Knockout of the lignin pathway gene BnF5H decreases the S/G lignin compositional ratio and improves Sclerotinia sclerotiorum resistance in Brassica napus

Ferulate-5-hydroxylase is a key enzyme involved in the conversion of the guaiacyl monolignol to the syringyl monolignol in angiosperms. The monolignol ratio has been proposed to affect biomass recalcitrance and the resistance to plant disease. Stem rot caused by the fungus Sclerotinia sclerotiorum in Brassica napus causes severe losses in its production. To date, there is no information about the effect of the lignin monomer ratio on the resistance to S. sclerotiorum in B. napus. Four dominantly expressed ferulate-5-hydroxylase genes were concertedly knocked out by CRISPR/Cas9 in B. napus, and three mutant lines were generated. The S/G lignin compositional ratio was decreased compared to that of the wild type based on the results of Mӓule staining and 2D-NMR profiling in KO-7. The resistance to S. sclerotiorum in stems and leaves increased for the three f5h mutant lines compared with WT. Furthermore, we found that the stem strength of f5h mutant lines was significantly increased. Overall, we demonstrate for the first time that decreasing the S/G ratio by knocking out of the F5H gene improves S. sclerotiorum resistance in B. napus and increases stem strength.

Social protection and the level and inequality of child mortality in 101 low- and middle-income countries: A statistical modelling analysis

Background

Expanding social protection programme is a major target of the Sustainable Development Goals. Previous studies provided evidence for the relationship of social protection programme to greater use of health services and some improved health outcomes for children. Yet, its impact on child mortality has not been clearly revealed. In this study, we examined the association between social protection programmes and child mortality.

Methods

We obtained child mortality data from 379 nationally representative surveys involving 101 low- and middle-income countries (LMICs). We included five child mortality outcomes in the study, which were neonatal mortality rate (NMR), post-neonatal mortality rate (PMR), childhood mortality rate (CMR), infant mortality rate (IMR), and under-5 mortality rate (U5MR). We extracted data on social protection programmes from multiple data sources (eg, Atlas of Social Protection Indicators of Resilience and Equity). Social protection and labour programme (SPL) was the major type of social protection we included. We also included four subtypes of SPL - social assistance, cash transfer, social insurance, and labour market protection. Both unadjusted and adjusted regressions were conducted to measure the associations between characteristics of social protection programmes and child mortality, as well as inequalities in child mortality.

Results

Among the 101 countries, the median coverage rate of SPL was 28.5%, with an interquartile range between 6.5% and 55.2%. Using the adjusted model, we found a one-percentage-point increase in SPL coverage is associated with a reduction of 0.09 (95% confidence interval (CI) = 0.04, 0.14) per 1000 live births in NMR, 0.11 (95% CI = 0.04, 0.18) in PMR, and 0.25 (95% CI = 0.11, 0.38) in CMR. Social assistance programme was the only subtype of SPL to be significantly associated with lower mortality rates. A higher SPL coverage was associated with better equity in child mortality – as the coverage of SPL increased by one percentage point, the concentration index of CMR would increase by 0.08 (95% CI = 0.03, 0.13) in the adjusted model, suggesting an improvement in equity.

Conclusions

The strong association between social protection programme and child mortality suggests that to achieve the SDG targets of universal social protection and to reduce child mortality, LMICs shall consider prioritizing the expansion of social protection programmes.

Multicomponent superconducting order parameter in UTe2

An unconventional superconducting state was recently discovered in uranium ditelluride (UTe₂), in which spin-triplet superconductivity emerges from the paramagnetic normal state of a heavy-fermion material. The coexistence of magnetic fluctuations and superconductivity, together with the crystal structure of this material, suggests that a distinctive set of symmetries, magnetic properties, and topology underlie the superconducting state. Here, we report observations of a nonzero polar Kerr effect and of two transitions in the specific heat upon entering the superconducting state, which together suggest that the superconductivity in UTe₂ is characterized by a two-component order parameter that breaks time-reversal symmetry. These data place constraints on the symmetries of the order parameter and inform the discussion on the presence of topological superconductivity in UTe₂.

Computational modelling for the spiral flow in umbilical arteries with different systole/diastole flow velocity ratios

The systole/diastole (S/D) flow velocity ratios in umbilical arteries (UAs) have been used to assess the health status of the feto-placental circulation, yet its connection to the morphology of UAs, specifically its coiling pattern remains unclear. Spiral flow induces unbalanced wall shear stress (WSS) distribution in UAs, and may contribute to the uneven arterial wall thickness, and the chirality. In this paper, we use a 3D computational fluid dynamics (CFD) technique to quantify the wall shear stress (WSS) in UA models of two configurations, i.e. at 0.17 and 0.50 spirals per centimeter, to represent normo- and hyper-coiling, respectively. For CFD simulations we use two different S/D ratios (3.02 and 5.70) revealed from the ultrasonography waveforms of a normal and an intrauterine growth restriction (IUGR) case. We found that more coils in the UA model enhanced WSS throughout a cardiac cycle (up to 24%) with the same inflow condition. In addition, time-averaged WSS are generally increased and more uneven in the hyper-coiling model. We suggest that the large WSS difference between the peak systole and end diastole (62% higher in the IURG case than the normal case) may induce uneven stenosis distribution at UAs, and contribute to UA chirality.

Integrating GWAS, linkage mapping and gene expression analyses reveals the genetic control of growth period traits in rapeseed (Brassica napus L.)

BACKGROUND

Brassica napus is one of the most important oilseed crops, and also an important biofuel plant due to its low air pollution and renewability. Growth period are important traits that affect yield and are crucial for its adaptation to different environments in B. napus.

