Genomic profiling of Acute lymphoblastic leukemia in ataxia telangiectasia patients reveals tight link between ATM mutations and chromothripsis.

Recent developments in sequencing technologies led to the discovery of a novel form of genomic instability, termed chromothripsis. This catastrophic genomic event, involved in tumorigenesis, is characterized by tens to hundreds of simultaneously acquired locally clustered rearrangements on one chromosome. We hypothesized that leukemias developing in individuals with Ataxia Telangiectasia, who are born with two mutated copies of the ATM gene, an essential guardian of genome stability, would show a higher prevalence of chromothripsis due to the associated defect in DNA double-strand break repair. Using whole-genome sequencing, fluorescence in situ hybridization and RNA sequencing, we characterized the genomic landscape of Acute Lymphoblastic Leukemia (ALL) arising in patients with Ataxia Telangiectasia. We detected a high frequency of chromothriptic events in these tumors, specifically on acrocentric chromosomes, as compared with tumors from individuals with other types of DNA repair syndromes (27 cases total, 10 with Ataxia Telangiectasia). Our data suggest that the genomic landscape of Ataxia Telangiectasia ALL is clearly distinct from that of sporadic ALL. Mechanistically, short telomeres and compromised DNA damage response in cells of Ataxia Telangiectasia patients may be linked with frequent chromothripsis. Furthermore, we show that ATM loss is associated with increased chromothripsis prevalence in additional tumor entities.

Identification and analysis of CXCR4-positive synovial sarcoma-initiating cells.

Synovial sarcoma accounts for almost 10% of all soft tissue sarcomas, and its prognosis is poor with 5-year survival rates at 36%. Thus, new treatments and therapeutic targets for synovial sarcoma are required. Tumor-initiating cells have been defined by the ability for self-renewal and multipotent differentiation, and they exhibit higher tumorigenic capacity, chemoresistance and radiation resistance, expecting to be a new therapeutic target. In synovial sarcoma, the presence of such stemness remains largely unclear; thus, we analyzed whether synovial sarcoma possessed tumor-initiating cells and explored specific markers, and we discovered that synovial sarcoma cell lines possessed heterogeneity by way of containing a sphere-forming subpopulation highly expressing NANOG, OCT4 and SOX2. By expression microarray analysis, CXCR4 was identified to be highly expressed in the sphere subpopulation and correlated with stem-cell-associated markers. Inhibition of CXCR4 suppressed the cell proliferation of synovial sarcoma cell lines in vitro. The tumor-initiating ability of CXCR4-positive cells was demonstrated by xenograft propagation assay. CXCR4-positive cells showed higher tumorigenicity than negative ones and possessed both self-renewal and multipotent differentiation ability. Immunohistochemical analysis of 39 specimens of synovial sarcoma patients revealed that CXCR4 strongly correlated with poor prognosis of synovial sarcoma. Thus, we conclude that CXCR4 is the marker of synovial sarcoma-initiating cells, a new biomarker for prognosis and a new potential therapeutic target.

High expression of EVI1 and MEL1 is a compelling poor prognostic marker of pediatric AML.

EVI1 and MEL1 are homolog genes whose transcriptional activations by chromosomal translocations are known in small subsets of leukemia. From gene expression profiling data of 130 Japanese pediatric acute myeloid leukemia (AML) patients, we found that EVI1 and MEL1 were overexpressed in ~30% of patients without obvious translocations of these gene loci, and that their high expression was significantly associated with inferior survival. High EVI1 expression was detected mainly in myelomonocytic-lineage (designated as e-M4/M5 subtype) leukemia with MLL rearrangements and in megakaryocytic-lineage (designated as e-M7 subtype) leukemia, and its prognostic association was observed in the e-M4/M5 subtype but not in the e-M7 subtype. On the other hand, high MEL1 expression was detected in myelocytic-lineage (designated as e-M0/M1/M2 subtype) and e-M4/M5 subtype leukemia without MLL rearrangements, and its prognostic association was independent from the subtypes. Because of their subtype-dependent and mutually exclusive expression, a combined evaluation of their high expression enabled a clear distinction of patients with inferior survival (P<0.00001 in event-free survival (EFS) and overall survival (OS)). This association was confirmed by quantitative reverse transcription PCR analysis of an independent cohort of 81 patients (P=0.00017 in EFS, P=0.00028 in OS). We propose that the combined estimation of EVI1 and MEL1 expression will be an effective method to predict the prognosis of pediatric AML.

