Hypoxia-induced autophagy as an additional mechanism in human osteosarcoma radioresistance

AbstractOsteosarcoma (OS) responds poorly to radiotherapy, but the mechanism is unclear. We found OS tumor tissues expressed high level of protein HIF-1α, a common biological marker indicative of hypoxia. It is known that hypoxic cells are generally radioresistant because of reduced production of irradiation-induced DNA-damaging reactive oxygen species (ROS) in the anaerobic condition. Here we report another mechanism how hypoxia induces radioresistance. In MG-63 human osteosarcoma cells, hypoxic pretreatment increased the cellular survival in irradiation. These hypoxia-exposed cells displayed compartmental recruitment of GFP-tagged LC3 and expression of protein LC3-II, and restored the radiosensitivity upon autophagy inhibition. The following immunohistochemistry of OS tumor tissue sections revealed upregulated LC3 expression in a correlation with HIF-1α protein level, implying the possibly causative link between hypoxia and autophagy. Further studies in MG-63 cells demonstrated hypoxic pretreatment reduced cellular and mitochondrial ROS production during irradiation, while inhibition of autophagy re-elicited them. Taken together, our study suggests hypoxia can confer cells resistance to irradiation through activated autophagy to accelerate the clearance of cellular ROS products. This might exist in human osteosarcoma as an additional mechanism for radioresistance

Urban-Rural Disparity in Helicobacter Pylori Infection–Related Upper Gastrointestinal Cancer in China and the Decreasing Trend in Parallel with Socioeconomic Development and Urbanization in an Endemic Area

Background: Globally China has the largest urban-rural disparity in socioeconomic development, and the urban-rural difference in upper gastrointestinal cancer (UGIC) is similar to the difference between developed and developing countries. Objectives: To describe urban-rural disparity in UGIC and to emphasize prevention by socioeconomic development and urbanization in China. Methods: Age-standardized incidence rates (ASRs) of cancers in 2012 were compared between urban Shijiazhuang city and rural Shexian County, and trends from 2000-2015 in Shexian County were analyzed. Findings: Compared with urban Shijiazhuang city, the ASR of gastroesophageal cancers in rural Shexian County was 5.3 times higher in men (234.1 vs 44.2/100,000, 'P' 'Helicobacter pylori' infection prevalence of 75% vs 50%. From 2000-2015, the GDP per capita in Shexian County increased from US$860 to US$3000, urbanization rate increased from 22.4% to 54.8%, and prevalence of 'H pylori' infection among 3- to 10-year-old children decreased from 60% to 46.1% ('P' 'gallbladder cancers and leukemia in both sexes and breast, ovary, thyroid, and kidney cancer in women increased significantly. Despite this offset, ASR of all cancers combined decreased 25% in men (from 378.2 to 283.0/100,000, 'P' '=' '.'00) and 19% in women (from 238.5 to 193.6/100,000, 'P' '=' '.'00). ConclusionsUrban-rural disparity in UGIC is related to inequity in socioeconomic development. Economic growth and urbanization is effective for prevention in endemic regions in China and should be a policy priority

Bionic vision processing for epiretinal implant-based metaverse

We present an epiretinal implant featuring bionic vision processing as a paradigm shift of metaverse. The main contribution of this work is to provide a methodology to better understand the human vision and to reproduce the stepwise images along the visual pathway. The epiretinal implant functions by stimulating the axons of ganglions to transmit the visual information to the brain. For the information on virtual environments to be correctly processed by the brain, our bionic vision processing is capable of transforming the digital images into neural images by factoring into the physiological pipelines of vision. The principles or algorithms of visual pathway, field of vision, visual acuity, foveated blurring, bilateral neural image fusion, depth perception, edge detection, and saliency detection are discussed. Our simulation results include the retinal images, neural images, depth map, edge map, and saliency map

ZDHHC7-Mediated S-Palmitoylation of Scribble Regulates Cell Polarity

Scribble (SCRIB) is a tumor suppressor protein, playing critical roles in establishing and maintaining epithelial cell polarity. Paradoxically, SCRIB is frequently amplified in human cancers, however, fails to localize properly to cell-cell junctions, suggesting that mislocalization of SCRIB contributes to tumorigenesis. Using chemical reporters, here we showed that SCRIB localization is regulated by S-palmitoylation at conserved cysteine residues. The palmitoylation-deficient mutants of SCRIB are mislocalized, leading to disruption of cell polarity and loss of their tumor suppressive activities to oncogenic YAP, MAPK and PI3K/Akt pathways. We further found that ZDHHC7 is the major palmitoyl acyltransferase regulating SCRIB. Knockout of ZDHHC7 led to SCRIB mislocalization and YAP activation, and disruption of SCRIB’s suppressive activities in HRasV12-induced cell invasion. In summary, we demonstrated that ZDHHC7-mediated SCRIB palmitoylation is critical for SCRIB membrane targeting, cell polarity, and tumor suppression, providing new mechanistic insights of how dynamic protein palmitoylation regulates cell polarity and tumorigenesis

Postoperative recurrence of epithelial ovarian cancer patients and chemoresistance related protein analyses

