DYRK1A binds to an evolutionarily conserved WD40-repeat protein WDR68 and induces its nuclear translocation

DYRK1A is encoded in the Down's syndrome critical region on human chromosome 21, and plays an important role in the functional and developmental regulation of many types of cells, including neuronal cells. Here we have identified WDR68, an evolutionarily conserved protein with WD40-repeat domains, as a cellular binding partner of DYRK1A. WDR68 was originally identified in petunia as AN11 that controls the pigmentation of flowers by stimulating the transcription of anthocyanin biosynthetic genes. Experiments with RNA interference showed that WDR68 was indispensable for the optimal proliferation and survival of mammalian cultured cell, and WDR68 depletion induced cell apoptosis. DYRK1A and DYRK1B, but not DYRK2, DYRK3, or DYRK4, bound to endogenous and expressed WDR68. The N-terminal domain, but not the catalytic kinase domain or the C-terminal domain of DYRK1A, was responsible for the WDR68 binding. Deletions in the N-terminal or C-terminal region outside of the central WD40-repeats of WDR68 abolished its binding to DYRK1A, suggesting that WD40 repeats are not sufficient for the association with DYRK1A. Immunofluorescent staining revealed that WDR68 was distributed throughout the cell. Importantly, nuclear accumulation of WDR68 was observed upon co-expression of the wild type and a kinase-dead mutant of DYRK1A. Taken together, these results suggest that DYRK1A binds specifically to WDR68 in cells, and that the binding, but not the phosphorylation event, induces the nuclear translocation of WDR68.

Purity-enhanced bulk synthesis of thin single-wall carbon nanotubes using iron-copper catalysts

We report high purity and high yield synthesis of single-wall carbon nanotubes (SWCNTs) of narrow diameter from iron-copper bimetal catalysts. The SWCNTs with diameter of 0.8-1.2 nm are synthesized using the zeolite-supported alcohol chemical vapour deposition method. Single metal and bimetal catalysts are systematically investigated to achieve both the enhancement of SWCNT yield and the suppression of the undesired formation of graphitic impurities. The relative yield and purity of SWCNTs are quantified using optical absorption spectroscopy with an ultracentrifuge-based purification technique. For the single metal catalyst, iron shows the highest catalytic activity compared with the other metals such as cobalt, nickel, molybdenum, copper, and platinum. It has been found that the addition of copper to iron results in the suppression of carbonaceous impurity formation without decreasing the SWCNT yield. The purity-enhanced SWCNT shows fairly low sheet resistance due to the improvement of inter-nanotube contacts. This scalable design of SWCNT synthesis with enhanced purity is therefore a promising tool for shaping future high performance devices.

Stimulation of CK2-dependent Grp94 phosphorylation by the nuclear localization signal peptide

The nuclear localization signal sequence (NLS) of SV40 Large T antigen is essential and sufficient for the nuclear translocation of the protein. Phosphorylation often modulates the intracellular distribution of signaling proteins. In this study, we investigated effects of the NLS-peptide of Large T antigen on protein phosphorylation. When crude cell lysates were incubated with [γ-(32)P]ATP, phosphorylation of several endogenous substrates with molecular masses of 100, 80, 50, and 45 kDa by an endogenous kinase was stimulated by the addition of the wild type NLS-peptide (CPKKKRKVEDP). The mutated NLS-peptide (CPKTKRKVEDP) and the reversed NLS-peptide (PDEVKRKKKPC) are weak in the nuclear localization activity, and they only weakly stimulated phosphorylation of these substrates. The mobility of the 100 kDa phosphoprotein was indistinguishable with that of an endoplasmic reticulum (ER)-resident molecular chaperone glucose-regulated protein 94 (Grp94) belonging to the Hsp90 family, and purified Grp94 was phosphorylated by a kinase in cell lysates in an NLS-dependent fashion. The 100 kDa protein was identified as Grp94 by immunoprecipitation and reconstitution experiments. Purification of the NLS-dependent Grp94 kinase by sequential biochemical column chromatography steps resulted in isolation of two polypeptides with molecular masses of 42 and 27 kDa, which were identified as α and β subunit of protein kinase CK2, respectively, by western blotting analysis and biochemical characterization. Moreover, effect of an excess amount of GTP and V8 peptide mapping showed that the NLS-dependent Grp94 kinase in the cell lysate is identical with CK2. Surprisingly purified CK2 did phosphorylate Grp94 even without the NLS-peptide, suggesting that an additional suppressive factor is required for NLS-dependent phosphorylation of Grp94 by CK2. We suggest a possible general role for CK2-catalyzed phosphorylation in the regulation of NLS-dependent protein nuclear translocation.

