Deciphering the in situ phonon evolution of potassium sodium niobate under varying temperature and electric fields

The application of in situ Raman spectroscopy under multiple fields is widely recognized as an effective approach for investigating the physical mechanism of phase transitions in ferroelectrics, because it can directly provide the detailed information about the vibration evolution of various phonon modes within lattices, such as bond stretching and rotation. Based on this technique, our work aims to thoroughly probe the dynamics of phase transitions in traditional ferroelectric potassium sodium niobate [(K,Na)NbO3, KNN] under external fields, by analyzing the in situ dependence of wavenumber and intensity of phonon modes under the varying temperature and electric fields. The results indicate that different vibration modes respectively relating to the A-site ions and NbO6 octahedra in KNN exhibit distinct and abrupt distortion behavior during the orthorhombic-tetragonal and tetragonal-cubic transitions. Moreover, a certain degree of distortion can still be observed in the cubic phase above the Curie temperature. With an applied electric field, KNN presents quite different electrostriction in orthorhombic and tetragonal phases. Particularly, more than one kind of phonon mode undergoes non-linear variations under the varying electric fields, accompanied by the mutations at some fixed fields. These findings will be conducive to further understanding the phase transition mechanism in KNN from the perspective of phonon evolution. Simultaneously, it will also give crucial guidance for the design and development of KNN-based ferroelectrics as well as functional devices.

[Clinical characteristics of 272 437 patients with different histopathological subtypes of primary esophageal malignant tumors]

Objective: To characterize the histopathological subtypes and their clinicopathological parameters of gender and onset age by common, rare and sparse primary esophageal malignant tumors (PEMT). Methods: A total of 272 437 patients with PEMT were enrolled in this study, and all of the patients were received radical surgery. The clinicopathological information of the patients was obtained from the database established by the State Key Laboratory of Esophageal Cancer Prevention & Treatment from September 1973 to December 2020, which included the clinical treatment, pathological diagnosis and follow-up information of esophagus and gastric cardia cancers. All patients were diagnosed and classified by the criteria of esophageal tumor histopathological diagnosis and classification (2019) of the World Health Organization (WHO). The esophageal tumors, which were not included in the WHO classification, were analyzed separately according to the postoperative pathological diagnosis. The χ² test was performed by the SPSS 25.0 software on count data, and the test standard α=0.05. Results: A total of 32 histopathological types were identified in the enrolled PEMT patients, of which 10 subtypes were not included in the WHO classification. According to the frequency, PEMT were divided into common (esophageal squamous cell carcinoma, ESCC, accounting for 97.1%), rare (esophageal adenocarcinoma, EAC, accounting for 2.3%) and sparse (mainly esophageal small cell carcinoma, malignant melanoma, etc., accounting for 0.6%). All the common, rare, and sparse types occurred predominantly in male patients, and the gender difference of rare type was most significant (EAC, male∶ female, 2.67∶1), followed with common type (ESCC, male∶ female, 1.78∶1) and sparse type (male∶ female, 1.71∶1). The common type (ESCC) mainly occurred in the middle thoracic segment (65.2%), while the rare type (EAC) mainly occurred in the lower thoracic segment (56.8%). Among the sparse type, malignant melanoma and malignant fibrous histiocytoma were both predominantly located in the lower thoracic segment (51.7%, 66.7%), and the others were mainly in the middle thoracic segment. Conclusion: ESCC is the most common type among the 32 histopathological types of PEMT, followed by EAC as the rare type, and esophageal small cell carcinoma and malignant melanoma as the major sparse type, and all of which are mainly occur in male patients. The common type of ESCC mainly occur in the middle thoracic segment, while the rare type of EAC mainly in the lower thoracic segment. The mainly sparse type of malignant melanoma and malignant fibrous histiocytoma predominately occur in the lower thoracic segment, and the remaining sparse types mainly occur in the middle thoracic segment.

Measurement of the Cosmic Ray Helium Energy Spectrum from 70 GeV to 80 TeV with the DAMPE Space Mission

The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the Dark Matter Particle Explorer (DAMPE) is reported in this work. A hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of 4.3σ. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out.

[A prospective cohort study on the associations between vitamin D nutritional status and cardiometabolic abnormities in children]

Objective: To investigate the relationships between vitamin D nutritional status and the risks of cardiometabolic abnormities in children. Methods: Data were obtained from the School-based Cardiovascular and Bone Health Promotion Program. In 2017, a total of 15 391 children aged 6-16 years in Beijing were selected by using a stratified cluster sampling method in the baseline survey. A Follow-up investigation was conducted in 2019. Log-binomial regression was used to analyze the relationships between baseline vitamin D nutritional status and the risks of cardiometabolic abnormities (obesity, hypertension, hyperglycemia, and dyslipidemia). Results: A total of 10 482 participants were involved in the study. The average vitamin D level was (35.6 ± 12.0) nmol/L, and the deficiency rate was 35.1%. The 2-year cumulative incidence rates of obesity, hypertension, hyperglycemia, high TC, high LDL-C, low HDL-C, high TG, and high non-HDL-C were 4.3%, 10.8%, 8.5%, 3.1%, 2.5%, 3.4%, 2.5%, and 3.9% respectively. After the adjustment of potential confounding factors, children with vitamin D inadequacy or deficiency had higher risks of high TC [RR (95%CI): inadequacy, 2.06 (1.19-3.58); deficiency, 2.80 (1.61-4.89)], high LDL-C [RR (95%CI): inadequacy, 1.67 (1.02-2.73); deficiency, 1.99 (1.19-3.33)], and high non-HDL-C [RR (95%CI): inadequacy, 2.00 (1.26-3.17); deficiency, 2.45 (1.53-3.92)] compared with children with adequate vitamin D, and the risks of them increased with the decrease of vitamin D level (trend P<0.05). The gender-stratified analysis showed that vitamin D deficiency was remained associated with high TC [RR (95%CI): boy, 2.64 (1.19-5.87); girl, 3.13 (1.43-6.83)] and high non-HDL-C [RR (95%CI): boy, 2.58(1.40-4.77); girl, 2.31 (1.10-4.84)]. Conclusions: The risks of abnormal TC, LDL-C, and non-HDL-C were inversely associated with vitamin D level. Maintenance of adequate vitamin D status in children may contribute to the early prevention of cardiovascular diseases.

