Clinico-biological significance of suppressor of cytokine signaling 1 expression in acute myeloid leukemia.

Suppressor of cytokine signaling 1 (SOCS1) protein, which encodes a member of signal transducers and activators of transcription-induced inhibitors, takes part in a negative regulation of cytokine signaling. The mechanism of SOCS1 in tumor carcinogenesis is complex and there have been no studies concerning the clinic-biologic implication of SOCS1 expression in acute myeloid leukemia (AML). Here, we first identified that higher bone marrow (BM) SOCS1 expression was closely associated with older age, FLT3-ITD, NPM1 and DNMT3A mutations, but negatively correlated with CEBPA mutation in patients with de novo AML. Compared to patients with lower SOCS1 expression, those with higher expression had lower complete remission rates and shorter overall survival. Further, higher expression of SOCS1 in the BM was an independent unfavorable prognostic factor irrespective of age, white blood cell, cytogenetics and gene mutations. Next, we generated zebrafish model overexpressing SOCS1 by spi1 promoter, which showed kidney marrow from adult SOCS1 zebrafish had increased myelopoiesis, myeloid progenitors and the kidney or spleen structure were effaced and distorted, mimicking leukemia phenotype. The SOCS1/FLT3-ITD double transgenic fish could further facilitate the leukemic process. The results indicate SOCS1 plays an important role in AML and its higher expression serves as a new biomarker to risk-stratify AML patients.

Expression of CALR mutants causes mpl-dependent thrombocytosis in zebrafish.

CALR mutations are identified in about 30% of JAK2/MPL-unmutated myeloproliferative neoplasms (MPNs) including essential thrombocythemia (ET) and primary myelofibrosis. Although the molecular pathogenesis of CALR mutations leading to MPNs has been studied using in vitro cell lines models, how mutant CALR may affect developmental hematopoiesis remains unknown. Here we took advantage of the zebrafish model to examine the effects of mutant CALR on early hematopoiesis and model human CALR-mutated MPNs. We identified three zebrafish genes orthologous to human CALR, referred to as calr, calr3a and calr3b. The expression of CALR-del52 and CALR-ins5 mutants caused an increase in the hematopoietic stem/progenitor cells followed by thrombocytosis without affecting normal angiogenesis. The expression of CALR mutants also perturbed early developmental hematopoiesis in zebrafish. Importantly, morpholino knockdown of mpl but not epor or csf3r could significantly attenuate the effects of mutant CALR. Furthermore, the expression of mutant CALR caused jak-stat signaling activation in zebrafish that could be blocked by JAK inhibitors (ruxolitinib and fedratinib). These findings showed that mutant CALR activates jak-stat signaling through an mpl-dependent mechanism to mediate pathogenic thrombopoiesis in zebrafish, and illustrated that the signaling machinery related to mutant CALR tumorigenesis are conserved between human and zebrafish.

Genetic alterations and their clinical implications in older patients with acute myeloid leukemia.

A number of patient-specific and leukemia-associated factors are related to the poor outcome in older patients with acute myeloid leukemia (AML). However, comprehensive studies regarding the impact of genetic alterations in this group of patients are limited. In this study, we compared relevant mutations in 21 genes between AML patients aged 60 years or older and those younger and exposed their prognostic implications. Compared with the younger patients, the elderly had significantly higher incidences of PTPN11, NPM1, RUNX1, ASXL1, TET2, DNMT3A and TP53 mutations but a lower frequency of WT1 mutations. The older patients more frequently harbored one or more adverse genetic alterations. Multivariate analysis showed that DNMT3A and TP53 mutations were independent poor prognostic factors among the elderly, while NPM1 mutation in the absence of FLT3/ITD was an independent favorable prognostic factor. Furthermore, the status of mutations could well stratify older patients with intermediate-risk cytogenetics into three risk groups. In conclusion, older AML patients showed distinct genetic alterations from the younger group. Integration of cytogenetics and molecular mutations can better risk-stratify older AML patients. Development of novel therapies is needed to improve the outcome of older patients with poor prognosis under current treatment modalities.

Prognostic significance of NPM1 mutation-modulated microRNA-mRNA regulation in acute myeloid leukemia.

