Acquired TERT promoter mutations stimulate TERT transcription in mantle cell lymphoma.

Mantle cell lymphoma (MCL) is an aggressive lymphoid neoplasm with poor prognosis. Acquired telomerase reverse transcriptase gene promoter (TERTp) mutations are among the most frequent somatic non-coding mutations in cancers. In this study, the prevalence of TERTp mutations in 24 MCL and 21 other lymphoid neoplasias (oLN) was investigated. Eight MCL samples (33%) carried TERTp mutations, two homozygous and six heterozygous (seven C228T and one C250T), which directly correlated with higher TERT transcription, mitochondrial DNA copy number, and IGHV mutational status in MCL neoplastic cells. TERTp mutations were not found in oLN. TERTp mutations correlated with more lymphoma proliferation and tumor burden, as suggested by the higher number of lymphoma cells circulating in peripheral blood, and tended to associate with longer MCL telomeres, especially in homozygous mutants, although not statistically significant. Telomere-biology genes were overexpressed in MCL cells in comparison to healthy lymphocytes, but were not influenced by mutation status. The findings described for the first time that acquired TERTp mutations are common in MCL but not in other lymphoid neoplasms. It was also demonstrated that TERTp mutations are associated with higher TERT mRNA expression in MCL cells in vivo and higher tumor burden, suggesting these mutations as a driver event in MCL development and progression.

Halofuginone inhibits phosphorylation of SMAD-2 reducing angiogenesis and leukemia burden in an acute promyelocytic leukemia mouse model.

BACKGROUND: Halofuginone (HF) is a low-molecular-weight alkaloid that has been demonstrated to interfere with Metalloproteinase-2 (MMP-2) and Tumor Growth Factor-ß (TGF-ß) function and, to present antiangiogenic, antiproliferative and proapoptotic properties in several solid tumor models. Based on the fact that high levels of Vascular Endothelial Growth Factor (VEGF) and increased angiogenesis have been described in acute myeloid leukemia and associated with disease progression, we studied the in vivo effects of HF using an Acute Promyelocytic Leukemia (APL) mouse model. METHODS: NOD/SCID mice were transplanted with leukemic cells from hCG-PML/RARA transgenic mice (TM) and treated with HF 150 µg/kg/day for 21 days. The leukemic infiltration and the percentage of VEGF+ cells were evaluated by morphology and flow cytometry. The effect of HF on the gene expression of several pro- and antiangiogenic factors, phosphorylation of SMAD2 and VEGF secretion was assessed in vitro using NB4 and HUVEC cells. RESULTS: HF treatment resulted in hematological remission with decreased accumulation of immature cell and lower amounts of VEGF in BM of leukemic mice. In vitro, HF modulated gene expression of several pro- and antiangiogenic factors, reduced VEGF secretion and phosphorylation of SMAD2, blocking TGF-ß-signaling. CONCLUSION: Taken together, our results demonstrate that HF inhibits SMAD2 signaling and reduces leukemia growth and angiogenesis.

Increased expression of miR-221 is associated with shorter overall survival in T-cell acute lymphoid leukemia.

BACKGROUND: CD56 expression has been associated with a poor prognosis in lymphoid neoplasms, including T-cell acute lymphoblastic leukemia (T-ALL). MicroRNAs (miRNAs) play an important role in lymphoid differentiation, and aberrant miRNA expression has been associated with treatment outcome in lymphoid malignancies. Here, we evaluated miRNA expression profiles in normal thymocytes, mature T-cells, and T-ALL samples with and without CD56 expression and correlated microRNA expression with treatment outcome. METHODS: The gene expression profile of 164 miRNAs were compared for T-ALL/CD56+ (n=12) and T-ALL/CD56- (n=36) patients by Real-Time Quantitative PCR. Based on this analysis, we decided to evaluate miR-221 and miR-374 expression in individual leukemic and normal samples. RESULTS: miR-221 and miR-374 were expressed at significantly higher levels in T-ALL/CD56+ than in T-ALL/CD56- cells and in leukemic blasts compared with normal thymocytes and peripheral blood (PB) T-cells. Age at diagnosis (15 or less vs grater than 15 years; HR: 2.19, 95% CI: 0.98-4.85; P=0.05), miR-221 expression level (median value as cut off in leukemic samples; HR: 3.17, 95% CI: 1.45-6.92; P=0.004), and the expression of CD56 (CD56-vs CD56+; HR: 2.99, 95% CI: 1.37-6.51; P=0.006) were predictive factors for shorter overall survival; whereas, only CD56 expression (HR: 2.73, 95% CI: 1.03-7.18; P=0.041) was associated with a shorter disease-free survival rate. CONCLUSIONS: miR-221 is highly expressed in T-ALL and its expression level may be associated with a poorer prognosis.

