Inhibitory effects of diarsenic trioxide (As2O3) on hepatocellular carcinoma cells exerted by regulation of promyelocytic leukemia protein levels

Previous Chinese research revealed that diarsenic trioxide (As2O3) inhibits acute promyelocytic leukemia (PML) cell proliferation and initiates apoptosis through degradation of the PML-retinoic acid receptor protein. This study was to analyse whether As2O3 also had an effect on hepatocellular carcinoma (HCC) cells. As2O3 effects on various HCC cell lines and primary HCC cells were investigated in time and dose series, including measurements of cell growth, PML mRNA and protein expression, xenografted tumor formation, and the self-renewal Oct4 and hepatocyte marker expressions in mouse model xenografts or cells treated with PML siRNA. The results were analyzed by immunocytochemistry, quantitative reverse transcription PCR and western blotting as well as indocyanine green and Periodic Acid Schiff staining. As2O3 inhibited HCC cell and HCC cell-derived xenograft tumor formation in a time-dependent manner and reduced PML protein expression in HCC cells, but had limited effects on PML mRNA levels in cell nuclei. The HCC cell line HuH7 treated with As2O3 showed a decreased expression of alpha-fetoprotein and increased expression and transcription of mature hepatocyte markers, indicating differentiation of HCC cells into hepatocytes. Cytokeratin 18 protein and mRNA levels as well as tyrosine aminotransferase and apolipoprotein B mRNA transcriptions were enhanced by As2O3 as were the numbers of indocyanine green and Periodic Acid Schiff stained cells. In addition, As2O3 downregulated the expression of Oct4. In conclusion, since As2O3 inhibited HCC cell proliferation and HCC cell-derived xenograft tumor formation it is suggested that an appropriate concentration of As2O3 might be a promising therapy to treat HCC.

Customizable trajectory of trapped particle in quadruple-beam optical trap.

We have presented and demonstrated a customizable trajectory of a trapped particle in the Quadruple-beam optical trap. The orbital motion of the trapped microsphere was realized by modulating the trapping power. The motion trajectories could be designed by adjusting the modulation frequency, amplitude, and phase. By using this method, we have realized the triangle, bowknot, ellipse, straight line, and hooklike trajectories. The motion frequencies and circumferences were also modulated. The customizable trajectory in the optical trap may result in more possibilities for directional movement, microfluidic mixing, driven machines, and even painting freely.

Simulations and Experiments on the Vibrational Characteristics of Cylindrical Resonators with First Three Harmonic Errors.

A cylindrical resonator gyroscope is a kind of Coriolis gyroscope, which measures angular velocity or angle via processing of the standing wave. The symmetry of a cylindrical resonator is destroyed by different degrees of geometric nonuniformity and structural damage in the machining process. The uneven mass distribution caused by the asymmetry of the resonator can be expressed in the form of a Fourier series. The first three harmonics will reduce the anti-interference ability of the resonator to the external vibration, as well as increase the angular random walk and zero-bias drift of the gyroscope. In this paper, the frequency split of different modes caused by the first three harmonic errors and the displacement of the center of the cylindrical resonator bottom plate are obtained by simulation, and the relationship between them is explored. The experimental results on five fused silica cylindrical resonators are consistent with the simulation, confirming the linear relationship between the n = 1 frequency split and second harmonic error. A method for evaluating the first three harmonic errors of fused silica cylindrical resonators is provided.

Online calibration technology for a one-dimensional laser Doppler velocimeter based on a strapdown inertial navigation system.

In the integrated navigation system, which consists of a laser Doppler velocimeter (LDV) and strapdown inertial navigation system, it is necessary to calibrate the LDV. We propose an online calibration method for a LDV based on the strapdown inertial navigation system. This system uses highly accurate output information in the early stage of the inertial navigation system to carry out coarse calibration for the velocimeter and then employs a Kalman filter to correct the results of coarse calibration to achieve high precision calibration for the velocimeter. Experimental results show that the relative distance error of dead reckoning is less than 0.02%, indicating that the proposed online calibration method can achieve high-precision calibration for the velocimeter.

Trimming of Imperfect Cylindrical Fused Silica Resonators by Chemical Etching.