Possible scenario of forming a catalyst layer for proton exchange membrane fuel cells

Ionomer in the catalyst layer provides an ion transport channel which is essential for many electrochemical devices. As the ionomer and electrochemical catalyst are packed together in the catalyst layer, it is difficult to have a clear image of the ionomer distribution in the catalyst layer and how the ionomer is in contact with Pt or carbon. A highly dispersed catalyst was deposited on the TEM SiN grid directly using the same (ultrasonic spray) or a similar way as the catalyst was deposited on the membrane. By analyzing the distribution of various elements (C, F, S, Pt etc.), we found that the ionomer may coexist in the catalyst layer in three ways: ionomer covered Pt particles due to the relatively strong interaction between Pt and the ionomer; ionomer covered C particles; packed free ionomer in between the aggregated catalyst particles. The results show that the ionomer is prone to covering the surface of Pt particles as further evidenced by the accelerated degradation test (ADT).

Ionomer in the catalyst layer provides an ion transport channel which is essential for many electrochemical devices.

Measurement of the cosmic ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 ¹/₂ years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

Contribution of biomimetic collagen-ligand interaction to intrafibrillar mineralization

Contemporary models of intrafibrillar mineralization mechanisms are established using collagen fibrils as templates without considering the contribution from collagen-bound apatite nucleation inhibitors. However, collagen matrices destined for mineralization in vertebrates contain bound matrix proteins for intrafibrillar mineralization. Negatively charged, high-molecular weight polycarboxylic acid is cross-linked to reconstituted collagen to create a model for examining the contribution of collagen-ligand interaction to intrafibrillar mineralization. Cryogenic electron microscopy and molecular dynamics simulation show that, after cross-linking to collagen, the bound polyelectrolyte caches prenucleation cluster singlets into chain-like aggregates along the fibrillar surface to increase the pool of mineralization precursors available for intrafibrillar mineralization. Higher-quality mineralized scaffolds with better biomechanical properties are achieved compared with mineralization of unmodified scaffolds in polyelectrolyte-stabilized mineralization solution. Collagen-ligand interaction provides insights on the genesis of heterogeneously mineralized tissues and the potential causes of ectopic calcification in nonmineralized body tissues.

[Current status of job burnout in clinical nurses in a grade A tertiary hospital and related influencing factors]

Objective: To investigate the current status of job burnout in clinical nurses in a grade A tertiary hospitalin Shaoxing,China and related influencing factors. Methods: In October 2016, the Nursing Burnout Scale (NBS)was used for the investigation of 304 clinical nurses in a grade A tertiary hospital.The contents of the investigation included general data(including age,education background,working years,marital status, frequency of night shifts,professional title, and way of employment), characteristics of working environment,burnout, personality characteristics,coping strategy,and psychosomatic symptoms.SPSS 18.0 was used to conduct Pearson correlation analysis of the scores of each dimension of NBS. A multivariate regression analysis was performed with the demographic features of clinical nurses as the independent variable and the scores of each dimension of NBS as the dependent variable. Results: Among the clinical nurses in this grade A tertiary hospital, the incidence rate of severe burnout was 74%.The Pearson correlation analysis showed that burnout,pessimistic personality,negative coping,and psychosomatic symptoms were positively correlated with working environment(r=0.530,0.316,0.116,and 0.502); pessimistic personality and psychosomatic symptoms were positively correlated with burnout(r=0.618 and 0.675); psychosomatic symptoms were positively correlated withpessimistic personality(r=0.540); negative coping was negatively correlated with pessimistic personality(r=-0.145).The multivariate linear regression analysis showed that department(Department of Internal Medicine or Department of Surgery,B=-0.364 and -0.428)and frequency of night shifts(<6 times/month and 6-10 times/month,B=0.199 and 0.256)were influencing factors for the score of working environment; department(Department of Internal Medicine or Department of Surgery, B=-0.350 and -0.360)was an influencing factor for the score of burnout; 1-3 working years(B=-0.238)was an influencing factor for the score of pessimistic personality; married state,1-3 working years,and department (Department of Internal Medicine or Department of Surgery)were influencing factors for the score of psychosomatic symptoms(B=0.263,-0.301,-0.322,and -0.391). Conclusion: There is a high incidence rate of job burnout among clinical nurses in this grade A tertiary hospital,which is associated with burnout,working environment, pessimistic personality,and psychosomatic symptoms.Marital status,working years,department,and frequency of night shifts are major influencing factors for job burnout.

Germanene on single-layer ZnSe substrate: novel electronic and optical properties

In this work, the structural, electronic and optical properties of germanene and ZnSe substrate nanocomposites have been investigated using first-principles calculations. We found that the large direct-gap ZnSe semiconductors and zero-gap germanene form a typical orbital hybridization heterostructure with a strong binding energy, which shows a moderate direct band gap of 0.503 eV in the most stable pattern. Furthermore, the heterostructure undergoes semiconductor-to-metal band gap transition when subjected to external out-of-plane electric field. We also found that applying external strain and compressing the interlayer distance are two simple ways of tuning the electronic structure. An unexpected indirect-direct band gap transition is also observed in the AAII pattern via adjusting the interlayer distance. Quite interestingly, the calculated results exhibit that the germanene/ZnSe heterobilayer structure has perfect optical absorption in the solar spectrum as well as the infrared and UV light zones, which is superior to that of the individual ZnSe substrate and germanene. The staggered interfacial gap and tunability of the energy band structure via interlayer distance and external electric field and strain thus make the germanene/ZnSe heterostructure a promising candidate for field effect transistors (FETs) and nanoelectronic applications.

Theoretical investigation of the strengthening mechanism and precipitation evolution in high strength Al-Zn-Mg alloys

Density-functional theory calculations have been performed to systematically investigate the behaviors of solute atoms in 7000 series Al-Zn-Mg based alloys. It is found that solute atoms Mg and Zn are likely to segregate to the Σ5(210)[001] tilt Al GB. The bonding environment and interface cohesion will be affected to different degrees. Also, for GPI(100) our calculations indicate that a Zn/Mg/Zn sandwich configuration in the Al matrix (100) planes is energetically favorable. However, for GPII(111) the disordered structure turns out to be the most stable one. It mainly results from strong 3d-3s hybridization interactions between Zn and Mg atoms. Furthermore, the properties of the metastable phase η' and the equilibrium phase η have also been addressed. The present study provides valuable insight for developing Al alloys with superior performance.

mRNA and protein expression levels of four candidate genes for ear size in Erhualian and Large White pigs

Porcine ear size is an important characteristic for distinguishing among pig breeds. In a previous genome-wide association study of porcine ear size, LEM domain-containing 3 (LEMD3), methionine sulfoxide reductase B3 (MSRB3), high mobility group AT-hook 2 (HMGA2), and Wnt inhibitory factor 1 (WIF1) were implicated as important candidate genes for ear size. This study investigated the expression levels of four candidate genes for ear size in Erhualian and Large White pigs. Ten Erhualian pigs with large ears and eight Large White pigs with small ears at 60 days of age were examined. The mRNA expression levels of the four candidate genes were quantified by real-time polymerase chain reaction. WIF1 mRNA expression was significantly higher in Large White than in Erhualian pigs (P < 0.05), whereas the expression levels of the other three genes were not significantly different between the two breeds. The protein expression levels of the four genes were analyzed using western blot. WIF1 protein expression was significantly higher in Large White than in Erhualian pigs (P < 0.01), whereas MSRB3 protein expression was significantly higher in Erhualian than in Large White pigs (P < 0.05). There were no significant differences between the two breeds in residual protein expression. These results suggest that WIF1 is the main causal gene for ear size in pigs.

