Chemical and chemoenzymatic syntheses of sialyl Lewisa tetrasaccharide antigen.

Sialyl Lewisa (sLea), also known as cancer antigen 19-9, is a tumor-associated carbohydrate antigen. In this article, chemical and chemoenzymatic syntheses of a tetrasaccharide glycan 1 structurally derived from sLea are reported. Challenges involved in the chemical synthesis include the highly stereoselective construction of 1,2-cis-α-L-fucoside and α-D-sialoside, as well as the assembly of the 3,4-disubstituted N-acetylglucosamine subunit. Perbenzylated thiofucoside and N-acetyl-5-N,4-O-oxazolidinone protected sialic acid thioglycoside were employed as glycosyl donors, respectively, for the efficient preparation of the desired α-fucoside and α-sialoside. The 3,4-branched glucosamine backbone was established through a 3-O and then 4-O glycosylation sequence in which the 3-hydroxyl group of the glucosamine moiety was glycosylated first and then the 4-hydroxyl. A facile chemoenzymatic approach was also exploited to synthesize the target molecule. The chemically obtained free disaccharide 30 was sequentially sialylated and fucosylated in an enzyme-catalyzed regio- and stereospecific manner to form 1 in high yields. The linker appended 1 can be covalently attached to a carrier protein for further immunological studies.

Histone deacetylase inhibitors inhibit lung adenocarcinoma metastasis via HDAC2/YY1 mediated downregulation of Cdh1.

Metastasis is a leading cause of mortality in patients with lung adenocarcinoma. Histone deacetylases have emerged as promising targets for anti-tumor drugs, with histone deacetylase inhibitors (HDACi) being an active area of research. However, the precise mechanisms by which HDACi inhibits lung cancer metastasis remain incompletely understood. In this study, we employed a range of techniques, including qPCR, immunoblotting, co-immunoprecipitation, chromatin-immunoprecipitation, and cell migration assays, in conjunction with online database analysis, to investigate the role of HDACi and HDAC2/YY1 in the process of lung adenocarcinoma migration. The present study has demonstrated that both trichostatin A (TSA) and sodium butyrate (NaBu) significantly inhibit the invasion and migration of lung cancer cells via Histone deacetylase 2 (HDAC2). Overexpression of HDAC2 promotes lung cancer cell migration, whereas shHDAC2 effectively inhibits it. Further investigation revealed that HDAC2 interacts with YY1 and deacetylates Lysine 27 and Lysine9 of Histone 3, thereby inhibiting Cdh1 transcriptional activity and promoting cell migration. These findings have shed light on a novel functional mechanism of HDAC2/YY1 in lung adenocarcinoma cell migration.

Dexamethasone Induces Senescence-Associated Changes in Trabecular Meshwork Cells by Increasing ROS Levels Via the TGFß/Smad3-NOX4 Axis.

Glaucoma is a serious complication of glucocorticoid (GC) therapy arising through elevations in intraocular pressure (IOP). Dexamethasone (DEX) is reported to contribute to elevated IOP through different effects on the trabecular meshwork but whether DEX contributes to glaucoma development through the induction of cellular senescence is still unclear. We explored the actions of DEX on transformed human trabecular meshwork cells (HTMCs) using RNA-seq and conducted bioinformatic analyses to determine the affected pathways. Among the 4,103 differentially expressed genes identified in transformed HTMCs treated with 400 nM DEX (2,036 upregulated and 2,067 downregulated genes, respectively), bioinformatic analyses revealed significant enrichment and potential interplay between the transforming growth factor beta (TGFß)41; signaling and cellular senescence pathways. DEX treatment induced senescence changes in primary and transformed HTMCs as indicated by increases in SA-ß-gal positivity, interleukin (IL)-6 secretion, and senescence-associated heterochromatin foci (SAHF) along with selective accumulation of senescence marker p15 and elevations in reactive oxygen species (ROS) levels. Notably, the DEX-induced senescence changes were rescued by treatment with the TGFß/Smad3 pathway inhibitor SIS3. Furthermore, we show that DEX increases cellular ROS levels via upregulation of NADPH oxidase 4 (NOX4) through activation of Smad3, and that SIS3 decreases ROS levels by downregulating NOX4. Instructively, inhibiting NOX4 with GLX351322 and scavenging ROS with NAC were both effective in preventing DEX-induced senescence changes. Similarly, we found in the mouse model that DEX-ac upregulated p15 and NOX4 expression in the trabecular meshwork, with cotreatment with GLX351322 alleviating elevations in IOP. We establish that DEX induces senescence changes in HTMCs by increasing ROS levels via the TGFß/Smad3/NOX4 axis, increasing IOP and contributing to glaucoma development.

