Effect of cigarette smoke on mucosal vaccine response with activation of plasmacytoid dendritic cells: The outcomes of in vivo and in vitro experiments.

Mucosal vaccines offer several advantages over transdermal vaccines, including the ability to acquire systemic and mucosal immunities. Smoking is a huge public health threat and major risk factor for various diseases that exacerbate or prolong respiratory symptoms and conditions. However, its impact on the efficacy of mucosal vaccines remains partially explored. Thus, this study investigates the effects of smoking on mucosal vaccine reactivity by assessing the induction of Th1 immunity, a vital response in infection defense. Cigarette smoke condensate was prepared as a substitute for mainstream smoke. We intranasally administered diphtheria toxoid as an antigen and natural CpG oligonucleotide G9.1, which enhances the Th1-type antibody (Ab) response in a plasmacytoid dendritic cells (pDCs) dependent manner, as an adjuvant to mice to assess the effect of cigarette smoke condensate on Ab responses. The mechanism of its effect was evaluated using human peripheral blood mononuclear cells and their pDC-rich fraction cultured with or without G9.1. In mice, cigarette smoke condensate tended to decrease diphtheria toxoid-specific Ab response, with a higher reduction in Th1-type IgG2 Ab response than in Th2-type IgG1 Ab response. In human peripheral blood mononuclear cells, cigarette smoke condensate significantly reduced the induction of IFN-α production by G9.1. Moreover, G9.1-induced increases in the CD83 expression in pDCs and the CD80 expression in DCs were suppressed via treatment with cigarette smoke condensate. Among the mechanisms suggested were decreased expression of toll-like receptor 9 mRNA, decreased expression of mRNA for IFN regulatory factor 7, and increased CpG methylation of its promoter region. The analysis of Tbet and GATA3 expressions revealed that cigarette smoke condensate exhibits Th1-directed immunostimulatory activity at a steady state but becomes more Th2-directed under G9.1 stimulation. In conclusion, smoking could reduce mucosal vaccine responses by decreasing pDC activation and, consequently, Th1-dominant immunity.

Prospective clinical study of R-CMD therapy for indolent B cell lymphoma and mantle cell lymphoma from the Hokuriku Hematology Oncology Study Group.

Standardized treatments for indolent B cell lymphoma primarily consisting of follicular lymphoma (FL) and for mantle cell lymphoma (MCL) have yet to be established. Here the Hokuriku Hematology Oncology Study Group conducted a multicenter prospective study to investigate the efficacy and safety of a combination regimen of rituximab, cladribine, mitoxantrone, and dexamethasone (R-CMD) in indolent B cell lymphoma and MCL. A total of 33 CD20-positive patients who received care between January 2008 and August 2011 were investigated. These patients' illnesses were FL (n = 21), nodal marginal zone B cell lymphoma (NMZB, n = 3), MCL (n = 3), splenic marginal zone B cell lymphoma (n = 2), hairy cell leukemia (n = 1), Waldenstrom macroglobulinemia (WM, n = 1), and lymphoplasmacytic lymphoma (LPL, n = 2). Patients received four 21-day cycles of rituximab 375 mg/m(2) (day 1), cladribine 0.10 mg/kg (days 1-3), mitoxantrone 8 mg/m(2) (day 1), and dexamethasone 8 mg/body (days 1-3), with four additional rituximab doses at 4-week intervals. Of the 33 patients, 26 achieved complete response/unconfirmed complete response, and six achieved a partial response (4 with FL, 1 with NMZB, 1 with WM). One had progressive disease (FL), and four relapsed after remission (1 with FL, 2 with MCL, 1 with LPL). R-CMD therapy was relatively convenient and effective in indolent B cell lymphoma and MCL. Nonetheless, to suppress the number and function of both B cells and T cells, comprehensive infection prevention and follow-up are necessary in the future.

Reduced administration of rasburicase for tumor lysis syndrome: A single-institution experience.