RESULTS

To elucidate the genetic basis of growth period traits, genome-wide association analysis (GWAS) and linkage mapping were employed to detect the quantitative trait loci (QTL) for days to initial flowering (DIF), days to final flowering (DFF), flowering period (FP), maturity time (MT), and whole growth period (GP). A total of 146 SNPs were identified by association mapping, and 83 QTLs were identified by linkage mapping using the RIL population. Among these QTLs, 19 were pleiotropic SNPs related to multiple traits, and six (q18DFF.A03-2, q18MT.A03-2, q17DFF.A05-1, q18FP.C04, q17DIF.C05 and q17GP.C09) were consistently detected using both mapping methods. Additionally, we performed RNA sequencing to analyze the differential expression of gene (DEG) transcripts between early- and late-flowering lines selected from the RIL population, and the DEGs were integrated with association mapping and linkage analysis to confirm their roles in the growth period. Consequently, 12 candidate genes associated with growth period traits were identified in B. napus. Among these genes, seven have polymorphic sites in the coding sequence and the upstream 2-kb sequence based on the resequencing data. The haplotype BnaSOC1.A05-Haplb and BnaLNK2.C06-Hapla showed more favorable phenotypic traits.

CONCLUSIONS

The candidate genes identified in this study will contribute to our genetic understanding of growth period traits and can be used as targets for target mutations or marker-assisted breeding for rapeseed adapted to different environments.

Coexistence of ferromagnetic fluctuations and superconductivity in the actinide superconductor UTe2

We report low-temperature muon spin relaxation/rotation (μSR) measurements on single crystals of the actinide superconductor UTe₂. Below 5 K we observe a continuous slowing down of magnetic fluctuations that persists through the superconducting transition temperature (T _c = 1.6 K), but we find no evidence of long-range or local magnetic order down to 0.025 K. The temperature dependence of the dynamic relaxation rate down to 0.4 K agrees with the self-consistent renormalization theory of spin fluctuations for a three-dimensional weak itinerant ferromagnetic metal. Our μSR measurements also indicate that the superconductivity coexists with the magnetic fluctuations.

Phonon dispersion of Mo-stabilized γ-U measured using inelastic x-ray scattering

We have measured the room-temperature phonon spectrum of Mo-stabilized γ-U. The dispersion curves show unusual softening near the H point, q = [1/2, 1/2, 1/2], which may derive from the metastability of the γ-U phase or from strong electron-phonon coupling. Near the zone center, the dispersion curves agree well with theory, though significant differences are observed away from the zone center. The experimental phonon density of states is shifted to higher energy compared to theory and high-temperature neutron scattering. The elastic constants of γ-UMo are similar to those of body-centered cubic elemental metals.

Analogy Between the "Hidden Order" and the Orbital Antiferromagnetism in URu_{2-x}Fe_{x}Si_{2}

We study URu_{2-x}Fe_{x}Si_{2}, in which two types of staggered phases compete at low temperature as the iron concentration x is varied: the nonmagnetic "hidden order" (HO) phase below the critical concentration x_{c}, and unconventional antiferromagnetic (AFM) phase above x_{c}. By using polarization resolved Raman spectroscopy, we detect a collective mode of pseudovectorlike A_{2g} symmetry whose energy continuously evolves with increasing x; it monotonically decreases in the HO phase until it vanishes at x=x_{c}, and then reappears with increasing energy in the AFM phase. The mode's evolution provides direct evidence for a unified order parameter for both nonmagnetic and magnetic phases arising from the orbital degrees-of-freedom of the uranium-5f electrons.

Association of 3q13.32 variants with hip trochanter and intertrochanter bone mineral density identified by a genome-wide association study

We performed a GWAS of trochanter and intertrochanter bone mineral density (BMD) in the Framingham Heart Study and replicated in three independent studies. Our results identified one novel locus around the associated variations at chromosomal region 3q13.32 and replicated two loci at chromosomal regions 3p21 and 8q24. Our findings provide useful insights that enhance our understanding of bone development, osteoporosis, and fracture pathogenesis.

INTRODUCTION

Hip trochanter (TRO) and intertrochanter (INT) subregions have important clinical relevance to subtrochanteric and intertrochanteric fractures but have rarely been studied by genome-wide association studies (GWASs).

METHODS

Aiming to identify genomic loci associated with BMD variation at TRO and INT regions, we performed a GWAS utilizing the Framingham Heart Study (FHS, N = 6,912) as discovery sample and utilized the Women's Health Initiative (WHI) African-American subsample (N = 845), WHI Hispanic subsample (N = 446), and Omaha osteoporosis study (N = 971), for replication.

RESULTS

Combining the evidence from both the discovery and the replication samples, we identified one novel locus around the associated variations at chromosomal region 3q13.32 (rs1949542, discovery p = 6.16 × 10^-8, replication p = 2.86 × 10^-4 for INT-BMD; discovery p = 1.35 × 10^-7, replication p = 4.16 × 10^-4 for TRO-BMD, closest gene RP11-384F7.1). We also replicated two loci at chromosomal regions 3p21 (rs148725943, discovery p = 6.61 × 10^-7, replication p = 5.22 × 10^-4 for TRO-BMD, closest gene CTNNB1) and 8q24 (rs7839059, discovery p = 2.28 × 10^-7, replication p = 1.55 × 10^-3 for TRO-BMD, closest gene TNFRSF11B) that were reported previously. We demonstrated that the effects at both 3q13.32 and 3p21 were specific to the TRO, but not to the femoral neck and spine. In contrast, the effect at 8q24 was common to all the sites.

CONCLUSION

Our findings provide useful insights that enhance our understanding of bone development, osteoporosis, and fracture pathogenesis.

Assessment of dentinal tubule invasion capacity of Enterococcus faecalis under stress conditions ex vivo

AIM

To investigate the dentinal tubule invasion capacity of Enterococcus faecalis under alkaline and energy starvation stress conditions.

METHODOLOGY

The root canals from human single-rooted teeth (n = 40) were infected with E. faecalis under alkaline (pH 9, 10, 11 and 12) and energy starvation (no glucose, 0.05% glucose and 0.15% glucose) stress conditions. The root canals were prepared in a standard manner and treated to remove the smear layer before incubation. After 4 weeks of cultivation, the roots were split vertically into two halves: one half was processed for biofilm formation analysis using a scanning electron microscope; the other half was stained with fluorescent DNA-binding reagents, washed thoroughly and sectioned (100 μm thick), and the depth of tubule invasion by the microorganism was examined by confocal laser-scanning microscopy. The extent of dentine tubule invasion was analysed statistically.

