We investigated the relevance of signaling mechanisms regulated by the Ras-homologous GTPase Rac1 for survival of acute myeloid leukemia (AML) cells harbouring the MLL-AF9 oncogene due to t(9;11)(p21;q23) translocation. Monocytic MLL-AF9 expressing cells (MM6, THP-1) were hypersensitive to both small-molecule inhibitors targeting Rac1 (EHT 1864, NSC 23766) (IC50EHT ~12.5 μM) and lipid lowering drugs (lovastatin, atorvastatin) (IC50Lova ~7.5 μM) as compared to acute myelocytic leukemia (NOMO-1, HL60) and T cell leukemia (Jurkat) cells (IC50EHT >30 μM; IC50Lova >25 μM). Hypersensitivity of monocytic cells following Rac1 inhibition resulted from caspase-driven apoptosis as shown by profound activation of caspase-8,-9,-7,-3 and substantial (~90 %) decrease in protein expression of pro-survival factors (survivin, XIAP, p-Akt). Apoptotic death was preceded by S139-posphorylation of histone H2AX (γH2AX), a prototypical surrogate marker of DNA double-strand breaks (DSBs). Taken together, abrogation of Rac1 signaling causes DSBs in acute monocytic leukemia cells harbouring the MLL-AF9 oncogene, which, together with downregulation of survivin, XIAP and p-Akt, results in massive induction of caspase-driven apoptotic death. Apparently, Rac1 signaling is required for maintaining genetic stability and maintaining survival in specific subtypes of AML. Hence, targeting of Rac1 is considered a promising novel strategy to induce lethality in MLL-AF9 expressing AML.

Overall survival (OS) with acute myeloid leukemia (AML) remains poor. Determining prognostic factors will help in selecting patients for appropriate treatments. Our aim was to determine whether the level of drug-induced apoptosis (chemosensitivity) demonstrated by the microculture-kinetic drug-induced apoptosis (MiCK) assay significantly predicted outcomes after standard AML induction therapy. A total of 109 patients with untreated AML had blood and/or bone marrow aspirate samples analyzed for anthracycline-induced apoptosis using the MiCK assay. The amount of apoptosis observed over 48 h was determined and expressed as kinetic units of apoptosis (KU). Complete remission (CR) was significantly higher (72%) in patients with high idarubicin-induced apoptosis >3 KU compared to patients with apoptosis ≤ 3 KU (p = 0.01). Multivariate analysis showed the only significant variables to be idarubicin-induced apoptosis and karyotype. Median overall survival of patients with idarubicin-induced apoptosis >3 KU was 16.1 months compared to 4.5 months in patients with apoptosis ≤ 3 KU (p = 0.004). Multivariate analysis showed the only significant variable to be idarubicin-induced apoptosis. Chemotherapy-induced apoptosis measured by the MiCK assay demonstrated significant correlation with outcomes and appears predictive of complete remission and overall survival for patients receiving standard induction chemotherapy.

This study was purposed to detect the abnormal quantity and localization of pre-ALIP in bone marrow of acute myelocytic leukemia patients (AML) during the complete remission (CR) and investigate their correlation with AML relapse. The bone marrow biopsy and prognosis of 62 patients with CR were retrospectively analyzed. The bone marrow was divided into the pre-relapse group and the no-relapse group according to prognosis of patients. In order to clarify the correlation of abnormal quantity and localization of pre-ALIP with AML relapse, the number of single and double-cluster precursor cells and the sum of both were calculated, and their distance from bone trabeculae was surveyed with the computer image segment method. The results showed that the number of pre-ALIP in pre-relapse group (11 ± 11.71/mm(2)) and no-relapse group (8.33 ± 9.17/mm(2)) were more than that in normal control group (5.29 ± 4.00) (P < 0.01). The number of pre-ALIP more than 11/mm(2) was observed in 17 among all AML patients, and out of them 12 patients with pre-ALIP number >11/mm(2) (70.6) were found in the pre-relapse group, which was higher than that in no-relapse group (P < 0.05). While the distance between pre-ALIP and trabeculae [(341.31 ± 266.16) µm] in pre-relapse group showed the tendency of migrating to the intermediate zone of bone trabeculae, compared with that in no-relapse group [(242.41 ± 174.65) µm, P < 0.01]. Moreover, about 77.8 of 18 patients showed the distance of pre-ALIP from trabeculae was more than 341 µm in the pre-relapse group, and significantly higher than that in no-relapse group (P < 0.01). It is concluded that the average number of "pre-ALIP" more than 11/mm(2) or the average distance from trabeculae longer than 341 µm in bone marrow sections during CR may be the indicators for early relapse of AML.