Porcine MAP3K5 analysis: molecular cloning, characterization, tissue expression pattern, and copy number variations associated with residual feed intake

Mitogen-activated protein kinase kinase kinase 5 (MAP3K5) is essential for apoptosis, proliferation, differentiation, and immune responses, and is a candidate marker for residual feed intake (RFI) in pig. We cloned the full-length cDNA sequence of porcine MAP3K5 by rapid-amplification of cDNA ends. The 5451-bp gene contains a 5'-untranslated region (UTR) (718 bp), a coding region (3738 bp), and a 3'-UTR (995 bp), and encodes a peptide of 1245 amino acids, which shares 97, 99, 97, 93, 91, and 84% sequence identity with cattle, sheep, human, mouse, chicken, and zebrafish MAP3K5, respectively. The deduced MAP3K5 protein sequence contains two conserved domains: a DUF4071 domain and a protein kinase domain. Phylogenetic analysis showed that porcine MAP3K5 forms a separate branch to vicugna and camel MAP3K5. Tissue expression analysis using real-time quantitative polymerase chain reaction (qRT-PCR) revealed that MAP3K5 was expressed in the heart, liver, spleen, lung, kidney, muscle, fat, pancrea, ileum, and stomach tissues. Copy number variation was detected for porcine MAP3K5 and validated by qRT-PCR. Furthermore, a significant increase in average copy number was detected in the low RFI group when compared to the high RFI group in a Duroc pig population. These results provide useful information regarding the influence of MAP3K5 on RFI in pigs.

[Application of (125)I seeds combined with biliary stent implantation in the treatment of malignant obstructive jaundice]

OBJECTIVE

To study the feasibility and therapeutic effect of the application of (125)I seeds combined with biliary stent implantation on the treatment of malignant obstructive jaundice.

METHODS

Fifty patients with malignant obstructive jaundice treated from September 2010 to February 2013 in Yantai Yuhuangding Hospital were included in this study. Among them, 24 patients received biliary stent implantation combined with (125)I seeds intraluminal brachytherapy as experimental group, and 26 were treated by biliary stent implantation as control group.The total bilirubin, direct bilirubin and tumor markers (CA-199, CA-242, CEA) before and after surgery, the biliary stent patency status was assessed, and the survival time was evaluated.

RESULTS

The 24 patients in experimental group were implanted with 30 (125)I seeds successfully in a total of 450 seeds. Jaundice was improved greatly in both groups. The CA-199 and CA-242 after treatment in the experimental group were significantly decreased than that before treatment (P=0.003 and P=0.004). CEA was also decreased, but showed no statistical significance (P>0.05). There were no significant improvement comparing the CA-199, CA-242 and CEA before and 2 months after surgery in the control group (P>0.05). The rate of biliary stent patency was 83.3% (20/24) in the experimental group and 57.7% (15/26) in the control group (P=0.048). The mean biliary stent patency time in the experimental group was 9.84 months (range 1-15.5 months). The mean biliary stent patency time in the control group was 5.57 months (range 0.8-9 months). There was a significant difference between the two groups (P=0.018). The median survival time was 10.2 months in the experimental group and 5.4 months in the control group (P<0.05).

CONCLUSION

(125)I seeds combined with biliary stent implantation can inhibit the proliferation of vascular endothelial cells and the growth of tumor effectively, and can prolong the biliary stent patency time and the survival time obviously for patients with malignant obstructive jaundice, therefore, is a safe and effective treatment in this malignancy.

Molecular cloning, tissue expression pattern, and copy number variation of porcine SCUBE3

The signal peptide CUB EGF-like domain-containing protein 3 (SCUBE3) gene is a member of SCUBE gene family and plays important roles in bone cell biology and the determination of limb bone length. In this study, the full-length transcript of porcine SCUBE3 was cloned using reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends. The full-length sequence of porcine SCUBE3 cDNA was 4131 base pairs and included 21 exons. The SCUBE3 gene contained a 2895-base pair open reading frame that encoded a peptide of 965 amino acids. Comparison of the deduced amino acid sequences of porcine SCUBE3 with those of human, mouse, zebrafish, and rat showed 96, 95, 73, and 95% identities, respectively. Porcine SCUBE3 mRNA expression levels were highest in the backfat, bone marrow, and cartilage tissues. Copy number variation was detected in porcine SCUBE3 and validated by real-time quantitative polymerase chain reaction. Different copy number variations were present in randomly selected individuals and may, therefore, be a good marker for identifying phenotypic traits. Our findings provide a basis for further investigation of the functions and regulatory mechanisms of SCUBE3 in pigs.

Structural and electronic properties of the heterointerfaces for Cu2ZnSnS4 photovoltaic cells: a density-functional theory study

Density-functional theory calculations have been performed to investigate the structural and electronic properties of the CdS/CZTS heterointerfaces in CZTS-based cells.

Tunable catalytic reactivity of small palladium clusters supported on graphene: a first-principles study

The catalytic reactivity is controlled by the binding strength between the catalyst surface and reaction intermediates.

Study of the Mechanical Behavior of BCC Transition Metals Using Bond-Order Potentials

Deformation properties of body-centered-cubic transition metals are controlled by the core structure of screw dislocations and their studies involve extensive computer simulations. In this paper we present the recently constructed bond-order potentials (BOP) that are based on the realspace parametrized tight-binding method. In order to examine the applicability of the potentials we have evaluated the energy differences of alternative structures, investigated several transformation paths leading to large distortions and calculated phonon dispersions. Using these potentials we have calculated γ-surfaces that relate to the dislocation core structures and discuss then the importance of directional bonding in studies of dislocations in transition metals.

