N1,N12-diacetylspermine oxidase from Debaryomyces hansenii T-42: purification, characterization, molecular cloning and gene expression

Identification of urinary biomarkers of colorectal cancer: Towards the development of a colorectal screening test in limited resource settings

BACKGROUND

African colorectal cancer (CRC) rates are rising rapidly. A low-cost CRC screening approach is needed to identify CRC from non-CRC patients who should be sent for colonoscopy (a scarcity in Africa).

OBJECTIVE

To identify urinary metabolite biomarkers that, combined with easy-to-measure clinical variables, would identify patients that should be further screened for CRC by colonoscopy. Ideal metabolites would be water-soluble and easily translated into a sensitive, low-cost point-of-care (POC) test.

METHODS

Liquid-chromatography mass spectrometry (LC-MS/MS) was used to quantify 142 metabolites in spot urine samples from 514 Nigerian CRC patients and healthy controls. Metabolite concentration data and clinical characteristics were used to determine optimal sets of biomarkers for identifying CRC from non-CRC subjects.

RESULTS

Our statistical analysis identified N1, N12-diacetylspermine, hippurate, p-hydroxyhippurate, and glutamate as the best metabolites to discriminate CRC patients via POC screening. Logistic regression modeling using these metabolites plus clinical data achieved an area under the receiver-operator characteristic (AUCs) curves of 89.2% for the discovery set, and 89.7% for a separate validation set.

CONCLUSIONS

Effective urinary biomarkers for CRC screening do exist. These results could be transferred into a simple, POC urinary test for screening CRC patients in Africa.

Rapid and sensitive determination of diacetylpolyamines in human fingernail by ultraperformance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

A rapid and sensitive ultraperformance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method has been developed and validated for quantitatively determining diacetylpolyamines in the human fingernail. N(1),N(8)-diacetylspermidine (DiAct-Spd), N(1),N(12)- diacetylspermine (DiAct-Spm) and 1,6-diaminohexane (DAH) the [internal standard (IS)] were extracted from human fingernail samples by MeOH: 5 M HCl solution, followed by 4-(N,N-dimethylaminosulfonyl)-7-fluoro- 2,1,3-benzoxadiazole (DBD-F) derivatization, and then separated on an ACQUITY BEH C18 column with a gradient elution of acetonitrile and water containing 0.1% formic acid. The derivatives of the diacetylpolyamines were fully separated within a short run time (3.0 min). The triple quadrupole mass spectrometric detection was performed in the multiple reactions monitoring (MRM) mode by the UPLC-ESI- MS/MS system in the positive ionization mode. MRM using the fragmentation transitions of m/z 455.20→ 100.07, 737.25 → 100.07 and 567.10 → 479.07 in the positive ESI mode was performed to quantify DiAct-Spd, DiAct-Spm and IS, respectively. The calibration curve is between 0.04 ng mL(-1) for DiAct-Spd and DiAct-Spm. The detection limits (signal to noise ratio of five) were 5-10 pg mL(-1). A good linearity was achieved from the calibration curves (r(2) >0.9999), and the intra-day and inter-day assay precisions were less than 7.06%. Furthermore, the recoveries (%) of the diacetylpolyamines spiked in the human fingernails were 79.18-97.11. The present method proved that the high sensitivity is characterized by the specificity and feasibility of the sample analysis. Consequently, the proposed method was used to analyze human fingernail samples from 15 lung- cancer patients and 22 healthy volunteers. Diacetylpolyamines were detected from the fingernails of the lung- cancer patients for the first time. The concentration of DiAct-Spd in the lung-cancer patient group tended to be higher than those in the healthy volunteers.

Identification and determination of urinary acetylpolyamines in cancer patients by electrospray ionization and time-of-flight mass spectrometry

A method for the quantification of acetylpolyamines, N(1),N(12)-diacetylspermine (DiAcSpm), monoacetylspermidine (AcSpd), and N(1),N(8)-diacetylspermidine (DiAcSpd), identifying each compound simultaneously, was developed with the goal of evaluating these acetylpolyamines as potential biomarkers of cancer. The method consists of prepurification of acetylpolyamines in urine with commercially available cartridges and derivatization with heptafluorobutyric (HFB) anhydride. HFB derivatives of acetylpolyamines were determined simultaneously using (15)N-labeled acetylpolyamines as internal standards by electrospray ionization and time-of-flight mass spectrometry (ESI-TOF MS). After the method was validated, the urinary acetylpolyamines of 38 cancer patients were quantified with this method. A comparison of the concentrations of DiAcSpm with those measured by a colloidal gold aggregation method demonstrated a correlation coefficient of 0.996, showing that the two methods were equally satisfactory. Analysis of the correlation between DiAcSpd or AcSpd and DiAcSpm, performed for the first time, indicated the usefulness of DiAcSpm as a urinary biomarker of cancer. During the course of this work, two simple methods for the preparation of alpha,omega-diacetylpolyamines were developed, and a possibility to separate and determine the concentrations of the two isomers, N(1)-acetylspermidine and N(8)-acetylspermidine in AcSpd, was shown by tandem mass spectrometry (MS/MS).