DNA released by leukemic cells contributes to the disruption of the bone marrow microenvironment.

Reciprocal interactions between a tumor and its microenvironment control expansion of tumor cells. Here we show a specific type of interaction in which blasts of experimental leukemia destroy the bone marrow (BM) structures and kill stromal cells. The in vitro experiments showed that the cytotoxic agent released by leukemic cells is the fragmented DNA derived from their genome and occurring in nucleosome-like complexes. This DNA entered nuclei of BM or other cells and induced H2A.X phosphorylation at serine 139, similar to double-strand break-inducing agents. There was a correlation between large amounts of acquired DNA and death of recipient cells. Moreover, the DNA integrated into chromosomal DNA of recipient cells. Primary human acute myeloid leukemia cells also released fragmented DNA that penetrated the nuclei of other cells both in vitro and in vivo. We suggest that DNA fragments released from leukemic and also perhaps other types of tumor cells can activate DNA repair mechanisms or death in recipient cells of a tumor microenvironment, depending on the amount of the acquired DNA. This can impair DNA stability and viability of tumor stromal cells, undermine homeostatic capacity of tumor microenvironment and facilitate tumor progression.

[Patient with B-CLL with a history of unrelated hematopoietic cells donation--retrospective analysis of CLL development and implication for the recipient]. / Pacient s B-CLL s anamnézou darování krvetvorných bunek nepríbuznému pacientovi - retrospektivní sledování vývoje nemoci a dusledky pro príjemce.

BACKGROUND: Donor cell leukemia (DCL) is a relatively rare but well documented complication of hematopoietic stem cell transplantation. So far, publications described only DCL arising de novo in the recipient. OBSERVATION: In this study, we describe a case of chronic lymphocytic leukemia (B-CLL) developing in a volunteer unrelated donor from the Czech National Marrow Donors Registry (CNMDR) several years after donation. From archival DNA sample, we have retrospectively found that subclinical CLL clone was already present at the time of donation but early death of recipient prevented eventual development of DCL. This case documents well the long period between detection of B-CLL clone and full development of clinical-laboratory symptomatology. The medical and ethical questions posed by an isolated case of detection of hematological malignancy present either only in the donor or only in the recipient are discussed. CONCLUSION: The case demonstrates the increasing risk of development of various forms of DCL and thus highlights the need for long-term monitoring of stem cell donor, not only in terms of health of donor but also in terms of potential risks for the recipient.

Angiopoietin-2 mRNA expression is increased in chronic lymphocytic leukemia patients with poor prognostic features.

Several studies have demonstrated the potential prognostic importance of angiogenesis in chronic lymphocytic leukemia (CLL). Elevated expression of angiopoietin-2 (Ang-2), an angiogenic cytokine, was recently reported in CLL. However, data regarding prognostic significance of Ang-2 in CLL are limited. Therefore, we quantitated Ang-2 mRNA in purified mononuclear cells of 33 untreated CLL patients and compared the transcript levels to traditional as well as modern prognostic factors in patients with CLL (clinical stage, disease course, IgVH mutation status, CD38, and ZAP-70 expression). Elevated Ang-2 mRNA concentrations were detected in 12 cases; 21 patients had very low or undetectable levels of Ang-2 transcript. There was significant association between high Ang-2 mRNA levels and unmutated IgVH genes (n=27, P=0.010) and with CD38 expression (n=32, P=0.011), but not with ZAP-70 expression (n=32, P=0.784), Rai stage (n=33, P=0.305) or stable versus progressive clinical course (n=33, P=0.443). There was a trend towards shorter progression-free survival in patients with high Ang-2 expression; however, it did not reach statistical significance (P=0.090). Our pilot data show that Ang-2 mRNA is differentially expressed in patients with CLL and its increased expression appears to be associated with poor prognostic features. Further studies are needed to confirm the results in a larger patient cohort.

Genomic polymorphism and sepsis--is there a reason for optimism?

There is no doubt that, in infectious disease, genetic predisposition plays a very important role in clinical outcome. Sepsis is a polygenic syndrome initiated by infection. A fact confounding the situation is that two factors--the macroorganism and the microorganism--are at play at the same time; hence of genotype effect must be assessed in light of their interaction. From a phylogenetic point of view, infectious disease is a companion of man throughout their life and its role in terms of function of the system of innate immunity is perceived as a beneficial one. However, the presence of a major antigen load by the infectious agent results in pathological responses at the levels of the macroorganism. Assessment of the severity of the inflammatory process on the basis of genetic predisposition is a most challenging issue. Genetic polymorphisms in the immune response to infection have been shown to be associated with clinical outcomes. The advancement of single nucleotide polymorphism (SNP) genotyping in basic genes--CD14, Toll like receptors, LBP, cytokines, cytokine receptors and coagulation factors have provided valuable information on the interaction of the macro and microorganisms. The understanding of the variation in genes and differences in response to infection may contribute to tailored diagnostic and therapeutic interventions with improved outcome in these patients.