BACKGORUND: Although increased serum levels of soluble interleukin-2 receptor (sIL-2R) and their clinical importance are well known in mature type lymphoproliferative disorders (LD), little data is available about such information in acute type hematological malignancies.We examined the serum levels of sIL-2R in 57 adult patients with acute type leukemias: 32 with acute myeloid leukemia (AML), 14 acute lymphoblastic leukemia (ALL) and 11 chronic myelocytic leukemia in blast crisis (CMLBC), and in 29 adult patients with mature type LD, and assessed their cellular and clinical relevance in acute type leukemias.No significant differences were seen in the sIL-2R levels between acute type leukemias and mature type LD. In AML, serum sIL-2R levels were related to the cell surface CD4 expression on blast cells, and patients with higher levels ≧2000U/ml had a poorer prognosis (lower response to chemotherapy and shorter overall survival).These results suggest that serum sIL-2R level elevates in acute type leukemias like mature type LD, and increased sIL-2R levels in adult AML are correlated with certain biological and clinical characteristics.

To evaluate the incidence and dose-dependency of mitoxantrone (MTX)-associated acute myelocytic leukemia (AML) in the network of Italian multiple sclerosis (MS) clinics.We performed a multicenter retrospective cohort study of patients treated with MTX in MS centers under the Italian national health care system between 1998 and 2008. Demographic, disease, treatment, and follow-up information were collected using hospital records.Data were available for 3,220 patients (63% women) from 40 Italian centers. Follow-up (mean ± SD) was 49 ± 29 months (range 12-140 months). We observed 30 cases of AML (incidence 0.93% [95% confidence interval 0.60%-1.26%]). The mean cumulative dose was higher in patients with AML (78 vs 65 mg/m(2), p = 0.028). The median interval from the start of therapy to AML diagnosis was longer than expected at 33 months (range 13-84 months); 8 patients (27%) developed AML 4 years or more after the first MTX infusion. The rate of mortality associated with AML was 37%.This higher than expected risk of AML and related mortality requires that treatment decisions must be made jointly between clinicians and patients who understand their prognosis, treatment options, and treatment-related risks. The now large exposed MS population must be monitored for hematologic abnormalities for at least 6 years from the end of therapy, to ensure the rapid actions needed for early diagnosis and treatment of AML.

The purpose of this study was to evaluate the clinical value of interphase fluorescence in situ hybridization (I-FISH) in diagnosis of core-binding factor acute myelocytic leukemia (CBF AML). The cytogenetic characteristics in leukemia cells from 82 cases of AML-M(2) and 43 cases of AML-M(4)/M(5) were detected by using I-FISH with AML1-ETO double color double fusion probe and double color break point isolated gene probe CBFβ-MYH11, and the detected results were compared with results detected by conventional cytogenetic R banding technique (CC). The results indicated that AML1-ETO fusion gene was detected in 30.5% cases (25/82) by FISH, and t(8;21)(q22;q22) karyotypic aberrations was found in 28.0% cases (23/82) by CC method. Among 25 FISH positive cases, typical FISH positive signal pattern (1R1G2F) was displayed in 22 cases and atypical signal pattern (1R2G1F and 2R1G2F) was found in the other 3 cases. Among all 43 AML-M(4)/M(5) cases, the CBFβ-MYH11 fusion gene was detected in 23.3% cases (10/43) by FISH, which sensitivity was significant higher than that by CC method (2/43) (p < 0.05). It is concluded that some insufficiency of CC technique can be compensated by FISH, and combination of I-FISH with CC technique play a crucial role in diagnosis of CBF AML and in monitoring of minimal residual disease.

Maternal smoking during pregnancy has been often implicated in the development of childhood leukemia with ambiguous results. Hence, we conducted a meta-analysis aiming to summarize current evidence and quantify any tentative impact.We retrieved one cohort (553 leukemias compared to 1,440,542 children), 20 case-control studies and also analyzed the updated Greek case-control dataset with unpublished data, yielding in total 11,092 cases and 25,221 controls.Odds ratios reported in the studies included ranged from 0.70 to 2.20 for acute lymphocytic (ALL) and from 0.60 to 2.17 for acute myelocytic leukemia (AML). The combined effect regarding the association of maternal smoking (any vs. no) and leukemia risk was 1.03 for ALL (95% CI = 0.95-1.12, random effects model) and 0.99 for AML (95% CI = 0.90-1.09, fixed effects model). The results remained unchanged when sensitivity analyses were undertaken of studies reporting same maternal smoking periods, those focusing only on childhood leukemia deaths or investigations which did not clearly define AML subtype.The findings of the meta-analysis challenge the limits of traditional epidemiology to provide sound inferences when point estimates of constituent studies range around the null. In particular, this study provides no support to a hypothesis linking maternal smoking during pregnancy with subsequent development of main childhood leukemia subtypes. Further investigations employing molecular and genetic epidemiology, however, might be needed in the hope to reveal even minimal risks pertaining individuals with specific susceptibility to tobacco compounds who sustain high environmental exposures prenatally or postnatally.