RESULTS

The E. faecalis strain resulted in biofilm formation and dentine tubules invasion under all of the stress conditions, except for pH 11 and 12 conditions. However, the tubule penetration distance was markedly reduced in these stress conditions (P < 0.01) compared with in tryptic soy broth (TSB) or pH 7 medium. The invasion depth in the middle root dentine was significantly higher than in the apical sections in TSB and energy starvation medium (P < 0.01).

CONCLUSIONS

Ex vivo E. faecalis formed biofilms and colonized dentine under alkaline and glucose starvation stress conditions, but its ability to invade dentine tubules was significantly decreased.

Inelastic neutron scattering study of a nonmagnetic collapsed tetragonal phase in nonsuperconducting CaFe2As2: evidence of the impact of spin fluctuations on superconductivity in the iron-arsenide compounds

The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the nonsuperconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is nonmagnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds.

Coexistence of cluster spin glass and superconductivity in Ba(Fe(1-x)Co(x))2As2 for 0.060≤x≤0.071

We present 75As nuclear magnetic resonance data from measurements of a series of Ba(Fe(1-x)Co(x))2As2 crystals with 0.00≤x≤0.075 that reveals the coexistence of frozen antiferromagnetic domains and superconductivity for 0.060≤x≤0.071. Although bulk probes reveal no long range antiferromagnetic order beyond x=0.06, we find that the local spin dynamics reveal no qualitative change across this transition. The characteristic domain sizes vary by more than an order of magnitude, reaching a maximum variation at x=0.06. This inhomogeneous glassy dynamics may be an intrinsic response to the competition between superconductivity and antiferromagnetism in this system.

Magnonlike dispersion of spin resonance in Ni-doped BaFe2As2

Inelastic neutron scattering measurements on Ba(Fe0.963Ni0.037)2As2 manifest a neutron spin resonance in the superconducting state with anisotropic dispersion within the Fe layer. Whereas the resonance is sharply peaked at the antiferromagnetic (AFM) wave vector Q(AFM) along the orthorhombic a axis, the resonance disperses upwards away from Q(AFM) along the b axis. In contrast to the downward dispersing resonance and hourglass shape of the spin excitations in superconducting cuprates, the resonance in electron-doped BaFe2As2 compounds possesses a magnonlike upwards dispersion.

Effects of transition metal substitutions on the incommensurability and spin fluctuations in BaFe2As2 by elastic and inelastic neutron scattering

The spin fluctuation spectra from nonsuperconducting Cu-substituted, and superconducting Co-substituted, BaFe(2)As(2) are compared quantitatively by inelastic neutron scattering measurements and are found to be indistinguishable. Whereas diffraction studies show the appearance of incommensurate spin-density wave order in Co and Ni substituted samples, the magnetic phase diagram for Cu substitution does not display incommensurate order, demonstrating that simple electron counting based on rigid-band concepts is invalid. These results, supported by theoretical calculations, suggest that substitutional impurity effects in the Fe plane play a significant role in controlling magnetism and the appearance of superconductivity, with Cu distinguished by enhanced impurity scattering and split-band behavior.

Abstract P1-03-09: Combination of nab-Paclitaxel and Bevacizumab Inhibited Tumor Growth and Metastasis of New Inflammatory Breast Cancer Models

Background: Inflammatory breast cancer (IBC) is a highly lethal form of breast cancer which is characterized by skin redness, irritation, swelling, pain, as well as extensive lymph nodes (LN) and hematogenous metastasis. Animal models of IBC are highly desirable for studying its pathology and for designing effective therapies. In this study, we established two new luciferase-and fluorescently-labeled IBC models and tested the efficacy of the novel drug combination nab-paclitaxel and bevacizumab. Methods: Inflammatory SUM149 breast cancer cells were stably transfected with Red Fluorescent Protein (RFP) and Renilla luciferase to establish SUM149-RR, or infected with lentivirus encoding Green Fluorescent Protein (GFP) and Firefly luciferase to establish SUM149- GL. The new cell lines were characterized both in vitro and in vivo. Immunodeficient mice bearing SUM149-RR tumors of 150mm3 in size were treated with saline (control), bevacizumab (4 mg/kg, i.p., twice a week, for 10 weeks), nab-paclitaxel (10 mg/kg, i.v., qdx5), or the combination. Metastasis was analyzed by measuring luciferase activity in the lymph nodes (LN) and lungs.

Results: Luciferase measurements and in vivo imaging showed that both SUM149-RR and-GL clones were highly metastatic to LN, lungs, liver, brain, and spleen. SUM149-RR tumors in control mice displayed ulcerations, edema and redness similar to the clinical disease, while tumors in mice treated with bevacizumab or combination therapy showed no signs of inflammation. Bevacizumab alone decreased tumor growth at later but not early stages of tumor growth, whereas nab-paclitaxel alone inhibited tumor growth by 73%. Combination therapy increased inhibition to 96%, and resulted in 22% (2/9) complete responses. Histologically, tumors from bevacizumab treated groups were more morphologically intact with reduced vascular abnormalities than tumors from control or nab-paclitaxel treated mice. LN and lung metastasis was significantly reduced in all treated groups as compared with control.

Conclusions: The SUM149-RR and SUM149-GL lines are new double-tagged models of human IBC that allow organ visualization and accurate quantification of metastasis. These models can be used to study the biology and treatment of IBC. Combination of nab-paclitaxel with bevacizumab was highly effective against SUM149-RR, suggesting the potential usefulness of this regimen for treatment of IBC patients.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-03-09.

