Glycosylation in Indolent, Significant and Aggressive Prostate Cancer by Automated High-Throughput N-Glycan Profiling

The diagnosis and treatment of prostate cancer (PCa) is a major health-care concern worldwide. This cancer can manifest itself in many distinct forms and the transition from clinically indolent PCa to the more invasive aggressive form remains poorly understood. It is now universally accepted that glycan expression patterns change with the cellular modifications that accompany the onset of tumorigenesis. The aim of this study was to investigate if differential glycosylation patterns could distinguish between indolent, significant, and aggressive PCa. Whole serum N-glycan profiling was carried out on 117 prostate cancer patients’ serum using our automated, high-throughput analysis platform for glycan-profiling which utilizes ultra-performance liquid chromatography (UPLC) to obtain high resolution separation of N-linked glycans released from the serum glycoproteins. We observed increases in hybrid, oligomannose, and biantennary digalactosylated monosialylated glycans (M5A1G1S1, M8, and A2G2S1), bisecting glycans (A2B, A2(6)BG1) and monoantennary glycans (A1), and decreases in triantennary trigalactosylated trisialylated glycans with and without core fucose (A3G3S3 and FA3G3S3) with PCa progression from indolent through significant and aggressive disease. These changes give us an insight into the disease pathogenesis and identify potential biomarkers for monitoring the PCa progression, however these need further confirmation studies.

Integrating biomarkers across omic platforms: an approach to improve stratification of patients with indolent and aggressive prostate cancer

Classifying indolent prostate cancer represents a significant clinical challenge. We investigated whether integrating data from different omic platforms could identify a biomarker panel with improved performance compared to individual platforms alone. DNA methylation, transcripts, protein and glycosylation biomarkers were assessed in a single cohort of patients treated by radical prostatectomy. Novel multiblock statistical data integration approaches were used to deal with missing data and modelled via stepwise multinomial logistic regression, or LASSO. After applying leave‐one‐out cross‐validation to each model, the probabilistic predictions of disease type for each individual panel were aggregated to improve prediction accuracy using all available information for a given patient. Through assessment of three performance parameters of area under the curve (AUC) values, calibration and decision curve analysis, the study identified an integrated biomarker panel which predicts disease type with a high level of accuracy, with Multi AUC value of 0.91 (0.89, 0.94) and Ordinal C‐Index (ORC) value of 0.94 (0.91, 0.96), which was significantly improved compared to the values for the clinical panel alone of 0.67 (0.62, 0.72) Multi AUC and 0.72 (0.67, 0.78) ORC. Biomarker integration across different omic platforms significantly improves prediction accuracy. We provide a novel multiplatform approach for the analysis, determination and performance assessment of novel panels which can be applied to other diseases. With further refinement and validation, this panel could form a tool to help inform appropriate treatment strategies impacting on patient outcome in early stage prostate cancer.

Detection of prostate specific antigen based on electrocatalytic platinum nanoparticles conjugated to a recombinant scFv antibody

Highly sensitive and label free detection of prostate specific antigen (PSA) still remains a challenge in prostate cancer diagnosis. In this paper, we propose a sensitive electrochemical immunosensor based on electrocatalytic platinum nanoparticles conjugated to a recombinant scFv antibody. Gold disc electrodes functionalised with a l-Cysteine (Cys) self-assembled monolayer (SAM) were used to covalently bind PSA specific monoclonal antibody (anti-PSA) using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide (EDC/NHS) chemistry. Immunosensing was completed using sandwich-type immunoreaction of the PSA-antigen (1-30 ng/mL) between anti-PSA immobilized on the l-Cys modified electrode using label free electrochemical impedance (EIS) technique. Furthermore, highly specific in-house generated scFv fragments as receptor proteins were utilised for one step site-directed immobilisation on the surface of platinum nanoparticles (PtNPs). To improve the sensitivity of the immunoassay, these scFV labelled electrocatalytic PtNPs were then used for covalent hybridisation to the PSA modified electrode and then applied in a hybridisation assay to determine the concentration of the PSA by measuring the faradaic current associated with reduction of peroxide in solution. Semi-log plots of the PSA concentration vs. faradaic current are linear from 1 to 30 ng/mL and pM concentrations can be detected without the need for molecular, e.g., PCR or NASBA, amplification.

Reconciling the structural attributes of avian antibodies

Antibodies are high value therapeutic, diagnostic, biotechnological, and research tools. Combinatorial approaches to antibody discovery have facilitated access to unique antibodies by surpassing the diversity limitations of the natural repertoire, exploitation of immune repertoires from multiple species, and tailoring selections to isolate antibodies with desirable biophysical attributes. The V-gene repertoire of the chicken does not utilize highly diverse sequence and structures, which is in stark contrast to the mechanism employed by humans, mice, and primates. Recent exploitation of the avian immune system has generated high quality, high affinity antibodies to a wide range of antigens for a number of therapeutic, diagnostic and biotechnological applications. Furthermore, extensive examination of the amino acid characteristics of the chicken repertoire has provided significant insight into mechanisms employed by the avian immune system. A paucity of avian antibody crystal structures has limited our understanding of the structural consequences of these uniquely chicken features. This paper presents the crystal structure of two chicken single chain fragment variable (scFv) antibodies generated from large libraries by phage display against important human antigen targets, which capture two unique CDRL1 canonical classes in the presence and absence of a non-canonical disulfide constrained CDRH3. These structures cast light on the unique structural features of chicken antibodies and contribute further to our collective understanding of the unique mechanisms of diversity and biochemical attributes that render the chicken repertoire of particular value for antibody generation.

Aberrant PSA glycosylation--a sweet predictor of prostate cancer

Prostate cancer--the most commonly diagnosed cancer in men worldwide--can have a substantial effect on quality of life, regardless of the route the cancer takes. The serum PSA assay is the current gold standard option for diagnosing prostate cancer. However, a growing body of evidence suggests that PSA screening for prostate cancer results in extensive overdiagnosis and overtreatment. It is increasingly evident that the potential harm from overdiagnosis (in terms of unnecessary biopsies) must be weighed against the benefit derived from the early detection and treatment of potentially fatal prostate cancers. Rapid screening methods have been used to analyse glycosylation patterns on glycoproteins in large cohorts of patients, enabling the identification of a new generation of disease biomarkers. Changes to the expression status of certain glycan structures are now widely thought to be common features of tumour progression. In light of this development, much research has focused on the potential role of altered PSA glycosylation patterns in discriminating between significant and insignificant prostate cancers, with the aim of developing a more reliable diagnostic tool than the current serum PSA test.