In the present study, the dosage and duration of rasburicase administration were retrospectively evaluated for the ability to control the serum uric acid (S-UA) level in 13 patients diagnosed with hematological malignancies and tumor lysis syndrome (TLS), or those at risk of developing TLS, at the University of Fukui Hospital. At the time of diagnosis, seven patients already exhibited laboratory TLS, and three demonstrated clinical TLS. All patients received rasburicase in addition to chemotherapy agents. The median dose was 0.19 mg/kg (range, 0.13-0.25 mg/kg), and the median duration was four days (range, 1-7 days). Six patients sequentially received a xanthine oxidase inhibitor, allopurinol or febuxostat. The primary estimate was the normalization of the S-UA level at the end of rasburicase treatment and on treatment day seven. The average S-UA level prior to treatment was 10.4±4.5 mg/dl (mean ±standard deviation), and 11 out of 13 patients demonstrated a S-UA level >7 mg/dl. The S-UA level at the end of rasburicase administration was 0.5±1.5 mg/dl and the S-UA level at day seven was 1.4±1.5 mg/dl. All the patients achieved normalization of the S-UA level. On day seven subsequent to the initiation of treatment, the patients receiving rasburicase for a maximum of three days exhibited an S-UA level of 1.9±1.8 mg/dl, while the patients receiving rasburicase for longer than three days demonstrated an S-UA level of 1.0±1.3 mg/dl (P=0.20; Mann-Whitney test). The administration of 0.13 mg/kg and 0.22 mg/kg resulted in comparable UA level reductions. The administration of allopurinol or febuxostat following rasburicase administration suppressed the re-increase in S-UA level. Therefore, it was concluded that reduced administration of rasburicase successfully controlled the S-UA level in TLS.

Evaluation of staging and early response to chemotherapy with whole-body diffusion-weighted MRI in malignant lymphoma patients: A comparison with FDG-PET/CT.

BACKGROUND: To examine the utility of diffusion-weighted MRI (DW-MRI) for staging and early response to chemotherapy assessment in lymphoma patients as compared with fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). METHODS: Twenty-eight patients with histologically confirmed malignant lymphoma underwent both MRI and FDG-PET/CT before (pretreatment) and after two courses of chemotherapy (mid-treatment). Staging with MRI (DW-MRI alone and with T2-weighted images) and FDG-PET was compared visually, and the concordance rate (kappa value, κ) was calculated. To evaluate early response to chemotherapy, patients were divided into two groups, lesion-positive (LP) and lesion-negative (LN), based on a proposed original criterion. Progression-free survival (PFS) was compared between the groups using the Kaplan-Meier method. RESULTS: The stage diagnosed with DW-MRI alone and with FDG-PET/CT was concordant in 22 patients (κ = 0.71; P < 0.05), and by adding T2-weighted images, the number of concordant patients increased to 26 (κ = 0.90; P < 0.05). On mid-treatment imaging, 19 patients were diagnosed as LN from both modalities. PFS differed significantly between LP and LN on both DW-MRI (P = 0.0013) and FDG-PET/CT (P = 0.037). CONCLUSION: DW-MRI is a promising tool for staging and evaluation of early response to chemotherapy in patients with lymphoma.

Clinical usefulness of the PAXgene™ bone marrow RNA system for stabilizing total RNA.

The collection of clinical samples, such as bone marrow (BM) and peripheral blood, is an important procedure for the extraction of the cellular RNA. It is essential to preserve the extracted RNA during and after the collection of clinical samples to ensure the accurate analysis of gene expression. To date, the PAXgene™ Blood RNA System has been proven useful for stabilizing RNA extracted from peripheral blood; however, a problem concerning the stability of the total RNA stored using the system has been identified. The PAXgene™ Bone Marrow RNA System (BM system) is a newly developed system, and its clinical usefulness as a stabilizer for the cellular RNA in BM and peripheral blood was investigated with respect to the quality of RNA extracted using this system. A quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was carried out using total RNA extracted with the BM system, which showed that total RNA was more stable in the BM system than in the conventional system, indicating that the BM system can be applied to RT-PCR. The BM system enabled us to detect Wilms' tumor suppressor gene (WT1) more effectively than the conventional system. In conclusion, the BM system is clinically valuable for extracting and stabilizing total RNA of high quality.