Distinct microRNA (miRNA) and mRNA signatures were reported in nucleophosmin (NPM1)-mutated acute myeloid leukemia (AML). However, it remains unknown whether the mutation participates in the dynamic interaction between miRNA and mRNA. In this study, we aimed to investigate the role of NPM1 mutation in modulating miRNA-mRNA regulation (MMR). From the sample-paired miRNA/mRNA microarrays of 181 de novo AML patients, we found that MMR was dynamic and could be affected by NPM1 mutation. By a systematic framework, we identified 493 NPM1 mutation-modulated MMR pairs, where the strength of MMR was significantly attenuated in patients carrying NPM1 mutations, compared to those with wild-type NPM1. These miRNAs/mRNAs were associated with pathways implicated in cancer and known functions of NPM1 mutation. Such modulation of MMR was validated in two independent cohorts as well as in cells with different NPM1 mutant burdens. Furthermore, we showed that the regulatory strength of nine MMR pairs could predict patients' outcomes. Combining these pairs, a scoring system was proposed and shown to predict survival in discovery and validation data sets, independent of other known prognostic factors. Our study provides novel biological insights into the role of NPM1 mutation as a modulator of MMR, based on which a novel prognostic marker is proposed in AML.

TP53 mutations in de novo acute myeloid leukemia patients: longitudinal follow-ups show the mutation is stable during disease evolution.

The TP53 mutation is frequently detected in acute myeloid leukemia (AML) patients with complex karyotype (CK), but the stability of this mutation during the clinical course remains unclear. In this study, TP53 mutations were identified in 7% of 500 patients with de novo AML and 58.8% of patients with CK. TP53 mutations were closely associated with older age, lower white blood cell (WBC) and platelet counts, FAB M6 subtype, unfavorable-risk cytogenetics and CK, but negatively associated with NPM1 mutation, FLT3/ITD and DNMT3A mutation. Multivariate analysis demonstrated that TP53 mutation was an independent poor prognostic factor for overall survival and disease-free survival among the total cohort and the subgroup of patients with CK. A scoring system incorporating TP53 mutation and nine other prognostic factors, including age, WBC counts, cytogenetics and gene mutations, into survival analysis proved to be very useful to stratify AML patients. Sequential study of 420 samples showed that TP53 mutations were stable during AML evolution, whereas the mutation was acquired only in 1 of the 126 TP53 wild-type patients when therapy-related AML originated from different clone emerged. In conclusion, TP53 mutations are associated with distinct clinic-biological features and poor prognosis in de novo AML patients and are rather stable during disease progression.

Dynamics of ASXL1 mutation and other associated genetic alterations during disease progression in patients with primary myelodysplastic syndrome.

Recently, mutations of the additional sex comb-like 1 (ASXL1) gene were identified in patients with myelodysplastic syndrome (MDS), but the interaction of this mutation with other genetic alterations and its dynamic changes during disease progression remain to be determined. In this study, ASXL1 mutations were identified in 106 (22.7%) of the 466 patients with primary MDS based on the French-American-British (FAB) classification and 62 (17.1%) of the 362 patients based on the World Health Organization (WHO) classification. ASXL1 mutation was closely associated with trisomy 8 and mutations of RUNX1, EZH2, IDH, NRAS, JAK2, SETBP1 and SRSF2, but was negatively associated with SF3B1 mutation. Most ASXL1-mutated patients (85%) had concurrent other gene mutations at diagnosis. ASXL1 mutation was an independent poor prognostic factor for survival. Sequential studies showed that the original ASXL1 mutation remained unchanged at disease progression in all 32 ASXL1-mutated patients but were frequently accompanied with acquisition of mutations of other genes, including RUNX1, NRAS, KRAS, SF3B1, SETBP1 and chromosomal evolution. On the other side, among the 80 ASXL1-wild patients, only one acquired ASXL1 mutation at leukemia transformation. In conclusion, ASXL1 mutations in association with other genetic alterations may have a role in the development of MDS but contribute little to disease progression.

Integration of cytogenetic and molecular alterations in risk stratification of 318 patients with de novo non-M3 acute myeloid leukemia.