The cylindrical resonator gyroscope (CRG) is a kind of solid-state gyroscope with a wide application market. The cylindrical resonator is the key component of CRG, whose quality factor and symmetry will directly affect the performance of the gyroscope. Due to the material properties and fabrication limitations, the actual resonator always has some defects. Therefore, frequency trimming, i.e., altering the local mass or stiffness distribution by certain methods, is needed to improve the overall symmetry of the resonator. In this paper, we made further derivation based on the chemical trimming theory proposed by Basarab et al. We built up the relation between the frequency split and the balanced mass to determine the mass to be removed. Chemical trimming experiments were conducted on three cylindrical fused silica resonators. The frequency splits of the three resonators were around 0.05 Hz after chemical trimming. The relation between frequency split and balanced mass established from experimental data was consistent with the theoretical calculation. Therefore, frequency split can be reduced to lower than 0.05 Hz under rigorous theoretical calculation and optimized chemical trimming parameters.

Elliptical polarization of near-resonant linearly polarized probe light in optically pumped alkali metal vapor.

Optically pumped alkali metal atoms currently provide a sensitive solution for magnetic microscopic measurements. As the most practicable plan, Faraday rotation of linearly polarized light is extensively used in spin polarization measurements of alkali metal atoms. In some cases, near-resonant Faraday rotation is applied to improve the sensitivity. However, the near-resonant linearly polarized probe light is elliptically polarized after passing through optically pumped alkali metal vapor. The ellipticity of transmitted near-resonant probe light is numerically calculated and experimentally measured. In addition, we also analyze the negative impact of elliptical polarization on Faraday rotation measurements. From our theoretical estimate and experimental results, the elliptical polarization forms an inevitable error in spin polarization measurements.

Arsenite inhibits the function of CD133+ CD13+ liver cancer stem cells by reducing PML and Oct4 protein expression.

Cancer stem cells (CSCs) can form new tumors and contribute to post-operative recurrence and metastasis. We showed that CD133+CD13+ hepatocytes isolated from HuH7 cells and primary HCC cells display biochemical and functional characteristics typical of CSCs, suggesting that CD133+CD13+ hepatocytes in primary HCC tumors function as CSCs. We also found that arsenite treatment reduced the viability and stemness of CD133+CD13+ hepatocytes, enhanced the sensitivity of HuH7 cells to pirarubicin, and reduced the tumorigenicity of CD133+CD13+ hepatocytes xenografts in mice. The effects of sodium arsenite treatment in CD133+CD13+ hepatocytes were mediated by the post-transcriptional suppression of PML expression and the inhibition of Oct4, Sox2, and Klf4 expression at the transcriptional level. Incomplete rescue of Oct4 expression in arsenic-treated cells ectopically expressing an siRNA-resistant PML transcript suggested that OCT4 regulation in liver CSCs involves other factors in addition to PML. Our findings provide evidence of a specific role for PML in regulating Oct4 levels in liver CSCs and highlight the clinical importance of arsenic for improving the efficacy of other chemotherapeutic agents and the prevention of post-operative HCC recurrence and metastasis.

Super-transmission from a finite subwavelength arrangement of slits in a metal film.

A theory is presented for the transmission of transverse magnetic waves through a finite number of subwavelength slits in metal film. While a single slit achieves the single channel limit on resonance, multiple slits show super-transmission exceeding the single channel limit. The phenomenon of super-transmission is revealed as a result of cross-coupling of modes and confirmed by simulations. The influence of finite permittivity in the IR and microwave regime is included by perturbative corrections to the theory. The theory agrees quantitatively with past experiments and finite-difference time-domain simulations. By considering two or more modes in the slit region, our theory provides an approach to the analysis of cross-coupling among slits, which allows for super-transmission and features of a Fano resonance.

[Hepatitis B virus X protein regulates c-met promoter via the ERKs singal pathway in HepG2 cells].

OBJECTIVE: To explore the signal pathway mediating the regulatory effect of Hepatitis B virus X protein (HBX) on c-met gene promoter in HepG2 cells. METHODS: The expression of c-met in HBX-transfected HepG2 cells treated with different signal pathway inhibitors was detected by western blot, the invasion capability of cells was determined by Matrigel invasion assay. RESULTS: ERK inhibitor U0126 inhibited the expression of the c-Met in HBx-transfected HepG2 cells. However, both p38MAPK inhibitor SB203580 and PI-3K inhibitor wortmanin had no effect on expression of the c-Met in HBx-transfected HepG2 cells. Furthermore, the ERK inhibitor U0126 also inhibited the invasiveness of HBX-transfected HepG2 cells. CONCLUSION: HBx induces invasion of HCC via activation of ERK pathway.