The mTOR inhibitor, everolimus (RAD001), overcomes resistance to imatinib in quiescent Ph-positive acute lymphoblastic leukemia cells

In Ph-positive (Ph⁺) leukemia, the quiescent cell state is one of the reasons for resistance to the BCR-ABL-kinase inhibitor, imatinib. In order to examine the mechanisms of resistance due to quiescence and the effect of the mammalian target of rapamycin inhibitor, everolimus, for such a resistant population, we used Ph⁺ acute lymphoblastic leukemia patient cells serially xenotransplanted into NOD/SCID/IL2rγ^null (NOG) mice. Spleen cells from leukemic mice showed a higher percentage of slow-cycling G₀ cells in the CD34⁺CD38⁻ population compared with the CD34⁺CD38⁺ and CD34⁻ populations. After ex vivo imatinib treatment, more residual cells were observed in the CD34⁺CD38⁻ population than in the other populations. Although slow-cycling G₀ cells were insensitive to imatinib in spite of BCR-ABL and CrkL dephosphorylation, combination treatment with everolimus induced substantial cell death, including that of the CD34⁺CD38⁻ population, with p70-S6 K dephosphorylation and decrease of MCL-1 expression. The leukemic non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mouse system with the in vivo combination treatment with imatinib and everolimus showed a decrease of tumor burden including CD34⁺ cells. These results imply that treatment with everolimus can overcome resistance to imatinib in Ph⁺ leukemia due to quiescence.

The use of trastuzumab in Japanese patients with HER2-positive advanced or metastatic gastric cancer

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Background: The Trastuzumab for Gastric Cancer (ToGA) study showed the efficacy of trastuzumab for HER2-positive gastric cancer (HGA). The aim of this study is to evaluate the benefit of trastuzumab for Japanese HGA patients.

Methods: ToGA was an open-label, international, phase III, randomized controlled trial undertaken in 122 centers in 24 countries. Median overall survival (OS) was 13.8 months in those assigned to trastuzumab plus chemotherapy (C+T) compared with 11.1 months in those assigned to chemotherapy alone (C) with hazard (HR) ratio of 0.74. Subgroup analyses of patients enrolled from Japan were undertaken to estimate the hazard ratio (HR) for OS in the Japanese population. Based upon the prescribed protocol for Japan, we calculated HR using multiple Cox regression model with prespecified covariates in the ToGA study in order to make up for the small number of Japanese patients and reduce the bias in the baseline characteristics between two groups.

Results: Sixteen institutes participated and 102 patients were enrolled, of which 101 patients were evaluable for this research. The median OS was 15.9 months in C+T arm versus 17.7 months in C arm. The HR for OS was 1.00 [95% CI: 0.59-1.69]. However, the HR for OS adjusted for the above covariates was estimated to be 0.68 [95% CI: 0.36-1.27]. There were differences between C+T arm and C arm in some baseline characteristics. Higher frequencies were seen in C arm as follow: intestinal type, prior gastrectomy, and smaller number of metastatic sites. For HER2 status, the percentage of patients with IHC0/FISH+ was lower in C+T arm (5.9%) than in C arm (18.0%), while that of patients with HER2 status IHC2+/FISH+ was higher in C+T arm (35.3%) than in C arm (26.0%).