Linker for activation of T-cell family member2 (LAT2) a lipid raft adaptor protein for AKT signaling, is an early mediator of alkylphospholipid anti-leukemic activity.

Lipid rafts are highly ordered membrane domains rich in cholesterol and sphingolipids that provide a scaffold for signal transduction proteins; altered raft structure has also been implicated in cancer progression. We have shown that 25 µm 10-(octyloxy) decyl-2-(trimethylammonium) ethyl phosphate (ODPC), an alkylphospholipid, targets high cholesterol domains in model membranes and induces apoptosis in leukemia cells but spares normal hematopoietic and epithelial cells under the same conditions. We performed a quantitative (SILAC) proteomic screening of ODPC targets in a lipid-raft-enriched fraction of leukemic cells to identify early events prior to the initiation of apoptosis. Six proteins, three with demonstrated palmitoylation sites, were reduced in abundance. One, the linker for activation of T-cell family member 2 (LAT2), is an adaptor protein associated with lipid rafts in its palmitoylated form and is specifically expressed in B lymphocytes and myeloid cells. Interestingly, LAT2 is not expressed in K562, a cell line more resistant to ODPC-induced apoptosis. There was an early loss of LAT2 in the lipid-raft-enriched fraction of NB4 cells within 3 h following treatment with 25 µm ODPC. Subsequent degradation of LAT2 by proteasomes was observed. Twenty-five µm ODPC inhibited AKT activation via myeloid growth factors, and LAT2 knockdown in NB4 cells by shRNA reproduced this effect. LAT2 knockdown in NB4 cells also decreased cell proliferation and increased cell sensitivity to ODPC (7.5×), perifosine (3×), and arsenic trioxide (8.5×). Taken together, these data indicate that LAT2 is an early mediator of the anti-leukemic activity of alkylphospholipids and arsenic trioxide. Thus, LAT2 may be used as a target for the design of drugs for cancer therapy.

Methionine-induced hyperhomocysteinemia reverts fibrinolytic pathway activation in a murine model of acute promyelocytic leukemia.

Increased fibrinolysis is an important component of acute promyelocytic leukemia (APL) bleeding diathesis. APL blasts overexpress annexin II (ANXII), a receptor for tissue plasminogen activator (tPA), and plasminogen, thereby increasing plasmin generation. Previous studies suggested that ANXII plays a pivotal role in APL coagulopathy. ANXII binding to tPA can be inhibited by homocysteine and hyperhomocysteinemia can be induced by L-methionine supplementation. In the present study, we used an APL mouse model to study ANXII function and the effects of hyperhomocysteinemia in vivo. Leukemic cells expressed higher ANXII and tPA plasma levels (11.95 ng/mL in leukemic vs 10.74 ng/mL in wild-type; P = .004). In leukemic mice, administration of L-methionine significantly increased homocysteine levels (49.0 µmol/mL and < 6.0 µmol/mL in the treated and nontreated groups, respectively) and reduced tPA levels to baseline concentrations. The latter were also decreased after infusion of the LCKLSL peptide, a competitor for the ANXII tPA-binding site (11.07 ng/mL; P = .001). We also expressed and purified the p36 component of ANXII in Pichia methanolica. The infusion of p36 in wild-type mice increased tPA and thrombin-antithrombin levels, and the latter was reversed by L-methionine administration. The results of the present study demonstrate the relevance of ANXII in vivo and suggest that methionine-induced hyperhomocysteinemia may reverse hyperfibrinolysis in APL.

The Aurora A and B kinases are up-regulated in bone marrow-derived chronic lymphocytic leukemia cells and represent potential therapeutic targets.

