| 1. |
- Gad, Helge, et al.
(författare)
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MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
- 2014
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 508:7495, s. 215-221
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Tidskriftsartikel (refereegranskat)abstract
- Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bindin the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.
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| 2. |
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| 3. |
- Saleh, Aljona, et al.
(författare)
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A Bioanalytical Method for Quantification of Thioredoxins in Bacillus anthracis by Digestion with Immobilized Pepsin and LC-MS/MS and On-line LC/LC-MS/MS
- 2016
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Ingår i: Chromatographia. - : Springer Science and Business Media LLC. - 0009-5893 .- 1612-1112. ; 79:7-8, s. 383-393
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Tidskriftsartikel (refereegranskat)abstract
- We describe a method for the quantification of proteins in a biological matrix through digestion with pepsin. Pepsin is a gastric protease that efficiently cleaves proteins in an acidic environment. In this study, it has been used to generate peptides used for the quantification of physiologically relevant thioredoxin proteins in a lysate of Bacillus anthracis-the causative agent of anthrax. Carefully selected signature peptides for proteins that were digested with pepsin were immobilized on agarose gel. Filtered samples were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and by two-dimensional liquid chromatography tandem mass spectrometry (LC/LC-MS/MS) when additional selectivity was needed. Some important incubation parameters were adjusted to get the highest possible peptide yield. Escherichia coli was used as a surrogate matrix for the method development. The method was validated at a low nM range for selectivity, accuracy and precision. Validation showed that signature peptides were selective for the proteins, and that the method accuracy varied between 89 and 115 % with a precision of less than 12 %. The results from using pepsin in analyzing samples from Bacillus anthracis were similar to those previously obtained using western blot, and they validate pepsin as a suitable protease to generate signature peptides in a complex biological matrix as an alternative to trypsin.
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| 4. |
- Saleh, Aljona, 1983-
(författare)
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Analysis of drugs and proteins in biological matrices, using different types of sample preparations and mass spectrometry
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes bioanalysis of small and large molecules in biological matrices and includes screening of illegal drugs in urine with high resolution mass spectrometer, bioanalysis of MTH1 inhibitors in mice plasma and quantification of proteins in plasma and cell lysates.Screening of illegal drugs was based on high resolving power mass spectrometer (QTOF) and the results were compared to immunoassays. For the study, the nine most commonly abused drugs were selected for screening of a large number of authentic urine samples. Evaluation of the screening results showed that the QTOF generated a low rate of false positive and false negative results and can be used as an alternative or a complementary to immunoassays.In another study, a bioanalytical method for the two new anticancer targets TH588 and TH287 was developed and validated. The compounds inhibit the MTH1 protein that is required for cancer cell survival. To study the pharmacokinetic properties of the substances, a bioanalytical method was developed using a fast sample preparation followed by LC-MS/MS analysis. Validation showed that the method was linear, accurate and precise in the studied concentration range. Stability tests showed that the substances were stable in mice plasma and under different storage conditions. The study also addresses other important factors such as solubility, chromatography and fragmentation mechanisms.Two other studies focused on quantification of specific proteins in biological specimens; plasma and bacterial lysates. The matrices are rich in endogenous proteins making quantitative analysis of target proteins challenging. Therefore a new strategy is proposed that combines known procedures in a way it has not been used before. The methods are based on quantification with isotopically labelled peptides added after proteolytic digestion of the sample with immobilized thermolysin or pepsin. The sample digest was analysed on LC-MS/MS and LC/LC-MS/MS systems.
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| 5. |
- Saleh, Aljona, et al.
(författare)
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Development and validation of method for TH588 and TH287, potent MTH1 inhibitors and new anti-cancer agents, for pharmacokinetic studies in mice plasma
- 2015
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier BV. - 0731-7085 .- 1873-264X. ; 104, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- MTH1 is a protein that is required for cancer cell survival and is overexpressed in cancer cells. TH588 and TH287 are two new compounds that inhibit the MTH1 protein. The inhibitors were tested in pharmacokinetic studies on mice. A bioanalytical method was developed and validated for determination in mice plasma. The method was based on protein precipitation followed by LC-MS/MS analysis. The separation was performed on an Ascentis Express RP-Amide C-18 column. The mass spectrometer was operated in positive electrospray ionization mode and the analytes were determined with multiple reaction monitoring (MRM). Abundant monoisotopic fragments were used for quantification. Two additional fragments were used for conformational analysis. The recovery of the compounds in plasma varied between 61 and 91% and the matrix effects were low and ranged between -3% and +2%. The method showed to be selective, linear, accurate and precise, and applicable for preclinical pharmacokinetic studies of TH588 and TH287 in mouse plasma. Half-life (T-1/2) was <= 3.5 h and maximum concentration (C-max) ranged between 0.82 and 338 mu M for the different administration routes and compounds.