The response to induction therapy is crucial for the treatment outcomes of elderly patients with acute myeloid leukemia: single-institution experience.

BACKGROUND/AIM: The prognosis of acute myeloid leukemia (AML) in elderly patients remains poor due to their poor general condition and the intrinsic chemotherapy-resistant nature of their leukemia cells. The present retrospective study evaluated the clinical background as well as the response to treatment, of an unselected group of elderly patients with AML who were admitted to our Institution over a period of six years. PATIENTS AND METHODS: Patients aged 65 years or older with AML admitted to our Institution between January 2005 and May 2011 were evaluated retrospectively. RESULTS: Forty-six patients were admitted to our Institution, among whom 41 received remission induction chemotherapy. Twenty-four patients received intensive chemotherapy, while 13 received low-dose cytarabine-based chemotherapy. Other modalities were used in four patients. Complete remission was obtained in 20 patients (48.8%). The complete remission rate (50.0%) tended to be higher in patients receiving intensive chemotherapy than in those receiving low-dose cytarabine-based regimens (30.7%; p=0.25). The median survival time for the whole patient group was 12 months and the 2-year overall survival was 18%. The median survival times for patients with complete remission and for non-responding patients were 14 months and 7 months, respectively. The 2-year overall survival in patients with complete remission was 32%, while that of non-responding patients was 6% (p=0.0025, log-rank test). CONCLUSION: The present study suggests the necessity of achieving complete remission for obtaining better survival for elderly patients with AML.

Controlling serum uric acid using febuxostat in cancer patients at risk of tumor lysis syndrome.

Tumor lysis syndrome (TLS) is a life-threatening oncological emergency, in which control of serum uric acid (S-UA) levels is important. S-UA-lowering efficacy of a new xanthine oxidase inhibitor, febuxostat, was retrospectively evaluated in seven patients with hematological malignancies who were at an intermediate risk of developing TLS. A 10-mg dose of febuxostat was initiated and chemotherapy was started within 24 h of administering the first dose of febuxostat. Febuxostat was continued until at least day 7 of chemotherapy treatment. The UA-lowering treatment was considered effective if febuxostat reduced S-UA levels to ≤7.5 mg/dl by day 5. The mean S-UA level at base line was 6.4±2.6 mg/dl and, on day 5, the mean S-UA level was 4.7±1.8 mg/dl. All the patients achieved S-UA levels ≤7.5 mg/dl. Serum creatinine levels decreased from 0.93±0.25 to 0.85±0.25 mg/dl. The estimated glomerular filtration rate values increased from 69.7±24.5 to 76.9±26.2 ml/min. No adverse reactions were noted during the study period and no patients experienced progressive TLS. Successful control of S-UA and improved renal function were obtained in response to febuxostat treatment in cancer patients at a risk of TLS.

A high serum uric acid level is associated with poor prognosis in patients with acute myeloid leukemia.

Uric acid in serum (S-UA) is produced by the breakdown of the cellular nucleic acids of leukemia cells, and may be a marker of disease aggressiveness. S-UA levels were examined for association with clinical outcomes in patients with acute myeloid leukemia (AML). Fifty-six patients with AML admitted to our Institution were evaluated retrospectively. The median S-UA level at diagnosis was 5.0 mg/dl (range 2-13.8 mg/dl). The S-UA levels did not correlate with peripheral lactate dehydrogenase, peripheral white blood cell counts, or peripheral blast counts, and were not proportional to bone marrow blast counts or marrow cellularity. The S-UA levels in the patients who achieved complete remission were slightly lower than those in those who did not. S-UA levels less than, or equal to the median (5.0 mg/dl) were significantly associated with better prognoses, compared with S-UA levels greater than 5.0 mg/dl. Thus, the S-UA level may predict the prognosis of AML, and is a versatile and cost-effective test for such a purpose.

Detectable Wilms' tumor-1 transcription at treatment completion is associated with poor prognosis of acute myeloid leukemia: a single institution's experience.