Nanoscale Structure/Property Correlation Through Aberration-Corrected Stem And Theory

The combination of atomic-resolution Z-contrast microscopy, electron energy loss spectroscopy and first-principles theory has proved to be a powerful means for structure property correlations at interfaces and nanostructures. The scanning transmission electron microscope (STEM) now routinely provides atomic-sized electron beams, allowing simultaneous Z-contrast imaging and EELS as shown in Fig. 1. The feasiblity of correcting the inherently large spherical aberration of microscope objective lenses promises to at least double the achievable resolution. The potential benefits for the STEM, however, may turn out to be much greater than those for the conventional TEM because it is very much less sensitive to chromatic instabilities. The 100 kV VG Microscopes HB501UX at Oak Ridge National Laboratory (ORNL) is now fitted with an aberration corrector constructed by Nion Co., which improved its resolution from 2.2 Å (full-width-half-maximum probe intensity) to around 1.3 Å. It is now very comparable in performance to the uncorrected 300 kV HB603U STEM at ORNL which, before correction, also had a directly interpretable resolution of 1.3 Å, although information transfer had been demonstrated down to 0.78 Å8. Initial results after installing an aberration corrector on the 300 kV STEM indicate a resolution of 0.84 Å. The theoretically achievable probe size in the absence of instabilities is predicted to be 0.5 Å.

In vitro degradation and mechanical integrity of Mg-Zn-Ca alloy coated with Ca-deficient hydroxyapatite by the pulse electrodeposition process

The key to manufacturing magnesium-based alloys that are suitable as biodegradable orthopaedic implants is how to adjust their degradation rates and mechanical integrity in the physiological environment. In this study, to solve this challenge, a soluble Ca-deficient hydroxyapatite (Ca-def HA) coating was deposited on an Mg-Zn-Ca alloy substrate by pulse eletrodeposition. This deposition can be demonstrated by X-ray diffractometry and energy dispersion spectroscopy analyses, and the Ca/P atomic ratio of as-deposited coating is about 1.33 (within the range from 1.33 to 1.65). By regulating the appropriate pulse amplitude and width, the Ca-def HA coating shows better adhesion to Mg-Zn-Ca alloy, whose lap shear strength is increased to 41.8+/-2.7 MPa. Potentiodynamic polarization results in Kokubo's simulated body fluid (SBF) indicate that the corrosion potential of Mg alloy increases from -1645 to -1414 mV, while the corrosion current density decreases from 110 to 25 microA/cm(2), which illustrates that the Ca-def HA coating improves the substrate corrosion resistance significantly. Since orthopaedic implants generally serve under conditions of stress corrosion, the mechanical integrity of the Mg-Zn-Ca alloy was measured using the slow strain rate tensile (SSRT) testing technique in SBF. The SSRT results show that the ultimate tensile strength and time of fracture for the coated Mg-Zn-Ca alloy are higher than those of the uncoated one, which is beneficial in supporting fractured bone for a longer time. Thus Mg-Zn-Ca alloy coated with Ca-def HA is be a promising candidate for biodegradable orthopaedic implants, and is worthwhile to further investigate the in vivo degradation behavior.

Crystallographic plane tuning of charge and spin transport in semiconductor quantum wires

We investigate theoretically the charge and spin transport in quantum wires grown along different crystallographic planes in the presence of the Rashba spin-orbit interaction (RSOI) and the Dresselhaus spin-orbit interaction (DSOI). We find that changing the crystallographic planes leads to a variation of the anisotropy of the conductance due to a different interplay between the RSOI and DSOI, since the DSOI is induced by bulk inversion asymmetry, which is determined by crystallographic plane. This interplay depends sensitively on the crystallographic planes, and consequently leads to the anisotropic charge and spin transport in quantum wires embedded in different crystallographic planes.

Conductance oscillations in a nanowire double junction

The interaction between two nanowire cross-junctions is studied in a three-wire double-junction structure. The dc conductances between terminals in the double-junction structure are calculated from the Green's function, which is obtained using the modular Green's function approach. Significant oscillations are found in the inter-wire conductances in both junctions, which are the consequence of interference of electron waves reflected between junctions. A phenomenological expression, which can relate the positions of neighboring oscillation peaks, is developed based on the interference mechanism. The interaction between quasi-bound states formed at the junctions is found to be negligible and has no significant effect on the inter-wire conductance peaks. Our results show that interaction between neighboring junctions should be properly considered in the modeling and design of nanowire devices and circuits.

De-repression of the p21 promoter in prostate cancer cells by an isothiocyanate via inhibition of HDACs and c-Myc

Natural isothiocyanates from cruciferous vegetables have been described as important dietary factors for prostate cancer prevention. Phenethyl isothiocyanate (PEITC), found rich in watercress, induces growth arrest and apoptosis in prostate cancer cells, and also inhibits the testosterone-mediated growth of prostates by regulating the androgen receptor and cell cycle progression in rats. PEITC has been recently identified as an inhibitor of histone deacetylases (HDACs). Herein we describe the mechanism of PEITC-mediated growth attenuation in relation to HDAC inhibition in human prostate cancer cells. Exposure of androgen-dependent prostate cancer cells LNCaP to PEITC resulted in cell cycle arrest and a p53-independent up-regulation of the inhibitors of cyclin-dependent kinases, including p21WAF1 and p27. The mechanism of p21 activation was investigated. PEITC significantly enhanced histone acetylation and induced selective modification of histone methylation for chromatin remodeling. Chromatin immunoprecipitation revealed that the p21 gene was associated with the PEITC-induced hyperacetylated histones. As a result, the chromatin unfolding permitted the transcription activation of the p21 gene. PEITC also significantly reduced the expression of c-Myc which represses p21. Pull-down assays using Sp1 affinity oligo beads of the p21 promoter, showed decreased c-Myc binding to the Sp1 transcriptional complexes in the p21 promoter, resulting in reduced p21 repression. The quantity of PEITC (0.5-1 micro M) effective to mediate cell cycle arrest was less than that for inhibiting c-Myc (2-5 micro M), suggesting that the inhibition of HDACs may be the primary mechanism for p21 activation. The PEITC-mediated growth attenuation of prostate cancer cells includes an interactive mechanism involving HDAC and c-Myc inhibition.

Modulating testosterone stimulated prostate growth by phenethyl isothiocyanate via Sp1 and androgen receptor down-regulation

BACKGROUND

The effects of phenethyl isothiocyanate (PEITC), present naturally in cruciferous vegetables, on androgen-influenced growth of the prostate such as benign hyperplasia, was investigated.

METHODS

Rats dosed with cyproterone acetate and testosterone, were fed at the same time with either PEITC or vehicle control. The growth of the prostates was compared to untreated rats.

RESULTS

While testosterone increased the prostate mass (30%) and hyperplastic seminiferous tubules as compared to the untreated rats, PEITC feeding decreased the prostate mass and hyperplasia to roughly the levels of untreated rats (P < 0.05). PEITC negated the testosterone-mediated enhancement of the androgen receptor (AR), via down-regulating transcription factor Sp1 expression and Sp1 binding complex formation. Cell cycle progression was attenuated with decreases of cyclins, Rb, and up-regulates p27.