Identification of somatic hypermutations in the TP53 gene in B-cell chronic lymphocytic leukemia.

Abnormalities of the TP53 gene are associated with a particularly severe prognosis in patients with B-cell chronic lymphocytic leukemia (B-CLL). This tumor-suppressor is mostly inactivated by the deletion of one and point mutation of the other allele and has not been previously shown to be hypermutated in B-CLL. We identified two patients whose lymphocytes showed repeatedly an extensive proportion of TP53 mutated cells by FASAY analysis (the yeast functional assay) and harbored various TP53 mutations, mostly single-base substitutions, in individual cells. The mutation targeting exhibited characteristic traits of the somatic hypermutation process. In the first patient (harboring the unmutated IgVH locus) a significant bias to point mutations at CG pairs (21/25; P=0.009), their remarkable preference for the RGYW/WRCY motives (28%) and the highest expression of the activation-induced cytidine deaminase (AID) mRNA among the 34 tested B-CLL samples. In the second patient no CG bias was observed but the targeting of point mutations into the RGYW/WRCY motives was even more prominent here (7/16; 44%). Moreover, six out of eight point mutations affecting AT pairs were localized in the WA/TW motives, which are also characteristic for the somatic hypermutations. This patient, who was IgVH-mutated, already did not express any significant amount of the AID transcript. Our findings add a new aspect to the mosaic of the p53 mutability in B-CLL.

[Isolated lymphadenopathy as the first presentation of systemic mastocytosis--description of two cases]. / Izolovaná lymfadenopatie jako první projev systémové mastocytózy--popis dvou prípadu.

Presented are two cases of systemic mastocytosis in 46- and 63-year-old women, where the correct diagnosis was established in randomly disclosed cervical respectively intraabdominal lymphadenopathy. Both cases lacked characteristic skin and systemic mast-cell mediator symptoms at the time of histologic diagnosis. The first case was classified as a indolent systemic mastocytosis without any proven genetic alteration, the second one met the criteria of aggressive systemic mastocytosis with eosinophilia, where the point mutation asp816val in c-kit gene was confirmed and the patient responded unexpectedly well to Gleevec. Discussed are both conventional morphological differential diagnosis of mastocytosis in lymph nodes and recent advances in genetics of these systemic clonal mast cell proliferations. The latter not only outlines the oncopathogenesis but, in particular, also provides important prognostic and biological implications of this peculiar disease.

[Expression of cyclin-dependent kinase inhibitors in leukemia]. / Exprese inhibitoru cyklin-dependentních kináz u leukémií.

BACKGROUND: Leukemias develop due to defects in proliferation, differentiation and apoptosis, which take place in stem cells or progenitors of hematopoiesis. These processes have several crossing points, one of them is the role of inhibitors of cyclin-dependent kinases. The aim of this study was to study the expression of cyclin-dependent kinases inhibitors p21 Cip and p27 Kip and expression of proliferative antigen Ki-67 in leukocytes of human leukemia. METHODS AND RESULTS: The expression of cyclin-dependent kinases inhibitors was detected at mRNA level mainly by comparative reverse-transcription polymerase chain reaction and in selected samples also by the real-time polymerase chain reaction. While p27 Kip expression in leukocytes of leukemic patients and healthy persons was universal, large differences in expression of p21 Cip were found both among individual patients of the same type of leukemia and between different types of leukemias and healthy persons. The p21 Cip expression was significantly higher in acute leukemias than in chronic ones and healthy persons. A comparison of p21 Cip expression with the clinical outcome of the leukemic patients showed that the group of 14 acute leukemia patients surviving more than 30 months had a significantly lower expression of p21 Cip than 12 patients of this type of leukemia who died within this time limit. Moreover, the results obtained on a smaller set of acute promyelocytic leukemia patients indicated that the lower p21 expression is connected with a better prognosis. CONCLUSION: Our results pointed out the importance of the cyclin-dependent kinase inhibitor p21 Cip in human leukemias and indicated that the lower p21 Cip expression might be a positive prognostic factor in acute myeloid leukemia patients.