Nestin-mediated cytoskeletal remodeling in endothelial cells: novel mechanistic insight into VEGF-induced cell migration in angiogenesis.

Nestin is highly expressed in poorly differentiated and newly formed proliferating endothelial cells (ECs); however, the role of this protein in angiogenesis remains unknown. Additionally, the cytoskeleton and associated cytoskeleton-binding proteins mediate the migration of vascular ECs. Therefore, the aim of the present study was to determine whether VEGF regulates the cytoskeleton, as well as other associated proteins, to promote the migration of vascular ECs. The coexpression of nestin and CD31 during angiogenesis in alkali-burned rat corneas was examined via immunohistochemical analysis. Western blot analyses revealed that the exposure of human umbilical vein endothelial cells (HUVECs) to hypoxia promoted nestin expression in vitro. Additionally, nestin silencing via siRNA significantly inhibited many of the process associated with VEGF-induced angiogenesis, including tube formation and the migration and proliferation of HUVECs. Moreover, FITC-phalloidin labeling revealed that F-actin filaments were successfully organized into microfilaments in VEGF-treated cells, suggesting a network rearrangement accomplished via F-actin that contrasted with the uniform and loose actin filament network observed in the siRNA-nestin cells. The results of the present study highlight the key role played by nestin in activated HUVECs during angiogenesis. The inhibition of the ERK pathway suppressed the nestin expression induced by VEGF in the HUVECs. Therefore, our study provides the first evidence that nestin-mediated cytoskeleton remodeling in ECs occurs via filopodia formation along the cell edge, facilitating both filopodia localization and cell polarization and ultimately promoting HUVEC migration via VEGF induction, which may be associated with ERK pathway activation.

Akt Activation and Inhibition of Cytochrome C Release: Mechanistic Insights into Leptin-promoted Survival of Type II Alveolar Epithelial Cells.

Fetal growth restriction (FGR) increases the risk of perinatal death, partly due to defects in lung development. Leptin, a polypeptide hormone, is involved in fetal lung development. We previously demonstrated that treatment with exogenous leptin during gestation significantly promotes fetal lung maturity in the rat model of FGR. In this study, to delineate the molecular pathways through which leptin may enhance fetal lung development, we investigated the impact of leptin treatment on the survival of type II alveolar epithelial cells (AECs), essential leptin-responsive cells involved in lung development, in a rat model of FGR. The rat model of FGR was induced in pregnant Sprague-Dawley rats by partial uterine artery and vein ligation. In vivo and in vitro analyses of fetal lung tissues and freshly-isolated cultured AECs, respectively, showed that leptin protects type II AECs from hypoxia-induced apoptosis. Further molecular studies revealed the role of Akt activation in the leptin-mediated promotion of survival of type II AECs. The data also showed that the anti-apoptotic effects of leptin are dependent on phosphoinositol 3-kinase (PI3K) activation, and involve the down-regulation of caspases 3 and 9, upregulation of pro-survival proteins Bcl-2, and p-Bad, and inhibition of the release of cytochrome c from mitochondria. Taken together, our data suggested that leptin enhances the maturity of fetal lungs by mediating the regulation of caspase-3 and -9 during hypoxia-induced apoptosis of type II AECs and provide support for the potential of leptin as a therapeutic agent for promoting lung development in FGR.

Comparison of the diagnostic performance and clinical role of different ultrasound-based thyroid malignancy risk stratification systems for medullary thyroid carcinoma.

Background: This study sought to investigate the applicability of different ultrasound (US) thyroid risk stratification systems in diagnosing medullary thyroid carcinoma (MTC) and determining the need for biopsy. Methods: In total, 34 MTC nodules, 54 papillary thyroid carcinoma (PTC) nodules, and 62 benign thyroid nodules were examined in this study. All the diagnoses were histopathologically confirmed postoperatively. All the thyroid nodule sonographic features were recorded and categorized by 2 independent reviewers according to the Thyroid Imaging Reporting and Data System (TIRADS) of the American College of Radiology (ACR), the American Thyroid Association (ATA) guidelines, the European Thyroid Association (EU) TIRADS, the Kwak-TIRADS, and the Chinese TIRADS (C-TIRADS). The sonographic differences and risk stratifications of the MTCs, PTCs, and benign thyroid nodules were analyzed. The diagnostic performance and recommended biopsy rates for each classification system were evaluated. Results: The risk stratifications of MTCs were all higher than the benign thyroid nodules (P<0.01) and lower than PTCs (P<0.01) with each classification system. Hypoechogenicity and malignant marginal features were independent risk factors for identifying malignant thyroid nodules, and the area under the receiver operating characteristic curve (AUC) for identifying MTCs was lower than that for identifying PTCs (0.873 vs. 0.954, respectively). The AUCs, sensitivity, specificity, positive predictive values, negative predictive values, and accuracy values of the 5 systems for MTC were all lower than those for PTC. The best cut-off values for diagnosing MTC were TIRADS (TR) 4 in the ACR-TIRADS, intermediate suspicion in the ATA guidelines, TR 4 in EU-TIRADS, and TR 4b in both the Kwak-TIRADS and the C-TIRADS. The Kwak-TIRADS had the highest recommended biopsy rate for MTCs (97.1%), followed by the ATA guidelines, the EU-TIRADS (88.2%), the C-TIRADS (85.3%), and the ACR-TIRADS (79.4%). Conclusions: The US-based thyroid malignancy risk stratification systems analyzed in this study were able to satisfactorily identify MTC and recommend biopsy, but the diagnostic performance of these systems for MTC was not as good as that for PTC.