Sex-specific expression of apolipoprotein levels following replenishment of vitamin D

Numerous studies have been done to establish the relationship between vitamin D and lipids, yet a definitive causal link is not found. This interventional study aims to evaluate and compare levels of apolipoproteins among vitamin D deficient subjects at baseline and after they achieved full vitamin D status correction.120 Saudi adults with vitamin D deficiency [25(OH)D < 50nmol/l] were recruited and given 50,000IU cholecalciferol weekly for first 2 months, then twice a month for next 2 months, followed by daily 1000IU until month 6. Blood samples were taken at baseline and after 6 months. Serum 25(OH)D, lipid profile and apolipoproteins (A1, A2, B, C1, C2, C3, E and H) were analyzed using commercially available kits. Overall, serum 25(OH)D increased significantly(63.3 ± 16.5nmol/l at end of study vs. 32.5 ± 10.8 at baseline; p < 0.0001). In parallel, a significant increase in apolipoproteins C1, C2, C3 and E (all p-values < 0.01) and a significant decrease in apolipoprotein B (p = 0.02) was observed. Following, stratification according to sex, apolipoproteins C2 and C3 significantly increased only in males (p-values < 0.01) while apolipoprotein C1 significantly increased only in females (p < 0.01). In addition, apolipoprotein B significantly decreased only in females (p = 0.002). These results suggests role of vitamin D in modulation of circulating levels of lipoproteins. The sexual dimorphism observed in circulating levels of measured apolipoproteins following vitamin D correction may explain, in part, known sexual disparity in the events of cardiometabolic health.

IGF and IGFBP as an index for discrimination between vitamin D supplementation responders and nonresponders in overweight Saudi subjects

Vitamin D deficiency is common in the Kingdom of Saudi Arabia (KSA). Therefore, it is significant to recognize which biochemical markers modulate serum 25 hydroxyvitamin D (25(OH)D) in response to vitamin D supplementation in such a population. Our aim was to study the correlation of insulin-like growth factor (IGF) and insulin growth factor binding protein (IGFBP) with serum 25(OH)D in response to vitamin D supplementation in a Saudi population. A total of 199 (89 males/110 females) vitamin D deficient subjects (25(OH)D level <50 nmol/L), aged 40.4 ± 11.4 years, were given vitamin D supplements (50,000 IU/mL every week) for the first 2 months, then twice a month for 2 months, followed by daily 1000 IU in the last 2 months. Fasting blood samples were taken at baseline and 6 months after the final dose of vitamin D. Serum 25(OH)D, IGF-1 and IGF-2, and IGFBPs 2-5 were measured. Vitamin D response was computed for all subjects as the difference in levels of serum 25(OH)D concentration at the end of 6 months compared to baseline. After intervention, serum 25(OH)D concentration significantly increased from 35.6 nmol/L (26.6-43.5) to 61.8 nmol/L (54.8-73.3) in responder subjects (P < .01) and from 35.1 nmol/L (21.2-58.2) to 38.3 nmol/L (25.5-48.3) in nonresponders (P = .13). Subjects with lower baseline serum IGF-II, IGFBP-2, and IGF-1/IGFBP-3 ratio are more sensitive to acute vitamin D status changes. IGF1 and IGF-1/IGFBP-3 ratio significantly increased in all subjects after 6 months (P = .01). Changes in 25(OH)D was significantly associated with changes in IGFBP-2 and IGF-1/IGFBP-3 ratio in responders only. This study proposes that changes in circulating IGF-I and IGFBP-3 are modulated by vitamin D supplementation and can be taken into consideration in investigations involving vitamin D correction. Moreover, increase in serum 25(OH)D and IGF-I/IGFBP-3 molar ratio are more sensitive markers for the response to vitamin D supplementation in Saudi population.