CONCLUSIONS

PEITC modulates the testosterone-influenced growth by repressing Sp1, thus down-regulating AR and proliferation. PEITC from cruciferous vegetables may represent a regulator for hormone-dependent growth of the prostate.

Dual action on promoter demethylation and chromatin by an isothiocyanate restored GSTP1 silenced in prostate cancer

Prostate carcinoma is characterized by the silencing of pi-class glutathione S-transferase gene (GSTP1), which encodes a detoxifying enzyme. The silencing of GSTP1, due to aberrant methylation at the CpG island in the promoter/5'-UTR, occurs in the vast majority of prostate tumors and precancerous lesions. It is a pathologic marker and probably an underlying cause of oxidative damage and inflammation at tumor initiation. Inhibition of the aberrant promoter methylation could therefore be an effective mean to prevent carcinogenesis. Several isothiocyanates, including phenethyl isothiocyanate (PEITC), found naturally in cruciferous vegetables, induced growth arrest and apoptosis in prostate cancer cells in culture and xenografts. The effects of PEITC to reactivate GSTP1 were investigated. Exposure of prostate cancer LNCaP cells to PEITC inhibited the activity and level of histone deacetylases (HDACs), and induced selective histone acetylation and methylation for chromatin unfolding. Concurrently PEITC demethylated the promoter and restored the unmethylated GSTP1 in both androgen-dependent and -independent LNCaP cancer cells to the level found in normal prostatic cells, as quantified by methylation-specific PCR and pyrosequencing. The dual action of PEITC on both the DNA and chromatin was more effective than 5'-Aza-2'-deoxycytidine, sodium butyrate, or trichostatin A (TSA), and may de-repress the methyl-binding domain (MBD) on gene transcription. The PEITC-mediated cross-talk between the DNA and chromatin in demethylating and reactivating GSTP1 genes, which is critically inactivated in prostate carcinogenesis, underlines a primary mechanism of cancer chemoprevention. Consequently, new approaches could be developed, with isothiocyanates to prevent and inhibit malignancies.

Repression of androgen receptor in prostate cancer cells by phenethyl isothiocyanate

BACKGROUND

Prostate cancer usually progresses to androgen refractory after an initial anti-androgen treatment. The androgen receptor (AR) is a pivotal factor for the androgen-mediated growth and maintenance of the prostate. Abnormality of the AR, such as overexpression has been postulated to be related to the hormone independent growth of the cancer. Although we previously demonstrated that the AR expression could be modulated by isothiocyanates, which are natural constituents of cruciferous vegetables, the mechanism, however, remained to be clarified. We have since investigated the mechanism of phenethyl isothiocyanate (PEITC) in AR regulation.

METHODS

A human androgen dependent prostate cancer cell line LNCaP (AD) and its sub-line LNCaP (AI), i.e. androgen independent but overexpressing AR, were exposed to PEITC. The effects of PEITC on cell growth and AR expression/transcription were analyzed with MTT assay, real-time PCR and western blotting. The AR promoter activity was analyzed with the reporter activity after transfection with pAR-luc. The effects on Sp1, the major transcription factor of the AR, were tested with Sp1-luc activity, western blotting and electrophoretic mobility shift assay.

RESULTS

PEITC induced a significant growth inhibition, with equal IC(50), in both AD and AI cells. The AR present in both cells was repressed as demonstrated with real-time PCR and western blot. PEITC mediates dual effects at transcriptional and post-translational levels to regulate the AR. At transcriptional level the AR level was reduced via inhibition of the transcription factor Sp1, and at post-translational level by accelerating protein degradation.

CONCLUSION

PEITC represses AR transcription and expression, and mediates growth arrest in androgen dependent and independent prostate cancer cells. With the AR modulation and growth attenuation, PEITC and possibly other isothiocyanates, may prevent and inhibit hormone sensitive and refractory prostate cancer.

Unique induction of p21(WAF1/CIP1)expression by vinorelbine in androgen-independent prostate cancer cells

To study the mechanisms of the development of hormone refractory prostate cancer, we established an androgen-independent (AI) prostate cancer cell line derived from hormone-dependent (AD) LNCaP cells. Our previous studies have demonstrated that AI cells are deficient in expression of p21(WAFl/CIP1) (p21) due to overexpressed AR and are resistant to apoptosis. In this study, the induction of p53 and p21 expression by vinorelbine (Navelbine) was compared between AD and AI cells in an attempt to understand the difference(s) in apoptotic signalling pathways in these cells. Using a series of deletion of p21 reporter constructs, we found that vinorelbine mediated p21 induction in a p53-dependent manner in AD cells. In contrast, p21 expression restored by vinorelbine in AI cells was found to be through both p53-dependent and-independent pathways. In the absence of two p53 binding sites, Spl-3 and Spl-4 sites, in the promoter of human p21 gene, were found to be required for vinorelbine-mediated p21 activation. No p21 induction was observed by paclitaxel in AI cells. Exposure of AI cells to paciltaxel followed by vinorelbine produced synergism. Our data, thus, provide a basis for the synergistic combination of vinorelbine and paclitaxel for the treatment of advanced prostate cancer.

Cluster-doping approach for wide-gap semiconductors: the case of p-type ZnO

First-principles calculations on p-type doping of the paradigm wide-gap ZnO semiconductor reveal that successful doping depends much on engineering a stable local chemical bonding environment. We suggest a cluster-doping approach in which a locally stable chemical environment is realized by using few dopant species. We explain two puzzling experimental observations, i.e., that monodoping N in ZnO via N2 fails to produce p-type behavior, whereas using an NO source produces metastable p-type behavior, which disappears over time.

Adaptive crystal structures: CuAu and NiPt

We discover that Au-rich Cu1-xAux and Pt-rich Ni1-xPtx contain a composition range in which there is a quasicontinuum of stable, ordered "adaptive structures" made of (001) repeat units of simple structural motifs. This is found by searching approximately 3x10(6) different fcc configurations whose energies are parametrized via a "cluster expansion" of first-principles-calculated total energies of just a few structures. This structural adaptivity is explained in terms of an anisotropic, long-range strain energy.

The role of the nanoscale in surface reactions: CO2 on CdSe

Cd-rich CdSe nanocrystals below a critical size, under illumination, catalyze CO2 fixation, but bulk CdSe surfaces do not. We report first-principles calculations in which we determine the roles of faceting, deviations from stoichiometry, photoexcitation, and electron confinement, and the specific physics of the nanoscale. We further establish that catalysis does not occur at the nanocrystal surface; instead, neutral molecules adsorb, desorb negatively charged, and react elsewhere. Finally, we predict that n-type doped CdSe nanocrystals would be effective catalysts without photoexcitation.