Conclusions: Although ToGA's overall OS HR = 0.74 (p = 0.0046), in the Japan patient subgroup, the unadjusted hazard ratio was 1.00. However, there was an imbalance of the baseline characteristics between the treatment arms in Japanese population. When adjusted for these characteristics, the HR was 0.68 which is similar to those in the ToGA study. Adding trastuzumab to chemotherapy in Japanese population appears to confer a similar magnitude of benefit compared to the whole population enrolled in the ToGA study.

[Table: see text]

Short disease-free interval is a significant risk factor for intrapulmonary recurrence after resection of pulmonary metastases in colorectal cancer

OBJECTIVE

Surgical resection has been the first choice of treatment for resectable pulmonary metastases from colorectal cancer. However, early intrapulmonary recurrence is often observed and appropriate assessment of prognostic factors is controversial. The aim of this study was to define the factors affecting survival and intrapulmonary recurrence after surgical treatment of metastatic pulmonary tumours from colorectal cancer.

METHOD

A retrospective analysis was performed of 56 consecutive patients who underwent pulmonary resection for colorectal metastases with a focus on prognostic factors and risk factors for intrapulmonary recurrence.

RESULTS

The overall 5-year survival rate was 48.2%. In a univariate analysis, a short disease-free interval (DFI), multiple pulmonary metastases and abnormal prethoracotomy carcinoembryonic antigen (CEA) levels were poor prognostic factors. In a multivariate analysis, a short DFI and abnormal prethoracotomy CEA levels were independent prognostic factors. Twenty-two (39.3%) of the 56 patients had recurrences in the remnant lung after resection for pulmonary metastases, and 8 (36.4%) of these 22 patients underwent repeated pulmonary resections. The median DFI between first and second lung metastasis was 13 months. Univariate analyses revealed that multiple and bilateral lung metastases were risk factors for intrapulmonary recurrence. There was also a strong correlation between the DFI for intrapulmonary recurrence after the first pulmonary resection and the DFI for first pulmonary metastases.

CONCLUSIONS

A short DFI was a risk factor for early tumour recurrence after resection for pulmonary metastases. The DFI might reflect oncological characteristics such as the tumour doubling time in colorectal cancer.

Phase II study of S-1 plus leucovorin in patients with metastatic colorectal cancer

BACKGROUND

S-1, a novel oral fluoropyrimidine, is well tolerated in patients with metastatic colorectal cancer (mCRC). The response rate of S-1 for colorectal cancer is high, ranging from 35% to 40%. This study aimed to evaluate the safety and efficacy of S-1 combined with oral leucovorin (LV) to enhance antitumor activity in chemotherapy-naive patients with mCRC.

PATIENTS AND METHODS

S-1 was given orally twice daily for two consecutive weeks at a daily dose of 80-120 mg, followed by a 2-week rest period, within a 4-week cycle. LV was given orally twice a day at a daily dose of 50 mg, simultaneously with S-1.

RESULTS

Of the 56 patients with previously untreated mCRC, 32 (57%) had partial responses. The median follow-up period was 27.2 months. The median time to progression was 6.7 months (95% confidence interval 5.4-7.9). The median survival time was 24.3 months. There was no treatment-related death or grade 4 toxicity. The most common grade 3 toxic effects were diarrhea (32%), anorexia (21%), stomatitis (20%), and neutropenia (14%).

CONCLUSION

S-1 combined with LV therapy demonstrated promising efficacy and acceptable safety in chemotherapy-naive patients with mCRC without the concurrent use of irinotecan, oxaliplatin, or molecular-targeted drugs.

Involvement of the protein kinase CK2 in the regulation of mammalian circadian rhythms

Posttranslational modifications of clock proteins are crucial to generating proper circadian rhythms of the correct length and amplitude. Here, we show that the protein kinase CK2 (casein kinase 2) plays a role in regulating the mammalian circadian clock. We found that inhibiting CK2 activity resulted in a decrease in the amplitude and an increase in the period of oscillations in circadian gene expression. CK2 specifically bound and phosphorylated PERIOD2 (PER2) and collaborated with the protein kinase CKIepsilon to promote PER2 degradation. We also identified a CK2 phosphorylation site (serine-53) in PER2, whose phosphorylation played a role in fine-tuning circadian rhythms and regulating PER2 stability but was dispensable for the cooperative effect of CK2 and CKIepsilon. Thus, our study identifies CK2 as a regulatory element of mammalian circadian rhythms and uncovers a role for CK2 in PER2 degradation.

