Recently, a novel CXCL12-binding receptor, has been identified. This CXCL12-binding receptor commonly known as CXCR7 (CXC chemokine receptor 7), has lately, based on a novel nomenclature, has received the name ACKR3 (atypical chemokine receptor 3). In this study, we aimed to investigate the expression of CXCR7 in leukemic cells, as well as its participation in CXCL12 response. Interesting, we clearly demonstrated that CXCR7 is highly expressed in acute lymphoid leukemic cells compared with myeloid or normal hematopoietic cells and that CXCR7 contributed to T-acute lymphoid leukemic cell migration induced by CXCL12. Moreover, we showed that the cellular location of CXCR7 varied among T-lymphoid cells and this finding may be related to their migration capacity. Finally, we hypothesized that CXCR7 potentiates CXCR4 response and may contribute to the maintenance of leukemia by initiating cell recruitment to bone marrow niches that were once occupied by normal hematopoietic stem cells.

No abstract

Backgroundmyelodysplastic syndromes (MDS) are a heterogeneous group of hematopoietic clonal disorders. So, prognostic variables are important to separate patients with a similar biology and clinical outcome. We compared the importance of risk stratification in primary MDS of IPSS and WPSS with the just described revision of IPSS (IPSS-R), and examined if variables obtained by bone marrow immunophenotyping could add prognostic information to any of the scores.MethodsIn this prospective study of 101 cases of primary MDS we compared the relation of patients’ overall survival with WHO types, IPSS, IPSS-R, WPSS and phenotypic abnormalities of hematopoietic precursors. We examined aberrancies in myelomonocytic precursors and CD34+ cells. Patients were censored when receiving chemotherapy or BM transplantation. Survival analysis was made by Cox regressions and stability of the models was examined by bootstrap resampling.Resultsmedian age: 64 years (15–93). WHO types: 2 cases of 5q- syndrome, 7 of RA, 64 of RCDM and 28 of RAEB. In the univariate Cox analysis, increasing risk category of all scores, degree of anemia, higher percentage of BM blasts, higher number of CD34+ cells and their myeloid fractions besides increasing number of phenotypic abnormalities detected were significantly associated with a shorter survival. In the multivariate analysis comparing the three scores, IPSS-R was the only independent risk factor. Comparing WPSS with phenotypic variables (CD34+/CD13+ cells, CD34+/CD13− cells and “total alterations”) the score and “CD34+/CD13+ cells” remained in the model. When IPSS was tested together with these phenotypic variables, only “CD34+/CD13+ cells”, and “total alterations” remained in the model. Testing IPSS-R with the phenotypic variables studied, only the score and “CD34+/CD13+ cells” entered the model.ConclusionsImmunophenotypic analysis of myelomonocytic progenitors provides additional prognostic information to all clinical scores studied. IPSS-R improved risk stratification in MDS compared to the former scores.

ANKHD1 is highly expressed in human acute leukemia cells and potentially regulates multiple cellular functions through its ankyrin-repeat domains. In order to identify interaction partners of the ANKHD1 protein and its role in leukemia cells, we performed a yeast two-hybrid system screen and identified SIVA, a cellular protein known to be involved in proapoptotic signaling pathways. The interaction between ANKHD1 and SIVA was confirmed by co-imunoprecipitation assays. Using human leukemia cell models and lentivirus-mediated shRNA approaches, we showed that ANKHD1 and SIVA proteins have opposing effects. While it is known that SIVA silencing promotes Stathmin 1 activation, increased cell migration and xenograft tumor growth, we showed that ANKHD1 silencing leads to Stathmin 1 inactivation, reduced cell migration and xenograft tumor growth, likely through the inhibition of SIVA/Stathmin 1 association. In addition, we observed that ANKHD1 knockdown decreases cell proliferation, without modulating apoptosis of leukemia cells, while SIVA has a proapoptotic function in U937 cells, but does not modulate proliferation in vitro. Results indicate that ANKHD1 binds to SIVA and has an important role in inducing leukemia cell proliferation and migration via the Stathmin 1 pathway. ANKHD1 may be an oncogene and participate in the leukemia cell phenotype.

No abstract

The role of the immune system in myelodysplastic syndrome (MDS) progression has been widely accepted, although mechanisms underlying this immune dysfunction are not clear. CD4(+) and CD8(+) lymphocyte profiles in the peripheral blood of MDS patients were evaluated and correlated with clinical characteristics, the expression of FOXP3 and the anti-inflammatory cytokines IL10, TGFβ1 and CTLA4. IL10 expression inversely correlated with the percentage of CD8(+) cells and was higher in high-risk MDS. Our findings provide further evidence for the role of T cell-mediated IL10 production in MDS and strengthen the idea of distinct cytokine profiles in low and high-risk MDS.

The interaction between the bone marrow microenvironment and malignant hematopoietic cells can result in the protection of leukemia cells from chemotherapy in both myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). We, herein, characterized the changes in cytokine expression and the function of mesenchymal stromal cells (MSC) in patients with MDS, AML with myelodysplasia-related changes (MRC), a well-recognized clinical subtype of secondary AML, and de novo AML. We observed a significant inhibitory effect of MDS-MSC on T lymphocyte proliferation and no significant differences in any of the cytokines tested. AML-MSC inhibited T-cell proliferation only at a very low MSC/T cell ratio. When compared to the control, AML-MRCderived MSC presented a significant increase in IL6 expression, whereas de novo AML MSC presented a significant increase in the expression levels of VEGFA, CXCL12, RPGE2, IDO, IL1β, IL6 and IL32, followed by a decrease in IL10 expression. Furthermore, data indicate that IL-32 regulates stromal cell proliferation, has a chemotactic potential and participates in stromal cell crosstalk with leukemia cells, which could result in chemoresistance. Our results suggest that the differences between AML-MRC and de novo AML also extend into the leukemic stem cell niche and that IL-32 can participate in the regulation of the bone marrow cytokine milieu.

TET2, a member of the ten-eleven-translocation (TET) family genes that modify DNA by converting 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC), is located in chromosome 4q24 and is frequently mutated in myeloid malignancies. The impact of TET2 mutation on survival outcomes is still controversial; however, functional studies have proved that it is a loss-of-function mutation that impairs myeloid cell differentiation and contributes to the phenotype of myeloid neoplasia. We, herein, aimed to investigate TET2 expression in patients with myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). A significantly decreased TET2 expression was observed in bone marrow cells from AML (n = 53) and patients with MDS (n = 64), compared to normal donors (n = 22). In MDS, TET2 expression was significantly reduced in RAEB-1/RAEB-2 compared to other WHO 2008 classifications, and a lower TET2 expression was observed at the time of MDS disease progression in four of five patients. In multivariate analysis, low TET2 expression (P = 0.03), male gender (P = 0.02), and WHO 2008 classification (P < 0.0001) were independent predictors of poorer overall survival. These results suggest that defective TET2 expression plays a role in the MDS pathophysiology and predicts survival outcomes in this disease.