Libuse Lizcova

Acute leukemias with ETV6/ABL1 (TEL/ABL) fusion: poor prognosis and prenatal origin.

The ETV6/ABL1 (TEL/ABL) fusion gene is a rare aberration in malignant disorders. Only 19 cases of ETV6/ABL1‐positive hematological malignancy have been published, diagnosed with chronic myeloid leukemia, other types of chronic myeloproliferative neoplasm, acute myeloid leukemia or acute lymphoblastic leukemia (ALL). This study reports three new cases (aged 8 months, 5 years, and 33 years) of ALL with the ETV6/ABL1 fusion found by screening 392 newly diagnosed ALL patients (335 children and 57 adults). A thorough review of the literature and an analysis of all published data, including the three new cases, suggest poor prognosis of ETV6/ABL1‐positive acute leukemias. The course of the disease in the two pediatric patients is characterized by minimal residual disease monitoring, using quantification of both the ETV6/ABL1 transcript and immunoreceptor gene rearrangements. Eosinophilia could not be confirmed as a hallmark of the ETV6/ABL1‐positive disease. Studies of neonatal blood spots demonstrated that, in the child diagnosed at five years, the ETV6/ABL1 fusion initiating the ALL originated prenatally.

Involvement of deleted chromosome 5 in complex chromosomal aberrations in newly diagnosed myelodysplastic syndromes (MDS) is correlated with extremely adverse prognosis

MDS with complex chromosomal aberrations (CCA) are characterized by short survival and a high rate of transformation to AML. A comprehensive genome-wide analysis of bone-marrow cells of 157 adults with newly diagnosed MDS and CCA revealed a large spectrum of nonrandom genomic changes related to the advanced stages of MDS. Chromosome shattering, probably resulting from chromothripsis, was found in 47% of patients. Deleted chromosome 5 was unstable and often involved in different types of cryptic unbalanced rearrangements. No true monosomy 5 was observed. Patients with CCA involving deleted chromosome 5 had an extremely poor prognosis (median overall survival, 2 months).

Coupled expression of dipeptidyl peptidase-IV and fibroblast activation protein-α in transformed astrocytic cells

Dipeptidyl peptidase-IV (DPP-IV) and fibroblast activation protein-α (FAP) are speculated to participate in the regulation of multiple biological processes, because of their unique enzymatic activity, as well as by non-hydrolytic molecular interactions. At present, the role of DPP-IV and FAP in the development and progression of various types of tumors, including glioblastoma, is intensively studied, and their functional crosstalk is hypothesized. In this article, we describe the correlative expression of DPP-IV and FAP mRNA in primary cell cultures derived from human glioblastoma and associated expression dynamics of both molecules in astrocytoma cell lines depending on culture conditions. Although the molecular mechanisms of DPP-IV and FAP co-regulations remain unclear, uncoupled expression of transgenic DPP-IV and the endogenous FAP suggests that it occurs rather at the transcriptional than at the posttranscriptional level. Understanding of the expressional and functional coordinations of DPP-IV and FAP may help clarify the mechanisms of biological roles of both molecules in transformed astrocytic cells.

Cytogenetic manifestation of chromosome 11 duplication/amplification in acute myeloid leukemia

Gene amplification is a frequent genetic abnormality in solid tumors, and many oncogenes are activated in this way. In acute myeloid leukemia (AML), a frequent target of gene amplification is chromosome 11, particularly chromosome region 11q23, including the MLL (myeloid/lymphoid leukemia) gene. However, the number of other amplicons from the long arm of chromosome 11 has also been described. Duplication/amplification of chromosome 11 was found by cytogenetic methods in 10 of 119 newly diagnosed patients with AML. The amplification was presented as: amplification including only the 5 segment of the MLL gene (1 patient), trisomy 11 (3 patients), partial trisomy 11q (2 patients), isochromosome 11q (1 patient), and multiple amplification of specific regions (3 patients). In two cases, amplification involved parts of not only long arm but also of short arm of the chromosome 11: 11p15 and 11p11.1 to 11p13.