Protein kinase CK2 in health and disease: CK2: the kinase controlling the Hsp90 chaperone machinery

CK2 is a ubiquitous and essential protein kinase with pleiotropic substrates and function, but it remains unclear how, when, and where CK2 activity is regulated in cells. Hsp90 is a major molecular chaperone that is required for the folding and function of its client proteins. A complex containing Hsp90 and its client protein includes co-chaperones such as steroid hormone receptor-specific FKBP52 and signaling kinase-specific Cdc37. Co-chaperones work cooperatively with Hsp90 to stabilize client proteins and to keep them in a conformation amenable to activation under appropriate conditions. In this review, critical roles of CK2 in the regulation of the Hsp90-mediated chaperone system are described. CK2 phosphorylates and modulates Hsp90 and its co-chaperones FKBP52 and Cdc37. CK2-dependent phosphorylation of Cdc37 is essential for the chaperoning function of Hsp90-Cdc37 for multiple signaling protein kinases. The tumor kinome appears to become addicted to the Hsp90-Cdc37 chaperone system, thus, targeting Hsp90, Cdc37, and CK2 is a promising strategy for cancer treatment.

Upgrade of the analyzer design for multipoint measurements by a gold neutral beam probe on the GAMMA 10 tandem mirror

The study of the mechanisms of both transport and fluctuations is one of the main issues of fusion plasma researches. Spatial fluctuation structure measurements are important for studying of cross correlation between the two fluctuations. Gold neutral beam probe systems are used in GAMMA 10 tandem mirror plasma device. Currently, the plasma potential and its fluctuations cannot be measured at different radial positions simultaneously. This paper presents the upgrade design of the 45 degrees electrostatic energy analyzer for the simultaneous multipoint measurements of plasma parameters.

Study of radial potential fluctuations by using a gold neutral beam probe system

A study of fluctuation is one of the main issues in fusion plasma researches. The potential and its fluctuation are measured by a gold neutral beam probe (GNBP) in the tandem mirror GAMMA10. Since there is no stable isotope ((197)Au approximately 100%), there are little measurement errors. GNBP system can measure the potential with about +/-30 V of error. The time and spatial resolutions are estimated to be about 3 micros and 5 mm, respectively. During the formation of axial confining potentials, the radial profiles of the potential and its fluctuation were successfully measured in GAMMA10. GNBP is a useful tool for the study of radial potential fluctuation directly in plasmas.

Radial density profile measurement by using the multichannel microwave interferometer in GAMMA 10

Plasma density radial profile measurements are an important study for fusion plasma researches. We reconstructed a multichannel microwave interferometer for radial plasma electron density and density fluctuation measurements with both changing the transmission horn position and using the Teflon lens by only using this system in a single plasma shot. By using this system, we can successfully measure the radial density and density fluctuation spectra in a single plasma shot.

Evaluating CK2 activity with the antibody specific for the CK2-phosphorylated form of a kinase-targeting cochaperone Cdc37