Conventionally, acute myeloid leukemia (AML) patients are categorized into good-, intermediate- and poor-risk groups according to cytogenetic changes. However, patients with intermediate-risk cytogenetics represent a largely heterogeneous population regarding treatment response and clinical outcome. In this study, we integrated cytogenetics and molecular mutations in the analysis of 318 patients with de novo non-M3 AML who received standard chemotherapy. According to the mutation status of eight genes, including NPM1, CEBPA, IDH2, RUNX1, WT1, ASXL1, DNMT3A and FLT3, that had prognostic significance, 229 patients with intermediate-risk cytogenetics could be refinedly stratified into three groups with distinct prognosis (P<0.001); patients with good-risk genotypes had a favorable outcome (overall survival, OS, not reached) similar to those with good-risk cytogenetics, whereas those with poor-risk genotypes had an unfavorable prognosis (OS, 10 months) similar to those with poor-risk cytogenetics (OS, 13.5 months), and the remaining patients with other genotypes had an intermediate outcome (OS, 25 months). Integration of cytogenetic and molecular profiling could thus reduce the number of intermediate-risk AML patients from around three-fourth to one-fourth. In conclusion, integration of cytogenetic and molecular changes improves the prognostic stratification of AML patients, especially those with intermediate-risk cytogenetics, and may lead to better decision on therapeutic strategy.

Distinct association between aberrant methylation of Wnt inhibitors and genetic alterations in acute myeloid leukaemia.

BACKGROUND: Aberrant activation of Wnt signalling through hypermethylation of Wnt inhibitor genes is involved in several human malignancies, including acute myeloid leukaemia (AML). It remains unclear whether hypermethylation of Wnt inhibitors is associated with molecular gene mutations in the development of AML. METHODS: We investigated the association of the promoter hypermethylation of six Wnt inhibitors (Wif-1, SFRP1, SFRR2, SFRP4, SFRP5, and DKK1) with gene aberrations in the leukaemogenesis of 269 AML patients. RESULTS: In total, 166 patients (61.7%) had hypermethylation of at least one Wnt inhibitor. The majority (68.5%) of patients with Wnt inhibitor hypermethylation had concurrent Class II gene mutations that affect transcription factors or cofactors. There was a close association of Wif-1 hypermethylation with t(15;17) (P=0.0005) and CEBPA mutation (P<0.0001), DKK1 hypermethylation with t(8;21) (P<0.0001) and ASXL1 mutation (P=0.0078), SFRP-1 hypermethylation with t(8;21) (P<0.0001), SFRP-2 hypermethylation with AML1/RUNX1 mutation (P=0.0012), and SFRP-5 hypermethylation with MLL/PTD (P=0.0505). On the other side, hypermethylation of Wnt inhibitors was always negatively associated with NPM1 mutation and FLT3/ITD. CONCLUSION: There was distinct association between hypermethylation of individual Wnt inhibitors and specific gene aberrations, especially Class II mutations. The Wnt inhibitor hypermethylation might interact with genetic alterations in the leukaemogenesis.

Clinical and biological implications of partial tandem duplication of the MLL gene in acute myeloid leukemia without chromosomal abnormalities at 11q23.

The clinical and biological features of acute myeloid leukemia (AML) with 11q23/MLL translocations are well known, but the characteristics of AML with partial tandem duplication of the MLL gene have not been explored comprehensively. In this study, MLL duplication was analyzed, in 81 AML patients without chromosomal abnormalities at 11q23, using Southern blotting, genomic DNA polymerase chain reaction (PCR), reverse-transcription PCR and complementary DNA sequencing. Nine patients showed partial tandem duplication of the MLL gene, including eight (12%) of the 68 with normal karyotype. Seven patients showed fusion of exon 6/exon 2 (e6/e2), one, combination of differentially spliced transcripts e7/e2 and e6/e2, and the remaining one, combination of e8/e2 and e7/e2. Among the patients with normal karyotype, children aged 1 to 15 showed a trend to higher frequency of MLL duplication than other patients (2/5 or 40% vs 6/62 or 10%, P = 0.102). The patients with tandem duplication of the MLL gene had a significantly higher incidence of CD11b expression on leukemic cells than did those without in the subgroup of patients with normal karyotype (75% vs 28%, P = 0.017). There were no significant differences in the expression of lymphoid antigens or other myeloid antigens between the two groups of patients. In adults, the patients with MLL duplication had a shorter median survival time than those without (4.5 months vs 12 months, P = 0.036). In conclusion, partial tandem duplication of the MLL gene is associated with increased expression of CD11b on leukemic blasts and implicates poor prognosis in adult AML patients. The higher frequency of MLL duplication in children older than 1 year, than in other age groups, needs to be confirmed by further studies.