Copy number neutral loss of heterozygosity at 17p and homozygous mutations of TP53 are associated with complex chromosomal aberrations in patients newly diagnosed with myelodysplastic syndromes

Complex karyotypes are seen in approximately 20% of patients with myelodysplastic syndromes (MDS) and are associated with a high risk of transformation to acute myeloid leukemia and poor outcomes in patients. Copy number neutral loss of heterozygosity (CN-LOH, i.e., both copies of a chromosomal pair or their parts originate from one parent) might contribute to increased genomic instability in the bone-marrow cells of patients with MDS. The pathological potential of CN-LOH, which arises as a clonal aberration in a proportion of somatic cells, consists of tumor suppressor gene and oncogene homozygous mutations. The aim of our study was to evaluate the frequency of CN-LOH at 17p in bone-marrow cells of newly diagnosed MDS patients with complex chromosomal aberrations and to assess its correlation with mutations in the TP53 gene (17p13.1). CN-LOH was detected in 40 chromosomal regions in 21 (29%) of 72 patients analyzed. The changes in 27 of the 40 regions identified were sporadic. The most common finding was CN-LOH of the short arm of chromosome 17, which was detected in 13 (18%) of 72 patients. A mutational analysis confirmed the homozygous mutation of TP53 in all CN-LOH 17p patients, among which two frameshift mutations are not registered in the International Agency for Research on Cancer TP53 Database. CN-LOH 17p correlated with aggressive disease (median overall survival 4 months) and was strongly associated with a complex karyotype in the cohort studied, which might cause rapid disease progression in high-risk MDS. No other CN-LOH region previously recorded in MDS or AML patients (1p, 4q, 7q, 11q, 13q, 19q, 21q) was detected in our cohort of patients with complex karyotype examined at the diagnosis of MDS. The LOH region appeared to be balanced (i.e., with no DNA copy number change) when examined with conventional and molecular cytogenetic methods. Therefore, a microarray that detects single-nucleotide polymorphisms is an ideal method with which to identify and further characterize CN-LOH. Our data should specify the prognosis and should lead to the identification of potential targets for therapeutic interventions.

Genetic and epigenetic characterization of low-grade gliomas reveals frequent methylation of the MLH3 gene.

Diffuse astrocytomas and oligodendrogliomas (WHO grade II) are the most common histological subtypes of low‐grade gliomas (LGGs). Several molecular and epigenetic markers have been identified that predict tumor progression. Our aim was in detail to investigate the genetic and epigenetic background of LGGs and to identify new markers that might play a role in tumor behavior. Twenty‐three patients with oligodendroglioma or oligoastrocytoma (LGO) and 22 patients with diffuse astrocytoma (LGA) were investigated using several molecular‐cytogenetic and molecular methods to assess their copy number variations, mutational status and level of promoter methylation. The most frequent findings were a 1p/19q codeletion in 83% of LGO and copy‐neutral loss of heterozygosity (CN‐LOH) of 17p in 72% of LGA. Somatic mutations in the isocitrate dehydrogenase 1 or 2 (IDH1/IDH2) genes were detected in 96% of LGO and 91% of LGA. The O‐6‐methylguanine‐DNA‐methyltransferase (MGMT) promoter was methylated in 83% of LGO and 59% of LGA. MutL homolog 3 (MLH3) promoter methylation was observed in 61% of LGO and 27% of LGA. Methylation of the MGMT promoter, 1p/19q codeletion, mutated IDH1, and CN‐LOH of 17p were the most frequent genetic aberrations in LGGs. The findings were more diverse in LGA than in LGO. To the best of our knowledge, this is the first time description of methylation of the MLH3 gene promoter in LGGs. Further studies are required to determine the role of the methylated MLH3 promoter and the other aberrations detected.

A novel recurrent chromosomal aberration involving chromosome 7 in childhood myelodysplastic syndrome.

Monosomy 7 and/or deletion of the long arm of chromosome 7 is a common cytogenetic aberration in children with myelodysplastic syndrome (MDS) and is associated with poor outcome. In this report, we present an unusual cytogenetic abnormality leading to loss of both the whole short and whole long arms of chromosome 7, which was found in the bone marrow cells of three pediatric patients with MDS. Using a combination of conventional and molecular cytogenetic methods, a tiny dot-like marker chromosome was found and described as der(7)del(7)(p11)del(7)(q11). Together with one previously published case, this chromosomal aberration represents a new rare recurrent karyotypic abnormality involving chromosome 7 in children with MDS.