Abstract P1-03-11: Combination of nab-Paclitaxel and Bevacizumab Inhibited Tumor Growth and Metastasis of a New Triple Negative Breast Cancer Model

Background: Triple-negative breast cancers are highly aggressive and resistant to chemotherapy. In this study, we established a new model of triple-negative breast cancer and used it to test the novel combination of nab-paclitaxel with anti-VEGF antibody bevacizumab, which has been effective in treating other metastatic cancer types. Methods: The triple-negative HCC1806 beast cancer cells were stably transfected with dual reporters Red Fluorescent Protein (RFP) and Renilla luciferase to establish the new HCC1806-RR model. Immunodeficient mice bearing orthotopic HCC1806-RR tumors of 150mm3 in size were treated with saline (control), bevacizumab (4 mg/kg. i.p., twice a week, for 10 weeks), nab-paclitaxel (10 mg/kg, i.v., qdx5), or with combination of nab-paclitaxel and bevacizumab. Metastasis was analyzed by measuring luciferase activity in the lymph nodes (LN) and lungs. Results: The HCC1806-RR cells had identical morphology, proliferation rates and sensitivity to nab-paclitaxel as the parental HCC1806 cell line. HCC1806-RR tumors primarily metastasized to LN, with lung being a secondary metastatic site. Combination therapy of nab-paclitaxel and bevacizumab inhibited tumor growth by 100%, as compared to 0% for bevacizumab (P &lt; 0.001) and 90% for nab-paclitaxel (P = 0.024). Importantly, only combination therapy reduced incidence of LN and lung metastases by 50% (P = 0.007) and 87% (P = 0.001). Overall, 50% of the mice in the combination therapy group (n = 10) had complete regressions of both primary tumors and metastases at both regional and distant sites. Conclusions : The HCC1806-RR is a new triple-negative breast model with dual reporters to allow for quantitative assessment of metastatic spread. This model can be used to study the biology and treatment of triple-negative breast cancer. Combination of nab-paclitaxel with bevacizumab was highly effective against HCC 1806-RR tumors, suggesting that this regimen could provide clinical benefits to patients with triple-negative breast cancers.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-03-11.

Antitumor activity, and antiangiogenic activity of nanoparticle albumin-bound nab-rapamycin in combination with nab-paclitaxel

Abstract #3125

Background: Rapamycin inhibits downstream signals from the mammalian target of rapamycin (mTOR), a known kinase member of a signaling pathway that promotes tumor growth. Rapamycin's poor aqueous solubility and poor chemical stability have limited its development as an intravenous (IV) anticancer agent. Nab-rapamycin utilizes the albumin-bound technology to allow for IV administration of rapamycin and has demonstrated dose-linear pharmacokinetics and safety up to 90 mg/kg with effective antitumor activity at 40 mg/kg against a human panel of tumor xenografts. This study investigated the efficacy of combined therapy with nab-paclitaxel (Abraxane®) utilizing invasive human breast (MDA-MB-231) and colon (HT29) cancer xenograft models.&#x2028; Material and Methods: Xenograft transplants using luciferase-tagged MDA-MB-231 cells were implanted into mammary fatpad of SCID mice and allowed to reach 460 mm3 in size prior to IV administration of saline (vehicle, n = 9); nab-rapamycin, 3x wkly for 2 wks at 40 mg/kg (nab-rap-2W; n = 8); nab-rapamycin, 3x wkly for 4 wks at 40 mg/kg (nab-rap-4W; n = 8); Abraxane, qdx5 at 30 mg/kg (ABX; n = 8); nab-rap-2W + ABX (n = 9); or nab-rap-4W + ABX (n = 8). HT29 xenografts were also treated with nab-rap-4W (n = 8) and nab-rap-4W + ABX (10 mg/kg, qdx5, IP, n = 8). The in vivo antiangiogenic effect of nab-rapamycin was evaluated using the standard in vivo chick chorioallantoic membrane (CAM) assay with 3-day old embryos (n = 18).&#x2028; Results: Relative to vehicle controls, nab-rap-2W (P &lt; 0.00011), nab-rap-4W (P &lt; 0.0001), and ABX (P &lt; 0.0001) were effective against MDA-MB-231 tumor xenograft models with tumor growth inhibition (TGI) of 60%, 66%, and 73% respectively. Additive antitumor effects were observed with combination of nab-rapamycin + ABX with TGI of 81% and 86% for nab-rap-2W + ABX and nab-rap-4W + ABX groups, respectively. For HT29 tumors, the combination of ABX and nab-rapamycin also showed greater TGI (89%) compared to nab-rapamycin alone (81%). In the chick CAM assay, nab-rapamycin demonstrated antiangiogenic efficacy at doses of 10 µg and above without affecting embryo viability.&#x2028; Conclusions: Combination therapy of nab-rapamycin and Abraxane was more effective at inhibiting breast and colon xenograft tumor growth than single therapy of either drug. The enhanced antitumor activity seen with combined nab-rapamycin-Abraxane may in part be due to the observed antiangiogenic activity of nab-rapamycin.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3125.

Mechanisms of nab-paclitaxel and bevacizumab cooperation in inhibition of breast tumor growth and metastasis

Abstract #1032

Background: Nab-paclitaxel, also known as Abraxane®, is paclitaxel formulated in nanoparticles that consist of human albumin encapsulating the hydrophobic drug moiety. This drug has shown numerous advantages including linear pharmacokinetics, significantly higher tumor retention, and increased maximal-tolerated dose due to reduced toxicity. We previously showed that combination of Abraxane and anti-VEGF-A antibody, bevacizumab, is significantly more efficacious in suppression of breast tumor xenografts and metastasis as compared to treatments with each of these drugs alone. We hypothesized that the mechanism underlying the therapeutic success of the combined therapy might include bevacizumab-dependent abrogation of the stress response elicited by paclitaxel in the tumor cells surviving chemotherapy.&#x2028; Materials and Methods: Cultured MDA-MB-231 cells were treated with 0, 2.5, 5, 10, and 30 nM of Abraxane followed by detection of angiogenic (VEGF-A), prosurvival (p42 & p44 kinase, bcl-2) and inflammatory (IL-6, IL-8, and TNF-α) proteins using Western blotting and ELISA. MDA-MB-231 tumors were extracted from mice upon cessation of intravenous (IV) Abraxane therapy (10 to 30 mg/kg, qdx5) followed by Western blot and immunohistochemical analyses.&#x2028; Results: In vitro, Abraxane treatment increased expression of VEGF-A, p42/44 kinase, bcl-2 as well as total and phosphorylated p65 subunit of NF-κB. Treated cells secreted 25- to 30-fold higher concentrations of inflammatory cytokines IL-6, IL-8, and TNF-α into conditioned media as compared with untreated control cells. Likewise, significant increases in bcl-2 and inflammatory cytokines were observed in tumors extracted immediately after paclitaxel therapy in vivo as confirmed by both Western blotting and immunohistochemical analyses.&#x2028; Discussion: These findings suggest that paclitaxel elicits VEGF-A dependent prosurvival and proinflammatory stress responses in tumor cells surviving the cytotoxic therapy. Activation of these pathways suggests that concurrent therapy with VEGF-A neutralizing antibody might significantly improve the efficacy of paclitaxel-based therapies by counteracting the stress responses in the therapy-spared tumor cells.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1032.

