Characterization of Concanavalin A-based lectin sorbents for the extraction of the human chorionic gonadotropin glycoforms prior to analysis by nano liquid chromatography-high resolution mass spectrometry.

Human chorionic gonadotropin (hCG) is constituted of the hCGα and hCGß subunits and is a highly glycosylated protein. Affinity supports based on immobilized Concanavalin A (Con A) lectin were used in solid phase extraction (SPE) to fractionate the hCG glycoforms according to their glycosylation state. For the first time, the lectin SPE fractions were off-line analysed by a nano liquid chromatography - high-resolution mass spectrometry (nanoLC-HRMS) method keeping the glycoforms intact. For this, home-made Con A sorbents were prepared by immobilizing lectin on Sepharose with a mean grafting yield of 98.2% (relative standard deviation (RSD) of 3.5%, n = 15). A capacity of about 100 µg of purified urinary hCG (uhCG) per ml of sorbent, grafted with a density of 10 mg of Con A per ml, was estimated. Average extraction yields of around 60% for both hCGα and hCGß glycoforms were obtained after optimization of the extraction protocol. Intra- and inter-assay evaluation led to average RSD values of around 10%, indicating a repeatable extraction procedure. Similar results were obtained with commercial Con A-based sorbents but only after their 3rd use or after an extensive pre-conditioning step. Finally, the Con A SPE led to the fractionation of some glycoforms of uhCG, allowing the detection of an hCGα glycoform with two tetra-antennary N-glycans that couldn't be detected by direct analysis in nanoLC-HRMS without Con A SPE. Regarding a recombinant hCG, a fractionation was also observed leading to the detection of unretained hCGα glycoforms with tri-antennary N-glycans. Therefore, the combination of lectin SPE with intact protein analysis by nanoLC-HRMS can contribute to a more detailed glycosylation characterization of the hCG protein.

Development of ion-imprinted polymers for the selective extraction of Cu(II) ions in environmental waters.

Several ion-imprinted polymers (IIPs) were synthesized via bulk polymerization with Cu(II) as template ion, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinking agent, and azobisisobutyronitrile as initiator in acetonitrile or methanol as porogen solvent. Non-imprinted polymers (NIPs) were similarly synthesized but without Cu(II). After grounding and sieving, the template ions were removed from IIPs particles through several cycles of elimination in 3 M HCl. All NIPs were equally subjected to this acid treatment with the exception of one NIP, called unwashed NIP. The resulting IIP/NIP particles were packed in solid phase extraction (SPE) cartridges for characterization. The SPE protocol was designed by optimizing a washing step following the sample percolation to eliminate potential interfering ions prior to the elution of Cu(II), all fractions analyzed by inductively coupled plasma mass spectrometry. The best IIP showed a high specificity (recovery of Cu(II) vs. interfering ions) and a good selectivity (retention on IIP vs. NIP). Its adsorption capacity was determined to be 63 µg g-1. Then, a volume of 50 mL was percolated with 30 mg of IIP, thus giving rise to an enrichment factor of 24. Finally, applications to real samples (mineral and sea waters) were successfully performed. In addition, Brunauer-Emmett-Teller analyses showed that the surface area of the washed NIP was almost double that of the unwashed one (140.70 vs. 74.49 m2 g-1), demonstrating for the first time that the post-treatment of a NIP after its synthesis may have a significant impact on its porous structure, and thus need to be more precisely detailed by authors in the future papers.

Identification and semi-relative quantification of intact glycoforms of human chorionic gonadotropin alpha and beta subunits by nano liquid chromatography-Orbitrap mass spectrometry.

The human chorionic gonadotropin (hCG) protein belongs to a family of glycoprotein hormones called gonadotropins. It is a heterodimer made of two non-covalently linked subunits. The α-subunit structure, hCGα, has 2 N-glycosylation sites, while the beta subunit, hCGß, has 2 N- and 4 O-glycosylation sites. This leads to numerous glycoforms. A method based on the analysis of hCG glycoforms at the intact level by nano-reversed phase liquid chromatography coupled to high resolution mass spectrometry (nanoLC-HRMS) with an Orbitrap analyzer was previously developed using a recombinant hCG-based drug, Ovitrelle®, as standard. It allowed the detection of about 30 hCGα glycoforms, but didn't allow the detection of hCGß glycoforms. This method was thus here significantly modified (addition of a pre-concentration step of the sample to increase the sample volume from 70 nl to 1 µl, optimization of the gradient slope and the nature and content of the acidic additive in the mobile phase). It led to an improvement of the separation of hCGα and hCGß glycoforms, which allowed for the first time the detection of 33 hCGß glycoforms at intact level. In addition, a higher number of hCGα glycoforms (42 in total, i.e. a 40% increase) was detected. The figures of merit of this new method were next assessed. The relative standard deviations (RSDs) of the retention time ranged between 0.02 and 0.95% (n = 3), with an average value of 0.36% for the alpha glycoforms and between 0.01 and 1.08% (n = 3) with an average value of 0.23% for the beta glycoforms. The RSDs of the relative peak area measured on the extracted ion chromatogram of each glycoform were below 20% (n = 3), with an average value of 9.8%, thus allowing semi-relative quantification. Therefore, this method has a high potential for rapid quality control aiming for the detection and comparison of glycoforms present in glycoprotein-based pharmaceutical preparations.