Prognostic implications of CEBPA mutations in pediatric acute myeloid leukemia: a report from the Japanese Pediatric Leukemia/Lymphoma Study Group.

CCAAT/enhancer-binding protein alpha (CEBPA) mutations are a favorable prognostic factor in adult acute myeloid leukemia (AML) patients; however, few studies have examined their significance in pediatric AML patients. Here we examined the CEBPA mutation status and clinical outcomes of pediatric AML patients treated in the AML-05 study. We found that 47 (14.9%) of the 315 evaluable patients harbored mutations in CEBPA; 26 cases (8.3%) harbored a single mutation (CEBPA-single) and 21 (6.7%) harbored double or triple mutations (CEBPA-double). After excluding core-binding factor-AML cases, patients harboring CEBPA mutations showed better overall survival (OS; P=0.048), but not event-free survival (EFS; P=0.051), than wild-type patients. Multivariate analysis identified CEBPA-single and CEBPA-double as independent favorable prognostic factors for EFS in the total cohort (hazard ratio (HR): 0.47 and 0.33; P=0.02 and 0.01, respectively). CEBPA-double was also an independent favorable prognostic factor for OS (HR: 0.30; P=0.04). CEBPA-double remained an independent favorable factor for EFS (HR: 0.28; P=0.04) in the normal karyotype cohort. These results suggest that CEBPA mutations, particularly CEBPA-double, are an independent favorable prognostic factor in pediatric AML patients, which will have important implications for risk-stratified therapy.

Pharmacokinetic and pharmacodynamic investigation of irinotecan hydrochloride in pediatric patients with recurrent or progressive solid tumors.

OBJECTIVE: A multicenter Phase I/II study of Irinotecan hydrochloride (CPT-11; 40-45 mg/m(2)/dose) was conducted for the treatment of refractory pediatric solid tumors. The pharmacokinetics of CPT-11 and its metabolites were characterized using both traditional noncompartmental analysis and population pharmacokinetics using NONMEM VI; pharmacokinetic pharmacodynamic relationships of SN-38 with indices of toxicity were also evaluated. METHOD: 11 patients between 3 and 18 years were enrolled. Pharmacokinetic parameters and consideration of relevant covariates (performance status (PS), BSA, corrected body weight (CBW), exponent of 3/4 on weight, etc.) were evaluated. Relationships between pharmacokinetic parameters of SN-38 and percentage change from baseline in patient biochemical response data were investigated via regression analysis. RESULT: CPT-11 exhibited a mean clearance (CL) of 15.31 +/- 5.95 (l/h) (13.06 +/- 3.58 (l/hr/m(2))) and AUC(0-inf) of 3547.0 +/- 1406.5 (ng x h/ml); the AUC ratio of parent CPT-11 to SN-38 was 5.0%. Based on the population pharmacokinetic analysis, decreasing PS was significantly dependent on reduction in CL of CPT-11 (p < 0.001). The final model for CPT-11 are as follows: CL (l/h) = 1.31 x CBW(0.75) (omegaCL = 21.7%), Vss (l) = 2.66 x CBW (omegaVss = 21.2%), Vc (l) = 1.13 x CBW, inter-compartment CL (l/h) = 0.257 x CBW(0.75). Percentage changes of leucocyte and neutrophil count within a first month treatment were significantly correlated with Cmax of SN-38 (r = 0.78 and r = 0.74) and AUC0-2 of SN-38 (r = 0.73 and r = 0.73). CONCLUSION: Pharmacokinetic parameters were similar to results published in several past reports. An allometric scaling of CBW(0.75) would seem to provide a good index of dosage requirement of CPT-11 in pediatric patients.

