Summary
Microtubule inhibitors are important cancer drugs that induce mitotic arrest by activating the spindle assembly checkpoint (SAC), which in turn inhibits the ubiquitin ligase activity of the Anaphase-Promoting Complex (APC). Here we report a small molecule, Tosyl-L-Arginine Methyl Ester (TAME), which binds to the APC and prevents its activation by Cdc20 and Cdh1. A prodrug of TAME arrests cells in metaphase without perturbing the spindle, but nonetheless the arrest is dependent on the SAC. Metaphase arrest induced by a proteasome inhibitor is also SAC-dependent, suggesting that APC-dependent proteolysis is required to inactivate the SAC. We propose that mutual antagonism between the APC and the SAC yields a positive feedback loop that amplifies the ability of TAME to induce mitotic arrest.
Bilateral frontoparietal polymicrogyria (BFPP) is a congenital brain malformation resulting in irregularities on the surface of the cortex, where normally convoluted gyri are replaced by numerous (poly) and noticeably smaller (micro) gyri. Individuals with BFPP suffer from epilepsy, mental retardation, language impairment and motor developmental delay. Mutations in the gene-encoding G protein-coupled receptor 56 (GPR56) cause BFPP; however, it remains unclear how these mutations affect GPR56 function. Here, we examine the biochemical properties and protein trafficking of wild-type and mutant GPR56. We demonstrate that GPR56 protein undergoes two major modifications, GPS domain-mediated protein cleavage and N-glycosylation, and that the N-terminal fragment can be released from the cell surface. In contrast to the wild-type protein, disease-associated GPR56 missense mutations in the tip of the N-terminal domain (R38Q, R38W, Y88C and C91S) produce proteins with reduced intracellular trafficking and poor cell surface expression, whereas the two mutations in the GPS domain (C346S and W349S) produce proteins with dramatically impaired cleavage that fail to traffic beyond the endoplasmic reticulum. Cell-trafficking impairments are abrogated in part by pharmacological chaperones that can partially rescue mutant GPR56 cell surface expression. These data demonstrate that some BFPP-associated mutations in GPR56 impair trafficking of the mutant protein to the plasma membrane, thus providing insights into how BFPP-associated mutations affect GPR56 function.
Conventional gastric balloons for weight loss require endoscopy for placement and removal. The Elipse device is swallowed, resides in the stomach for 4 months, and is then expelled. The objectives of this study were to assess the safety of Elipse and to measure its effects on weight loss, metabolic parameters, and quality of life. Each participant swallowed one Elipse device, which was filled with 550 mL of filling fluid through a thin delivery catheter that was then removed. Weight was measured every 2 weeks, and metabolic parameters and quality of life were assessed at baseline and at trial exit. 34 patients, with a mean body mass index of 34.8 kg/m, were enrolled. All 34 patients successfully swallowed the Elipse device. All adverse events were either self-limiting or resolved with medication. All balloons were safely excreted. At 4 months, the mean percent total body weight loss was 10 %. Mean waist circumference was reduced by 8.4 cm. Improvements were also seen in hemoglobin A1c, triglycerides, low density lipoprotein, and blood pressure. At trial exit, quality of life measures had improved across all domains. These results demonstrate clinically significant weight loss with the Elipse, the first procedureless gastric balloon. The weight loss was similar to that seen in previous studies of endoscopically placed balloons. In addition, Elipse therapy led to improvements in waist circumference, several metabolic parameters, and overall quality of life.ClinicalTrials.gov identifier: NCT 02802007.
Drug-eluting bead chemoembolization is a reasonable alternative to hepatic arterial embolization and chemoembolization for the treatment of metastatic neuroendocrine tumor to the liver.
This pilot study demonstrates the safety and performance of Elipse™, a procedureless gastric balloon for weight loss. Future studies will test a commercial design filled to 550 mL intended to last in the stomach for at least 12 weeks.
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