A partial nontandem duplication of the MLL gene in four patients with acute myeloid leukemia

Unusual MLL gene rearrangements were found in bone marrow cells of four patients with acute myeloid leukemia. A combination of conventional and molecular cytogenetic methods were used to describe translocations t(9;12;11)(p22;p13;q23), t(11;19)(q23;p13.3), and t(10;11)(p12;23) and inverted insertion ins(10;11)(p12;q23.3q23.1). Partial nontandem duplication of the MLL gene was identified by reverse transcriptase-polymerase chain reaction in all cases. The duplication, which included MLL exons 2 through 8-9, was interrupted by a cryptic insertion of one or two exons from the respective MLL partner gene: MLLT10, MLLT3, or MLLT1.

Recurrent chromosomal breakpoints in patients with myelodysplastic syndromes and complex karyotype versus fragile sites

The myelodysplastic syndromes (MDS) represent a heterogeeous group of clonal disorders characterized by a maturation efect in hematopoietic stem cells. Ineffective hematopoiesis leads o cytopenia, clonal instability and an increased risk of transformaion to acute myeloid leukemia (AML). Biologic and genetic tests, in ddition to cytogenetic and molecular cytogenetic analyses of bone arrow cells, are needed to confirm an MDS diagnosis to place he patient in the correct predictive risk group and to select the ost effective therapy. The MDS karyotype has been established s an independent prognostic factor for survival, for response to herapy and for estimating the probability of AML evolution [1]. lonal chromosomal aberrations are detected in the bone marow (BM) in ∼50% of newly diagnosed cases of MDS, and up to 0% of cases have complex chromosomal aberrations (CCA). CCA re defined as numerical or structural changes involving three or ore chromosomes and/or rearrangements with three or more hromosomal breaks that are strongly associated with a very poor rognosis. Recurrent chromosomal aberrations (del(5)(q), monoomy 7, del(20)(q) and trisomy 8) have been described in BM rom ∼50% of newly diagnosed MDS patients, frequently as a part f CCA. Recently, there have been several published reports of hromosomal breakpoints that are associated with cancer genesis nd progression that have confirmed the co-localization of these hromosomal breakpoints to known fragile sites (FS). Breakpoints ssociated with structural changes that are localized to the FS (comon or rare) may play a significant role in inactivation of tumor uppressor genes or activation of oncogenes. FS can be defined as eritable-specific loci on human chromosomes that exhibit nonandom gaps or breaks when chromosomes are exposed to specific ell culture conditions. Rare fragile sites (RFS) are identifiable in less han 5% of the population, while common fragile sites (CFS) are ntrinsic parts of normal chromosome structure that are present n all individuals. We applied microarray technology to analyze enomic structural aberrations in MDS patients with complex aryotypes to identify recurrent chromosomal breakpoints and to valuate and compare their potential associations with FS.

High frequency of dicentric chromosomes detected by multi-centromeric FISH in patients with acute myeloid leukemia and complex karyotype

Dicentric chromosomes (DCs) are considered markers of cancer in various malignancies. However, they can be overlooked when conventional analysis or multicolor fluorescence in situ hybridization (mFISH) is used to detect complex karyotypes. We analyzed the karyotypes of 114 patients with acute myeloid leukemia (AML) and complex karyotypes and verified the presence of monosomies by FISH using multi-centromeric probes. Monosomy was detected in 63% of patients by G-banding/mFISH and confirmed in 55% of patients by centromeric FISH. FISH analysis indicated a high frequency of DCs that were previously considered monosomies. In some cases, it was apparent that the derivative monocentric chromosome was a primary DC. DCs were formed mostly by chromosomes 17 and 20. In conclusion, chromosome loss and unbalanced translocation suggest the presence of a hidden DC or its previous existence. DCs undergo several stabilizing changes and can induce other chromosomal aberrations and/or the formation of new DCs. This can result in the clonal evolution of abnormal cells, which is considered an independent prognostic marker of an unfavorable disease course and short survival.