Incidence and predictors of isolated systolic hypertension and isolated diastolic hypertension in Taiwan.

BACKGROUND AND PURPOSE: The significance of isolated systolic hypertension (ISH) has been well documented, particularly in the elderly. However, isolated diastolic hypertension (IDH) has not been formally recognized as a unique hypertension entity. This study compared the ages of onset and characteristics of ISH and IDH. METHODS: The Cardiovascular Disease Risk Factors Two-Township Study (CVDFACTS) is an ongoing longitudinal study of the risk factors for and pathogenesis of cardiovascular disease in two Taiwanese townships, Chu-Dung (a Hakka community) and Pu-Tzu (a Fukienese community); participating patients were included in our study. Among the 3,357 subjects who were aged at least 20 years, free of hypertension, and had complete data at baseline, 2,374 subjects were followed. The average duration of follow-up was 3.23 years and the follow-up rate was 71%. Data regarding smoking, alcohol consumption, health and socioeconomic background, blood pressure, and body mass index were collected. Clinical and hemostatic profiles were assessed. RESULTS: ISH (systolic blood pressure, SBP > or = 140 mmHg and diastolic blood pressure, DBP < or = 90 mmHg) incidence increased with age in general (men: 0 per 1,000 person-years at age 20-34 yr, 1.9 at age 35-49, 14.3 at age 50-64, 40.9 at age 65-74, and 73.3 at age 75+ yr; women: 0 per 1,000 person-yr at age 20-34 yr, 3.6 at age 35-49, 17.8 at age 50-64, 64.9 9 at age 65-74, and 33.5 at age 75+ yr), but peak incidence of IDH (DBP > or = 90 mmHg and SBP < or = 140 mmHg) occurred between 35 and 49 years (men: 8.9 per 1,000 person-yr at age 20-34 yr, 14.5 at age 35-49, 12.3 at age 50-64, 2.7 at age 65-74, and 0 at age 75+ yr; women: 1.7 per 1,000 person-yr at age 20-34, 4.2 at age 35-49, 3.7 at age 50-64, 0 at age 65-74, and 0 at age 75+ yr). Significant predictors for ISH were older age (men: hazard ratio, HR = 8.25 at 45-64 yr and HR = 22.91 at 65+ yr; women: HR = 34.11 at 45-64 yr and HR = 97.98 at 65+ yr), diabetes (HR = 2.57) and elevated fibrinogen (HR = 1.49) in men, and shorter clotting time in women (HR = 1.23). Significant predictors for IDH were elevated body mass index (men: HR = 4.03; women: HR = 7.4), and higher glucose (HR = 1.46) and uric acid concentrations (HR = 1.94) in men. CONCLUSIONS: The results of this study indicate that ISH and IDH have different age incidence patterns and predictors, and suggest that the pathogenesis of ISH and IDH may be different.

Characterization of acute myeloid leukemia with MLL rearrangements--no increase in the incidence of coexpression of lymphoid-associated antigens on leukemic blasts.

MLL gene rearrangements are associated with coexpression of myeloid- and lymphoid-associated antigens on leukemic blasts and a dismal outcome in acute lymphoblastic leukemia (ALL). Whether the same conditions can apply to acute myeloid leukemia (AML) is not quite clear. Rearrangements of the MLL gene were analyzed on 113 patients with newly diagnosed de novo AML in a single institution. Sixteen (14%) of them showed rearranged bands by Southern blot analysis, including three (50%) of six infants, three (14%) of 21 children between 1 and 15 years and 10 (12%) of 86 adults. MLL rearrangements were not only detected in M5 (four of 12 patients, 33%) and M4 (six of 31, 19%) subtypes but also in other non-M4-M5 AML (six of 70, 9%), including M1, M2 and M7, but not M3 subtype. Seven patients had chromosomal abnormalities involving 11q23, but nine did not. The latter comprised three (6%) of 48 patients with normal karyotype, one with t(8;21), none with t(15;17), inv(16) or t(9;22), and four (15%) of 27 with cytogenetic aberrations other than those specific structural abnormalities. In contrast to ALL, AML patients with MLL rearrangements did not tend to coexpress lymphoid- and myeloid-associated antigens simultaneously on leukemic blasts and have similar outcome as those without the gene rearrangements.