Differential effect of vinorelbine versus paclitaxel on ERK2 kinase activity during apoptosis in MCF-7 cells

The effects of vinorelbine and paclitaxel on the activity of extracellular signal-regulated protein kinase2 (ERK2), a member of MAP kinase, and its role in the induction of bcl-2 phosphorylation and apoptosis were evaluated in MCF-7 cells. We demonstrated that ERK2 was activated rapidly by vinorelbine, and was inhibited by either paclitaxel or estramustine. A 3-fold increase of ERK2 kinase activity was observed within 30 min when MCF-7 cells were treated with 0.1 microM vinorelbine. In contrast, the same treatment with paclitaxel resulted in a significant decrease of ERK2 kinase activity. We also demonstrated that elevated bcl-2 phosphorylation induced by vinorelbine is paralleled by decrease of a complex formation between bcl-2 and bax, cleavage of poly (ADP) ribose polymerase (PARP) protein, activation of caspase-7, and apoptosis. The levels of bcl-2 phosphorylation, bax, and PARP were not significantly affected by 2'-amino-3'-methoxyflavone (PD 98059), an ERK kinase specific inhibitor. Thus, our data suggest that the apoptosis induced by vinorelbine in MCF-7 cells is mediated through the bcl-2 phosphorylation/bax/caspases pathways, and that activation of ERK2 by vinorelbine does not directly lead to the drug-mediated apoptosis. Since decrease of PARP occurred quickly following the treatment of MCF-7 cells with either 0.1 microM of vinorelbine or paclitaxel, this protein may serve as an early indicator of apoptosis induced not only by DNA damaging agents, but also by antimicrotubule drugs.

Overexpressed androgen receptor linked to p21WAF1 silencing may be responsible for androgen independence and resistance to apoptosis of a prostate cancer cell line

An androgen-independent (AI) prostate cancer cell line, derived recently from an LNCaP cell line maintained in androgen-poor conditions, has properties resembling a subgroup of advanced prostate cancers in that it has an overexpressed androgen receptor (AR), undetectable levels of p21WAF1 and prostate-specific antigen, and is resistant to apoptosis. The loss of prostate-specific antigen expression but not the p21WAF1 is attributable to gene silencing by hypermethylation. The high AR and undetectable p21WAF1 of AI cells, and lower AR but highly expressed p21WAF1 of androgen-dependent parental LNCaP cells, suggest a possibility of a functional link between these two proteins. Therefore, we examined the impact the modulation of AR will have on the expression of p21WAF1. Treatment of androgen-dependent cells with an androgen agonist, R1881, increased the AR protein level, whereas it simultaneously reduced the endogenous p21WAF1-protein 8-fold and the activity of a transiently transfected p21-promoter-reporter 10-fold. The down-regulation of p21WAF1 promoter appeared to be ARE mediated, dependent on AR, and not cell-type specific. Furthermore, a reduction of the AR level in AI cells by AR-antisense oligonucleotide increased the p21WAF1 promoter-reporter activity by approximately 4-fold, confirming a functional link between these two proteins. A strong, direct induction of p21WAF1 expression achieved by treatment of AI cells with trichostatin A produced a partial reversion of the AI phenotype evidenced by increased sensitivity of these cells to paclitaxel-induced apoptosis. Moreover, a reduction of AR level by antisense treatment, which also increased p21WAF1 expression, partially restored the androgen dependence of AI cells for growth. The functional link between AR dosage and p21WAF1 expression suggests that therapeutic reduction of AR protein in advanced prostate cancers with elevated AR levels may re-establish their hormone dependence and improve therapeutic response to repeated hormonal ablation and/or induction of apoptosis.

Human movement characteristics of target acquisition

Objective. This paper deals with the problem of human movement characteristics of target acquisition. Method. A hypothetical model was posed by using experimental data. Result. The conception of final target size was put forward, an equation for calculating the movement time of target acquisition was obtained, and a new definition of index of difficulty was given. Conclusion. Analysis of experimental data showed that this equation could give a better description of target acquisition in a wide range.

Synergism of cytotoxic effects of vinorelbine and paclitaxel in vitro

Empiric combinations of vinca alkaloids with taxanes have been recently used in clinical oncology. To enhance the activity of these two classes of agents, we evaluated the sequence and duration of exposure, looking for synergistic effects. Cell lines DU 145, PC 3, LnCaP, LL 86, MCF7wt, and MCF7/ADR (NCI/ADR-RES) were incubated with varying concentrations of paclitaxel or vinorelbine. Cytotoxicity was evaluated by a semiautomated MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) method. Synergism or antagonism of these two agents either sequentially or in combination was determined by median effect analysis. Prolonged exposure of cells to either drug enhanced cytotoxic effect. Synergism or antagonism with vinorelbine and paclitaxel were both sequence dependent and cell line specific. In the case of MCF7wt, synergism was seen when a 48-hr exposure to vinorelbine preceded paclitaxel, whereas antagonism was noted when both agents were applied simultaneously or when the sequence was reversed. Concurrent vinorelbine and paclitaxel were synergistic in four of six cell lines when the exposure was extended to 96 hr but not for shorter durations of exposure. Sequential exposure of vinorelbine preceding paclitaxel or prolonged exposure to both agents concurrently needs to be tested clinically to determine whether the antitumor activity of this combination can be enhanced. In addition, these studies suggest concurrent administration of these two agents may lead to a less than optimal cytotoxic result.

[Physical parameter measurement and quality assurance of X-knife]

The treatment of X-knife with linear accelerator, the results and the methods used in physical parameter measurement, are introduced in this paper. We also discusses some problems about quality control. It is proved that our results can be used in X-knife treatment.

[Material selection and structural design of simulated space module for field]

OBJECTIVE

To select the suitable material for the structure of simulated space cabin to meet the special requirements which the unitary metallic material cannot do.

METHOD

The structural material was selected through comparison between the mechanical properties of fiber reinforced plastics (FRP) and a few conventional metallic materials. The content and arrangement of the fibers in the composite material were suitably designed according to load condition and structural shape of the cabin.

RESULT

High strength and high stiffness, light weight, anti-fatigue and shock proof were achieved for the whole module structure. It meets the medical and hygienic standard for hazardous gases.

CONCLUSION

The structural design of fiber glass reinforced plastics composite module was proved to be successful. It reduced the weight of the module body, and increased the strength and toughness of the whole module.