Malignant transformation in craniopharyngioma after radiation therapy: a case report and review of the literature.

OBJECTIVE: Craniopharyngioma is a benign epithelial tumor that is thought to arise from the remnant of the Rathke pouch. Malignant transformation in craniopharyngioma is extremely rare. Herein, we report a case of malignant transformation in craniopharyngioma after radiation therapy. MATERIALS AND METHODS: Histopathological and immunohistochemical analyses were carried out for specimens of the suprasellar tumor (from three resections, with the third surgery performed after radiation therapy). RESULTS: The resected tumors from the first and second surgeries comprised islands of loosely cohesive aggregates of epithelial cells, so-called stellate reticulum. At the periphery of the nests, palisaded columnar epithelium was observed. Wet keratins were scattered, and few mitotic figures were seen. The third surgical specimen was composed of irregular large nests of basaloid cells that had large, round to oval nuclei with prominent nucleoli, and mitotic figures were frequently seen (21/10 high power fields). In the center of the nests, eosinophilic ghost cells, resembling wet keratin, were observed. Accordingly, the diagnosis of malignant transformation in craniopharyngioma was made. Immunohistochemical studies revealed that the p53 protein was over-expressed in the malignant component, whereas its expression was much lower in the benign component. CONCLUSIONS: Similar to the ten previously reported cases of malignant transformation in craniopharyngioma, the present case occurred after radiation therapy. p53 protein overexpression was also observed in the earlier cases of malignant craniopharyngioma as well as in the present case (6/6 cases). We concluded that radiation therapy and p53 mutations could be involved in malignant transformation in craniopharyngioma.

Negative regulatory effect of an oligodendrocytic bHLH factor OLIG2 on the astrocytic differentiation pathway.

In the developing vertebrate nervous system, multipotent neural stem cells produce both neurons and glia. OLIG2 is a basic helix-loop-helix transcription factor that plays critical roles in oligodendrocyte and motor neuron development; however, its role in astrocytic development remains elusive. In this study, we analyzed an effect of OLIG2 on cytokine-induced astrocytic differentiation from mouse telencephalic neuroepithelial cells. We show that the presence of OLIG2 protein leads to inhibition of the promoter activation of astrocyte-specific glial fibrillary acidic protein gene. We found that OLIG2 abolishes complex formation between a transcriptional coactivator p300 and a transcription factor, signal transducer and activator of transcription 3 (STAT3), which is activated by astrocytic differentiation-inducing cytokines, such as leukemia inhibitory factor (LIF). The enforced expression of OLIG2 in neuroepithelial cells inhibits the LIF-induced astrocytic differentiation. We also show that the OLIG2 protein in the nuclei of neural precursor cells disappears in accordance with astrocytic differentiation during culture with LIF. Together, these results reveal a novel molecular function of OLIG2 on the astrocyte development. Cell Death and Differentiation (2004) 11, 196-202. doi:10.1038/sj.cdd.4401332 Published online 24 October 2003

Inhibition of BMP2-induced, TAK1 kinase-mediated neurite outgrowth by Smad6 and Smad7.

BACKGROUND: BMP2 is known to play a wide variety of roles, including some in the development of the nervous system. This cytokine has been reported to induce neurite outgrowth in rat pheochromocytoma PC12 cells via the activation of a p38 MAP kinase, although its regulatory mechanism remains largely to be elucidated. RESULTS: BMP2-induced neurite outgrowth in PC12 cells was inhibited by the introduction of a kinase-negative form of a MAP kinase kinase kinase, TAK1, an upstream regulatory kinase for p38 kinase. Following BMP2 stimulation, the expression of Smad6 and Smad7, inhibitory Smad species that are known to inhibit the BMP2-restricted Smad species, Smad1, Smad5 and Smad8, was up-regulated. Unexpectedly, over-expression of either Smad6 or Smad7 in PC12 cells repressed the BMP2-induced neurite outgrowth and severely impeded the p38 kinase pathway. Both of these inhibitory Smads were found to interact physically with TAK1-binding protein, a molecule required for TAK1 activation. CONCLUSIONS: This study demonstrates that BMP2-induced neurite outgrowth in PC12 cells involves activation of the TAK1-p38 kinase pathway which is inhibited by Smad6 and Smad7.

