João Kleber Novais Pereira

FMNL1 promotes proliferation and migration of leukemia cells

The human FMNL1 is expressed predominantly in hematopoietic cells and has been described previously as overexpressed in hematopoietic malignancies. However, it is not known whether FMNL1 contributes to leukemogenesis. Here, we investigate the FMNL1 function using two different human leukemia models: Namalwa and K562 cell lines. FMNL1 depletion reduced cell proliferation and colony formation in both leukemic cell types, as well as a decrease in the tumor growth of FMNL1‐depleted Namalwa cell xenografts. In addition, there was a decrease in migration and in TEM in FMNL1‐depleted Namalwa cells. FMNL1 endogenously associates with Rac1, and FMNL1 silencing resulted in an increased Rac1 activity. The reduced migration observed in FMNL1‐depleted cells was restored by inhibiting Rac activity. Our results indicate that FMNL1 stimulates leukemia cell proliferation as well as migration. This suggests that FMNL1 contributes to leukemogenesis and could act in part through Rac1 regulation.

Distinct expression profiles of MSI2 and NUMB genes in myelodysplastic syndromes and acute myeloid leukemia patients

Recent studies have indicated the Musashi2/NUMB pathway as the key regulator of differentiation in chronic myeloid leukemia; however, a comparison of both gene expressions has not yet been made in myelodysplastic syndrome (MDS) and in acute myeloid leukemia (AML). We herein, demonstrate a statistically significant down-modulation of NUMB expression level in high-risk MDS and AML, compared with control individuals. MSI2 expression was significantly reduced in low and high-risk MDS compared with normal control samples. NUMB expression was significantly lower than that of MSI2 in both MDS and AML patient samples, but no differences in the expression levels for either gene were observed in healthy bone marrow cells. Finally, NUMB expression was significantly up-regulated during differentiation of normal and low-risk MDS CD34(+) cells through the erythroid lineage. Taken together, results suggest the involvement of NUMB in MDS erythropoiesis; its down-modulation may have a role in MDS progression.

IL10 inversely correlates with the percentage of CD8 + cells in MDS patients

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.

Molecular effects of the phosphatidylinositol-3-kinase inhibitor NVP-BKM120 on T and B-cell acute lymphoblastic leukaemia.

BACKGROUND Constitutive activation of the PI3K pathway in T cell acute lymphoblastic leukaemia (T-ALL) has been reported and in a mouse model, PI3K activation, together with MYC, cooperates in Burkitt lymphoma (BL) pathogenesis. We investigated the effects of NVP-BKM120, a potent pan-class I PI3K inhibitor, in lymphoblastic leukaemia cell lines. METHODS Effects of NVP-BKM120 on cell viability, clonogenicity, apoptosis, cell cycle, cell signalling and autophagy were assessed in vitro on T-ALL (Jurkat and MOLT-4) and BL (Daudi and NAMALWA) cell lines. RESULTS NVP-BKM120 treatment decreased cell viability and clonogenic growth in all tested cells. Moreover, the drug arrested cell cycling in association with a decrease in Cyclin B1 protein levels, and increased apoptosis. Immunoblotting analysis of cells treated with the drug revealed decreased phosphorylation, in a dose-dependent manner, of AKT, mTOR, P70S6K and 4EBP1, with stable total protein levels. Additionally, we observed a dose-dependent decrease in BAD phosphorylation, in association with augmented BAX:BCL2 ratio. Quantification of autophagy showed a dose-dependent increase in acidic vesicular organelles in all cells tested. CONCLUSION In summary, our present study establishes that NVP-BKM120 presents an effective antitumour activity against T-ALL and BL cell lines.

De novo AML exhibits greater microenvironment dysregulation compared to AML with myelodysplasia-related changes

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.

IL32 expression in peripheral blood CD3+ cells from myelodysplastic syndromes patients

BackgroundMyelodysplastic syndromes (MDS) are a heterogeneous group of disorders characterized by ineffective hematopoiesis and risk of leukemia transformation. There is evidence to suggest the participation of immune system deregulation in MDS pathogenesis. Interleukin-32 (IL-32) is a newly described multifunctional cytokine reported as an important mediator in autoimmune and inflammatory disorders. In the present study, we reported the expression of IL32 and IL32 transcript variants (α, β, γ and δ) in peripheral blood CD3+ cells from healthy controls and MDS patients.MethodsCD3+ cells were isolated by immunomagnetic cell sorting from thirty-nine untreated MDS patients and twenty-nine healthy donors. Gene expression was evaluated by quantitative PCR. For statistical analysis, Mann–Whitney test, Kruskal-Wallis test with Dunns post test and Log-rank (Mantel-Cox) were used, as appropriate. A p value <0.05 was considered statistically significant.ResultsIL32 expression and IL32 transcript variants IL32α, IL32β, IL32γ, and IL32δ, were similar in peripheral blood CD3+ cells from healthy donors and MDS patients. Increased IL-32α expression was an independent predictor for MDS disease progression by univariate and multivariate analysis.ConclusionsWe observed that IL32 expression is not differently expressed in CD3+ cells from MDS patients; nevertheless IL32α has a potential role in disease progression.