BACKGROUND/AIM: The present retrospective study was conducted to measure Wilms' tumor-1 (WT1) mRNA levels in the peripheral blood of patients with acute myeloid leukemia (AML) in order to examine any association with the clinical outcomes. PATIENTS AND METHODS: A total of 58 AML patients were evaluated retrospectively in our institution. WT1 transcripts were determined by real-time reverse transcriptase-polymerase chain reaction in peripheral blood samples. RESULTS: WT1 levels at diagnosis did not vary according to response of induction treatments, and the levels were comparable between the patients with durable remission and the patients with relapse of disease. WT1 levels at the completion of the treatment were higher in the group with relapse of disease than in the group with sustained remission. Detectable WT1 transcripts after the completion of chemotherapy courses were associated with poor prognoses. CONCLUSION: WT1 mRNA levels at treatment completion may predict for prognosis of AML.

Utility of PCR amplification and DNA microarray hybridization of 16S rDNA for rapid diagnosis of bacteremia associated with hematological diseases.

OBJECTIVES: The rapid diagnosis of bacteremia is crucial for patient management including the choice of antimicrobial therapy, especially in cases of hematological disease, because neutropenia occurs frequently during antineoplastic chemotherapy or disease progression. We describe a rapid detection and identification system that uses universal PCR primers to amplify a variable region of bacterial 16S ribosomal DNA (rDNA), followed by DNA microarray hybridization. METHODS: Probes for 72 microorganisms including most causal clinical pathogens were spotted onto a microarray plate. The DNA microarray and conventional methods of identification were applied to 335 cultures from patients with hematological diseases. RESULTS: Forty-one samples (12.2%) tested positive by conventional blood culture test in a few days, while 40 cases (11.9%) were identified by the new method within 24 h. The sensitivity and specificity of this new method were 93% and 99%, respectively, compared with conventional blood culture testing. CONCLUSIONS: PCR combined with a DNA microarray is useful for the management of febrile patients with hematological diseases.

Early relapse is associated with high serum soluble interleukin-2 receptor after the sixth cycle of R-CHOP chemotherapy in patients with advanced diffuse large B-cell lymphoma.

The clinical significance of serum soluble interleukin-2 receptor (sIL2R) levels was retrospectively assessed in patients with advanced diffuse large B-cell lymphoma (DLBCL). Twenty-one patients, who were newly-diagnosed with advanced DLBCL (stage III and IV) between 2006 and 2009, were evaluated. The median follow-up period was 37 months. All patients received 6-8 cycles of chemotherapy with rituximab in combination with doxorubicin, cyclophosphamide, vincristine, and prednisolone (CHOP)-like regimens and attained complete remission. Although all patients reached complete remission, six patients experienced disease relapse within 1 year after treatment completion. The overall survival was significantly poorer in patients with relapse than in patients with durable remission. The sIL2R levels after the sixth cycle of treatment were significantly higher in the relapse group than in the non-relapse group. Thus, the present study suggests sIL2R levels to be a valuable predictor for the prognosis of patients with advanced DLBCL.

Wilms' tumor-1 transcript in peripheral blood helps diagnose acute myeloid leukemia and myelodysplastic syndrome in patients with pancytopenia.

BACKGROUND/AIM: Pancytopenia is caused by acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), aplastic anemia (AA), or by non-hematological diseases. Because Wilms' tumor-1 (WT1) is overexpressed in patients with AML and MDS, its expression level may be helpful for diagnosing these hematological malignancies. PATIENTS AND METHODS: We retrospectively investigated the WT1 transcripts in peripheral blood (PB) from 47 patients with decreased blood cell counts. RESULTS: The final diagnoses included AML, MDS, AA, drug poisoning, and non-hematological diseases. PB WT1 mRNA was overexpressed in AML and MDS, whereas the patients with other diseases mostly tested negatively for the transcript. The patients with MDS with higher marrow blast counts had higher PB WT1 mRNA levels. The sensitivity of the PB WT1 transcript in detecting AML and MDS was 78%, and the specificity was 90%. CONCLUSION: The WT1 mRNA level in PB may help diagnose AML and MDS in patients with pancytopenia.

