ABSTRACT
The effects of grain boundary misorientation angle (θ) on mechanical properties and the mechanism of plastic deformation of the Ni/Ni3Al interface under tensile loading were investigated using molecular dynamics simulations. The results show that the space lattice arrangement at the interface is dependent on grain boundary misorientations, while the interfacial energy is dependent on the arrangement. The interfacial energy varies in a W pattern as the grain boundary misorientation increases from 0° to 90°. Specifically, the interfacial energy first decreases and then increases in both segments of 0-60° and 60-90°. The yield strength, elastic modulus, and mean flow stress decrease as the interfacial energy increases. The mechanism of plastic deformation varies as the grain boundary misorientation angle (θ) increases from 0° to 90°. When θ = 0°, the microscopic plastic deformation mechanisms of the Ni and Ni3Al layers are both dominated by stacking faults induced by Shockley dislocations. When θ = 30°, 60°, and 80°, the mechanisms of plastic deformation of the Ni and Ni3Al layers are the decomposition of stacking faults into twin grain boundaries caused by extended dislocations and the proliferation of stacking faults, respectively. When θ = 90°, the mechanisms of plastic deformation of both the Ni and Ni3Al layers are dominated by twinning area growth resulting from extended dislocations.
ABSTRACT
BACKGROUND: The Notch-regulated ankyrin repeat protein (NRARP) is recently found to promote proliferation of breast cancer cells. The role of NRARP in carcinogenesis deserves extensive investigations. This study attempted to investigate the expression of NRARP in thyroid cancer tissues and assess the influence of NRARP on cell proliferation, apoptosis, cell cycle, and invasion in thyroid cancer. METHODS: Thirty-four cases with thyroid cancer were collected from the Department of General Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine between 2011 and 2012. Immunohistochemistry was used to detect the level of NRARP in cancer tissues. Lentivirus carrying NRARP-shRNA (Lenti-NRARP-shRNA) was applied to down-regulate NRARP expression. Cell viability was tested after treatment with Lenti-NRARP-shRNA using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis and cell cycle distribution were determined by flow cytometry. Cell invasion was tested using Transwell invasion assay. In addition, expressions of several cell cycle-associated and apoptosis-associated proteins were examined using Western blotting after transfection. Student's t-test, one-way analysis of variance (ANOVA), or Kaplan-Meier were used to analyze the differences between two group or three groups. RESULTS: NRARP was highly expressed in thyroid cancer tissues. Lenti-NRARP-shRNA showed significantly inhibitory activities against cell growth at a multiplicity of infection of 10 or higher (P < 0.05). Lenti-NRARP-shRNA-induced G1 arrest (BHT101: 72.57% ± 5.32%; 8305C: 75.45% ± 5.26%) by promoting p21 expression, induced apoptosis by promoting bax expression and suppressing bcl-2 expression, and inhibited cell invasion by suppressing matrix metalloproteinase-9 expression. CONCLUSION: Downregulation of NRARP expression exerts significant antitumor activities against cell growth and invasion of thyroid cancer, that suggests a potential role of NRARP in thyroid cancer targeted therapy.
Subject(s)
Neoplasm Proteins/metabolism , Proteins/metabolism , Thyroid Neoplasms/metabolism , Thyroid Neoplasms/pathology , Adult , Aged , Animals , Apoptosis/genetics , Apoptosis/physiology , Cell Cycle/genetics , Cell Cycle/physiology , Cell Line, Tumor , Cell Proliferation/genetics , Cell Proliferation/physiology , Cell Survival/genetics , Cell Survival/physiology , Female , Humans , In Vitro Techniques , Intracellular Signaling Peptides and Proteins , Kaplan-Meier Estimate , Male , Mice , Mice, Nude , Middle Aged , Neoplasm Proteins/genetics , Proteins/genetics , RNA, Small Interfering/genetics , Thyroid Neoplasms/genetics , Thyroid Neoplasms/mortalityABSTRACT
OBJECTIVE: This study aimed to investigate the expression of B7-H4 in human thyroid cancer and determine any association with patient clinicopathological parameters and survival. METHODS: B7-H4 expression in 64 clinical thyroid cancer specimens was assessed with immunohistochemistry. Moreover, B7-H4 mRNA expression in 10 fresh resected specimens were evaluated by the reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemical staining of CD3 was performed to assess the number of tumor infiltrating T lymphocytes (TILs) in thyroid cancers. RESULTS: Positive B7-H4 immunohistochemical staining was observed in 61 out of 64 (95.3%) specimens of thyroid cancer tissues. Significantly more B7-H4 mRNA copies were found in thyroid cancer tissue than that adjacent normal tissue. Moreover, B7-H4 expression in human thyroid cancer tissues was significantly correlated with patient TNM stages and extrathyroidal extension (P<0.05), being inversely correlated with the number of TILs (P<0.05). The overall survival rate of the patients with higher B7-H4 expression was significantly worse than that of the patients with lower B7-H4 expression. CONCLUSIONS: This present study suggests that high B7-H4 expression is associated with cancer progression, reduced tumor immunosurveillance and worse patient outcomes in human thyroid cancer.