitudinal study in a patient over a period of more than 20 years.

The female carrier of a de novo interstitial deletion 9q [karyotype 46,XX,del(9)(q31.2q33.1)] was followed up over a period of more than 20 years. She shows facial dysmorphisms and significant growth retardation. Motor abilities are restricted by muscular hypotonia and malposition of the feet. She has mental retardation. There was no speech development and phases of autism were reported. By analyses with FISH and short tandem repeat markers, the interstitial deletion was confirmed and characterized to span 9q31.2q33.1, comprising at least 7.07 Mb. The aberration is of paternal origin.

First report of a partial trisomy 3q12-q23 de novo--FISH breakpoint determination and phenotypic characterization.

We present a 1-year-old boy with mild mental retardation, postnatal growth retardation, and facial dysmorphisms such as frontal bossing, laterally accentuated bushy eyebrows, deep set eyes with long lashes, hypertelorism, and a broad nasal bridge. Except for hip dysplasia, no congenital malformations were detected. By conventional cytogenetics a derivative chromosome 3 de novo was diagnosed which was identified as tandem dup(3)(q12q23) by fluorescence in situ hybridization (FISH) applying arm specific paints and eight different YAC-probes. The duplicated segment lies proximally from the reported dup(3q) syndrome critical region, thus explaining the absence of characteristic phenotypic features of dup(3q) syndrome. To our knowledge this is the first report of a patient with pure trisomy of this proximal region of the long arm of chromosome 3.

Mosaic tetrasomy 14pter-q13 due to a supernumerary isodicentric derivate of proximal chromosome 14q.

Tetrasomy of proximal 14q is an extremely rare condition and has never been reported to be associated with survival. We here report on the first case of mosaic tetrasomy of 14pter-q13 due to a de-novo supernumerary pseudoisodicentric chromosome in a 2-year-old boy with multiple dysmorphisms and malformations. The marker was detectable in nearly 25% of lymphocytes as well as in cells from buccal mucosa. Detailed fluorescence in situ hybridization (FISH) analyses allowed the characterization of the marker to entirely consist of proximal 14q material and to be symmetric. The pattern of clinical features in our patient only slightly correspond to that of patients with trisomy of proximal 14q, but further cases are needed to define whether tetrasomy of proximal 14q is a separate entity.

Pathogenesis of conjunctival petechiae.

Conjunctival petechiae from 15 cases (cause of death: different natural and unnatural) were analysed using confocal laser scanning microscopy (CLSM) in order to visualize the kind of the damage within the vessel wall (diapedesis versus rhexis). The pathomorphological findings with multiple ruptures of vessels appearing to be filled to bursting point define the conjunctival petechiae as a rhexis-haemorrhage.

Cryptic chromosomal aberrations leading to an AML1/ETO rearrangement are frequently caused by small insertions.

The translocation t(8;21)(q22;q22), which results in the fusion of the AML1 (RUNX1) and ETO (CBFA2T1) genes, is a recurrent aberration in acute myeloid leukemia (AML), preferentially correlated with FAB M2, and has the highest incidence in childhood AML. Because of the favorable prognosis, the evidence of the t(8;21) or the AML1/ETO fusion gene is mandatory in most of the therapy trials, allowing the stratification of the patients to the correct risk group in terms of treatment. Here we present six out of 59 children with AML who were positive for AML1/ETO by RT-PCR, but showed no evidence of the classical t(8;21)(q22;q22) by conventional cytogenetics. Because of the discrepancies between molecular and cytogenetic analyses, these six patients were further investigated by fluorescence in situ hybridization analysis. Small hidden interstitial insertions resulting in an AML1/ETO rearrangement were detected in five (8.5%) of the 59 patients, whereas the sixth patient showed a cryptic three-way translocation. The insertions could be characterized as ins(21;8) in three patients and ins(8;21) in the remaining two. Additionally, three of the patients showed secondary chromosome aberrations leading to a higher complexity of the karyotype. In conclusion, the combination of more than one standard technique in the analysis of AML1/ETO is useful to reveal the overall frequency of cryptic chromosome rearrangements and permits a better understanding of the mechanisms involved in the generation of this fusion gene.

Genomic gain of PIK3CA and increased expression of p110alpha are associated with progression of dysplasia into invasive squamous cell carcinoma.

PIK3CA, encoding the catalytic subunit p110alpha of phosphatidylinositol 3-kinase (PI3K), is activated in malignant diseases. However, the role of the PIK3CA gene aberrations for tumourigenesis of head and neck squamous cell carcinoma (HNSCC) is to date unclear. The present study was designed to determine the genomic aberration of PIK3CA in invasive HNSCC and dysplastic precursor lesions by fluorescence in situ hybridization (FISH) with a YAC probe, containing the PIK3CA gene, on isolated interphase nuclei from histomorphologically well-defined regions of formalin-fixed tissue sections and to compare these data with protein and mRNA expression of p110alpha. The mRNA and protein levels of p110alpha were assessed, respectively, by in situ hybridization and immunohistochemistry on consecutive tissue sections. Copy number gains at 3q26 were observed in one of six low-to-moderate dysplasias (17%) and in seven of nine high-grade dysplasias (78%), as well as in 11 carcinomas (100%). In addition, one of seven high-grade dysplasias (14%) and 6 of 11 carcinomas (55%) had amplifications of 3q26. The majority of cases with copy number gain in more than 50% of the cells and/or amplification in more than 10% of cells showed increased p110alpha mRNA and protein expression, whereas only two cases (18%) (one high-grade dysplasia and one carcinoma) with no gain or low-level gain displayed increased p110alpha protein expression. These data suggest that 3q26 copy number gain and amplification represent early genomic aberrations in HNSCC carcinogenesis. In addition, p110alpha mRNA and protein expression in HNSCC may be regulated by these genomic aberrations as well as by epigenetic events.

Visualization of postmortem chondrocyte damage by vital staining and confocal laser scanning 3D microscopy.

The present study was designed to investigate whether the combination of vital dyes [calcein acetomethyl ester and ethidium homodimer (LIVE/DEAD Viability/Cytoxicity Kit)] together with confocal laser scanning 3D microscopy was a suitable process to detect postmortem chondrocyte damage, and whether this process could be used to establish postmortem interval. Human knee cartilage from 13 autopsies (postmortem interval from 1 day to 2.5 months) was incubated with the two dyes. The chondrocytes revealed intense staining according to their vitality. For those cases that were stored mainly at 4 degrees C there was a vitality of approximately 88 to 96% within the first 4.5 days, which decreased to 58% after 6 days and to 9% after 1.5 months. After 2 days and 14 days at summer temperatures there were 70% and 8% vital chondrocytes respectively. Three of the 13 cases showed that altered body and storage conditions limited the efficacy of the method. Initial data suggested a time and temperature dependent increase in cell breakdown. Under stable cooling conditions the use of vital dyes and confocal laser scanning 3D microscopy to measure chondrocyte loss may be a valuable tool for estimating the postmortem interval.