Induction of DNA strand breaks is critical to predict the cytotoxicity of gemtuzumab ozogamicin against leukemic cells.

Gemtuzumab ozogamicin (GO) consists of the CD33 antibody linked to calicheamicin. The binding of GO to the CD33 antigen on leukemic cells results in internalization followed by the release of calicheamicin, thereby inducing DNA strand breaks. We hypothesized that the induction of DNA strand breaks would be a surrogate marker of GO cytotoxcity. Here, two GO-resistant variants (HL/GO-CSA [225-fold], HL/GO [200-fold]) were established by serially incubating human leukemia HL-60 cells with GO with or without a P-glycoprotein (P-gp) inhibitor, cyclosporine A, respectively. The CD33 positivity was reduced in both variants. The HL/GO-CSA cells showed an increased multidrug resistance protein-1 (MRP1) transcript, and an MRP1 inhibitor partially reversed GO resistance. The HL/GO cells had neither P-gp nor MRP1 overexpression. Microarray analysis and Western blotting indicated elevated levels of DNA repair-associated proteins in both variants. Two other leukemic subclones, showing either P-gp or MRP1 overexpression, were also GO-resistant. Using single cell gel electrophoresis analysis, it was determined that GO-induced DNA strand breaks increased dose-dependently in HL-60 cells, whereas the number of breaks was reduced in the GO-resistant cell lines. The induction of DNA strand breaks was correlated with GO sensitivity among these cell lines. The CD33 positivity and the expression levels of transporters were not proportional to drug sensitivity. Using primary leukemic cells, the induction of DNA strand breaks appeared to be associated with GO sensitivity. Thus, GO-induced DNA strand breaks as the final output of the mechanism of action would be critical to predict GO cytotoxicity.

Marked upregulation of Survivin and Aurora-B kinase is associated with disease progression in the myelodysplastic syndromes.

BACKGROUND: Myelodysplastic syndromes are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis. Survivin is a member of the inhibitor of apoptosis family and suppresses apoptosis. Survivin also functions as a subunit of the chromosomal passenger complex for regulating mitosis with Aurora-B. Survivin and Aurora-B play an important role in maintaining genome stability. The aim of this study was to determine the role of Survivin and Aurora-B kinase in disease progression and prognosis of myelodysplastic syndromes. DESIGN AND METHODS: We evaluated the expression levels of these two genes in CD34(+) cells prepared from 64 patients with myelodysplastic syndrome or leukemic blasts from 50 patients with de novo acute myeloid leukemia using quantitative real-time PCR. RESULTS: Survivin and Aurora-B expression levels were highly correlated with the type of myelodysplastic syndrome, were much higher in refractory anemia with excess blasts-1, refractory anemia with excess blasts-2, and secondary acute myeloid leukemia following myelodysplastic syndrome than in normal control, and increased during disease progression. There was a significant correlation between these expression levels and the International Prognostic Scoring System. Interestingly, these levels were remarkably higher in patients with secondary acute myeloid leukemia following myelodysplastic syndromes than in those with de novo acute myeloid leukemia. CONCLUSIONS: This is the first report showing that high levels of Survivin and Aurora-B kinase expression in CD34(+) cells are distinctive molecular features of high-risk myelodysplastic syndromes and secondary acute myeloid leukemia following myelodysplastic syndrome. Marked upregulation of Survivin and Aurora-B kinase may contribute to genetic instability and disease progression of myelodysplastic syndromes. Our data may explain why patients with high-risk myelodysplastic syndromes frequently show complex chromosomal abnormality.

A randomized comparison of modified intermediate-dose Ara-C versus high-dose ara-c in post-remission therapy for acute myeloid leukemia.