Proteomics Profiling of CLL Versus Healthy B-cells Identifies Putative Therapeutic Targets and a Subtype-independent Signature of Spliceosome Dysregulation

Chronic lymphocytic leukemia (CLL) is a heterogeneous B-cell cancer exhibiting a wide spectrum of disease courses and treatment responses. Molecular characterization of RNA and DNA from CLL cases has led to the identification of important driver mutations and disease subtypes, but the precise mechanisms of disease progression remain elusive. To further our understanding of CLL biology we performed isobaric labeling and mass spectrometry proteomics on 14 CLL samples, comparing them with B-cells from healthy donors (HDB). Of 8694 identified proteins, ∼6000 were relatively quantitated between all samples (q<0.01). A clear CLL signature, independent of subtype, of 544 significantly overexpressed proteins relative to HDB was identified, highlighting established hallmarks of CLL (e.g. CD5, BCL2, ROR1 and CD23 overexpression). Previously unrecognized surface markers demonstrated overexpression (e.g. CKAP4, PIGR, TMCC3 and CD75) and three of these (LAX1, CLEC17A and ATP2B4) were implicated in B-cell receptor signaling, which plays an important role in CLL pathogenesis. Several other proteins (e.g. Wee1, HMOX1/2, HDAC7 and INPP5F) were identified with significant overexpression that also represent potential targets. Western blotting confirmed overexpression of a selection of these proteins in an independent cohort. mRNA processing machinery were broadly upregulated across the CLL samples. Spliceosome components demonstrated consistent overexpression (p = 1.3 × 10-21) suggesting dysregulation in CLL, independent of SF3B1 mutations. This study highlights the potential of proteomics in the identification of putative CLL therapeutic targets and reveals a subtype-independent protein expression signature in CLL.

Detection of candidate biomarkers of prostate cancer progression in serum: a depletion-free 3D LC/MS quantitative proteomics pilot study

BACKGROUND

Prostate cancer (PCa) is the most common male cancer in the United Kingdom and we aimed to identify clinically relevant biomarkers corresponding to stage progression of the disease.

METHODS

We used enhanced proteomic profiling of PCa progression using iTRAQ 3D LC mass spectrometry on high-quality serum samples to identify biomarkers of PCa.

RESULTS

We identified >1000 proteins. Following specific inclusion/exclusion criteria we targeted seven proteins of which two were validated by ELISA and six potentially interacted forming an 'interactome' with only a single protein linking each marker. This network also includes accepted cancer markers, such as TNF, STAT3, NF-κB and IL6.

CONCLUSIONS

Our linked and interrelated biomarker network highlights the potential utility of six of our seven markers as a panel for diagnosing PCa and, critically, in determining the stage of the disease. Our validation analysis of the MS-identified proteins found that SAA alongside KLK3 may improve categorisation of PCa than by KLK3 alone, and that TSR1, although not significant in this model, might also be a clinically relevant biomarker.

Systems proteomic analysis reveals that clusterin and tissue inhibitor of metalloproteinases 3 increase in leptomeningeal arteries affected by cerebral amyloid angiopathy

Aims

Amyloid beta (Aβ) accumulation in the walls of leptomeningeal arteries as cerebral amyloid angiopathy (CAA) is a major feature of Alzheimer's disease. In this study, we used global quantitative proteomic analysis to examine the hypothesis that the leptomeningeal arteries derived from patients with CAA have a distinct endophenotypic profile compared to those from young and elderly controls.

Methods

Freshly dissected leptomeningeal arteries from the Newcastle Brain Tissue Resource and Edinburgh Sudden Death Brain Bank from seven elderly (82.9 ± 7.5 years) females with severe capillary and arterial CAA, as well as seven elderly (88.3 ± 8.6 years) and five young (45.4 ± 3.9 years) females without CAA were used in this study. Arteries from four patients with CAA, two young and two elderly controls were individually analysed using quantitative proteomics. Key proteomic findings were then validated using immunohistochemistry.