Loading of DNA-binding factors to an erythroid enhancer.

The HS-40 enhancer is the major cis-acting regulatory element responsible for the developmental stage- and erythroid lineage-specific expression of the human alpha-like globin genes, the embryonic zeta and the adult alpha2/alpha/1. A model has been proposed in which competitive factor binding at one of the HS-40 motifs, 3'-NA, modulates the capability of HS-40 to activate the embryonic zeta-globin promoter. Furthermore, this modulation was thought to be mediated through configurational changes of the HS-40 enhanceosome during development. In this study, we have further investigated the molecular basis of this model. First, human erythroid K562 cells stably integrated with various HS-40 mutants cis linked to a human alpha-globin promoter-growth hormone hybrid gene were analyzed by genomic footprinting and expression analysis. By the assay, we demonstrate that factors bound at different motifs of HS-40 indeed act in concert to build a fully functional enhanceosome. Thus, modification of factor binding at a single motif could drastically change the configuration and function of the HS-40 enhanceosome. Second, a specific 1-bp, GC-->TA mutation in the 3'-NA motif of HS-40, 3'-NA(II), has been shown previously to cause significant derepression of the embryonic zeta-globin promoter activity in erythroid cells. This derepression was hypothesized to be regulated through competitive binding of different nuclear factors, in particular AP1 and NF-E2, to the 3'-NA motif. By gel mobility shift and transient cotransfection assays, we now show that 3'-NA(II) mutation completely abolishes the binding of small MafK homodimer. Surprisingly, NF-E2 as well as AP1 can still bind to the 3'-NA(II) sequence. The association constants of both NF-E2 and AP1 are similar to their interactions with the wild-type 3'-NA motif. However, the 3'-NA(II) mutation causes an approximately twofold reduction of the binding affinity of NF-E2 factor to the 3'-NA motif. This reduction of affinity could be accounted for by a twofold-higher rate of dissociation of the NF-E2-3'-NA(II) complex. Finally, we show by chromatin immunoprecipitation experiments that only binding of NF-E2, not AP1, could be detected in vivo in K562 cells around the HS-40 region. These data exclude a role for AP1 in the developmental regulation of the human alpha-globin locus via the 3'-NA motif of HS-40 in embryonic/fetal erythroid cells. Furthermore, extrapolation of the in vitro binding studies suggests that factors other than NF-E2, such as the small Maf homodimers, are likely involved in the regulation of the HS-40 function in vivo.

Self-assembly of the infectious bursal disease virus capsid protein, rVP2, expressed in insect cells and purification of immunogenic chimeric rVP2H particles by immobilized metal-ion affinity chromatography.

A gene encoding a structural protein (VP2) of a local strain (P3009) of infectious bursal disease virus (IBDV) was cloned and expressed using the baculovirus expression system to develop a subunit vaccine against IBDV infection in Taiwan. The expressed rVP2 proteins formed particles of approximately 20-30 nm in diameter. Those particles were partially purified employing sucrose density gradient ultracentrifugation, and the purified particles were recognized by a monoclonal antibody against the VP2 protein of IBDV P3009. To facilitate the purification of the particles, the VP2 protein was engineered to incorporate a metal ion binding site (His)(6 )at its C-terminus. The chimeric rVP2H proteins also formed particles, which could be affinity-purified in one step with immobilized metal ions (Ni(2+)). Particle formation was confirmed by direct observation under the electron microscope. The production level of rVP2H protein was determined to be 20 mg/L in a batch culture of Hi-5 cells by quantifying the concentration of the purified proteins. The chicken protection assay was performed to evaluate the immunogenicity of the rVP2H protein. When susceptible chickens were inoculated with the recombinant rVP2H proteins (40 microg/bird), virus-neutralizing antibodies were induced, thereby conferring a high level of protection against the challenge of a very virulent strain of IBDV. In conclusion, the most significant finding in this work is that both of the expressed rVP2 and rVP2H proteins can form a particulate structure capable of inducing a strong immunological response in a vaccinated chicken.