Chemoprotection by VEGF: Rationale for combination nab-paclitaxel and bevacizumab

1064

Background: Nanoparticle albumin-bound (nab-) paclitaxel (ABX) has shown greater efficacy and less toxicity than solvent-based paclitaxel (TAX) in xenograft models and clinical trials. The goal of this study was to determine the effects of VEGF modulation in human MDA-MB-231 breast tumor cell line and the effects of ABX and VEGF-neutralizing antibody bevacizumab (AVA) combination on the growth and metastasis of orthotopically implanted MDA-MB-231 tumors. Methods: VEGF expression was evaluated by ELISA in MDA-MB-231 tumor extract one week after treatment (qdx5) with saline, doxorubicin (10 mg/kg), TAX (10 mg/kg), or ABX (15 mg/kg). VEGF-receptor expression in MDA-MB-231 was quantitated by RT-PCR. MDA-MB-231 cytotoxicity with ABX, VEGF, AVA alone or in combination was measured by cytotoxicity and clonogenic assays. Implanted MDA-MB-231 tumors expressing luciferase were treated with saline, 2 cycles of ABX (10 mg/kg, two qdx5 cycles separated by 1 week, N=5) alone or in combination with AVA (2, 4 and 8 mg/kg, 2/wkx6). Tumor lymph node and pulmonary metastasis was determined by measuring luciferase activity. Results: Compared with saline, MDA-MB-231 tumors following chemotherapies exhibited significant tumor shrinkage (p≤0.006, t-test) and VEGF induction (p<0.0001, t-test). MDA-MB-231 was shown to express VEGFR2. Exogenous VEGF had a protective effect on MDA-MB-231 tumor cells by reducing cytotoxicity of ABX in both cytotoxicity and clonogenic assays. Sequestration of VEGF with AVA increased cytotoxicity of ABX in vitro. Treatment of MDA-MB-231 breast tumors with ABX and AVA combination resulted in greater than additive antitumor response and significantly reduced metastasis to the lungs (p=0.025 vs control) and LN (p=0.022) at the highest AVA dose. Conclusions: Chemotherapies induced VEGF expression in MDA-MD-231 breast tumor in vivo. In vitro, VEGF exerted a protective effect against ABX chemotherapy in VEGFR2-expressing MDA-MD-231 cells, which was abrogated by addition of AVA. In vivo, ABX and AVA combination significantly inhibited the metastatic potential of MDA-MB-231 tumor cells. These data provide a rational basis for the combination of nab- paclitaxel and bevacizumab in VEGF-receptor expressing tumors.

[Table: see text]

Characterization of the cell-surface procoagulant activity of T-lymphoblastoid cell lines

The procoagulant activity (PCA) of four T-lymphoblastoid cell lines (CEM-CCRF, Jurkat, Molt-4 and A3.01) at different stages of differentiation has been characterized and compared with that of a monocytoid cell line (THP-1). Four assay systems were employed; the activated partial thromboplastin time (APTT); prothrombin time/tissue factor (TF) activity; a purified factor (F)Xa generation system and cancer procoagulant. High levels of TF activity were seen only with the monocytic cells. However the more differentiated of the T-lymphoblastoid cells (Molt-4 and A3.01) were more active than monocytic cells in supporting FXa generation. This pattern was not repeated for the APTT assay, which was related to cell-surface TF activity, since it was partially inhibited by antiTF antibody. Annexin V totally inhibited the activity observed in all three assay systems, indicating that the PCA of T-lymphoblastoid cells is primarily due to expression of negatively charged phospholipids. However, antiphosphatidylserine antibody even at a high concentration gave only partial inhibition of the activity observed in the APTT and FXa generation systems for the cells compared with almost total inhibition for the phospholipid standard, suggesting either that cellular phosphatidylserine (PS) is less accessible to the antibody, or that PS is not the sole negatively charged phospholipid responsible for this activity. Flow cytometry studies using propidium iodide and annexin V showed that the PCA, although linked to PS exposure, was not the result of apoptosis.

Vascular endothelial growth factor inhibits the development of dendritic cells and dramatically affects the differentiation of multiple hematopoietic lineages in vivo

Defective function of dendritic cells (DC) in cancer has been recently described and may represent one of the mechanisms of tumor evasion from immune system control. We have previously shown in vitro that vascular endothelial growth factor (VEGF), produced by almost all tumors, is one of the tumor-derived factors responsible for the defective function of these cells. In this study, we investigated whether in vivo infusion of recombinant VEGF could reproduce the observed DC dysfunction. Continuous VEGF infusion, at rates as low as 50 ng/h (resulting in serum VEGF concentrations of 120 to 160 pg/mL), resulted in a dramatic inhibition of dendritic cell development, associated with an increase in the production of B cells and immature Gr-1(+) myeloid cells. Infusion of VEGF was associated with inhibition of the activity of the transcription factor NF-kappaB in bone marrow progenitor cells. Experiments in vitro showed that VEGF itself, and not factors released by VEGF-activated endothelial cells, affected polypotent stem cells resulting in the observed abnormal hematopoiesis. These data suggest that VEGF, at pathologically relevant concentrations in vivo, may exert effects on pluripotent stem cells that result in blocked DC development as well as affect many other hematopoietic lineages.

