The p38 MAPK-regulated PKD1/CREB/Bcl-2 pathway contributes to selenite-induced colorectal cancer cell apoptosis in vitro and in vivo

AbstractSupranutritional selenite has anti-cancer therapeutic effects in vivo; however, the detailed mechanisms underlying these effects are not clearly understood. Further studies would broaden our understanding of the anti-cancer effects of this compound and provide a theoretical basis for its clinical application. In this study, we primarily found that selenite exposure inhibited phosphorylation of cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB), leading to suppression of Bcl-2 in HCT116 and SW480 colorectal cancer (CRC) cells. Moreover, the selenite-induced inhibitory effect on PKD1 activation was involved in suppression of the CREB signalling pathway. Additionally, we discovered that selenite treatment can upregulate p38 MAPK phosphorylation, which results in inhibition of the PKD1/CREB/Bcl-2 survival pathway and triggers apoptosis. Finally, we established a colorectal cancer xenograft model and found that selenite treatment markedly inhibits tumour growth through the MAPK/PKD1/CREB/Bcl-2 pathway in vivo. Our results demonstrated that a supranutritional dose of selenite induced CRC cell apoptosis through inhibition of the PKD1/CREB/Bcl-2 axis both in vitro and in vivo

ATF4 activation by the p38MAPK–eIF4E axis mediates apoptosis and autophagy induced by selenite in Jurkat cells

AbstractPrevious studies have shown that selenite exerts pro-apoptosis and pro-autophagy effects and is associated with the activation of ER stress in T-cell acute lymphoblastic leukemia (T-ALL). Herein we demonstrate the underlying mechanisms by which the activation of p38MAPK plays essential roles in apoptosis and autophagy and the coordination of cellular metabolic processes during leukemia therapy. MKK3/6-dependent activation of p38MAPK is required for the phosphorylation of eIF4E, thus initiating the translation of ER stress-related transcription factor ATF4. Upregulated ATF4 results in the transcriptional initiation of the apoptosis-related chop gene and autophagy-related map1lc3b gene, through which selenite links ER stress to apoptosis and autophagy during leukemia treatment. Moreover, autophagy induction enhances cell apoptosis under this condition

Sodium selenite alters microtubule assembly and induces apoptosis in vitro and in vivo

BACKGROUND: Previous studies demonstrated that selenite induced cancer-cell apoptosis through multiple mechanisms; however, effects of selenite on microtubules in leukemic cells have not been demonstrated. METHODS: The toxic effect of selenite on leukemic HL60 cells was performed with cell counting kit 8. Selenite effects on cell cycle distribution and apoptosis induction were determined by flow cytometry. The contents of cyclin B1, Mcl-1, AIF, cytochrome C, insoluble and soluble tubulins were detected with western blotting. Microtubules were visualized with indirect immunofluorescence microscopy. The interaction between CDK1 and Mcl-1 was assessed with immunoprecipitation. Decreasing Mcl-1 and cyclin B1 expression were carried out through siRNA interference. The alterations of Mcl-1 and cyclin B1 in animal model were detected with either immunohistochemical staining or western blotting. In situ detection of apoptotic ratio was performed with TUNEL assay. RESULTS: Our current results showed that selenite inhibited the growth of HL60 cells and induced mitochondrial-related apoptosis. Furthermore, we found that microtubule assembly in HL60 cells was altered, those cells were arrested at G2/M phase, and Cyclin B1 was up-regulated and interacted with CDK1, which led to down-regulation of the anti-apoptotic protein Mcl-1. Finally, in vivo experiments confirmed the in vitro microtubule disruption effect and alterations in Cyclin B1 and Mcl-1 levels by selenite. CONCLUSIONS: Taken together, the results from our study indicate that microtubules are novel targets of selenite in leukemic HL60 cells

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Effect of light polariztion on pattern illumination super-resolution imaging

Far-field fluorescence microscopy has made great progress in the spatial resolution, limited by light diffraction, since the super-resolution imaging technology appeared. And stimulated emission depletion (STED) microscopy and structured illumination microscopy (SIM) can be grouped into one class of the super-resolution imaging technology, which use pattern illumination strategy to circumvent the diffraction limit. We simulated the images of the beads of SIM imaging, the intensity distribution of STED excitation light and depletion light in order to observe effects of the polarized light on imaging quality. Compared to fixed linear polarization, circularly polarized light is more suitable for SIM on reconstructed image. And right-handed circular polarization (CP) light is more appropriate for both the excitation and depletion light in STED system. Therefore the right-handed CP light would be the best candidate when the SIM and STED are combined into one microscope. Good understanding of the polarization will provide a reference for the patterned illumination experiment to achieve better resolution and better image quality

Hsa_circ_0001615 downregulation inhibits esophageal cancer development through miR-142-5p/β-catenin