CK2-dependent phosphorylation of a kinase-specific Hsp90 co-chaperone Cdc37 on a conserved serine residue (Ser13) is essential for the function of Cdc37 [Bandhakavi S. et al. J. Biol. Chem. 278:2829-2836, 2003; Shao J. et al. J. Biol. Chem. 278:38117-38220, 2003; Miyata Y., & Nishida E. Mol. Cell. Biol. 24:4065-4074, 2004]. We have recently produced an anti-[pSer13]-Cdc37 antibody which specifically recognizes Cdc37 that is phosphorylated on Ser 13 [Miyata Y. & Nishida E. FEBS J. 274:5690-5703, 2007]. Here we investigated CK2 activity both in vitro and in cultured cells by using anti-[pSer13]-Cdc37 antibody. Immunoblotting with this antibody showed that heparin and 4,5,6,7-tetrabromobenzotriazole (TBB), known CK2 inhibitors, inhibited in vitro phosphorylation of Cdc37 on Ser13 by CK2 holoenzyme or CK2alpha, confirming the specificity of the antibody to detect CK2 activity. Treatment of cells with TBB resulted in the decrease in the phosphorylation level of endogenous Cdc37 on Ser13, as revealed by anti-[pSer13]-Cdc37, and overexpression of either CK2alpha or CK2beta subunit enhanced the Cdc37 phosphorylation level. While CK2 is suggested to be involved in cell proliferation, mitogenic stimulation of starved cells by fresh serum or insulin-like growth factor-I did not enhance phosphorylation of Cdc37 on Ser13. CK2 inhibitors are known to induce cell apoptosis, suggesting a reverse correlation between cell apoptosis and CK2 activity. However, cellular apoptotic stresses, such as anisomycin treatment and UV irradiation, were found to rather modestly increase phosphorylation of Cdc37 on Ser13. These results show that the anti-[pSer13]-Cdc37 antibody can be a promising new tool to evaluate in vivo CK2 activity.

RNA editing in the anticodon of tRNA Leu (CAA) occurs before group I intron splicing in plastids of a moss Takakia lepidozioides S. Hatt. & Inoue

RNA editing of cytidine (C) to uridine (U) transitions occurs in plastids and mitochondria of most land plants. In this study, we amplified and sequenced the group I intron-containing tRNA Leu gene, trnL-CAA, from Takakia lepidozioides, a moss. DNA sequence analysis revealed that the T. lepidozioides tRNA Leu gene consisted of a 35-bp 5' exon, a 469-bp group I intron and a 50-bp 3' exon. The intron was inserted between the first and second position of the tRNA Leu anticodon. In general, plastid tRNA Leu genes with a group I intron code for a TAA anticodon in most land plants. This strongly suggests that the first nucleotide of the CAA anticodon could be edited in T. lepidozioides plastids. To investigate this possibility, we analysed cDNAs derived from the trnL-CAA transcripts. We demonstrated that the first nucleotide C of the anticodon was edited to create a canonical UAA anticodon in T. lepidozioides plastids. cDNA sequencing analyses of the spliced or unspliced tRNA Leu transcripts revealed that, while the spliced tRNA was completely edited, editing in the unspliced tRNAs were only partial. This is the first experimental evidence that the anticodon editing of tRNA occurs before RNA splicing in plastids. This suggests that this editing is a prerequisite to splicing of pre-tRNA Leu.

Heat shock transcription factor 1 is required for maintenance of ciliary beating in mice

Heat shock transcription factors (HSFs) maintain protein homeostasis through regulating expression of heat shock proteins, especially in stressed conditions. In addition, HSFs are involved in cellular differentiation and development by regulating development-related genes, as well as heat shock genes. Here, we showed chronic sinusitis and mild hydrocephalus in postnatal HSF1-null mice, which are associated with impaired mucociliary clearance and cerebrospinal flow, respectively. Analysis of ciliary beating revealed that the amplitude of the beating was significantly reduced, and ciliary beat frequencies were lower in the respiratory epithelium, ependymal cells, oviduct, and trachea of HSF1-null mice than those of wild-type mice. Cilia possess a common axonema structure composed of microtubules of alpha- and beta-tubulin. We found a marked reduction in alpha- and ciliary betaiv-tubulin in the HSF1-null cilia, which is developmentally associated with reduced Hsp90 expression in HSF1-null mice. Treatment of the respiratory epithelium with geldanamycin resulted in rapid reduction of ciliary beating in a dose-dependent manner. Furthermore, Hsp90 was physically associated with ciliary betaiv-tubulin, and Hsp90 stabilizes tubulin polymerization in vitro. These results indicate that HSF1 is required to maintain ciliary beating in postnatal mice, probably by regulating constitutive expression of Hsp90 that is important for tubulin polymerization.