Synergistic effect of estramustine and [3'-keto-Bmtl]-[Val2]-cyclosporine (PSC 833) on the inhibition of androgen receptor phosphorylation in LNCaP cells

Estramustine phosphate has been used frequently alone or in combination with other drugs for the treatment of hormone-refractory prostate cancer. Estramustine is one of the major active metabolites of estramustine phosphate in vivo. We recently demonstrated that estramustine acts as an androgen antagonist, and the combination of estramustine with [3'-keto-Bmtl]-[Val2]-cyclosporine (PSC 833) results in synergistic cytotoxicity. Unlike other regulators of microtubules, such as paclitaxel, the present study demonstrated that estramustine alone or in combination with PSC 833 did not induce bcl-2 phosphorylation in LNCaP cells. No synergism between estramustine and PSC 833 in the induction of bcl-2 phosphorylation was obtained in MCF-7 cells exposed for 16 hr to estramustine (5-15 microM) and PSC 833 (5 microM). A significant synergistic antiandrogenic effect as measured by the inhibition of dihydrotestosterone-induced reporter gene luciferase expression in both wild-type and mutated androgen receptor (AR) cDNA-transfected HeLa cells was observed when the cells were exposed to estramustine and PSC 833. Treatment of LNCaP cells with estramustine alone (5-15 microM) resulted in a decrease of AR expression and phosphorylation. This effect was enhanced markedly by PSC 833. A strong correlation between AR phosphorylation and expression of the AR target gene PSA was obtained in dihydrotestosterone-stimulated LNCaP cells. The up-regulated PSA expression is a function of the level of the phosphorylated AR (r = 0.9814), but not the dephosphorylated form of the receptor protein (r = 0.4808). Thus, our studies suggest that the synergism between estramustine and PSC 833 in LNCaP cells is a consequence of inhibition of AR expression and phosphorylation, thus leading to interruption of AR-mediated gene expression.

The effect of antimicrotubule agents on signal transduction pathways of apoptosis: a review

PURPOSE

Microtubules are important cytoskeletal components involved in many cellular events. Antimicrotubule agents including polymerizing agents (paclitaxel and docetaxel) and depolymerizing drugs (vincristine, vinorelbine, and estramustine phosphate) are widely used either alone or in combination with other anticancer drugs. These antimicrotubule agents are promoters of apoptosis in cancer cells. In this review, we discuss the role of bcl-2 family genes in the regulation of apoptosis, and summarize effects of microtubule targeting agents on apoptotic signal transduction pathways.

CONCLUSION

Disruption of microtubule structure by antimicrotubule drugs results in induction of tumor suppressor gene p53 and inhibitor of cyclin-dependent kinases, p21WAF1/CIP1 (p21), and activation/inactivation of several protein kinases including Ras/Raf, PKC/PKA I/II, MAP kinases, and p34cdc2. These protein kinases are associated directly or indirectly with phosphorylation of bcl-2. Phosphorylation of bcl-2 and the elevations of p53 and p21 lead to apoptosis. New pathways of antitumor agents could be directed at this p53, p21 and bcl-2/bax function, and may enhance the effect of existing agents.

Anti-tumor effect of angiogenesis inhibitor TNP-470 on the human nasopharyngeal carcinoma cell line NPC/HK1

The efficacy and targeting cells of angiogenesis inhibitor TNP-470 on human squamous cell nasopharyngeal carcinoma (NPC) were investigated. The colorimetric MTT assay was used to evaluate the IC50 values of NPC/HK1 cells and human dermal microvascular endothelial cells (HDMEC) for TNP-470. An NPC human tumor model was built by tumor-bearing nude mice using the NPC cell line of NPC/HK1. TNP-470 (30 mg/kg s.c.) was injected every other day. The results showed that the IC50 of NPC/HK1 cells for TNP-470 was 3.8 times higher than that of HDMEC. A significant difference in tumor volume between control and treatment groups was found after 7 days of treatment and increased thereafter. At the end of the treatment, tumor volume was 773.7 +/- 287.1 mm3 (n = 8) in the control group versus 454.5 +/- 132.8 mm3 (n = 8) in the treatment group (p = 0. 013); the ratio of the mean tumor volume in treated animals to that of control animals was 0.587, resulting a 41.3% decrease in tumor growth. The necrotic area was larger in the treatment group. Physical toxicity did not result from the treatment. These studies suggest that angiogenesis inhibitor TNP-470 is effective in the treatment of squamous cell NPC without obvious toxicity.

Phosphorylation/dephosphorylation of androgen receptor as a determinant of androgen agonistic or antagonistic activity

Protein phosphorylation/dephosphorylation is an important posttranslational modification that plays a critical role in signal transduction. The androgen receptor (AR) is under such control. We demonstrate that androgen receptor phosphorylation determines whether or not AR ligands perform as agonists or antagonists in LNCaP cells. Androgen receptor ligands (such as dihydrotestosterone and beta-estradiol) stimulate receptor expression and phosphorylation and, as a result, they act as agonists or partial agonists. In contrast, agents such as bicalutamide and estramustine inhibit the receptor phosphorylation and act as antagonists. This model is supported by gene expression and transactivation assays. Significant increases in levels of both mRNA and protein of prostate-specific antigen (PSA), a natural AR target gene, occur following the treatment of LNCaP cells with DHT, beta-estradiol, or hydroxyflutamide. In contrast, exposure of LNCaP cells to bicalutamide or estramustine results in a sharp decrease of PSA expression. Agonistic or antagonistic effect of these compounds on PSA expression parallels the level of phosphorylated, but not dephosphorylated androgen receptors. These agonistic or antagonistic effects are also observed in HeLa cells transfected with wild-type AR expression plasmid (pAR0) and AR-driven luciferase expression plasmid GRE-tk-LUC in the presence of different groups of AR blockers. Our data indicate that the functional status of androgen receptors is strongly correlated with the phosphorylation status of the receptors, and that the phosphorylated androgen receptor is the form of the receptor transcriptionally active in regulation. Thus the androgen receptor phosphorylation/dephosphorylation may serve as a new molecular target for screening androgen antagonists for the treatment of prostate cancer.