Identification and semi-relative quantification of intact glycoforms by nano-LC-(Orbitrap)MS: application to the α-subunit of human chorionic gonadotropin and follicle-stimulating hormone.

Human chorionic gonadotropin (hCG) and follicle-stimulating hormone (FSH) belong to the family of glycoprotein polypeptide hormones called gonadotropins. They are heterodimers sharing the α-subunit structure that has 2 N-glycosylation sites. A method based on nano-reversed-phase liquid chromatography coupled to high-resolution mass spectrometry with an Orbitrap analyzer was developed for the first time to characterize the glycosylation state of the α-subunit at the intact level. A recombinant hCG-based drug, Ovitrelle®, was analyzed. This method combined with an appropriate data treatment allowed the detection of not only the major isoforms but also the minority ones with a high mass accuracy. More than 30 hCGα glycoforms were detected without overlapping of the isotopic patterns. The figures of merit of the method were assessed. The relative standard deviations (RSDs) of the retention time ranged between 0.1 and 6.08% (n = 3), with an average of 0.4%. The RSDs of the peak area measured on the extracted ion chromatogram of each glycoform are below 38% (n = 3), with an average of 16%, thus allowing semi-relative quantification. The ability to accurately profile glycosylated variants of hCGα was next demonstrated by comparing qualitatively and semi-quantitatively 3 batches of Ovitrelle®. The method was also used to analyze 3 batches of a recombinant FSH-based drug, Puregon®, and 30 FSHα glycoforms were detected and semi-quantified. This demonstrates the high potential of this method for fast quality control or comparison of the glycosylation of glycoprotein-based pharmaceutical preparations. Graphical abstract.

Analysis of the human chorionic gonadotropin protein at the intact level by HILIC-MS and comparison with RPLC-MS.

In the present work, the human chorionic gonadotropin (hCG) hormone was characterized for the first time by hydrophilic interaction liquid chromatography (HILIC) coupled to high-resolution (HR) quadrupole/time-of-flight (qTOF) mass spectrometry (MS) at the intact level. This heterodimeric protein, consisting of two subunits (hCGα and hCGß), possesses 8 potential glycosylation sites leading to a high number of glycoforms and has a molecular weight of about 35 kDa. The HILIC conditions optimized in a first paper but using UV detection were applied here with MS for the analysis of two hCG-based drugs, a recombinant hCG and a hCG isolated from the urine of pregnant women. An amide column (150 × 2.1 mm, 2.6 µm, 150 Å), a mobile phase composed of acetonitrile and water both containing 0.1% of trifluoroacetic acid, and a temperature of 60 °C were used. The gradient was from 85 to 40% ACN in 30 min. The use of TFA that had been shown to be necessary for the separation of glycoforms caused, as expected, an ion suppression effect in MS that was partially overcome by increasing the amount of protein injected (2 µL at 1 mg mL-1) and reducing the detection m/z range (from 1500 to 300). These conditions allowed the detection of different glycoforms of hCGα. The performance of the HILIC-HRMS method was compared with that previously obtained in RPLC-HRMS in terms of the number of detected glycoforms, selectivity, and sensitivity. The complementarity and orthogonality of the HILIC and RP modes for the analysis of hCG at the intact level were demonstrated.

Selective solid phase extraction of lanthanides from tap and river waters with ion imprinted polymers.