BACKGROUND: The malignant B cells in chronic lymphocytic leukemia receive signals from the bone marrow and lymph node microenvironments which regulate their survival and proliferation. Characterization of these signals and the pathways that propagate them to the interior of the cell is important for the identification of novel potential targets for therapeutic intervention. DESIGN AND METHODS: We compared the gene expression profiles of chronic lymphocytic leukemia B cells purified from bone marrow and peripheral blood to identify genes that are induced by the bone marrow microenvironment. Two of the differentially expressed genes were further studied in cell culture experiments and in an animal model to determine whether they could represent appropriate therapeutic targets in chronic lymphocytic leukemia. RESULTS: Functional classification analysis revealed that the majority of differentially expressed genes belong to gene ontology categories related to cell cycle and mitosis. Significantly up-regulated genes in bone marrow-derived tumor cells included important cell cycle regulators, such as Aurora A and B, survivin and CDK6. Down-regulation of Aurora A and B by RNA interference inhibited proliferation of chronic lymphocytic leukemia-derived cell lines and induced low levels of apoptosis. A similar effect was observed with the Aurora kinase inhibitor VX-680 in primary chronic lymphocytic leukemia cells that were induced to proliferate by CpG-oligonucleotides and interleukin-2. Moreover, VX-680 significantly blocked leukemia growth in a mouse model of chronic lymphocytic leukemia. CONCLUSIONS: Aurora A and B are up-regulated in proliferating chronic lymphocytic leukemia cells and represent potential therapeutic targets in this disease.

Halofuginone has anti-proliferative effects in acute promyelocytic leukemia by modulating the transforming growth factor beta signaling pathway.

Promyelocytic leukemia-retinoic acid receptor alpha (PML-RARα) expression in acute promyelocytic leukemia (APL) impairs transforming growth factor beta (TGFß) signaling, leading to cell growth advantage. Halofuginone (HF), a low-molecular-weight alkaloid that modulates TGFß signaling, was used to treat APL cell lines and non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice subjected to transplantation with leukemic cells from human chorionic gonadotrophin-PML-RARα transgenic mice (TG). Cell cycle analysis using incorporated bromodeoxyuridine and 7-amino-actinomycin D showed that, in NB4 and NB4-R2 APL cell lines, HF inhibited cellular proliferation (P<0.001) and induced apoptosis (P = 0.002) after a 24-hour incubation. Addition of TGFß revealed that NB4 cells were resistant to its growth-suppressive effects and that HF induced these effects in the presence or absence of the cytokine. Cell growth inhibition was associated with up-regulation of TGFß target genes involved in cell cycle regulation (TGFB, TGFBRI, SMAD3, p15, and p21) and down-regulation of MYC. Additionally, TGFß protein levels were decreased in leukemic TG animals and HF in vivo could restore TGFß values to normal. To test the in vivo anti-leukemic activity of HF, we transplanted NOD/SCID mice with TG leukemic cells and treated them with HF for 21 days. HF induced partial hematological remission in the peripheral blood, bone marrow, and spleen. Together, these results suggest that HF has anti-proliferative and anti-leukemic effects by reversing the TGFß blockade in APL. Since loss of the TGFß response in leukemic cells may be an important second oncogenic hit, modulation of TGFß signaling may be of therapeutic interest.

Antibody-targeted horseradish peroxidase associated with indole-3-acetic acid induces apoptosis in vitro in hematological malignancies.

Indole-3-acetic acid (IAA), when oxidized by horseradish peroxidase (HRP), is transformed into cytotoxic molecules capable of inducing cell injury. The aim of this study was to test if, by targeting hematopoietic tumors with HRP-conjugated antibodies in association with IAA treatment, there is induction of apoptosis. We used two lineages of hematologic tumors: NB4, derived from acute promyelocytic leukemia (APL) and Granta-519 from mantle cell lymphoma (MCL). We also tested cells from 12 patients with acute myeloid leukemia (AML) and from 10 patients with chronic lymphocytic leukemia (CLL). HRP targeting was performed with anti-CD33 or anti-CD19 antibodies (depending on the origin of the cell), followed by incubation with goat anti-mouse antibody conjugated with HRP. Eight experimental groups were analyzed: control, HRP targeted, HRP targeted and incubated with 1, 5 and 10mM IAA, and cells not HRP targeted but incubated with 1, 5 and 10mM IAA. Apoptosis was analyzed by flow cytometry using annexin V-FITC and propidium iodide labeling. Results showed that apoptosis was dependent on the dose of IAA utilized, the duration of exposure to the prodrug and the origin of the neoplasia. Targeting HRP with antibodies was efficient in activating IAA and inducing apoptosis.

Segmental amplification of MLL gene associated with high expression of AURKA and AURKB genes in a case of acute monoblastic leukemia with complex karyotype.

