Elevated expression of CDK4 in lung cancer

<p/> <p>Background</p> <p>The aim of the present study was to analyze the expression of Cyclin-dependent kinase 4 (<it>CDK4</it>) in lung cancer and its correlation with clinicopathologic features. Furthermore, the involvement of <it>CDK4</it>-mediated cell cycle progression and its molecular basis were investigated in the pathogenesis of lung cancer.</p> <p>Methods</p> <p>Using immunohistochemistry analysis, we analyzed <it>CDK4 </it>protein expression in 89 clinicopathologically characterized lung cancer patients (59 males and 30 females) with ages ranging from 36 to 78 years and compared them to 23 normal lung tissues. Cases with cytoplasmic and nuclear <it>CDK4 </it>immunostaining score values greater than or equal to 7 were regarded as high expression while scores less than 7 were considered low expression. The correlation between the expression level of <it>CDK4 </it>and clinical features was analyzed. Furthermore, we used lentiviral-mediated shRNA to suppress the expression of CDK4 and investigate its function and molecular mechanism for mediating cell cycle progression.</p> <p>Results</p> <p>The expression level of <it>CDK4 </it>protein was significantly increased in lung cancer tissues compared to normal tissues (<it>P </it>< 0.001). In addition, high levels of <it>CDK4 </it>protein were positively correlated with the status of pathology classification (<it>P </it>= 0.047), lymph node metastasis (<it>P </it>= 0.007), and clinical stage (<it>P </it>= 0.004) of lung cancer patients. Patients with higher <it>CDK4 </it>expression had a markedly shorter overall survival time than patients with low <it>CDK4 </it>expression. Multivariate analysis suggested the level of <it>CDK4 </it>expression was an independent prognostic indicator (<it>P </it>< 0.001) for the survival of patients with lung cancer. Use of lentiviral-mediated shRNA to inhibit the expression of <it>CDK4 </it>in lung cancer cell line A549 not only inhibited cell cycle progression, but also dramatically suppressed cell proliferation, colony formation, and migration. Furthermore, suppressing <it>CDK4 </it>expression also significantly elevated the expression of cell cycle regulator <it>p21</it></p> <p>Conclusion</p> <p>Overexpressed <it>CDK4 </it>is a potential unfavorable prognostic factor and mediates cell cycle progression by regulating the expression of <it>p21 </it>in lung cancer</p

ZEB2 Mediates Multiple Pathways Regulating Cell Proliferation, Migration, Invasion, and Apoptosis in Glioma

BACKGROUND: The aim of the present study was to analyze the expression of Zinc finger E-box Binding homeobox 2 (ZEB2) in glioma and to explore the molecular mechanisms of ZEB2 that regulate cell proliferation, migration, invasion, and apoptosis. METHODOLOGY/PRINCIPAL FINDINGS: Expression of ZEB2 in 90 clinicopathologically characterized glioma patients was analyzed by immunohistochemistry. Furthermore, siRNA targeting ZEB2 was transfected into U251 and U87 glioma cell lines in vitro and proliferation, migration, invasion, and apoptosis were examined separately by MTT assay, Transwell chamber assay, flow cytometry, and western blot. RESULTS: The expression level of ZEB2 protein was significantly increased in glioma tissues compared to normal brain tissues (P<0.001). In addition, high levels of ZEB2 protein were positively correlated with pathology grade classification (P = 0.024) of glioma patients. Knockdown of ZEB2 by siRNA suppressed cell proliferation, migration and invasion, as well as induced cell apoptosis in glioma cells. Furthermore, ZEB2 downregulation was accompanied by decreased expression of CDK4/6, Cyclin D1, Cyclin E, E2F1, and c-myc, while p15 and p21 were upregulated. Lowered expression of ZEB2 enhanced E-cadherin levels but also inhibited β-Catenin, Vimentin, N-cadherin, and Snail expression. Several apoptosis-related regulators such as Caspase-3, Caspase-6, Caspase-9, and Cleaved-PARP were activated while PARP was inhibited after ZEB2 siRNA treatment. CONCLUSION: Overexpression of ZEB2 is an unfavorable factor that may facilitate glioma progression. Knockdown ZEB2 expression by siRNA suppressed cell proliferation, migration, invasion and promoted cell apoptosis in glioma cells

Numerical investigation of steady and unsteady state hopper flows

This paper presents a numerical study of the steady and unsteady state granular flows in a cylindrical hopper with flat bottom by means of the discrete element method (DEM). For both flows, the simulations were conducted under comparable conditions so that the similarity and difference between them can be examined. The distributions of the physical properties including velocity, force structure, stress and couple stress for the two hopper flows are investigated. The results suggest that the trends of these distributions for the two hopper flows are similar. In particular, for both cases, the distributions of the normal stresses are related to the normal force structures. Thus, corresponding to the large interaction forces between particles near the bottom corner and in the transitional zone, all the normal stresses are large near the bottom corner, and the radial and circumferential normal stresses are relatively large in the transitional zone. However, there are differences in the magnitudes of some physical properties for the unsteady and steady state flows. Compared with the steady state flow, the unsteady state flow has a narrower velocity distribution, and more particles experience large contact forces. Its radial and circumferential normal stresses in the plug flow and transitional zones are larger. With the decrease of the number of particles or with discharging time, the plug flow and transitional zones reduce, and the differences in the considered properties except wall shear stress and couple stress between the two flows decrease