For the first time, an ion imprinted polymer (IIP) able to selectively extract simultaneously all the lanthanide ions was successfully synthesized in acetonitrile using Nd3+ as a template ion, methacrylic acid as a complexing monomer, and ethylene glycol dimethacrylate as a cross-linker. A non-imprinted polymer (NIP) was synthesized under the same conditions as those of the IIP, but in the absence of the template ion. After the removal of the template ions, grounding and sieving, the IIP particles were packed in solid phase extraction (SPE) cartridges. The selectivity of the IIP was evaluated by comparing its behavior with the one of the NIP. Each SPE step (percolation, washing, and elution) was optimized in order to find the best compromise between the selectivity and the extraction recoveries. Using the optimized SPE conditions, the extraction recoveries of eight lanthanide ions representative of the lanthanide family were higher than 77% with an average value of 83% with the IIP, whereas, in the case of the NIP, they ranged between 14 and 36% and they were below 3% for the interfering ions from alkali, transition, and post-transition metal families with the IIP. A first evaluation of the reproducibility of the SPE profiles was carried out by performing statistical tests on the data obtained with several cartridges filled with particles obtained from two different IIP and NIP syntheses. Promising results were obtained. The specific capacity, i. e. the adsorption capacity of Nd3+ ions by the specific cavities of the imprinted polymer, was about 9 mg of Nd3+ per gram of IIP (60 µmol g-1), which is more than enough for the extraction of the lanthanide ions at trace levels. The breakthrough volume was about 1 mL per mg of IIP, leading to an enrichment factor of 15, which allows not only to selectively extract the lanthanides but also to concentrate them. Finally, the imprinted polymer was successfully used to selectively extract lanthanides from tap and river waters spiked at 1 µg L-1.

Regulation of Catalytic and Non-catalytic Functions of the Drosophila Ste20 Kinase Slik by Activation Segment Phosphorylation.

Protein kinases carry out important functions in cells both by phosphorylating substrates and by means of regulated non-catalytic activities. Such non-catalytic functions have been ascribed to many kinases, including some members of the Ste20 family. The Drosophila Ste20 kinase Slik phosphorylates and activates Moesin in developing epithelial tissues to promote epithelial tissue integrity. It also functions non-catalytically to promote epithelial cell proliferation and tissue growth. We carried out a structure-function analysis to determine how these two distinct activities of Slik are controlled. We find that the conserved C-terminal coiled-coil domain of Slik, which is necessary and sufficient for apical localization of the kinase in epithelial cells, is not required for Moesin phosphorylation but is critical for the growth-promoting function of Slik. Slik is auto- and trans-phosphorylated in vivo. Phosphorylation of at least two of three conserved sites in the activation segment is required for both efficient catalytic activity and non-catalytic signaling. Slik function is thus dependent upon proper localization of the kinase via the C-terminal coiled-coil domain and activation via activation segment phosphorylation, which enhances both phosphorylation of substrates like Moesin and engagement of effectors of its non-catalytic growth-promoting activity.

Capillary electrophoresis analysis of inorganic cations in post-blast residue extracts applying a guanidinium-based electrolyte and bilayer-coated capillaries.

A new CE method was developed for the identification and quantitation of inorganic cations in post-blast residues. The simultaneous analysis in 20 min total runtime of eight cations in post-blast residues (ammonium, potassium, monomethylammonium, calcium, sodium, magnesium, strontium), plus lithium cation as the internal reference, was carried out with a BGE involving a non-CMR (carcinogenic, mutagenic, and harmful to reproduction) chromophore (guanidinium cation) and a double-layer modified capillary (hexadimethrine bromide/polyvinylsulfonate). A study of UV detection conditions using guanidinium ion as the probe led us to set the analysis and reference wavelengths and their associated bandwidths as well as the probe concentration fixed at 15 mM. The successive multiple ionic-polymer layer approach limited the cation adsorption on capillary wall and improved the EOF stability. These caused a significant improvement in method repeatability. Intermediate precisions were 2.4% for corrected areas and 1.3% for normalized migration times. Limits of detection close to 1 mg/L for all cations were obtained. The matrix effects were studied with chemometric approach for different matrices representative of those collected after explosion. Tests with blank matrix extracts of soil, cloth, and with simulated matrix extract containing 800 mg/L Ca²âº and 500 mg/L Fe²âº were carried out and no significant matrix effects were observed. Finally, analyses of real residues collected after cash dispenser and homemade firework explosions demonstrate excellent correlation between the CE results and those obtained with the ion chromatography method used routinely.

Simultaneous capillary electrophoretic analysis of inorganic anions and cations in post-blast extracts of acid-aluminum mixtures.

Bursts resulting from the chemical reaction between hydrochloric or nitric acid with aluminum foils are very often committed by the young delinquency in western countries because of its easiness of achievement. A fast, simple, selective, and cost-effective method allowing the simultaneous detection of chloride and nitrate anions and aluminum(III) was thus required. This article focused on the development and validation of a CE method using a BGE containing 2,6-pyridinedicarboxylic acid (PDC) acting as both an anionic chromophore and as an aluminum(III) complexing agent. First, the achievement of the speciation diagram of Al(III) in the presence of PDC allowed the choice of pH conditions for which aluminum(III) was globally anionic. The study of the selectivity for Al(III) in the presence of ten other cationic species potentially present in post-blast residues dictated the choice of the PDC concentration at 20 mM. The validation step next demonstrated the figures of merit of the method, with an intermediate precision for Al(III) of 2% on normalized migration times and 3.5% on corrected areas. Finally, this method was used for analyses of real post-blast extracts from acid-aluminum mixtures.