We report a case of acute monoblastic leukemia showing a jumping translocation with the MLL gene in a 17-year-old male. Classic cytogenetic and spectral karyotyping revealed a complex karyotype, and fluorescence in situ hybridization (FISH) demonstrated amplification of the MLL gene followed by translocation to chromosomes 15q, 17q, and 19q. In addition, molecular analyses showed a high expression of AURKA and AURKB genes. It is already known that overexpression of Aurora kinases is associated with chromosomal instability and poor prognosis. The formation of jumping translocations is a rare cytogenetic event and there is evidence pointing toward preferential involvement of the heterochromatin region of donor chromosomes and the telomere ends of recipient chromosomes. Jumping translocation with the MLL gene rearrangement is an uncommon phenomenon reported in leukemia cytogenetics.

Monoclonal B-cell lymphocytosis in first-degree relatives of patients with sporadic (non-familial) chronic lymphocytic leukaemia.

Although biological similarities have been described among monoclonal B-cell lymphocytosis (MBL) and chronic lymphocytic leukaemia (CLL), the relationships between these two conditions are not fully understood, and new epidemiological studies in different populations and different countries continue to be reported. Here, we investigated 167 first-degree relatives from 42 families of patients with non-familial (sporadic) CLL, using four-colour flow cytometry. MBL was found in seven of 167 subjects (4.1%). Monoclonality was detected in all cases either by light-chain restriction or by polymerase chain reaction. Fluorescence in situ hybridization did not show any chromosomal abnormality. The prevalence of MBL according to age was 0 (0/54) in individuals aged less than 40 years, 2.5% (2/81) between 40 and 60 years, and 15.6% (5/32) in individuals over 60 years. The prevalence of MBL cases in individuals over 60 years was similar to that found in familial CLL relatives at the same age group. This suggests that in older first-degree relatives of patients with sporadic CLL, the risk of MBL detection is as high as in older first-degree relatives from CLL families, which could render these individuals belonging to 'sporadic CLL families' as susceptible as individuals from 'familial CLL' to the development of clinical CLL.

Constitutional hypomorphic telomerase mutations in patients with acute myeloid leukemia.

Loss-of-function mutations in telomerase complex genes can cause bone marrow failure, dyskeratosis congenita, and acquired aplastic anemia, both diseases that predispose to acute myeloid leukemia. Loss of telomerase function produces short telomeres, potentially resulting in chromosome recombination, end-to-end fusion, and recognition as damaged DNA. We investigated whether mutations in telomerase genes also occur in acute myeloid leukemia. We screened bone marrow samples from 133 consecutive patients with acute myeloid leukemia and 198 controls for variations in TERT and TERC genes. An additional 89 patients from a second cohort, selected based on cytogenetic status, and 528 controls were further examined for mutations. A third cohort of 372 patients and 384 controls were specifically tested for one TERT gene variant. In the first cohort, 11 patients carried missense TERT gene variants that were not present in controls (P < 0.0001); in the second cohort, TERT mutations were associated with trisomy 8 and inversion 16. Mutation germ-line origin was demonstrated in 5 patients from whom other tissues were available. Analysis of all 3 cohorts (n = 594) for the most common gene variant (A1062T) indicated a prevalence 3 times higher in patients than in controls (n = 1,110; P = 0.0009). Introduction of TERT mutants into telomerase-deficient cells resulted in loss of enzymatic activity by haploinsufficiency. Inherited mutations in TERT that reduce telomerase activity are risk factors for acute myeloid leukemia. We propose that short and dysfunctional telomeres limit normal stem cell proliferation and predispose for leukemia by selection of stem cells with defective DNA damage responses that are prone to genome instability.

The presence of CD56/CD16 in T-cell acute lymphoblastic leukaemia correlates with the expression of cytotoxic molecules and is associated with worse response to treatment.