Analysis of the CK2-dependent phosphorylation of serine 13 in Cdc37 using a phospho-specific antibody and phospho-affinity gel electrophoresis

The CK2-dependent phosphorylation of Ser13 in cell division cycle protein 37 (Cdc37), a kinase-specific heat shock protein 90 (Hsp90) cochaperone, has previously been reported to be essential for the association of Cdc37 with signaling protein kinases [Bandhakavi S, McCann RO, Hanna DE & Glover CVC (2003) J Biol Chem278, 2829-2836; Shao J, Prince T, Hartson SD & Matts RL (2003) J Biol Chem278, 38117-38220; Miyata Y & Nishida E (2004) Mol Cell Biol24, 4065-4074]. Here we describe a new phospho-specific antibody against Cdc37 that recognizes recombinant purified Cdc37 only when incubated with CK2 in the presence of Mg(2+) and ATP. The replacement of Ser13 in Cdc37 by nonphosphorylatable amino acids abolished binding to this antibody. The antibody was specific for phosphorylated Cdc37 and did not crossreact with other CK2 substrates such as Hsp90 and FK506-binding protein 52. Using this antibody, we showed that complexes of Hsp90 with its client signaling kinases, Cdk4, MOK, v-Src, and Raf1, contained the CK2-phosphorylated form of Cdc37 in vivo. Immunofluorescent staining showed that Hsp90 and the phosphorylated form of Cdc37 accumulated in epidermal growth factor-induced membrane ruffles. We further characterized the phosphorylation of Cdc37 using phospho-affinity gel electrophoresis. Our analyses demonstrated that the CK2-dependent phosphorylation of Cdc37 on Ser13 caused a specific gel mobility shift, and that Cdc37 in the complexes between Hsp90 and its client signaling protein kinases was in the phosphorylated form. Our results show the physiological importance of CK2-dependent Cdc37 phosphorylation and the usefulness of phospho-affinity gel electrophoresis in protein phosphorylation analysis.

A phase II study of chemoradiotherapy in patients with stage II, III esophageal squamous cell carcinoma (ESCC): (JCOG 9906)

15137

Background: The study objective was to evaluate the efficacy and toxicity of chemoradiotherapy (CRT) with cisplatin and 5- fluorouracil (5FU) in patients with stage II, III ESCC. Methods: Patients with clinical stage II or III (T1N1 or T2–3N0–1 and M0) thoracic ESCC, age of 70 or younger, preserved organ functions were eligible. Treatment consisted of two courses of cisplatin 40 mg/m2 (day 1, 8) and 5FU 400 mg/m2/day (days 1–5, 8–12), q5w combined with concurrent radiotherapy of 60 Gy in 30 fractions over 8 weeks with 2-week break. For responders, two courses of chemotherapy of cisplatin 80 mg/m2 (day 1) and 5FU 800 mg/m2/day (days 1–5) q4w were added. The primary endpoint was overall survival and the secondary endpoints were response, toxicity, and progression-free survival. Results: From April 2000 to March 2002, 76 patients were accrued from 12 institutions. Characteristics of all patients were as follows: median age of 61 (range 39–70), male/female; 68/8, PS 0/1; 59/17, stage IIA/IIB/III; 26/12/38. There were two ineligible cases with inadequate liver function and T4 disease. Grade 4 neutropenia, leukopenia, and anemia occurred in 1.3%, 1.3% and 2.6%. Grade 3/4 esophagitis, stomatitis and infection occurred in 17%, 8% and 17%. Grade 3/4 late toxicities occurred in the following incidences; esophagus (dysphagia, mucositis, stenosis, and fistula) in 13%, pericardial effusion in 17%, pleural effusion in 8%, and radiation pneumonitis in 4%. There were 4 treatment related deaths due to late toxicities such as esophageal fistula, radiation pneumonitis, and the other cardiopulmonary diseases. Of eligible 74 patients, there were 50 complete responses (CRs) with a CR rate of 68% (95% Confidence Interval (CI): 56–78%). Median survival time was 31 months and the 2, 3-year survival rates were 55% (95% CI: 43–67%), 47% (95% CI: 36–59%), respectively. Conclusion: CRT for stage II, III ESCC is effective with acceptable acute toxicities, however, careful follow up is necessary for late toxicities.

No significant financial relationships to disclose.