DNA methylation is a critical cell-intrinsic determinant of astrocyte differentiation in the fetal brain.

Astrocyte differentiation, which occurs late in brain development, is largely dependent on the activation of a transcription factor, STAT3. We show that astrocytes, as judged by glial fibrillary acidic protein (GFAP) expression, never emerge from neuroepithelial cells on embryonic day (E) 11.5 even when STAT3 is activated, in contrast to E14.5 neuroepithelial cells. A CpG dinucleotide within a STAT3 binding element in the GFAP promoter is highly methylated in E11.5 neuroepithelial cells, but is demethylated in cells responsive to the STAT3 activation signal to express GFAP. This CpG methylation leads to inaccessibility of STAT3 to the binding element. We suggest that methylation of a cell type-specific gene promoter is a pivotal event in regulating lineage specification in the developing brain.

Prognostic impact of CD45 antigen expression in high-risk, childhood B-cell precursor acute lymphoblastic leukemia.

To evaluate the clinical implications of CD45 expression in acute childhood lymphoblastic leukemia (ALL), we measured the CD45 expression of blast cells from 133 untreated patients with childhood B-precursor ALL (n = 118) or T-ALL (n = 15). CD45 expression (> or = 20%) was detected in all 15 cases (100%) of T-ALL, and 101 cases (86%) of B-precursor ALL. In 122 cases, the fluorescence intensity of the CD45 expression was measured as a relative value; the ratio of average linear values (RALV) of CD45 on the blasts to that on CD3-positive T-lymphocytes from the same specimen. The expression was more intense in the T-ALL cases than in the B-precursor ALL cases (RALV, mean +/- SE: T-ALL 0.230 +/- 0.04 vs. pro-B ALL 0.150 +/- 0.012/pre-B ALL 0.153 +/- 0.019, p < 0.05). However, the intensity of the CD10, CD19, CD20 and CD34 antigen immunoreactivity did not correlate with the CD45 expression. Patients with hyperdiploidy (chromosome number > 50) showed significantly lower levels of CD45 expression than patients with t(1;19) or normal karyotypes (RALV, mean +/- SE: 0.081 +/- 0.022 vs. 0.133 +/- 0.03/0.143 +/- 0.019, p < 0.05). Other clinical features such as age, gender and WBC count did not correlate with CD45 expression. The prognostic implications of CD45 expression were studied in non-high-risk (low-risk + intermediate-risk) (n = 60) and high-risk patients (n = 52) with B-precursor ALL who had been treated with the risk-directed protocol of ALL-941 trial. Although CD45 expression did not correlate with the event-free survival (EFS) of the non-high-risk patients, there was a significant correlation between the expression levels and the EFS of the high-risk patients: the 3-year EFS rate of the CD45low group (n = 26, RALV = 0.017-0.132) was 88 +/- 7% versus the CD45high group (n = 26, RALV = 0.133-0.450) at 34 +/- 24% (p < 0.05). These results show that the levels of expression of the CD45 antigen on leukemic lymphoblasts are significantly correlated with the clinical features and prognosis of childhood ALL.

Endomucin is expressed in embryonic dorsal aorta and is able to inhibit cell adhesion.

Recent studies have suggested the existence of progenitors common to hematopoietic and endothelial cells, called hemangioblasts, in, for instance, embryonic dorsal aorta. To identify a membrane-bound or secretory molecule regulating early hematopoiesis, we screened a cDNA library from dorsal aortas of embryonic day (E) 10.5 mice by a signal sequence trap method and obtained a clone encoding a sialoprotein, endomucin-1. Immunohistochemistry revealed that the endomucin-1 transcript was specifically expressed in the endothelial cells of dorsal aorta of E10.5 mouse embryo. Overexpression of endomucin-1 strongly inhibited adhesion and aggregation of cells, including cultured endothelial cells from E10.5 dorsal aorta. These data suggest that endomucin-1 may play a role in detachment of hematopoietic cells from endothelium during early hematopoiesis.