Some cases of T-cell acute lymphoblastic leukaemia (ALL) express markers found in natural-killer (NK) cells, such as CD56 and CD16. Out of 84 T-cell ALL cases diagnosed at our Institution, CD56 and/or CD16 was detected in 24 (28.5%), which we designated T/NK-ALL group. Clinical features, laboratory characteristics, survival and expression of cytotoxic molecules were compared in T/NK-ALL and T-ALL patients. Significant differences were observed regarding age (24.9 vs. 16.4 years in T/NK-ALL and T-ALL, respectively, P = 0.006) and platelet counts (177 x 10(9)/l vs. 75 x 10(9)/l in T/NK-ALL and T-ALL, respectively, P = 0.03). Immunophenotypic analysis demonstrated that CD34, CD45RA and CD33 were more expressed in T/NK-ALL patients, whereas CD8 and terminal deoxynucleotidyl transferase were more expressed in T-ALL patients (P < 0.05). The mean overall survival (863 vs. 1869 d, P = 0.02) and disease-free survival (855 vs. 2095 d, P = 0.002) were shorter in patients expressing CD56/CD16. However, multivariate analysis identified CD56/CD16 as an independent prognostic factor only for DFS. Cytotoxic molecules were highly expressed in T/NK-ALL compared to T-ALL. Perforin, granzyme B and TIA-1 were detected in 12/17, 4/17 and 7/24 T/NK-ALL patients and in 1/20, 0/20 and 1/20 T-ALL respectively (P < 0.001, P = 0.036 and P = 0.054). Therefore, the presence of CD56/CD16 was associated with distinct clinical features and expression of cytotoxic molecules in the blasts.

Smudge cells in peripheral blood smears did not differentiate chronic lymphocytic leukemia from other B-cell chronic lymphoprolipherative diseases / Sombras nucleares no esfregaço do sangue periférico não diferenciam a leucemia linfocítica crônica das outras doenças linfoproliferativas B crônicas

Smudge cells has been classically associated with chronic lymphocytic leukemia (CLL), but they are found in peripheral blood tests for other chronic B-cell lymphoproliferative diseases (CLD). We investigated whether the percentage of smudge cells in peripheral blood smears can be used in the clinical practice to differentiate CLL from other B-cell CLD. The peripheral blood smears of 63 patients with the diagnosis of CLL and 62 with other B-cell CLD were analyzed. Three hundred cells (both lymphoid cells and smudge cells) were counted for each peripheral blood smear. A comparison of the percentage of smudge cells between the two groups was performed and, subsequently, 5 cut-off values were fixed (10 percent, 20 percent, 30 percent, 40 percent and 50 percent of smudge cells) with the aim of defining cases as "positive" or "negative" for smudge cells and verifying whether there are any differences between CLL and the other B-cell CLD. The percentage of smudge cells in patients with CLL (median 26 percent, 4 percent-86 percent) was higher than in patients with B-cell CLD (median 14 percent, 1 percent-64 percent). However, none of the cut-off values tested presented suitable values of sensitivity, specificity and positive predictive value to separate the two groups. As it is necessary to have a single cut-off value with high sensitivity, specificity and positive predictive value to infer the diagnosis of CLL in the clinical practice, we concluded that smudge cells are not fitting to differentiate CLL from other B-cell CLD.

As sombras nucleares têm sido classicamente associadasà leucemia linfocítica crônica (LLC), embora possam ser encontradas nos esfregaços do sangue periférico de outras doenças linfoproliferativas B crônicas (DLBC). Nesse estudo, nós investigamos se a porcentagem de sombras nucleares nos esfregaços do sangue periférico pode ser utilizada na prática clínica da hematologia para diferenciar a LLC das outras DLBC. Foram analisados os esfregaços do sangue periférico de 63 pacientes com o diagnóstico de LLC e 62 com outras DLPC. Trezentas células, entre células linfoides e sombras nucleares, foram contadas em cada esfregaço. A comparação da porcentagem de sombras nucleares entre os dois grupos foi realizada e, subsequentemente, foram fixados 5 cut-offs de mais de 10 por cento, 20 por cento, 30 por cento, 40 por cento e 50 por cento de sombras nucleares com o propósito de definir um caso como "positivo para sombras nucleares" e verificar se havia diferenças entre a LLC e as outras DLBC. A porcentagem das sombras nucleares em pacientes com LLC (mediana 26 por cento, 4 por cento-86 por cento) foi maior do que em pacientes com DLBC (mediana 14 por cento, 1 por cento-64 por cento). Entretanto, nenhum dos cut-offs testados apresentou valores apropriados de sensibilidade, especificidade e valor preditivo positivo para distinguir os dois grupos. Desde queé necessário se dispor de um único valor de cut-off com alta sensibilidade, especificidade e valor preditivo positivo para inferir o diagnóstico de CLL na prática clínica, conclui-se que as sombras nucleares não são úteis para diferenciar a LLC das outras DLBC.

The expression of DeltaNTP73, TATP73 and TP53 genes in acute myeloid leukaemia is associated with recurrent cytogenetic abnormalities and in vitro susceptibility to cytarabine cytotoxicity.