Results

Bioinformatics interpretation of the results showed a significant enrichment of the immune response/classical complement and extracellular matrix remodelling pathways (P < 0.05) in arteries affected by CAA vs. those from young and elderly controls. Clusterin (apolipoprotein J) and tissue inhibitor of metalloproteinases‐3 (TIMP3), validated using immunohistochemistry, were shown to co‐localize with Aβ and to be up‐regulated in leptomeningeal arteries from CAA patients compared to young and elderly controls.

Conclusions

Global proteomic profiling of brain leptomeningeal arteries revealed that clusterin and TIMP3 increase in leptomeningeal arteries affected by CAA. We propose that clusterin and TIMP3 could facilitate perivascular clearance and may serve as novel candidate therapeutic targets for CAA.

Identification of markers of prostate cancer progression using candidate gene expression

BACKGROUND

Metastatic prostate cancer (PCa) has no curative treatment options. Some forms of PCa are indolent and slow growing, while others metastasise quickly and may prove fatal within a very short time. The basis of this variable prognosis is poorly understood, despite considerable research. The aim of this study was to identify markers associated with the progression of PCa.

METHODS

Artificial neuronal network analysis combined with data from literature and previous work produced a panel of putative PCa progression markers, which were used in a transcriptomic analysis of 29 radical prostatectomy samples and correlated with clinical outcome.

RESULTS

Statistical analysis yielded seven putative markers of PCa progression, ANPEP, ABL1, PSCA, EFNA1, HSPB1, INMT and TRIP13. Two data transformation methods were utilised with only markers that were significant in both selected for further analysis. ANPEP and EFNA1 were significantly correlated with Gleason score. Models of progression co-utilising markers ANPEP and ABL1 or ANPEP and PSCA had the ability to correctly predict indolent or aggressive disease, based on Gleason score, in 89.7% and 86.2% of cases, respectively. Another model of TRIP13 expression in combination with preoperative PSA level and Gleason score was able to correctly predict recurrence in 85.7% of cases.

CONCLUSION

This proof of principle study demonstrates a novel association of carcinogenic and tumourigenic gene expression with PCa stage and prognosis.

Determination of folates in human plasma using hydrophilic interaction chromatography-tandem mass spectrometry

Folic acid is an essential nutrient, and folate deficiency is associated with a variety of disorders including neural tube defects (during pregnancy) and heart disease. A fast, sensitive, and robust HPLC-tandem mass spectrometry (LC-MS-MS) method was developed for the quantification of free folic acid, tetrahydrofolate, 5'-methyltetrahydrofolate, and 5'-formyltetrahydrofolate in human plasma. Sample preparation required only acetonitrile precipitation of proteins followed by filtration instead of solid-phase extraction or solvent-solvent extraction as in other methods. The rapid and streamlined sample handling procedure minimized degradation of the highly unstable folate species. Hydrophilic interaction chromatography was used for additional sample cleanup on-line, and baseline separation and detection of all four folate species was achieved in less than 30 min. The folate species were detected using negative ion electrospray-tandem mass spectrometry with multiple reaction monitoring of the diagnostic fragment ions of each deprotonated molecule. The predominately organic (hydrophobic) solvent system combined with the microbore flow rate (50 microL/min) used for the chromatography resulted in enhanced electrospray signal response compared to reversed-phase HPLC using a wider bore column. The recovery of all folate species (from spiked plasma) was >97% over a concentration range from 300 pg/L to 12 mg/L with intraday precision (RSD, n = 5) of 3.7-6.5%. Stability studies were carried out for spiked samples in order to define storage and handling conditions. The folic acid limit of quantification (LOQ) in human plasma was 80 pmol/L +/- 10%, and the limit of detection (LOD) was 37.5 pmol/L. The LOQ and LOD for tetrahydrofolate, 5'-methyltetrahydrofolate, and 5'-formyltetrahydrofolate were 1250, 400, and 360 pmol/L of plasma and 425, 165, and 140 pmol/L of plasma, respectively.