Discrete and continuum modelling of granular flow

This paper analyses three popular methods simulating granular flow at different time and length scales: discrete element method (DEM), averaging method and viscous, elastic-plastic continuum model. The theoretical models of these methods and their applications to hopper flows are discussed. It is shown that DEM is an effective method to study the fundamentals of granular flow at a particle or microscopic scale. By use of the continuum approach, granular flow can also be described at a continuum or macroscopic scale. Macroscopic quantities such as velocity and stress can be obtained by use of such computational method as FEM. However, this approach depends on the constitutive relationship of materials and ignores the effect of microscopic structure of granular flow. The combined approach of DEM and averaging method can overcome this problem. The approach takes into account the discrete nature of granular materials and does not require any global assumption and thus allows a better understanding of the fundamental mechanisms of granular flow. However, it is difficult to adapt this approach to process modelling because of the limited number of particles which can be handled with the present computational capacity, and the difficulty in handling non-spherical particles. Further work is needed to develop an appropriate approach to overcome these problems

Review of the Relationships between Crack Initiation Stress, Mode I Fracture Toughness and Tensile Strength of Geo-Materials

It has been accepted that, in geo-materials, almost all the cracks forming at final failure in the tension test and those occurring at the crack initiation (CI) and crack propagation stages in the compression test are tensile cracks. Because of this, tensile strength is attracting more attention. Compared with the experiment for obtaining tensile strength, the results obtained from a CI stress experiment are inaccurate for the subjective judgments of the user, and the results obtained from the fracture toughness test show a rather large variation of 30–50%. A review was conducted to determine the relationships among CI stress, Mode I fracture toughness, and tensile strength from the view of the failure mechanism and the data gathered from the available literature. It was found that CI stress has a linear relationship with Brazilian tensile strength with the linear coefficient of 0.075, and the linear coefficient between Mode I fracture toughness and tensile strength is in the range of 0.1–0.15, although both correlation coefficients are at a low level. The relationships can be the basis for preliminary design purposes and for rock classification and characterization. It is suggested that the shape of the sample for testing should be consistent and the methods for obtaining each property should be standardized, and more data are needed for further study

Effect of packing method on packing formation and the correlation between packing density and interparticle force

The packing of cohesive particles is of paramount importance in many industries because the packing structure is closely related to process performance. A general relation between packing density and interparticle force was previously proposed based on packing structures formed without dynamic fluid flows. Its universality is examined here in two different packings, formed in settling and defluidization of static and dynamic fluids, respectively. First, it is shown that the packings of the same particles formed by two different methods have different structures because of different impact-induced pressures. Nevertheless, a one-to-one relationship between packing density and structural properties still holds regardless of the different packing methods, and the force distribution in those packings obeys similar rules. Finally, the packing densities obtained by the different methods are demonstrated to be universally correlated with the ratio of the interparticle force to the effective gravity. These findings indicate that different phenomena of particulate systems at a macro- or meso-scale may share similar microscopic origins, with the interparticle force playing a crucial role

Numerical investigation of crater phenomena in a particle stream impact onto a granular bed

This paper presents an experimental and numerical study of the impact of a particle stream onto a particle bed using a2D slot model. The numerical simulation is performed by means of the discrete element method (DEM). The results show that the DEM simulation can reproduce the experimental results well under comparative conditions. The dynamics in the formation of a crater is then analyzed in terms of velocity field, force structure, bottom stress distribution and energy exchange based on the DEM results. It is shown that as a result of impact by the falling particles, the particles in the top central region of the particle bed have relatively large velocities and contact forces. The velocities and forces propagate into the bed, and reach the bottom of the base layer quickly. They then continue to propagate leftwards and rightwards to create a crater. During the impact process, most of the energy from the falling particles is dissipated due to the inelastic collision and frictional contacts between particles, and only a small amount of the energy contributes to the formation of the crater. The crater size is shown to be affected by the discharging rate, discharging height and materials properties, and be related to the ratio of the input energy from the falling stream to the inertial energy from the original packing

CK2α Regulates the Metastases and Migration of Lung Adenocarcinoma A549 Cell Line through PI3K/Akt/GSK-3β Signal Pathway

Background and objective Lung cancer is the leading cancer-related death worldwide. Patients with lung cancer mainly died of tumor metastasis and invasion. Protein kinase CK2 is an ubiquitous serine/threonine protein kinase and is frequently upregulated in various human tumors. This study aims to explore the effect and molecular mechanism of the invasion and migration of lung adenocarcinoma A549 cells after knock-down of CK2α expression. Methods The pSilencerTM 4.1-siCK2α-eGFP of lentiviral-mediated shRNA was constructed. The expression of CK2α was knock-downed, and a stable A549 cell line was established. The invasion and migration of A549 cell line was detected through Transwell and Boyden chamber assays. The protein expression of the PI3K/Akt signaling pathway and mesenchymal-to-epithelial transition (EMT) was evaluated using Western blot analysis. Results The invasion and migration of A549 cells were significantly inhibited after the knockdown of CK2α expression compared with that in the control group. p-PTEN, Akt, p-Akt473, p-Akt308, p-PDK1, p-c-Raf, and p-GSK-3β were significantly downregulated, whereas PTEN was upregulated. Moreover, vimentin, β-catenin, Snail, MMP2, and MMP9 were significantly downregulated after reducing the CK2α expression. Conclusion CK2α might regulate the invasion and migration of A549 cells through the PI3K/Akt/GSK-3β/Snail signaling pathway, which controls EMT in lung adenocarcinoma