BACKGROUND: We conducted a prospective, multicenter cooperative study to compare two courses of modified intermediate-dose cytarabine (Ara-C) (mIDAC; Ara-C at a dose of 1.0 g/m(2) every 12 hours for 5 days) versus high-dose Ara-C (HDAC; Ara-C at a dose of 2.0 g/m(2) every 12 hours for 5 days) in post-remission therapy for acute myeloid leukemia (AML) to confirm the post-remission antileukemic efficacy and safety of mIDAC. PATIENTS AND METHODS: Twenty-six newly diagnosed patients with AML underwent remission induction therapy consisted of behenoyl Ara-C, mitoxantrone, etoposide, and 6-mercaptopurine. Post-remission therapy included four courses of consolidation and four courses of intensification. Patients who achieved complete remission (CR) were randomly assigned to mIDAC or HDAC for the second course of consolidation. The third course of intensification was the same as the second course of consolidation. Other post-remission therapies were the same in each group. RESULTS: Twenty-two patients (84.6%) achieved CR and 21 patients were randomly assigned to receive either mIDAC (n=11) or HDAC (n=10). The predicted 4-year relapse-free survival for the mIDAC group and for the HDAC group were 49% and 56%, respectively (p=0.86). Although HDAC developed severe leukocytopenia compared to mIDAC, there were no significant differences between HDAC and mIDAC in the incidence of ≥grade 3 and ≥grade 4 documented infections. The mean lowest white blood cell count (WBC) after HDAC was significantly lower than that after mIDAC (0.208±0.120×10(3)/mm(3) and 0.459±0.333×10(3)/mm(3), respectively, p<0.05). The time to WBC recovery to 2.0×10(3)/mm(3) after HDAC was significantly longer than that after mIDAC (34.3±12.1 days and 27.1±9.5 days, respectively, p<0.05). CONCLUSION: This study suggests that mIDAC may have an equivalent post-remission antileukemic efficacy to HDAC with less myelosuppression for AML patients.

Clinical utility of the neutrophil distribution pattern obtained using the CELL-DYN SAPPHIRE hematology analyzer for the diagnosis of myelodysplastic syndrome.

We evaluated the diagnostic utility of peripheral blood neutrophil distribution patterns obtained using the CELL-DYN SAPPHIRE hematology analyzer in patients with myelodysplastic syndrome (MDS). Peripheral blood was obtained from 467 individuals including 32 patients with MDS, and the respective neutrophil distribution patterns were observed using two light scatters [7-degree complexity (7D) and 90-degree lobularity (90D)]. These scattering intensities are shown as median (median neutrophil distribution: MND) and coefficient of variation (neutrophil distribution width: NDW). Generally, MDS patients showed lower 7D MND, higher 7D NDW, lower 90D MND and higher 90D NDW than other comparable groups. Whereas 90D parameters were more diagnostically efficient than 7D ones in patients with MDS. The sensitivity and specificity of 90D MND for MDS patients became 78.1 and 78.9%, respectively (cut-off value = 14,514). 90D NDW was most diagnostically effective with 87.5% sensitivity and 91.0% specificity (cut-off value = 21.2%). Both 90D parameters showed no evident correlation with the degree of either leukocytopenia or peripheral blood dysgranulopoiesis. In conclusion, neutrophil distribution parameters, especially 90D NDW, appear to provide convenient and objective markers for the screening of patients with MDS in routine laboratory hematology.

Characterization of cytarabine-resistant leukemic cell lines established from five different blood cell lineages using gene expression and proteomic analyses.

Cytarabine (ara-C) is the key drug for treatment of acute myeloid leukemia. Since intracellular cytarabine triphosphate (ara-CTP) is an active metabolite of ara-C, factors that reduce the amount of ara-CTP are known to induce drug resistance. However, these factors do not fully explain the development of resistance to ara-C. The present study was conducted to search for new candidate ara-C resistance factors, including those that are unrelated to ara-CTP production. For this purpose, we newly established five ara-C-resistant leukemic clones from different blood cell lineage leukemic cell lines (HL-60, K562, CEM, THP1 and U937). The resistant subclones were 5-58-fold more ara-C-resistant than their parental counterparts. All of the ara-C-resistant subclones, except for ara-C-resistant CEM cells, displayed alteration of ara-CTP-related factors such as ara-C membrane transport capacity, deoxycytidine kinase activity or cytosolic nucleotidase II activity. To identify new candidate factors, we used two comprehensive approaches: DNA microarray and proteome analyses. The DNA microarray analysis revealed eight genes (C19orf2, HSPA8, LGALS1, POU4F3, PSAP, AKT1, MBC2 and CACNA2D3) that were altered in all five ara-C-resistant lines compared to parental cells. Both proteome and DNA microarray analyses further detected a reduced protein level of stathmin1 in the ara-C-resistant CEM subclone compared to its parental line. Thus, the present findings suggested the involvement of novel multiple mechanisms in mediating the ara-C resistance of leukemic cells. The role of some of these molecules in resistance is still unclear.