The wnt target jagged-1 mediates the activation of notch signaling by progastrin in human colorectal cancer cells.

The Wnt and Notch signaling pathways are both abnormally activated in colorectal cancer (CRC). We recently showed that progastrin depletion inhibited Wnt signaling and increased goblet cell differentiation of CRC cells. Here, we show that progastrin down-regulation restores the expression by CRC cells of the early secretory lineage marker Math-1/Hath-1 due to an inhibition of Notch signaling. This effect is mediated by a decreased transcription of the Notch ligand Jagged-1, downstream of beta-catenin/Tcf-4. Accordingly, recombinant progastrin sequentially activated the transcription of Wnt and Notch target genes in progastrin-depleted cells. In addition, restoration of Jagged-1 levels in these cells is sufficient to activate Tcf-4 activity, demonstrating the occurrence of a feedback regulation from Notch toward Wnt signaling. These results suggest that progastrin could be instrumental in maintaining the concomitant activation of Wnt and Notch pathways in CRC cells, further highlighting the interest of progastrin targeting for the clinical management of CRC.

Phosphatidylethanol accumulation promotes intestinal hyperplasia by inducing ZONAB-mediated cell density increase in response to chronic ethanol exposure.

Chronic alcohol consumption is associated with increased risk of gastrointestinal cancer. High concentrations of ethanol trigger mucosal hyperregeneration, disrupt cell adhesion, and increase the sensitivity to carcinogens. Most of these effects are thought to be mediated by acetaldehyde, a genotoxic metabolite produced from ethanol by alcohol dehydrogenases. Here, we studied the role of low ethanol concentrations, more likely to mimic those found in the intestine in vivo, and used intestinal cells lacking alcohol dehydrogenase to identify the acetaldehyde-independent biological effects of ethanol. Under these conditions, ethanol did not stimulate the proliferation of nonconfluent cells, but significantly increased maximal cell density. Incorporation of phosphatidylethanol, produced from ethanol by phospholipase D, was instrumental to this effect. Phosphatidylethanol accumulation induced claudin-1 endocytosis and disrupted the claudin-1/ZO-1 association. The resulting nuclear translocation of ZONAB was shown to mediate the cell density increase in ethanol-treated cells. In vivo, incorporation of phosphatidylethanol and nuclear translocation of ZONAB correlated with increased proliferation in the colonic epithelium of ethanol-fed mice and in adenomas of chronic alcoholics. Our results show that phosphatidylethanol accumulation after chronic ethanol exposure disrupts signals that normally restrict proliferation in highly confluent intestinal cells, thus facilitating abnormal intestinal cell proliferation.

Beta-catenin/Tcf-4 inhibition after progastrin targeting reduces growth and drives differentiation of intestinal tumors.

BACKGROUND & AIMS: Aberrant activation of the beta-catenin/Tcf-4 transcriptional complex represents an initiating event for colorectal carcinogenesis, shifting the balance from differentiation toward proliferation in colonic crypts. Here, we assessed whether endogenous progastrin, encoded by a target gene of this complex, was in turn able to regulate beta-catenin/Tcf-4 activity in adenomatous polyposis coli (APC)-mutated cells, and we analyzed the impact of topical progastrin depletion on intestinal tumor growth in vivo. METHODS: Stable or transient RNA silencing of the GAST gene was induced in human tumor cells and in mice carrying a heterozygous Apc mutation (APCDelta14), which overexpress progastrin but not amidated or glycine-extended gastrin. RESULTS: Depletion of endogenous progastrin production strongly decreased intestinal tumor growth in vivo through a marked inhibition of constitutive beta-catenin/Tcf-4 activity in tumor cells. This effect was mediated by the de novo expression of the inhibitor of beta-catenin and Tcf-4 (ICAT), resulting from a down-regulation of integrin-linked kinase in progastrin-depleted cells. Accordingly, ICAT down-regulation was correlated with progastrin overexpression and Tcf-4 target gene activation in human colorectal tumors, and ICAT repression was detected in the colon epithelium of tumor-prone, progastrin-overexpressing mice. In APCDelta14 mice, small interfering RNA-mediated progastrin depletion not only reduced intestinal tumor size and numbers, but also increased goblet cell lineage differentiation and cell apoptosis in the remaining adenomas. CONCLUSIONS: Thus, depletion of endogenous progastrin inhibits the tumorigenicity of APC-mutated colorectal cancer cells in vivo by promoting ICAT expression, thereby counteracting Tcf-4 activity. Progastrin targeting strategies should provide an exciting prospect for the differentiation therapy of colorectal cancer.