Cryo-EM structure of a RAS/RAF recruitment complex.

RAF-family kinases are activated by recruitment to the plasma membrane by GTP-bound RAS, whereupon they initiate signaling through the MAP kinase cascade. Prior structural studies of KRAS with RAF have focused on the isolated RAS-binding and cysteine-rich domains of RAF (RBD and CRD, respectively), which interact directly with RAS. Here we describe cryo-EM structures of a KRAS bound to intact BRAF in an autoinhibited state with MEK1 and a 14-3-3 dimer. Analysis of this KRAS/BRAF/MEK1/14-3-3 complex reveals KRAS bound to the RAS-binding domain of BRAF, captured in two orientations. Core autoinhibitory interactions in the complex are unperturbed by binding of KRAS and in vitro activation studies confirm that KRAS binding is insufficient to activate BRAF, absent membrane recruitment. These structures illustrate the separability of binding and activation of BRAF by RAS and suggest stabilization of this pre-activation intermediate as an alternative therapeutic strategy to blocking binding of KRAS.

microRNA-944 overexpression is a biomarker for poor prognosis of advanced cervical cancer.

BACKGROUND: One-third of cervical cancer patients are still diagnosed at advanced stages. The five-year survival rate is decreased in about 50% of advanced stage cervical cancer patients worldwide, and the clinical outcomes are remarkably varied and difficult to predict. One of the miRNAs known to be associated with cancer tumorigenesis is miR-944. However, the prognostic value of miR-944 in cervical cancer has not been fully investigated. The aim of this study was to analyze clinical significance and prognostic value of miR-944 in cervical cancer. METHODS: The expression levels of miR-944 were detected using quantitative reverse transcription polymerase chain reaction in five types of cervical cancer cell lines and 116 formalin-fixed paraffin-embedded (FFPE) cervical tissues. The association between the expression levels of miR-944 and prognostic value was analyzed using the Kaplan-Meier analysis and Cox proportional hazards model. RESULTS: The expression levels of miR-944 in cervical cancer tissues were significantly higher compared with those in normal tissues (P < 0.0001). Moreover, the expression levels of miR-944 in cervical cancer cell lines and FFPE tissues with human papillomavirus (HPV) infection were significantly higher compared to those without HPV infection (P < 0.01 and P = 0.02). High miR-944 expression was also markedly associated with bulky tumor size (P = 0.026), advanced International Federation of Gynecology and Obstetrics (FIGO) stage (P = 0.042), and lymph node metastasis (P = 0.030). In particular, high miR-944 expression group showed shorter overall survival than the low miR-944 expression group in the advanced FIGO stage (84.4% vs. 44.4%, HR = 4.0, and P = 0.01). CONCLUSIONS: These results suggest that miR-944 may be used as a novel biomarker for improving prognosis and as a potential therapeutic target.

Activation of autophagy rescues amiodarone-induced apoptosis of lung epithelial cells and pulmonary toxicity in rats.

Amiodarone, bi-iodinated benzofuran derivative, is one of the most frequently prescribed and efficacious antiarrhythmic drugs. Despite its low incidence, amiodarone-induced pulmonary toxicity is of great concern and the leading cause of discontinuation. Autophagy is an essential homeostatic process that mediates continuous recycling of intracellular materials when nutrients are scarce. It either leads to a survival advantage or initiates death processes in cells under stress. In the present study, we investigated the role of autophagy in amiodarone-induced pulmonary toxicity. Amiodarone treatment-induced autophagy in H460 human lung epithelial cells and BEAS-2B normal human bronchial epithelial cells was demonstrated by increased LC3-II conversion, Atg7 upregulation, and autophagosome formation. Autophagic flux, as determined by the lysosomal inhibitor bafilomycin A1, was also increased following amiodarone treatment. To determine the role of autophagy in amiodarone toxicity, amiodarone-induced cell death was evaluated in the presence of 3-methyladenine or by knocking down the autophagy-related genes Atg7. Inhibition of autophagy decreased cellular viability and significantly increased apoptosis. Intratracheal instillation of amiodarone in rats increased the number of inflammatory cells recovered from bronchoalveolar lavage fluid, and periodic acid-Schiff-positive staining in bronchiolar epithelial cells. However, induction of autophagy by rapamycin treatment inhibited amiodarone-induced pulmonary toxicity. In conclusion, amiodarone treatment induced autophagy, which is involved in protection against cell death and pulmonary toxicity.

Effects of Medicinal herb Extracts and their Components on Steatogenic Hepatotoxicity in Sk-hep1 Cells.

Herbal medicines are widely used in many countries for the treatment of many diseases. Although the use of herb extracts as alternative medicine is growing, their toxicological properties have not been thoroughly investigated. In this study, we have investigated the effects of water and ethanol extracts of 18 herbs on the hepatic lipid metabolism and steatogenic hepatotoxicity. Ethanol extracts of Cirsium japonicum, Carthamus tinctorius, Rehmanniae glutinosa (preparata), Polygala tenuifolia, Foeniculum vulgare, Polygonum multiflorum, and Acorus gramineus and water extracts of Polygonum multiflorum and Rehmanniae glutinosa induced lipid accumulation in Sk-hep1 human hepatoma cells as determined by Nile red staining. These extracts increased the luciferase activity of sterol regulatory element (SRE) and decreased that of peroxisome proliferator response element (PPRE), indicating the possibilities of enhanced fatty acid synthesis and decreased fatty acid oxidation. To identify the components responsible for the fat accumulation, we tested 50 chemicals isolated from the nine herbs. Apigenin, luteolin, pectolinarin and lupeol from Cirsium japonicum, 8-methoxypsoralen and umbelliferone from Foeniculum vulgare and pomonic acid and jiocerebroside from Rehmanniae glutinosa significantly increased the accumulation of lipid droplets. These results suggest that ethanol extracts of Cirsium japonicum, Carthamus tinctorius, Rehmanniae glutinosa (preparata), Polygala tenuifolia, Foeniculum vulgare, Polygonum multiflorum, and Acorus gramineus and water extracts of Polygonum multiflorum and Rehmanniae glutinosa can cause fatty liver disease by decreasing ß-oxidation of fatty acid and increasing lipogenesis.