Glutathione S-transferase M1 inhibits dexamethasone-induced apoptosis in association with the suppression of Bim through dual mechanisms in a lymphoblastic leukemia cell line.

Glutathione S-transferase mu (GSTM1) is mainly known as a detoxification enzyme but it has also been shown to be a negative regulator of apoptosis-related signaling cascades. Recently GSTM1 has been reported to be a significant risk factor for hematological relapse in childhood acute lymphoblastic leukemia, although the underlying mechanism remains largely unknown. Glucocorticoids play a crucial role in the treatment of childhood acute lymphoblastic leukemia, therefore we hypothesized that GSTM1 plays important roles in glucocorticoid-induced apoptotic pathways. To clarify the relationship between GSTM1 and drug resistance, GSTM1 was transfected into a T-acute lymphoblastic leukemia cell line, CCRF-CEM (CEM), and we established the GSTM1-expressing cell lines CEM/M1-4 and CEM/M1-9. Transduction of GSTM1 into CEM selectively decreased cellular sensitivity to dexamethasone in a manner that was independent of glutathione conjugation, but was due to apoptosis inhibition. Dexamethasone-induced p38-MAPK and Bim activation were concomitantly suppressed. Interestingly, nuclear factor kappa b (NF-kappaB) p50 activity was upregulated in GSTM1-expressing CEM. Inhibition of NF-kappaB by the pharmacological agent BAY11-7082 greatly enhanced the sensitivity of the GSTM1-expressing CEM to dexamethasone and was accompanied by an increase in Bim expression. Thus, we propose that GSTM1, a novel regulator of dexamethasone-induced apoptosis, causes dexamethasone resistance by suppression of Bim through dual mechanisms of both downregulation of p38-MAPK and upregulation of NF-kappaB p50.

Intracellular cytarabine triphosphate production correlates to deoxycytidine kinase/cytosolic 5'-nucleotidase II expression ratio in primary acute myeloid leukemia cells.

Cytarabine (ara-C) is the key agent for treating acute myeloid leukemia (AML). After being transported into leukemic cells by human equilibrative nucleoside transporter 1 (hENT1), ara-C is phosphorylated to ara-C triphosphate (ara-CTP), an active metabolite, and then incorporated into DNA, thereby inhibiting DNA synthesis. Deoxycytidine kinase (dCK) and cytosolic 5'-nucleotidase II (cN-II) are associated with the production of ara-CTP. Because ara-C's cytotoxicity depends on ara-CTP production, parameters that are most related to ara-CTP formation would predict ara-C sensitivity and the clinical outcome of ara-C therapy. The present study focused on finding any correlation between the capacity to produce ara-CTP and ara-C-metabolizing factors. In vitro ara-CTP production, mRNA levels of hENT1, dCK, and cN-II, and ara-C sensitivity were evaluated in 34 blast samples from 33 leukemic patients including 26 with AML. A large degree of heterogeneity was seen in the capacity to produce ara-CTP and in mRNA levels of hENT1, dCK, and cN-II. Despite the lack of any association between each of the transcript levels and ara-CTP production, the ratio of dCK/cN-II transcript levels correlated significantly with the amount of ara-CTP among AML samples. The HL-60 cultured leukemia cell line and its three ara-C-resistant variants (HL-60/R1, HL-60/R2, HL-60/R3), which were 8-, 10-, and 500-fold more resistant than HL-60, respectively, were evaluated similarly. The dCK/cN-II ratio was again proportional to ara-CTP production and to ara-C sensitivity. The dCK/cN-II ratio may thus predict the capacity for ara-CTP production and ultimately, ara-C sensitivity in AML.