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Evidence of distinct disease propagating stem cells in myelodysplastic syndrome (MDS) has emerged in recent years. However, immunophenotypic characterization of these cancer stem cells remains sparse. In acute myeloid leukaemia (AML), we have previously described aberrant expression of the C-type lectin domain family 12, member A (CLEC12A) as a stable and reliable marker of leukaemia blasts and as a tool for assessing minimal residual disease. Furthermore, CLEC12A has been proposed as a promising marker of leukaemic stem cells in AML. The role of CLEC12A in MDS, however, remains to be elucidated. In this study, we found CLEC12A aberrantly expressed on the CD34(+) CD38(-) cell compartment in 71% (22/31) of MDS patients, distributed across all Revised International Prognostic Scoring System risk groups. We showed that the CD34(+) CD38(-) CLEC12A(+) cells were indeed malignant and possessed functional stem cell properties in the long-term colony-initiating cell assay. As opposed to reported findings in AML, we showed that cancer stem cells from MDS samples derived from both CLEC12A positive and negative CD34(+) CD38(-) subpopulations. Due to the absence of CLEC12A on normal haematopoietic stem cells, CLEC12A stem cell immunophenotyping may contribute to diagnosing and monitoring MDS patients and could furthermore add knowledge about disease propagating cells in MDS.

To evaluate the reproducibility and reliability of the histomorphological criteria differentiating severe aplastic anaemia (SAA) and hypoplastic refractory cytopenia of childhood (RCC), the most frequently acquired hypocellular bone marrow conditions of childhood.

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Udgivelsesdato: 2009-Sep Clinical characteristics and cytogenetic aberrations were ascertained and reviewed in a population-based consecutive series of 285 pediatric T-cell acute lymphoblastic leukemias (T-ALLs) diagnosed between 1992 and 2006 in the Nordic countries. Informative karyotypic results were obtained in 249 (87%) cases, of which 119 (48%) were cytogenetically abnormal. Most (62%) of the aberrant T-ALLs were pseudodiploid. Structural changes were more common than numerical ones; 86% displayed at least one structural abnormality and 41% at least one numerical anomaly. The most frequent abnormalities were T-cell receptor (TCR) gene rearrangements (20%) [TCR;11p13 (10%), TCR;10q24 (3%), TCR;other (8%)], del(9p) (17%), +8 (14%), del(6q) (12%), and 11q23 rearrangements (6%). The TCR;other group comprised the rare rearrangements t(X;14)(p11;q11), t(X;7)(q22;q34), t(1;14)(p32;q11), ins(14;5)(q11;q?q?), inv(7)(p15q34), t(8;14)(q24;q11), t(7;11)(q34;p15), and t(12;14)(p13;q11). The clinical characteristics of this Nordic patient cohort agreed well with previous larger series, with a median age of 9.0 years, male predominance (male/female ratio 3.1), median white blood cell (WBC) count of 66.5 x 10(9)/l, and a high incidence of mediastinal mass and central nervous system involvement (59% and 9.5%, respectively). These features did not differ significantly among the various genetic subgroups. 5-year event-free survival (EFS) and overall survival for all patients were 0.61 (+/-0.03) and 0.67 (+/-0.03), respectively. In a multivariate analysis, two factors affected negatively the EFS, namely a WBC count of > or =200 x 10(9)/l (P < 0.001) and the presence of rare TCR rearrangements (P = 0.001). In conclusion, in this large series of childhood T-ALLs from the Nordic countries, the cytogenetic findings were not associated with risk of therapy failure with the exception of the TCR;other group. However, further prospective and collaborative investigations of this genetically heterogeneous entity are needed to confirm these results.

Introduction. In recent years global gene expression profiling studies introduce several new potential prognostic markers in multiple myeloma (MM). Up-regulation and amplification of the gene CKS1B in myeloma cells has lately been associated with a poor prognosis in MM patients. The CKS1B gene is located on chromosome 1q and is involved in the induction of cell proliferation by inhibiting the cyclin-dependent kinase inhibitor p27(kip1). Materials and Methods. We investigated the prognostic value of CKS1B expression by real time quantitative polymerase chain reaction techniques in purified myeloma cells from 171 untreated, newly diagnosed MM-patients. 36% of the patients (2) with stem cell support. 56% (>65 years) were treated with standard melphalan and prednisolone, and 8% were untreated. Median follow-up was 53 months. The clonal myeloma cells in bone marrow aspirates were immunophenotyped by 3- og 4-colour flowcytometry, and patients were only included if an aberrant clone was identified. Herafter, aberrant plasma cells (CD38++/CD19-/CD45-/i/CD56-/+/++) were sorted directly into PCR tubes by fluorescence activated cell sorting (FACS) using af FACS Aria (BDIS). In all cases plasma cell purity above 98% was obtained. Purified normal plasma cells from 9 healthy volunteers were collected as controls. A cDNA archive was generated by global reverse transcription. By using a polyadenylating step 5/-oligo(dT)-transcript-poly(A)-3/cDNA were generated and finally amplified by PCR using a sequence independent X-(dT)24 primer. Gene expression of CSK1B and the housekeeping gene ß-actin were analysed by RQ-PCR and CKS1B expression levels were normalized to ß-actin. Expression of CKS1B was observed in 52% of the patients. Results and Conclusions. We investigated the prognostic value of CKS1B expression by quantitative PCR techniques in, flowcytometry sorted, highly purified myeloma cells from 171 untreated MM patients. CKS1B over-expression did not correlate with af poor outcome in the patients. In the high dose melphalan treated patients the overall survival was similar in patients with or without up-reulated CKS1B expression. In patients treated with conventional chemotherapy expression of CKS1B showed a trend towards a survival benefit (p=0.05). So, our data do not confirm that myeloma celle over-expression of CKS1B is associated with af poor prognosis.

Udgivelsesdato: Sep-25 PRV-1 is a new molecular marker within the Ph-negative chronic myeloproliferative disorders. PRV-1 is a useful, highly sensitive and specific marker in the differentiation between polycythaemia vera (PV) and secondary erythrocytosis (ET), and seems to identify those PV patients presenting in the early phase of the disease with dominating thrombocytosis and thus a clinical phenotype of ET. These PRV-1 positive ET patients can be regarded as having "masked" PV or, more accurately, as having early PV. Moreover, PRV-1 positivity may be associated with a particular risk of thromboembolic complications. The biological role of PRV-1 and the significance of alterations in PRV-1 gene expression levels during treatment remain to be clarified.