TP73 encodes for two proteins: full-length TAp73 and DeltaNp73, which have little transcriptional activity and exert dominant-negative function towards TP53 and TAp73. We compared TATP73 and DeltaNTP73 expression in acute myeloid leukaemia (AML) samples and normal CD34(+) progenitors. Both forms were more highly expressed in leukaemic cells. Amongst AML blasts, TATP73 was more expressed in AML harbouring the recurrent genetic abnormalities (RGA): PML-RARA, RUNX1-RUNX1T1 and CBFB-MYH11, whereas higher DeltaNTP73 expression was detected in non-RGA cases. TP53 expression did not vary according to DeltaNTP73/TATP73 expression ratio. Leukaemic cells with higher DeltaNTP73/TATP73 ratios were significantly more resistant to cytarabine-induced apoptosis.

SAGE analysis demonstrates increased expression of TOSO contributing to Fas-mediated resistance in CLL.

To identify novel genes involved in the molecular pathogenesis of chronic lymphocytic leukemia (CLL) we performed a serial analysis of gene expression (SAGE) in CLL cells, and compared this with healthy B cells (nCD19(+)). We found a high level of similarity among CLL subtypes, but a comparison of CLL versus nCD19(+) libraries revealed 55 genes that were over-represented and 49 genes that were down-regulated in CLL. A gene ontology analysis revealed that TOSO, which plays a functional role upstream of Fas extrinsic apoptosis pathway, was over-expressed in CLL cells. This finding was confirmed by real-time reverse transcription-polymerase chain reaction in 78 CLL and 12 nCD19(+) cases (P < .001). We validated expression using flow cytometry and tissue microarray and demonstrated a 5.6-fold increase of TOSO protein in circulating CLL cells (P = .013) and lymph nodes (P = .006). Our SAGE results have demonstrated that TOSO is a novel over-expressed antiapoptotic gene in CLL.

Determination of P-glycoprotein, MDR-related protein 1, breast cancer resistance protein, and lung-resistance protein expression in leukemic stem cells of acute myeloid leukemia.

BACKGROUND: The most primitive leukemic precursor in acute myeloid leukemia (AML) is thought to be the leukemic stem cell (LSC), which retains the properties of self-renewal and high proliferative capacity and quiescence of the hematopoietic stem cell. LSC seems to be immunophenotypically distinct and more resistant to chemotherapy than the more committed blasts. Considering that the multidrug resistance (MDR) constitutive expression may be a barrier to therapy in AML, we have investigated whether various MDR transporters were differentially expressed at the protein level by different leukemic subsets. METHODS: The relative expression of the drug-efflux pumps P-gp, MRP, LRP, and BCRP was evaluated by mean fluorescence index (MFI) and the Kolmogorov-Smirnov analysis (D values) in five leukemic subpopulations: CD34+CD38-CD123+ (LSCs), CD34+CD38+CD123-, CD34+CD38+CD123+, CD34+CD38+CD123-, and CD34- mature cells in 26 bone marrow samples of CD34+ AML cases. RESULTS: : The comparison between the two more immature subsets (LSC versus CD34+CD38-CD123- cells) revealed a higher P-gp, MRP, and LRP expression in LSCs. The comparative analysis between LSCs and subsets of intermediate maturation (CD34+CD38+) demonstrated the higher BCRP expression in the LSCs. In addition, P-gp expression was also significantly higher in the LSC compared to CD34+CD38+CD123- subpopulation. Finally, the comparative analysis between LSC and the most mature subset (CD34-) revealed higher MRP and LRP and lower P-gp expression in the LSCs. CONCLUSIONS: Considering the cellular heterogeneity of AML, the higher MDR transporters expression at the most immature, self-renewable, and quiescent LSC population reinforces that MDR is one of the mechanisms responsible for treatment failure.

Flow cytometry characterization of leukemic phase of nasal NK/T-cell lymphoma in tumor biopsies and peripheral blood.

We report the findings of the immunophenotypic profile of three cases of nasal T/NK cell lymphoma in leukemic phase. Flow cytometry analysis was carried out using cell suspensions of tumor nasal biopsies and peripheral blood. Tumor samples were composed by a mixture of a predominant subset of medium-size true NK cytCD3epsilon-, sCD3epsilon-, CD56+ cells mixed with a minor subset of medium-size T/NK sCD3epsilon+, CD56+ cells. Both subsets were also detected in peripheral blood. In addition, an infiltration of small-size sCD3epsilon+, CD56- normal T lymphocytes was also present.