Stereospecific 1,3-migration of an Fe(CO)3 group on acyclic conjugated polyenes: application to remote and iterative asymmetric induction.

The stereochemical outcome of the 1,3- and 1,5-migration of an Fe(CO)3 group on (acyclic polyene)Fe(CO)3 complexes and their application to stereoselective construction of remote and contiguous stereogenic centers are described. Treatment of the [(eta(4)-4-7)triene]Fe(CO)3 complexes 1a-d bearing an electron-withdrawing group on the terminal position of an uncomplexed olefin with a base such as KN(SiMe3)2 (KHMDS) and LiCH2CN induced the 1,3-migration reaction of the Fe(CO)3 group, giving the [(eta4-2-5)triene]Fe(CO)3 complexes 2a-d in moderate to good yields, depending on the electron-withdrawing groups. From an experiment using the chiral (trienenitril)Fe(CO)3 complex 5, it is revealed that the 1,3-migration proceeds with inversion of configuration. Similarly, the 1,5-migration reaction of the[(eta4-6-9)tetraenone]Fe(CO)3 complexes 9 occurred with a catalytic amount of KHMDS, giving the [(eta4-2-5)tetraenone]Fe(CO)3 complexes 10 with retention of configuration. Furthermore, we have succeeded in the first regio- and stereoselective nucleophilic substitution of the (3,5-diene-1,2-diol) Fe(CO)3 complexes (15 --> 24a-h) with various nucleophiles via the ortho esters 21. By using iterative manipulation of the above two reactions, remote stereocontrol of the terminal substituents on acyclic polyene (9 --> 12) and construction of contiguous stereogenic centers (19, 28) have been achieved.

Physiological rationale for responsiveness of mouse embryonic stem cells to gp130 cytokines.

Embryonic stem cells are established directly from the pluripotent epiblast of the preimplantation mouse embryo. Their derivation and propagation are dependent upon cytokine-stimulated activation of gp130 signal transduction. Embryonic stem cells maintain a close resemblance to epiblast in developmental potency and gene expression profile. The presumption of equivalence between embryonic stem cells and epiblast is challenged, however, by the finding that early embryogenesis can proceed in the absence of gp130. To explore this issue further, we have examined the capacity of gp130 mutant embryos to accommodate perturbation of normal developmental progression. Mouse embryos arrest at the late blastocyst stage when implantation is prevented. This process of diapause occurs naturally in lactating females or can be induced experimentally by removal of the ovaries. We report that gp130(-/-) embryos survive unimplanted in the uterus after ovariectomy but, in contrast to wild-type or heterozygous embryos, are subsequently unable to resume development. Inner cell masses explanted from gp130(-/-) delayed blastocysts produce only parietal endoderm, a derivative of the hypoblast. Intact mutant embryos show an absence of epiblast cells, and Hoechst staining and TUNEL analysis reveal a preceding increased incidence of cell death. These findings establish that gp130 signalling is essential for the prolonged maintenance of epiblast in vivo, which is commonly required of mouse embryos in the wild. We propose that the responsiveness of embryonic stem cells to gp130 signalling has its origin in this adaptive physiological function.

Sesquiterpene glucosides from anti-leukotriene B4 release fraction of Taraxacum officinale.

Chemical examination of the MeOH extract of the root of Taraxacum officinale, which exhibited inhibitory activity on the formation of leukotriene B4 from activated human neutrophils, has resulted in the isolation of 14-O-beta-D-glucosyl-11,13-dihydro-taraxinic acid (1) and 14-O-beta-D-glucosyl-taraxinic acid (2). The absolute stereostructure of 1 has been established by X-ray chrystallographic examination.

Astrocyte differentiation of fetal neuroepithelial cells involving cardiotrophin-1-induced activation of STAT3.