Elevated Angiotensin-II Levels Contribute to the Pathogenesis of Open-Angle Glaucoma Via Inducing the Expression of Fibrosis-Related Genes in Trabecular Meshwork Cells Through a ROS/NOX4/SMAD3 Axis.

Glaucoma including primary open-angle glaucoma (POAG) results from elevations in intraocular pressure (IOP). An eye-localized renin-angiotensin system (RAS) has been implicated in IOP regulation, although its mechanism of action and contribution to glaucoma is poorly understood. Here, we detected significant increases in the levels of angiotensin II (ANGII) in aqueous humor samples from POAG patients. Moreover, we determined that the concentrations of ANGII were positively correlated with IOP, suggesting a role for elevated ANGII levels in eye pathogenesis. Functional investigations demonstrated that ANGII induces the expression of fibrosis-related genes of transformed and primary human trabecular meshwork cells (HTMCs) through the transcriptional upregulation of key fibrotic genes. Parallel experiments using a murine periocular conjunctival fornix injection model confirmed that ANGII induces the expression of fibrosis-related genes in trabecular meshwork (TM) cells in vivo along with increasing IOP. ANGII was revealed to function through increasing the levels of reactive oxygen species (ROS) via selectively upregulating NOX4, with NOX4 knockdown or inhibition with GLX351322 alleviating fibrotic changes induced by ANGII. We further show that ANGII activates Smad3, with both GLX351322 and an inhibitor of Smad3 (SIS3) decreasing the phosphorylation of Smad3 and dampening the ANGII-induced increases in fibrotic proteins. Moreover, NOX4 and Smad3 inhibitors also partially rescued the elevated IOP levels induced by ANGII. Our collective results therefore highlight ANGII as a biomarker and treatment target in POAG together with establishing a causal relationship between ANGII and up-regulation of the expression of fibrosis-related genes of TM cells via a NOX4/ROS axis in cooperation with TGFß/Smad3 signaling.

Chemical Synthesis and Antigenic Evaluation of Inner Core Oligosaccharides from Acinetobacter baumannii Lipopolysaccharide.

Acinetobacter baumannii is currently posing a serious threat to global health. Lipopolysaccharide (LPS) is a potent virulence factor of pathogenic Gram-negative bacteria. To explore the antigenic properties of A. baumannii LPS, four Kdo-containing inner core glycans from A. baumannii strain ATCC 17904 were synthesized. A flexible and divergent method based on the use of the orthogonally substituted α-Kdo-(2→5)-Kdo disaccharides was developed. Selective removal of different protecting groups in these key precursors and elongation of sugar chain via α-stereocontrolled coupling with 5,7-O-di-tert-butylsilylene or 5-O-benzoyl protected Kdo thioglycosides and 2-azido-2-deoxyglucosyl thioglycoside allowed efficient assembly of the target molecules. Glycan microarray analysis of sera from infected patients revealed that the 4,5-branched Kdo trimer was a potential antigenic epitope, which is attractive for further immunological research to develop carbohydrate vaccines against A. baumannii.

Hyperthermia inhibits growth of nasopharyngeal carcinoma through degradation of c-Myc.