Abstract Objective To identify the plasma protein biomarkers related to the chemoresistance of postoperative recurrence of epithelial ovarian cancers. Methods Forty plasma samples from patients in chemotherapy-sensitive and chemotherapy-resistant groups (20 for each group) were collected at Gynecology Department in the Fourth Hospital of Hebei Medical University from September 2013 to September 2014. The differentially expressed proteins between two groups were screened with two-dimensional gel electrophoresis (2-DE) and further analyzed by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF–MS). Results Thirty-four differentially expressed spots were identified between the two groups. Compared with the chemo-sensitive group, 21 protein spots were up-regulated and 13 were down-regulated in the chemoresistant group, in which 14 differentially expressed proteins were identified by the Mass spectrometry and Mascot search. Among the 14 proteins, complement C4-A, IgJ chain, clusterin, α-1-antitrypsin and carbonic anhydrase 1 were up-regulated, and transthyretin, haptoglobin, β-2-glycoprotein, Ig γ-2 chain C region, Ig γ-1 chain C region, complement factor I light chain, Igκ chain C region, complement C3 and apolipoprotein E were down-regulated in the chemoresistant group when compared with the chemosensitive group. Conclusion The up-regulated proteins including transthyretin, apolipoprotein E and haptoglobin proteins and the down-regulated proteins such as clusterin, carbonic anhydrase 1, alpha-1-antitrypsin were differentially expressed in the plasma between the chemo-sensitive group and the chemoresistant group, which may be potential biomarkers for predicting the chemotresistance of epithelial ovarian cancer patients

Palmitoylation-dependent activation of MC1R prevents melanomagenesis

The melanocortin-1 receptor (MC1R), a G protein-coupled receptor, plays a crucial role in human and mouse pigmentation1–8. Activation of MC1R in melanocytes by α-melanocyte-stimulating hormone (α-MSH)9 stimulates cAMP signaling and melanin production and enhances DNA repair after UV irradiation (UVR)10–16. Individuals carrying MC1R variants, especially those associated with red hair color, fair skin and poor tanning ability (RHC-variants), are associated with higher risk of melanoma5,17,18,19,20. However, how MC1R activity might be modulated by UV irradiation, why redheads are more prone to developing melanoma, and whether the activity of RHC variants might be restored for therapeutic benefit remain unresolved questions. Here we demonstrate a potential MC1R-targeted intervention strategy to rescue loss-of-function MC1R in MC1R RHC-variants for therapeutic benefit based on activating MC1R protein palmitoylation. Specifically, MC1R palmitoylation, primarily mediated by the protein-acyl transferase (PAT) ZDHHC13, is essential for activating MC1R signaling that triggers increased pigmentation, UVB-induced G1-like cell cycle arrest and control of senescence and melanomagenesis in vitro and in vivo. Using C57BL/6J-MC1Re/eJ mice expressing MC1R RHC-variants we show that pharmacological activation of palmitoylation rescues the defects of MC1R RHC-variants and prevents melanomagenesis. The results highlight a central role for MC1R palmitoylation in pigmentation and protection against melanoma

Crystal Structure of a Four-Layer Aggregate of Engineered TMV CP Implies the Importance of Terminal Residues for Oligomer Assembly

<div><p>Background</p><p>Crystal structures of the tobacco mosaic virus (TMV) coat protein (CP) in its helical and disk conformations have previously been determined at the atomic level. For the helical structure, interactions of proteins and nucleic acids in the main chains were clearly observed; however, the conformation of residues at the C-terminus was flexible and disordered. For the four-layer aggregate disk structure, interactions of the main chain residues could only be observed through water–mediated hydrogen bonding with protein residues. In this study, the effects of the C-terminal peptides on the interactions of TMV CP were investigated by crystal structure determination.</p><p>Methodology/Principal Findings</p><p>The crystal structure of a genetically engineered TMV CP was resolved at 3.06 Å. For the genetically engineered TMV CP, a six-histidine (His) tag was introduced at the N-terminus, and the C-terminal residues 155 to 158 were truncated (N-His-TMV CP¹⁹). Overall, N-His-TMV CP¹⁹ protein self-assembled into the four-layer aggregate form. The conformations of residues Gln36, Thr59, Asp115 and Arg134 were carefully analyzed in the high radius and low radius regions of N-His-TMV CP¹⁹, which were found to be significantly different from those observed previously for the helical and four-layer aggregate forms. In addition, the aggregation of the N-His-TMV CP¹⁹ layers was found to primarily be mediated through direct hydrogen-bonding. Notably, this engineered protein also can package RNA effectively and assemble into an infectious virus particle.</p><p>Conclusion</p><p>The terminal sequence of amino acids influences the conformation and interactions of the four-layer aggregate. Direct protein–protein interactions are observed in the major overlap region when residues Gly155 to Thr158 at the C-terminus are truncated. This engineered TMV CP is reassembled by direct protein–protein interaction and maintains the normal function of the four-layer aggregate of TMV CP in the presence of RNA.</p></div

Characterization of reconstituted N-His-TMV CP¹⁹ virus using TEM in 10 mM PB, 100 mM NaCl, pH 7.2 after 20 h at 22°C.

<p>1 mL purified self-assembled N-His-TMV CP¹⁹ disks (1.8 mg/mL) in 10 mM PB, 100 mM NaCl, pH 7.2 was mixed with 0.2 mL purified TMV RNA for 20 h at 22°C. Four TEM images of the reconstituted virus are shown in A–D.</p