Infarction of solid Hodgkin's tumors in mice by antibody-directed targeting of tissue factor to tumor vasculature

We demonstrated previously that selective thrombosis of the blood vessels of solid tumors in mice can be achieved by targeting the extracellular domain of tissue factor by means of an antibody to an experimentally induced marker on tumor vascular endothelium. In the present study, we extend this finding to a naturally occurring marker of tumor vascular endothelium, vascular cell adhesion molecule-1 (VCAM-1). VCAM-1 is expressed by vascular endothelial cells in Hodgkin's disease and various solid tumors in mice and humans. It is absent from vascular endothelial cells in normal tissues in mice, with the exception of the heart and lungs, where it is present on venules. A monoclonal antibody to murine VCAM-1 was covalently linked to the extracellular domain of human tissue factor to create a "coaguligand." After i.v. administration to severe combined immunodeficient mice bearing human Hodgkin's tumors, the coaguligand localized selectively to VCAM-1-expressing vessels, caused thrombosis of those vessels, and retarded tumor growth. The coaguligand also localized to VCAM-1-expressing vessels in the heart and lungs of the mice but did not induce thrombosis in these sites. An immunohistochemical evaluation of the distribution of a monoclonal anti-phosphatidylserine (PS) antibody in the mice showed that the VCAM-1-expressing vessels in the tumor expressed PS, whereas the VCAM-1-expressing vessels in the heart and lungs lacked PS. The lack of thrombotic effect of the coaguligand on heart and lung vessels may be because PS is needed to provide the procoagulant surface upon which coagulation complexes can assemble. The requirement for coincident expression of the targeted marker and PS on tumor endothelium probably contributes to the selectivity of thrombotic action and the safety of coaguligands.

Vascular endothelial growth factor affects dendritic cell maturation through the inhibition of nuclear factor-kappa B activation in hemopoietic progenitor cells

Vascular endothelial growth factor (VEGF), produced by almost all tumor cells, affects the ability of hemopoietic progenitor cells (HPC) to differentiate into functional dendritic cells (DC) during the early stages of their maturation. In this study we demonstrate specific binding of VEGF to HPC. This binding was efficiently competed by placenta growth factor (PIGF), a ligand reportedly specific for the Flt-1 receptor. The number of binding sites for VEGF decreased during DC maturation in vitro associated with decreased levels of mRNA for Flt-1. VEGF significantly inhibited nuclear factor-kappa B (NF-kappa B)-dependent activation of reporter gene transcription during the first 24 h in culture. The presence of VEGF significantly decreased the specific DNA binding of NF-kappa B as early as 30 min after induction with TNF-alpha. This was followed on days 7 to 10 by decreases in the mRNA for RelB and c-Rel, two subunits of NF-kappa B. Blockade of NF-kappa B activity in HPC at early stages of differentiation with an adenovirus expressing a dominant I kappa B inhibitor of NF-kappa B reproduced the pattern of effects observed with VEGF. Thus, NF-kappa B plays an important role in maturation of HPCs to DC, and VEGF activation of the Flt-1 receptor is able to block the activation of NF-kappa B in this system. Blockade of NF-kappa B activation in HPCs by tumor-derived factors may therefore be a mechanism by which tumor cells can directly down-modulate the ability of the immune system to generate effective antitumor immune responses.

Functional reconstitution of a chloride channel protein from bovine trachea

We characterized the electrophysiological properties of a chloride channel protein isolated from bovine trachea after incorporation into planar lipid bilayers, and studied the effects of thiol-modulating agents on channel regulation both in bilayers and vesicular iodide uptake studies. Our experiments showed that this protein formed perfectly anion-selective channels in the bilayer, with an anion permeability sequence of I- (2.1) > NO3- (1.7) > Br- (1.2) > Cl- (1.0). The conductance of this channel was 25-30 picosiemens in 150 mM Cl-, and saturated with increasing chloride concentration. This channel could be completely inhibited by 4,4'-bis(isothiocyano)-2,2'-stilbenedisulfonate. Immunoblot analysis, using polyclonal antibodies (anti-p38), revealed one major band at 140 kDa. Upon reduction with dithiothreitol, 64- and 38-kDa polypeptides were observed. Functional experiments showed that reduction was accompanied by loss of 125I- uptake and single-channel activity. In the presence of dithiothreitol, only the low molecular mass protein forms (64 and 38 kDa) were detected by anti-p38 antibodies on Western blots. Cross-linking of S-S bonds with Cu(2+)-o-phenanthroline led to activation of chloride channels in vesicles and bilayers. Over-aggregation of chloride channels by this S-S cross-linking reagent caused inhibition of 125I- uptake by 80-100% and the abolishment of single-channel activity. We propose that the native chloride channel from bovine trachea can exist in vivo in different structural and functional forms depending upon its thiol-disulfide oxidation reduction status. The oxidized form has a molecular mass of 140 kDa and represents a fully active chloride channel. Inactivation of this channel might occur by over-aggregation of protein subunits, or by dissociation of the 140-kDa subunit by disulfide bond reduction.

Immunopurification and structural analysis of a putative epithelial Cl- channel protein isolated from bovine trachea

We have purified to homogeneity a 38-kDa protein (called p38) from bovine tracheal epithelium. This protein, when reconstituted into liposomes, mediates stilbene disulfonate-sensitive 125I- conductive uptake. On nonreduced or partially reduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis, this protein associates into a doublet of 62-64 kDa. In some experiments a multimer of 141 kDa was also observed. Rabbit polyclonal anti-P38 antibodies have been produced and used to immunopurify the native transporter. Upon reconstitution of the immunoaffinity-purified protein into liposomes, a 260-fold enhancement of 4,4'-bis(isothiocyano)-2,2'-stilbenedisulfonate and valinomycin-sensitive 125I- uptake was observed as compared to proteoliposomes containing unseparated material. On Western blots of total solubilized tracheal membrane proteins or semipurified fractions, the antibody recognized the 62-64-kDa doublet much better than the original 38-kDa antigen. Similar protein bands were detected in T84 and CFPAC cells as well. However, if apical membrane proteins were first separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions, the antibody recognized major bands at 140 and approximately 240 kDa. Upon partial reduction, immunolabeling of these proteins diminished with the concomitant appearance of the 62-64-kDa doublet. Upon complete reduction, the appearance of 32- and 38-kDa proteins was evident with the disappearance of the 62-64-kDa doublet. We hypothesize that the native Cl-channel is a heteromer containing at least four subunits connected by S-S bridges.