BACKGROUND: Hyperthermia is a widely used adjunct treatment for different cancers including nasopharyngeal carcinoma (NPC). The protooncogene c-Myc is up-regulated in NPC and its expression is associated with poor prognosis. OBJECTIVE: We hypothesized that c-Myc constitutes an important hyperthermia treatment target, and we investigated its contribution to hyperthermia responses in NPC. METHODS: The growth of the human NPC cell lines CNE1 and CNE2 was analyzed using CCK-8 and clonogenicity assays after 43 °C hyperthermia, knockdown or overexpression of c-Myc. Flow cytometry measurements assessed cell cycle parameters and apoptosis, while levels of c-Myc together with key transcriptional targets were determined using qPCR and Western blotting. Parallel experiments were undertaken using NPC xenografts in nude mice and lastly, global transcriptomic changes were determined using 'RNAseq'. RESULTS: Hyperthermia increased the ubiquitination and proteasomal destruction of c-Myc, causing a rapid decline in c-Myc protein levels in NPC cells. Similar to c-Myc knockdown, NPC cells treated with hyperthermia showed growth inhibition associated with the downregulation of c-Myc target genes. Moreover, low levels of c-Myc could be sustainably repressed in NPC cells through repeated hyperthermia treatments. Importantly, the key findings of growth inhibition and decreased c-Myc protein levels were reproduced in NPC tumor xenografts. Bioinformatic analyses showed that downregulation of c-Myc constituted a central node in the hyperthermia response of NPC cells. CONCLUSION: Our study reveals that hyperthermia can readily destabilize c-Myc levels in NPC cells and inhibit tumor growth. This proposes new strategies for implementing hyperthermia to target c-Myc-driven cancers to improve therapeutic efficacy.

Rabl2 GTP hydrolysis licenses BBSome-mediated export to fine-tune ciliary signaling.

Cilia of higher animals sense various environmental stimuli. Proper ciliary signaling requires appropriate extent of BBSome-mediated export of membrane receptors across ciliary barrier transition zone (TZ) through retrograde intraflagellar transport (IFT) machinery. How the barrier passage is controlled, however, remains unknown. Here, we show that small GTPase Rabl2 functions as a molecular switch for the outward TZ passage. Rabl2-GTP enters cilia by binding to IFT-B complex. Its GTP hydrolysis enables the outward TZ passage of the BBSome and its cargos with retrograde IFT machinery, whereas its persistent association leads to their shedding from IFT-B during the passing process and consequently ciliary retention. Rabl2 deficiency or expression of a GTP-locked mutant impairs the ciliary hedgehog signaling without interfering with ciliation and respectively results in different spectrums of mouse developmental disorders. We propose that the switch role of Rabl2 ensures proper turnover of the BBSome and ciliary membrane receptors to fine-tune cilia-dependent signaling for normal embryonic development and organismic homeostasis.

Vertebrate Dynein-f depends on Wdr78 for axonemal localization and is essential for ciliary beat.

Motile cilia and flagella are microtubule-based organelles important for cell locomotion and extracellular liquid flow through beating. Although axonenal dyneins that drive ciliary beat have been extensively studied in unicellular Chlamydomonas, to what extent such knowledge can be applied to vertebrate is poorly known. In Chlamydomonas, Dynein-f controls flagellar waveforms but is dispensable for beating. The flagellar assembly of its heavy chains (HCs) requires its intermediate chain (IC) IC140 but not IC138. Here we show that, unlike its Chlamydomonas counterpart, vertebrate Dynein-f is essential for ciliary beat. We confirmed that Wdr78 is the vertebrate orthologue of IC138. Wdr78 associated with Dynein-f subunits such as Dnah2 (a HC) and Wdr63 (IC140 orthologue). It was expressed as a motile cilium-specific protein in mammalian cells. Depletion of Wdr78 or Dnah2 by RNAi paralyzed mouse ependymal cilia. Zebrafish Wdr78 morphants displayed ciliopathy-related phenotypes, such as curved bodies, hydrocephalus, abnormal otolith, randomized left-right asymmetry, and pronephric cysts, accompanied with paralyzed pronephric cilia. Furthermore, all the HCs and ICs of Dynein-f failed to localize in the Wdr78-depleted mouse ependymal cilia. Therefore, both the functions and subunit dependency of Dynein-f are altered in evolution, probably to comply with ciliary roles in higher organisms.