Background Recent studies have found that circular RNAs (circRNAs) play important roles in tumorigenesis. This study aimed to determine the function and potential mechanisms of hsa_circ_0001615 in esophageal cancer. Methods Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) was used to validate the expression of hsa_circ_0001615 and miR-142-5p. Subsequently, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt, flow cytometry, clone formation, and transwell assays were used to assess the function of hsa_circ_0001615. Furthermore, qRT-PCR and Western blot analysis were used to verify cyclin D1, Bcl-2 associated X, B-cell lymphoma/leukemia gene-2, and β-catenin levels. Circular RNA Interactome was used to estimate the binding site between hsa_circ_0001615 and miR-142-5p. Additionally, dual-luciferase reporter assays were used to determine whether miR-142-5p was a direct target of hsa_circ_0001615. Pearson correlation analysis was used to explore the relationship between miR-142-5p and hsa_circ_0001615. Results In esophageal cancer, the expressions of hsa_circ_0001615 and miR-142-5p were increased and decreased, respectively. Hsa_circ_0001615 inhibition significantly reduced the proliferation, migration, and invasion but increased the apoptosis of esophageal cancer cells. Additionally, hsa_circ_0001615 knockdown increased miR-142-5p expression but decreased β-catenin expression. MiR-142-5p was a direct target of hsa_circ_0001615. Conclusion Hsa_circ_0001615 knockdown could mediate antitumor effects through the miR-142-5p/β-catenin pathway

Sodium selenite alters microtubule assembly and induces apoptosis in vitro and in vivo

Abstract Background Previous studies demonstrated that selenite induced cancer-cell apoptosis through multiple mechanisms; however, effects of selenite on microtubules in leukemic cells have not been demonstrated. Methods The toxic effect of selenite on leukemic HL60 cells was performed with cell counting kit 8. Selenite effects on cell cycle distribution and apoptosis induction were determined by flow cytometry. The contents of cyclin B1, Mcl-1, AIF, cytochrome C, insoluble and soluble tubulins were detected with western blotting. Microtubules were visualized with indirect immunofluorescence microscopy. The interaction between CDK1 and Mcl-1 was assessed with immunoprecipitation. Decreasing Mcl-1 and cyclin B1 expression were carried out through siRNA interference. The alterations of Mcl-1 and cyclin B1 in animal model were detected with either immunohistochemical staining or western blotting. In situ detection of apoptotic ratio was performed with TUNEL assay. Results Our current results showed that selenite inhibited the growth of HL60 cells and induced mitochondrial-related apoptosis. Furthermore, we found that microtubule assembly in HL60 cells was altered, those cells were arrested at G2/M phase, and Cyclin B1 was up-regulated and interacted with CDK1, which led to down-regulation of the anti-apoptotic protein Mcl-1. Finally, in vivo experiments confirmed the in vitro microtubule disruption effect and alterations in Cyclin B1 and Mcl-1 levels by selenite. Conclusions Taken together, the results from our study indicate that microtubules are novel targets of selenite in leukemic HL60 cells.</p

Cu/Zn superoxide dismutase (VdSOD1) mediates reactive oxygen species detoxification and modulates virulence in Verticillium dahliae.

The accumulation of reactive oxygen species (ROS) is a widespread defence mechanism in higher plants against pathogen attack and sometimes is the cause of cell death that facilitates attack by necrotrophic pathogens. Plant pathogens use superoxide dismutase (SOD) to scavenge ROS derived from their own metabolism or generated from host defence. The significance and roles of SODs in the vascular plant pathogen Verticillium dahliae are unclear. Our previous study showed a significant upregulation of Cu/Zn-SOD1 (VdSOD1) in cotton tissues following V.&nbsp;dahliae infection, suggesting that it may play a role in pathogen virulence. Here, we constructed VdSOD1 deletion mutants (ΔSOD1) and investigated its function in scavenging ROS and promoting pathogen virulence. ΔSOD1 had normal growth and conidiation but exhibited significantly higher sensitivity to the intracellular ROS generator menadione. Despite lacking a signal peptide, assays in vitro by western blot and in vivo by confocal microscopy revealed that secretion of VdSOD1 is dependent on the Golgi reassembly stacking protein (VdGRASP). Both menadione-treated ΔSOD1 and cotton roots infected with ΔSOD1 accumulated more O2- and less H2 O2 than with the wildtype strain. The absence of a functioning VdSOD1 significantly reduced symptom severity and pathogen colonization in both cotton and Nicotiana benthamiana. VdSOD1 is nonessential for growth or viability of V.&nbsp;dahliae, but is involved in the detoxification of both intracellular ROS and host-generated extracellular ROS, and contributes significantly to virulence in V.&nbsp;dahliae