Isolation and functional reconstitution of a 38-kDa chloride channel protein from bovine tracheal membranes

Secretion of chloride ions via apically located anion-selective channels in epithelia regulates fluid formation and cytosolic Cl- homeostasis. In order to understand the biochemical basis of Cl- channel function, we attempted to isolate this transporter from bovine tracheal apical membranes. Initially, peripheral polypeptides were removed from apically enriched vesicles by washing with alkaline buffer (pH 10.8) containing 2 mM CHAPS. The resulting pellet contained 50-60% of the original protein and displayed 2-fold enhanced Cl- channel activity compared to untreated vesicles. The pellet was treated with Triton X-100, and the solubilized proteins were separated on the cationic exchanger CM-cellufine. Washing the resin with a pH 8.0-8.3 buffer eluted a fraction with enriched Cl- channel activity. This fraction contained less than 5% of the total solubilized protein. A subsequent separation was performed using the anionic exchanger AM-cellufine. The highest activity was found in the fractions eluted by 80-120 mM KCl. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed a major 38,000-Da protein band. This band was electroeluted from the gel under nondenaturing and nonreducing conditions and reconstituted into phosphatidylcholine liposomes. KCl-loaded vesicles containing the purified 38-kDa protein transported up to 5 nmol of 125I-/mg of protein/5 min. This value was 15-fold higher than the uptake measured in vesicles reconstituted with total solubilized membrane proteins and 4-fold higher compared to the CM-cellufine-enriched fraction. The observed 125I- uptake was 90% inhibited by 100 microM 4,4-bis(isothiocyano)-2,2'-stilbenedisulfonate or 10 microM valinomycin. In summary, we have developed a biochemical protocol for the isolation of a 38 kDa protein mediating potential-dependent and 4,4-bis(isothiocyano)-2,2'-stilbenedisulfonate-sensitive Cl- channel activity.

Implanted IgE-Fc epsilon R complexes elicit IgE-mediated activation of RBL-2H cells

The high-affinity receptor for IgE (Fc epsilon R) is the cellular trigger of the antigen-induced activation of mast cells and basophils. To examine the functional integrity of Fc epsilon R, we have adopted a protein implantation procedure whereby the purified receptor complex was coreconstituted with Sendai virus envelopes. The latter promoted fusion of the hybrid vesicles with recipient cells such as rat basophilic leukemia, RBL-2H3, thus serving as a vehicle for the receptor. The implanted Fc epsilon R was complexed with 125I-labeled mouse IgE (anti-DNP) to permit receptor quantification as well as specific triggering by DNP20BSA. Implantation in the presence of unlabeled rat IgE, which blocked the native receptors on the recipient RBL-2H3 cells, resulted in incorporation of up to 15 ng of receptor-bound IgE/10(6) cells. This was roughly equivalent in amount to 10-20% of the native receptors on such cells. The exocytosis which was triggered in the recipient cells by reagents that specifically recognized the implanted IgE reached between 15 and 50% of the maximal response. Various treatments that interfered with the activities of the viral envelopes reduced both receptor incorporation (3-5-fold) and cell degranulation (3-10-fold). These included separation of the receptor from the reconstituted envelopes, addition of serum to the incubation mixture (to inhibit vesicle-cell binding), and trypsinization of the virus (to inhibit vesicle-cell fusion). Poly(ethylene glycol) 8000 (4%) enhanced both the incorporation of the receptor and its functional responses. These treatments distinguished between real incorporation of IgE-Fc epsilon R complexes and other mechanisms of 125I-IgE association with the recipient cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium specificity of the antigen-induced channels in rat basophilic leukemia cells

Ion channels, activated upon IgE-Fc epsilon receptor aggregation by specific antigen, were studied in micropipet-supported lipid bilayers. These bilayers were reconstituted with purified IgE-Fc epsilon receptor complex and the intact 110-kDa channel-forming protein, both isolated from plasma membranes of rat basophilic leukemia cells (line RBL-2H3). In order to identify the current carrier through these ion channels and to determine their ion selectivity, we investigated the currents flowing through the IgE-Fc epsilon receptor gated channels in the presence of a gradient of Ca2+ ions. Thus, the solution in which the micropipet-supported bilayer was immersed contained 1.8 mM CaCl2, while the interior of the micropipet contained 0.1 microM Ca2+ (buffered with EGTA). Both solutions also contained 150 mM of a monovalent cation chloride salt (either K+ or Na+). The currents induced upon specific aggregation of the IgE (by either antigen or anti-IgE antibodies) were examined over a range of potentials imposed on the bilayer. The type of conductance event most frequently observed under the employed experimental conditions was a channel that has a slope conductance of 3 pS and a reversal potential practically identical with the calculated value for the reversal potential of calcium (134 +/- 11 mV in the presence of sodium, 125 +/- 13 mV in the presence of potassium). These results indicate that this channel is highly selective for calcium against the monovalent cations sodium and potassium. This same channel has a conductance of 4-5 pS in the presence of symmetrical solutions containing only 100 mM CaCl2 and 8 pS in the presence of 0.5 M NaCl with no calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Reconstitution of fusogenic Sendai virus envelopes by the use of the detergent chaps

