Autophagy is characterized by the sequestration of bulk cytoplasm, including damaged proteins and organelles, and delivery of the cargo to lysosomes for degradation. Although the autophagic pathway is also linked to tumour suppression activity, the mechanism is not yet clear. Here we report that cytosolic FoxO1, a forkhead O family protein, is a mediator of autophagy. Endogenous FoxO1 was required for autophagy in human cancer cell lines in response to oxidative stress or serum starvation, but this process was independent of the transcriptional activity of FoxO1. In response to stress, FoxO1 was acetylated by dissociation from sirtuin-2 (SIRT2), a NAD(+)-dependent histone deacetylase, and the acetylated FoxO1 bound to Atg7, an E1-like protein, to influence the autophagic process leading to cell death. This FoxO1-modulated cell death is associated with tumour suppressor activity in human colon tumours and a xenograft mouse model. Our finding links the anti-neoplastic activity of FoxO1 and the process of autophagy.
We study the low-energy surface electronic structure of the transition-metal dichalcogenide superconductor PdTe_{2} by spin- and angle-resolved photoemission, scanning tunneling microscopy, and density-functional theory-based supercell calculations. Comparing PdTe_{2} with its sister compound PtSe_{2}, we demonstrate how enhanced interlayer hopping in the Te-based material drives a band inversion within the antibonding p-orbital manifold well above the Fermi level. We show how this mediates spin-polarized topological surface states which form rich multivalley Fermi surfaces with complex spin textures. Scanning tunneling spectroscopy reveals type-II superconductivity at the surface, and moreover shows no evidence for an unconventional component of its superconducting order parameter, despite the presence of topological surface states.
Purpose:The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest-abdomen-pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore, serve as a jumping point from which to create an unlimited number of 3D and 4D variations for imaging research. Conclusions: A population of phantoms that includes a range of anatomical variations representative of the public at large is needed to more closely mimic a clinical study or trial. The series of anatomically variable phantoms developed in this work provide a valuable resource for investigating 3D and 4D imaging devices and the effects of anatomy and motion in imaging. Combined with Monte Carlo simulation programs, the phantoms also provide a valuable tool to investigate patient-specific dose and image quality, and optimization for adults undergoing imaging procedures.
Histone deacetylase (HDAC) inhibitors have been shown to induce cell cycle arrest and apoptosis in cancer cells. However, the mechanisms of HDAC inhibitor induced apoptosis are incompletely understood. In this study, depsipeptide, a novel HDAC inhibitor, was shown to be able to induce significant apoptotic cell death in human lung cancer cells. Further study showed that Bim, a BH3-only proapoptotic protein, was significantly upregulated by depsipeptide in cancer cells, and Bim's function in depsipeptide-induced apoptosis was confirmed by knockdown of Bim with RNAi. In addition, we found that depsipeptide-induced expression of Bim was directly dependent on acetylation of forkhead box class O1 (FoxO1) that is catalyzed by cyclic adenosine monophosphate-responsive element-binding protein-binding protein, and indirectly induced by a decreased four-and-a-half LIM-domain protein 2. Moreover, our results demonstrated that FoxO1 acetylation is required for the depsipeptide-induced activation of Bim and apoptosis, using transfection with a plasmid containing FoxO1 mutated at lysine sites and a luciferase reporter assay. These data show for the first time that an HDAC inhibitor induces apoptosis through the FoxO1 acetylation-Bim pathway.
Histone deacetylase inhibitor (HDACi) has been shown to demethylate the mammalian genome, which further strengthens the concept that DNA methylation and histone modifications interact in regulation of gene expression. Here, we report that an HDAC inhibitor, depsipeptide, exhibited significant demethylating activity on the promoters of several genes, including p16, SALL3, and GATA4 in human lung cancer cell lines H719 and H23, colon cancer cell line HT-29, and pancreatic cancer cell line PANC1. Although expression of DNA methyltransferase 1 (DNMT1) was not affected by depsipeptide, a decrease in binding of DNMT1 to the promoter of these genes played a dominant role in depsipeptide-induced demethylation and reactivation. Depsipeptide also suppressed expression of histone methyltransferases G9A and SUV39H1, which in turn resulted in a decrease of di-and trimethylated H3K9 around these genes' promoter. Furthermore, both loading of heterochromatin-associated protein 1 (HP1␣ and HP1) to methylated H3K9 and binding of DNMT1 to these genes' promoter were significantly reduced in depsipeptide-treated cells. Similar DNA demethylation was induced by another HDAC inhibitor, apicidin, but not by trichostatin A. Our data describe a novel mechanism of HDACi-mediated DNA demethylation via suppression of histone methyltransferases and reduced recruitment of HP1 and DNMT1 to the genes' promoter.
Background Hip fracture is a public health concern because of its considerable morbidity, excess mortality, great risk of disability, and high societal healthcare costs. China has the largest population of older people in the world and is experiencing rapid population aging and facing great challenges from an increasing number of hip fractures. However, few studies reported the epidemiology, especially at a national level. We aimed to evaluate trends in hip fracture incidence and associated costs for hospitalization in China. Methods and findings We conducted a population-based study using data between 2012 and 2016 from the national databases of Urban Employee Basic Medical Insurance and Urban Resident Basic Medical Insurance in China, covering about 480 million residents. Data from around 102.56 million participants aged 55 years and older during the study period were analyzed. A total of 190,560 incident hip fracture patients (mean age 77.05 years, standard deviation 8.94; 63.99% female) were identified. Primary outcomes included the age-and sex-specific incidences of hip fracture. Associated annual costs for hospitalization were also calculated. Incidence was described as per 100,000 person-years at risk, and 95% confidence intervals were computed assuming a Poisson distribution. Hip fracture incidence overall in China did not increase during the study period despite rapid population aging. Incidence per 100,000
Multiple myeloma (MM) is the second most frequent malignancy of blood, and information on disease burden of MM is limited in developing countries. We aimed to estimate the prevalence and incidence of MM in China. We used data from the national urban employee and urban resident basic medical insurance from 2012 to 2016 in China. MM cases were based on the primary diagnosis (International Classification of Diseases (ICD) code, ICD for oncology, or text of diagnosis) of patients. The crude prevalence and incidence were 6.88 per 100,000 population (95% CI, 5.75-8.00) and 1.60 per 100,000 person-years (1.28-1.92), respectively. The standardized prevalence and incidence were 5.68 (5.64-5.72) and 1.15 (1.11-1.19), respectively. Overall, the rates were higher in males compared with females for prevalence (7.89 vs. 5.79, P < 0.05) and incidence (1.84 vs. 1.30, P < 0.05). Both rates increased with age, and the mean age (SD) of MM patients was 57.9 (14.4) years. Prevalence peaked between 55 and 74 years old for both genders. The incidence in women aged 55-59 had a significantly high incidence of 5.53 (4.98-6.11). The prevalence and incidence were significantly lower than those in North America, Australia, and Western Europe but were in the same range as those in Japan or Korea. MM should be one of the cancers in the spotlight from both medical and socioeconomic perspectives in low-resource but populous countries because of the incidence of more elderly MM patients in the next decade. Further research is warranted to examine the potential pathophysiologic mechanism.
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