Hydrogen peroxide (H2O2) functions as a second messenger that can activate cell proliferation through chemoselective oxidation of cysteine residues in signaling proteins. The connection between H2O2 signaling, thiol oxidation, and activation of growth pathways has emerged as fertile ground for the development of strategies for cancer treatment. Central to achieving this goal is the development of tools and assays that facilitate characterization of the molecular events associated with tumorigenesis and evaluation of patient response to therapy. Here we report on the development of an immunochemical method for detecting sulfenic acid, the initial oxidation product that results when a thiolate reacts with H2O2. For this approach, the sulfenic acid is derivatized with a chemical tag to generate a unique epitope for recognition. The elicited antibody is exquisitely specific, context-independent, and capable of visualizing sulfenic acid formation in cells. Applying this approach to several systems, including cancer cell lines, shows it can be used to monitor differences in thiol redox status and reveals a diverse pattern of sulfenic acid modifications across different subtypes of breast tumors. These studies demonstrate a general strategy for producing antibodies against a specific oxidation state of cysteine and show the utility of these reagents for profiling thiol oxidation associated with pathological conditions such as breast cancer.cancer ͉ chemical biology ͉ redox signaling ͉ thiol modification

Oxidation of the thiol functional group in cysteine (Cys-SH) to sulfenic (Cys-SOH), sulfinic (Cys-SO 2 H) and sulfonic acids (Cys-SO 3 H) is emerging as an important post-translational modification that can activate or deactivate the function of many proteins. Changes in thiol oxidation state have been implicated in a wide variety of cellular processes and correlate with disease states but are difficult to monitor in a physiological setting because of a lack of experimental tools. Here, we describe a method that enables live cell labeling of sulfenic acidmodified proteins. For this approach, we have synthesized the probe DAz-1, which is chemically selective for sulfenic acids and cell permeable. In addition, DAz-1 contains an azide chemical handle that can be selectively detected with phosphine reagents via the Staudinger ligation for identification, enrichment and visualization of modified proteins. Through a combination of biochemical, mass spectrometry and immunoblot approaches we characterize the reactivity of DAz-1 and highlight its utility for detecting protein sulfenic acids directly in mammalian cells. This novel method to isolate and identify sulfenic acid-modified proteins should be of widespread utility for elucidating signaling pathways and regulatory mechanisms that involve oxidation of cysteine residues.

Quantitative proteomics: The new technique mentioned in the title—in short, ICDID—enables quantification of sulfenic acid modifications in proteins (see picture). The approach permits S‐hydroxylation site occupancy to be monitored at individual cysteines within a single protein and is compatible with peptide‐based proteomic strategies.

BackgroundMethamphetamine (METH) is a commonly abused drug that may result in neurotoxic effects. Recent studies have suggested that involvement of neuroinflammatory processes in brain dysfunction is induced by misuse of this drug. However, the mechanism underlying METH-induced inflammation and neurotoxicity in neurons is still unclear. In this study, we investigated whether asiatic acid (AA) effected METH-mediated neuroinflammation and neurotoxicity in dopaminergic neuronal cells. And we further determined whether the effect involved in the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription (STAT)3 and extracellular signal-regulated kinase (ERK) pathway.MethodsWe used the human dopaminergic neuroblastoma SH-SY5Y cell line, murine microglial BV2 cell line, and primary culture of rat embryo mesencephalic neurons. Pro-inflammatory cytokine production was monitored by ELISA and RT/real-time PCR. The cell cycle distribution and mitochondrial membrane integrity was analyzed by flow cytometry. We used immunoblotting, DNA-binding activity, and immunofluorescence staining to analyze the effect of AA on activation of the NF-κB, STAT3, MAPK-ERK, and apoptosis signaling pathways.ResultsMETH induced TNF receptor (TNFR) expression and led to morphological changes of cells. Additionally, this drug increased pro-inflammatory cytokine (TNFα and IL-6) expression. AA significantly suppressed METH-induced TNFR expression in concentration dependent. Increased secretion of TNFα and IL-6 was inhibited in METH-stimulated neuronal cells by AA administration. AA showed significant protection against METH-induced translocation of NF-κB/STAT3 and ERK phosphorylation. AA inhibited METH-induced proteolytic fragmentation of caspase-3 and PARP. The pro-apoptotic protein Bax was significantly decreased, while the anti-apoptotic protein Bcl-xL was increased by AA treatment in METH-stimulated cells. A similar protective effect of AA on mitochondrial membrane integrity was also confirmed by flow cytometry and immunofluorescence staining.ConclusionsBased on the literatures and our findings, AA is a promising candidate for an anti-neurotoxic agent, and it can potentially be used for the prevention and treatment of various neurological disorders.Electronic supplementary materialThe online version of this article (10.1186/s12974-017-1009-0) contains supplementary material, which is available to authorized users.

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Sulforaphane [1-isothiocyanato-4-(methyl-sulfinyl) butane)], an isothiocyanate derived from cruciferous vegetables, has been shown to possess potent chemopreventive activity. We analyzed the effect of sulforaphane on the proliferation of pancreatic cancer cells. Sulforaphane inhibited pancreatic cancer cell growth in vitro with the IC50's around 10-15 μM and induced apoptosis. In pancreatic cancer xenograft mouse model, administration of sulforaphane showed remarkable inhibition of tumor growth without apparent toxicity noticed. We found that sulforaphane induced the degradation of heat shock protein 90 (Hsp90) client proteins and blocked the interaction of Hsp90 with its cochaperone p50Cdc37 in pancreatic cancer cells. Using Nuclear Magnetic Resonance Spectroscopy (NMR) with an isoleucine-specific labeling strategy, we overcame the protein size limit of conventional NMR and studied the interaction of sulforaphane with full-length Hsp90 dimer (170 kDa) in solution. NMR revealed multiple chemical shifts in sheet 2 and the adjacent loop in Hsp90 N-terminal domain after incubation of Hsp90 with sulforaphane. Liquid Chromatography coupled to Mass Spectrometry (LC-MS) further mapped a short peptide in this region that was tagged with sulforaphane. These data suggest a new mechanism of sulforaphane that disrupts protein-protein interaction in Hsp90 complex for its chemopreventive activity.

The serum concentrations of CBZ in 35 Korean epileptic patients were measured and their CYP3A5 genotype was determined. Fourteen patients were CYP3A5 expressors (two for CYP3A5*1/*1 and 12 for CYP3A5*1/*3) and 21 patients were CYP3A5 non-expressors (CYP3A5*3/*3). Dose-normalized concentrations (mean +/- SD) of CBZ were 9.9 +/- 3.4 ng/mL/mg for CYP3A5 expressors and 13.1 +/- 4.5 ng/mL/mg for CYP3A5 non-expressors (P = 0.032). The oral clearance of CBZ was significantly higher in CYP3A5 non-expressors than that of CYP3A5 expressors (0.056 +/-0.017 L/h/kg vs. 0.040 +/- 0.014 L/h/kg, P = 0.004). The CYP3A5 genotype affected the CBZ concentrations in Korean epileptic patients and is a factor that may contribute to inter-individual variability in CBZ disposition in epileptic patients.

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