Cardiotrophin-1 (CT-1) belongs to the interleukin (IL-)6 family of cytokines that share membrane glycoprotein 130 (gp130) as a receptor component critical for signal transduction. We here observed that CT-1 was expressed in mouse fetal neuroepithelial cells, and was capable of inducing astrocyte differentiation from these cells in a synergistic manner with bone morphogenetic protein (BMP)-2, whose expression was also found in the fetal brain. CT-1-induced astrocyte differentiation was solely gp130-dependent. CT-1-stimulation led to promoter activation of the gene for an astrocyte marker, glial fibrillary acidic protein (GFAP), which was clearly inhibited by expression of a dominant negative form of a gp130-downstream transcription factor, signal transducer and activator of transcription 3(STAT3), or by introduction of a mutation in a single STAT3-binding site in the promoter, suggesting a critical role of STAT3 in the CT-1-induced GFAP transcription. These results suggest that astrocyte differentiation in the developing brain involves CT-1-signaling which cooperates with BMP2.

Interaction between DNA-cationic liposome complexes and erythrocytes is an important factor in systemic gene transfer via the intravenous route in mice: the role of the neutral helper lipid.

Recent studies have indicated that there are many barriers to successful systemic gene delivery via cationic lipid vectors using the intravenous route. The purpose of this study was to investigate the effect of binding and interaction between erythrocytes, a major constituent of blood cells, and the complexes, in relation to the role of the helper lipid, on the in vivo gene delivery to the lung following intravenous injection. We used three types of cationic lipid vectors, DNA-DOTMA/Chol liposome complexes, DNA-DOTMA liposome complexes, and DNA-DOTMA/DOPE liposome complexes. Although the three types of vectors bind to murine blood cells in vivo and in vitro, DOTMA/Chol and DOTMA complexes with a higher in vivo transfection activity do not induce fusion between erythrocytes, whereas DOTMA/DOPE complexes, a less efficient vector in vivo, induce fusion between the erythrocytes after a short incubation period. Pre-incubation of DOTMA/DOPE complexes with erythrocytes significantly reduced the transfection efficiency while DOTMA/Chol- and DOTMA complexes were more resistant to such treatment. The differences in the physicochemical and structural properties of these complexes could explain the differences in interaction with erythrocytes and subsequent gene expression. Lipids in DOTMA/Chol and DOTMA complexes have a stable lamellar structure. However, lipids in DOTMA/DOPE complexes have a highly curved structure with high fluidity. These results indicate that the interaction with erythrocytes depends on the properties of the cationic lipid vectors and this is an important factor for intravenous gene delivery using cationic lipid vectors.

Ligand recognition by the vitamin D receptor.

Three-dimensional structure of the ligand binding domain (LBD) of the vitamin D receptor (VDR) docked with the natural ligand 1 alpha,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] has been mostly solved by the X-ray crystallographic analysis of the deletion mutant (VDR-LBD Delta 165-215). The important focus, from now on, is how the VDR recognizes and interacts with potent synthetic ligands. We now report the docking models of the VDR with three functionally and structurally interesting ligands, 22-oxa-1,25-(OH)(2)D(3) (OCT), 20-epi-1,25-(OH)(2)D(3) and 20-epi-22-oxa-24,26,27-trihomo-1,25-(OH)(2)D(3). In parallel with the computational docking studies, we prepared twelve one-point mutants of amino acid residues lining the ligand binding pocket of the VDR and examined their transactivation potency induced by 1,25-(OH)(2)D(3) and these synthetic ligands. The results indicate that L233, R274, W286, H397 and Y401 are essential for holding the all ligands tested, S278 and Q400 are not important at all, and the importance of S237, V234, S275, C288 and H305 is variable depending on the side-chain structure of the ligands. Based on these studies, we suggested key structural factors to bestow the selective action on OCT and the augmented activities on 20-epi-ligands. Furthermore, the docking models coincided well with our proposed active space-region theory of vitamin D based on the conformational analyses of ligands.