Sendai virus envelopes have been a useful tool in studying the mechanism of membrane-membrane fusion and have served as a vehicle for introducing foreign molecules (e.g., membrane proteins) into recipient cells. Reconstituted Sendai virus envelopes are routinely obtained following solubilization of virus particles with Triton X-100. This detergent has a low critical micellar concentration which precludes it from being the best detergent of choice in reconstitution studies. Nevertheless, it has remained in use since other detergents such as sodium deoxycholate and sodium cholate rendered the resultant vesicles inactive. Triton X-100 may be suboptimal for studies of some proteins that need be coreconstituted with the viral envelopes. Thus, alternative advantageous detergents, which retain the envelope fusogenic activity, have been sought. In this study we show that the synthetic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (Chaps) effectively solubilizes the Sendai virions, and that the vesicles formed by simple reconstitution protocols appear structurally and biochemically similar to those obtained with Triton X-100. The resultant vesicles retain functional integrity as assessed in both fusion and hemolysis assays. This protocol seems to be useful in sendai envelope-mediated reimplantation of Fc epsilon receptors into the plasma membranes of rat basophilic leukemia cells.

Activation of rat basophilic leukemia cells. Temporal identification of the signal calcium influx mediated by the receptor-operated channel pathway

Antigen-induced 45calcium influx into rat basophilic leukemia (RBL) cells was examined with emphasis on the early time domain under conditions that exclude loss of the cation during the subsequent washing step. Such preparations demonstrate a distinct, temporally separate influx peaking at 3 min, followed by a substantial efflux. This internalized 45Ca2+ approaches millimolar total intracellular concentration and is therefore either sequestered or becomes bound to intracellular components (proteins). The amplitude of this influx is linearly proportional to IgE-receptor occupancy at low receptor occupancies, and is sensitive to the anti-allergic drug cromolyn. Furthermore, the timing of both the maximal uptake and the maximal susceptibility to cromolyn correlates with the Quin-2 signal in these cells, and the initial degranulation pattern bears some resemblance to trends in the 45Ca2+ uptake curve. These qualities suggest that the early peak at 2-3 min, rather than any later 45Ca2+ uptake, comprises the initial signalling Ca2+ pool. Maximal apparent inhibition by cromolyn for 45Ca2+ uptake was about 65% and required a 10-15-min preincubation with the cells. The inhibitory effect was limited to the peak at 3 min, suggesting that tracer incorporation beyond 5-6 min largely involves other pools or pathways, triggered by receptor aggregation, yet only indirectly related to channel activity or to the signal proper. A quantitative similarity was found between the early peak measured on intact cells and the single channel conductance measured on reconstituted planar bilayers containing the purified receptor for IgE and the purified cromolyn-binding protein [Corcia, A. et al. (1986) EM BO J. 5, 849-854]. This, as well as the effects of cromolyn, support the assumption that cromolyn-binding protein is a major constituent involved in this early influx, or that influx is a principal pathway for the signaling calcium mass.

Sex-associated differences in the regulation of immune responses controlled by the MHC of the mouse

The immunologic potential of T lymphocytes and antigen-presenting cells (APC) from male and female mice were compared. Lymphocytes from female mice or from male mice that cannot produce and respond to testosterone (Tfm/y) were more reactive than male lymphocytes to alloantigens in MLR. Spleen cells from Tfm/y mice equipped with estrogen implants showed a higher responsiveness than control Tfm/y to alloantigens. The removal of suppressive adherent cells or the addition of T cell growth factor (TCGF) enhanced the proliferative activity of the cells in the MLR. The responsiveness of female cells to alloantigens, however, remained superior to that observed in male cells. Similarly, in the presence of TCGF, thymocytes from female mice react more effectively than male cells in MLR. In addition, Con A-stimulated spleen cells from female mice produce more interleukin 2 (IL 2) than do spleen cells from males or female mice treated with testosterone. Lymphocytes from immunized mice were tested for their ability to respond to soluble antigens (KLH and OVA) in vitro. Again, female immunocompetent cells respond more vigorously than male cells or cells originating in female mice with testosterone implants. APC from female spleen were more efficient than male APC in initiating a secondary response in primed lymphocytes from either males or female mice. Moreover, castration of male mice enhanced, and treatment of female mice with androgen reduced, the efficiency of antigen presentation. In conclusion, these data suggest that female cells are superior to male cells in immunologic functions that are known to be associated with reactions to and recognition of histocompatibility antigens, i.e., antigen presentation and MLR. Furthermore, our present data indicate that the differential reactivity of immunocytes between male and female mice depends on the hormonal balance of the animal.

Sex-associated differences in the regulation of immune responses controlled by the MHC of the mouse

The immunologic potential of T lymphocytes and antigen-presenting cells (APC) from male and female mice were compared. Lymphocytes from female mice or from male mice that cannot produce and respond to testosterone (Tfm/y) were more reactive than male lymphocytes to alloantigens in MLR. Spleen cells from Tfm/y mice equipped with estrogen implants showed a higher responsiveness than control Tfm/y to alloantigens. The removal of suppressive adherent cells or the addition of T cell growth factor (TCGF) enhanced the proliferative activity of the cells in the MLR. The responsiveness of female cells to alloantigens, however, remained superior to that observed in male cells. Similarly, in the presence of TCGF, thymocytes from female mice react more effectively than male cells in MLR. In addition, Con A-stimulated spleen cells from female mice produce more interleukin 2 (IL 2) than do spleen cells from males or female mice treated with testosterone. Lymphocytes from immunized mice were tested for their ability to respond to soluble antigens (KLH and OVA) in vitro. Again, female immunocompetent cells respond more vigorously than male cells or cells originating in female mice with testosterone implants. APC from female spleen were more efficient than male APC in initiating a secondary response in primed lymphocytes from either males or female mice. Moreover, castration of male mice enhanced, and treatment of female mice with androgen reduced, the efficiency of antigen presentation. In conclusion, these data suggest that female cells are superior to male cells in immunologic functions that are known to be associated with reactions to and recognition of histocompatibility antigens, i.e., antigen presentation and MLR. Furthermore, our present data indicate that the differential reactivity of immunocytes between male and female mice depends on the hormonal balance of the animal.