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| 6. |
- Saleh, Aljona, et al.
(författare)
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Digestion of Enolase and Carbonic Anhydrase as Model Proteins for Therapeutic Proteins in Blood Plasma with Immobilized Thermolysin and Quantification of Some of the Peptides by LC/LC-MS/MS
- 2014
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Ingår i: Chromatographia. - : Springer Science and Business Media LLC. - 0009-5893 .- 1612-1112. ; 77:1-2, s. 59-74
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for fast method development in the early drug discovery phase of therapeutic proteins. Thermolysin has not been used for quantification of proteins in blood plasma earlier. It is a thermostable protease which permits the use of high temperatures for fast hydrolysis of proteins. Model proteins were digested with immobilized thermolysin on agarose gel. Protein-specific peptides were selected for quantitation and quantified based on stable isotope dilution. Protein digests of blood plasma were cleaned and separated using an automated LC/LC-MS/MS system. Essential digestion parameters that influence thermolysin hydrolytic activity were optimized for high peptide yield. The validated methods were selective, linear, precise and accurate with a limit of detection of 2 nM for both proteins. The proposed strategy for method development could be valuable for quantification of proteins in blood plasma samples. The study underscores and discusses important features of the enzymatic digestion and chromatographic separation.
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| 7. |
- Saleh, Aljona, et al.
(författare)
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Evaluation of a direct high-capacity target screening approach for urine drug testing using liquid chromatography-time-of-flight mass spectrometry
- 2012
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Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; :909, s. 6-13
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Tidskriftsartikel (refereegranskat)abstract
- In this study a rapid liquid chromatography-time-of-flight mass spectrometry method was developed, validated and applied in order to evaluate the potential of this technique for routine urine drug testing. Approximately 800 authentic patient samples were analyzed for amphetamines (amphetamine and methamphetamine), opiates (morphine, morphine-3-glucuronide, morphine-6-glucuronide, codeine and codeine-6-glucuronide) and buprenorphines (buprenorphine and buprenorphine-glucuronide) using immunochemical screening assays and mass spectrometry confirmation methods for comparison. The chromatographic application utilized a rapid gradient with high flow and a reversed phase column with 1.8 mu m particles. Total analysis time was 4 min. The mass spectrometer operated with an electrospray interface in positive mode with a resolution power of >10,000 at m/z 956. The applied reporting limits were 100 ng/mL for amphetamines and opiates, and 5 ng/mL for buprenorphines, with lower limits of quantification were 2.8-41 ng/mL. Calibration curves showed a linear response with coefficients of correlation of 0.97-0.99. The intra- and interday imprecision in quantification at the reporting limits were <10% for all analytes but for buprenorphines <20%. Method validation data met performance criteria for a qualitative and quantitative method. The liquid chromatography-time-of-flight mass spectrometry method was found to be more selective than the immunochemical method by producing lower rates of false positives (0% for amphetamines and opiates; 3.2% for buprenorphines) and negatives (1.8% for amphetamines; 0.6% for opiates; 0% for buprenorphines). The overall agreement between the two screening methods was between 94.2 and 97.4%. Comparison of data with the confirmation (LC-MS) results for all individual 9 analytes showed that most deviating results were produced in samples with low levels of analytes. False negatives were mainly related to failure of detected peak to meet mass accuracy criteria (+/- 20 mDa). False positives was related to presence of interfering peaks meeting mass accuracy and retention time criteria and occurred mainly at low levels. It is concluded that liquid chromatography-time-of-flight mass spectrometry has potential both as a complement and as replacement of immunochemical screening assays.
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| 8. |
- Sroka-Markovic, Janina, et al.
(författare)
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Development of an HPLC Method for Determination of Related Impurities in Prilocaine Substance
- 2012
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Ingår i: Chromatographia. - : Springer Science and Business Media LLC. - 0009-5893 .- 1612-1112. ; 75:7-8, s. 329-336
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Tidskriftsartikel (refereegranskat)abstract
- Development of a reversed phase high performance liquid chromatographic method for determination of six related impurities in prilocaine substance is reported. The test of related impurities in European Pharmacopoeia (Ph. Eur.) cannot meet the demands with the chromatographic parameters given, therefore different types of chromatographic systems and eight columns have been evaluated in the present study. A new method with a Hypercarb column was developed and validated. This method fulfils the demands in the Ph. Eur., and the validation shows that the method is selective, reproducible, linear, accurate and robust with sufficient limits of detection (0.001-0.004% of 2.5 mg prilocaine mL(-1)) and quantification (0.002-0.009% of 2.5 mg prilocaine mL(-1)).
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