Androgen antagonistic effect of estramustine phosphate (EMP) metabolites on wild-type and mutated androgen receptor

Estramustine phosphate is used frequently, alone or in combination with other antitumor agents, for the treatment of hormone-refractory prostate cancer. Estramustine phosphate is metabolically activated in vivo, and its metabolites, estramustine, estromustine, estrone, and beta-estradiol inhibit the assembly of microtubules [for review see: Kreis W, In: Concepts, Mechanisms, and New Targets for Chemotherapy (Ed. Muggia FM), pp. 163-184. Kluwer Academic Publishers, Boston, 1995]. We investigated, by displacement of [3H]methyltrienolone in the presence of 2.5 mM of triamcinolone acetonide, the binding of estramustine phosphate and its metabolites, estramustine, estromustine, estrone, and beta-estradiol, as well as other antiandrogen agents including alpha-estradiol, bicalutamide, and hydroxyflutamide, to the mutated androgen receptor (m-AR) in LNCaP cells and to the wild-type androgen receptor in wild-type AR cDNA expression plasmid (w-pAR0) cDNA-transfected HeLa cells. Analogous to the antiandrogens, bicalutamide and hydroxyflutamide, binding of estramustine phosphate metabolites to the androgen receptor was observed. The EC50 values (in microM) were: estramustine phosphate, > 10; estramustine, 3.129 +/- 0.312; estromustine; 2.612 +/- 0.584; estrone, 0.800 +/- 0.090; alpha-estradiol, 1.051 +/- 0.096; beta-estradiol, 0.523 +/- 0.028; bicalutamide, 4.920 +/- 0.361; and hydroxyflutamide, 0.254 +/- 0.012. The transactivation assay demonstrated that, analogous to bicalutamide, estramustine could not induce luciferase activity in either w-pAR0 or m-pARL transfected HeLa cells. In contrast, a strong induction of the reporter activity by dihydrotestosterone was observed. Down-regulation of prostate-specific antigen (PSA) expression, an AR-target gene, by estramustine and bicalutamide was accompanied by the blockade of the mutated androgen receptor. Exposure of LNCaP cells to estramustine for 24 hr caused transcriptional inhibition of PSA in a concentration-dependent manner. The levels of PSA mRNA decreased 56 and 90% when LNCaP cells were treated with 5 and 10 microM of estramustine, respectively (IC50 = 10.97 +/- 1.68 microM). Binding of hydroxyflutamide to m-AR in LNCaP cells resulted in a concentration-dependent stimulation of PSA expression, suggesting that hydroxyflutamide acted as an agonist of the m-AR. Our data indicate that estramustine phosphate metabolites perform as androgen antagonists of AR, an additional mechanism involved in the therapeutic effect of estramustine phosphate in patients with prostate cancer.

Down-regulation of prostate-specific antigen expression by finasteride through inhibition of complex formation between androgen receptor and steroid receptor-binding consensus in the promoter of the PSA gene in LNCaP cells

As a specific competitive inhibitor of 5alpha-reductase, an intracellular enzyme that converts testosterone to dihydrotestosterone, finasteride is being extensively used for the treatment of benign prostatic hyperplasia and in experimental settings for prostate cancer. In this study, we showed that finasteride markedly inhibited prostate-specific antigen (PSA) secretion and expression. The promoter of the PSA gene contains several well-known cis-regulatory elements. Among them, steroid receptor-binding consensus (SRBC) has been identified as a functional androgen-responsive element. Our previous study showed that PSA was not only present in conditioned medium of the PSA-positive LNCaP cells but was also detectable in small amounts in PSA-negative cell lines, PC-3 and DU-145 (L. G. Wang et al., Oncol. Rep., 3: 911-917, 1996). A strong correlation between binding of nuclear factors to SRBC and the level of PSA present in the conditioned medium and cell extracts was found in these three cell lines, whereas no such correlation with binding was obtained using Sp1 oligonucleotide as a probe. Binding of LNCaP cell nuclear proteins to SRBC was diminished when the cells were exposed to 25 microM finasteride, at which concentration 50% of both PSA mRNA and protein were inhibited. As a major component of DNA-protein complexes, the level of androgen receptor was dramatically decreased in the cells treated with finasteride. Our data indicate that inhibition of complex formation between SRBC and nuclear proteins due to the remarkable decrease in the level of androgen receptor plays a key role in the down-regulation of PSA gene expression by finasteride in LNCaP cells.

Induction of differentiation and down-regulation of c-myb gene expression in ML-1 human myeloblastic leukemia cells by the clinically effective anti-leukemia agent meisoindigo

Meisoindigo, a second generation derivative of indirubin, is an effective chemotherapeutic agent with very low toxicity used in the treatment of chronic myeloid leukemia. To determine the nature of this activity, the effect of a nontoxic concentration (0.72 micrograms/mL) of this compound on ML-1 human myeloblastic leukemic cells was examined. At such a concentration, differentiation induction was found to be the most pronounced drug effect. During the 3-day drug incubation period, the viable cell number remained essentially constant, with approximately 48% of the cells demonstrating a mature phenotype with increased acid phosphatase activity and nitroblue tetrazolium dye reduction. As observed with other DNA-specific agents, induction of ML-1 differentiation by meisoindigo was accompanied by the down-regulation of c-myb gene expression. These data suggest that induction of leukemic cell differentiation associated with decreased c-myb expression may be one of the mechanisms of the antitumor action of meisoindigo.

Evidence that lipid peroxidation products bind to DNA in liver cells

Three lines of evidence are presented indicating the association of lipid peroxidation products with DNA in liver cells, labeled with [3H]arachidonic acid, in the presence of Fe(2+)-DTPA: (1) the nuclear DNA isolated from treated cells had higher radioactivity, compared to controls and the radioactivity increased with longer incubation times, (2) lipid-DNA adducts with a characteristic fluorescence spectrum were formed during the incubation with Fe(2+)-DTPA; (3) the association of peroxidation products with DNA could be inhibited by vitamin E and BHT. Compared with control DNA, purified lipid-DNA adducts showed a decrease of hyperchromicity and melting point, and partial resistance to hydrolysis by DNase I. On the other hand, the repair test shows that the lipid-DNA adducts in cells were not repaired by 4 h after removal of Fe(2+)-DTPA. A decrease in cell viability and in the activity of O6-alkylguanine acceptor protein was also observed with increasing incubation time. These data suggest that the lipid-DNA association, an oxidative DNA damage, occurs in cells treated by Fe(2+)-DTPA and could result in cytotoxicity if not repaired.

Activation of casein kinase II in ML-1 human myeloblastic leukemia cells requires IGF-1 and transferrin

Casein kinase II (CK II), a key enzyme involved in the regulation of cell growth, has been variously reported to be activated by diverse mitogens, including insulin-like growth factor 1 (IGF-1) and epidermal growth factor (EGF). Activation of the enzyme is generally carried out in the presence of serum, and we examined the question whether serum components participate in the activation process. We demonstrated previously that ML-1 cells require IGF-1 plus transferrin (TF) for growth and transforming growth factor beta or tumor necrosis factor alpha plus TF for differentiation. We now found that CK II is activated only when the cells are exposed to both IGF-1 and TF or when TF is replaced in this combination with relatively high levels of iron salts. Induction of differentiation with TGF-beta and TF did not result in CK II activation. These results show that CK II activation in ML-1 cells requires the application of both components of the growth signal, IGF-1 and TF, demonstrating that the growth factor alone is incapable of enhancing the activity of the enzyme.