The IRF-1 protein, a mammalian transcriptional factor encoded by a gene located in 5q23-q31, has antioncogenic properties. Involved in regulation of differentiation and proliferation, IRF-1 acts as a tumor suppressor gene and is inactivated by deletion of its one or more exons (exon skipping) in many hematological malignancies, including acute myelocytic leukemia (AML) and myelodysplastic syndromes (MDS). DNA samples, extracted from peripheral blood, taken from 50 Kashmiri AML subjects, were analysed using the polymerase chain reaction and compared with examples of age and gender matched healthy controls from the same population. Three different exon regions (2, 3 and 4) of the IRF-1 gene that were previously shown to be prone to deletion were selected for amplification and analysis. Deletion was observed in 31(62%) out of 50 AML patients (p=0.016). Exon 3 was most frequently deleted (58%), followed by exon 2 (28%), while exon 4 was least affected (12%), providing insights into critical roles in leukemogenesis. The number of deleted exons was variable, but single exon deletions were more frequent (30%). Of interest, IRF-1 gene deletions were not observed in 19 (38%) patients. In our study, the frequency of deletions of these three exons was slightly higher than in an Indian population (52%), but lower than in Sweden in Europe (95%). This study also explored the prevalence and clinical profile of IRF-1 deletions in AML patients. Adults had a significantly higher incidence than children (p=0.0168) and IRF-1 deletions were associated with low Hb (p< 0.0001), high TLC (p=0.0033) and a low platelet count (p=0.0076).

We report the case of a 6-year-old boy diagnosed with acute promyelocytic leukemia (AML-M3V) when he presented with pallor, abdominal pain, anorexia, and fatigue. Induction chemotherapy was started according to the AML-BFM 98 protocol along with Vesanoid (ATRA, All-trans retinoic acid). On the sixth day of induction, he developed splenic and gallbladder infarcts. Splenectomy and cholecystectomy were performed while chemotherapy induction continued as scheduled. Four days later, he developed ischemic areas in the kidneys and ischemic colitis in the sigmoid colon. Hypercoagulation studies showed severe deficiency of protein C. Tests showed protein C 16% (reference range 70-140%), protein S 87% (reference range 70-140%), antithrombin III 122% (reference range 80-120%), prothrombin time 13.6 s (reference = 11.3), INR (international normalized ratio) 1.21, partial thromboplastin time 33 s (reference = 33), fibrinogen 214 mg/dl, D-dimer 970 μg/ml, factor II 98%, and that antinuclear antibody, antiphospholipid antibodies, mutation for factor II gene (G20210A), and mutation for Arg506 Gln of factor V were all negative (factor V Leiden). There was no evidence of clinical disseminated intravascular coagulation (DIC). He was treated with low molecular weight heparin and did well. He continues to be in complete remission 7 years later with normal protein C levels. Acquired protein C deficiency can occur in a variety of settings and has been reported in acute myelocytic leukemia. However, clinically significant thrombosis in the absence of clinical DIC, such as our case, remains extremely rare.

In many acute leukemias, normal differentiation does not occur. However, in many cell lines derived from hematologic malignancies, differentiation or programmed cell death (apoptosis) can be induced by variety of agents including: Vitamin analogs, demethylating agents, cyclic AMP analogs and anti-proliferative agents. To the best of our knowledge there has been not any study specifically to analyze apoptotic and anti-proliferative effects of 4-HPR (a vitamin analog) in NB-4 cell line. To test whether this drug has activity in acute myeloid leukemia (AML), we first analyzed the anti-proliferative effect of 4-HPR in one AML cell line (NB-4) using MTT Assay. Next we tested whether this drug induced apoptotic cell death. The ability of this compound to induce apoptosis of cancer cells was examined by Annexin V-FITC Assay using Flow cytometry. We also analyzed the cell cycle progression by PI staining using flow cytometry. Using MTT assay, NB-4 cells exhibited increased inhibition of proliferation at micromolar concentrations of 4-HPR at 24, 48 and 72 hrs post treatment. Flow cytometry analysis indicates that 4-HPR is a potent inducer of in vitro apoptotic cell death, and cell cycle analysis revealed an increase in S phase population. In total, the results indicate that 4-HPR is a strong inhibitor of AML cell proliferation and a potent inducer of in vitro apoptotic cell death. Further studies are required to evaluate the in vitro effects of 4-HPR in AML blasts derived from AML patients.