Targeted determination of the early stage SCLC specific biomarker pro-gastrin-releasing peptide (ProGRP) at clinical concentration levels in human serum using LC-MS

Correlation analysis of serum cystatin C, uric acid and lactate dehydrogenase levels before chemotherapy on the prognosis of small-cell lung cancer

Related studies have reported that cystatin C (Cys C), uric acid (UA) and lactate dehydrogenase (LDH) affect tumor growth and invasion; however, the correlation between them and the prognosis of patients with small-cell lung cancer (SCLC) remains unclear. The present study aimed to investigate the effects of serum Cys C, UA and LDH concentrations on the prognosis of patients with SCLC prior to initial treatment, in order to identify potential targets for determining the clinical outcome of patients with SCLC. A total of 205 patients with SCLC were enrolled in the present study, and the clinical and laboratory data were obtained from the medical records. The receiver operating characteristic curve was used to determine the optimal cut-off values of Cys C, UA and LDH, while the Kaplan-Meier method was used for survival analysis. The Cox proportional hazard model was used for univariate and multivariate analyses to identify independent prognostic factors. The optimal cut-off values for Cys C, UA and LDH were 0.775 mg/l, 296.45 µmol/l and 198.5 U/l, respectively. The survival curves demonstrated that progression-free survival (PFS) and overall survival (OS) time were shorter in patients with high levels of Cys C, UA and LDH prior to chemotherapy. Univariate and multivariate analyses indicated that LDH concentration prior to chemotherapy may be an independent prognostic factor for both PFS and OS in patients with SCLC, while Cys C concentration may be an independent prognostic factor for PFS in patients with SCLC. The concentrations of Cys C, UA and LDH prior to chemotherapy were associated with prognosis of patients with SCLC. PFS and OS time were shorter, and the prognosis was poor in patients with elevated serum levels of Cys C, UA and LDH. Taken together, the results of the present study suggest that high concentrations of LDH and Cys C prior to chemotherapy may indicate rapid disease progression, thus it is important to focus on the progression and recurrence of the disease. High LDH concentration may also indicate a shorter survival time.

Magnetic Synthetic Receptors for Selective Clean-Up in Protein Biomarker Quantification

Biomarker analysis by mass spectrometry (MS) can allow for the rapid quantification of low abundant biomarkers. However, the complexity of human serum is a limiting factor in MS-based bioanalysis; therefore, novel biomarker enrichment strategies are of interest, particularly if the enrichment strategies are of low cost and are easy to use. One such strategy involves the use of molecularly imprinted polymers (MIPs) as synthetic receptors for biomarker enrichment. In the present study, a magnetic solid-phase extraction (mSPE) platform, based on magnetic MIP (mMIP) sorbents, is disclosed, for use in the MS-based quantification of proteins by the bottom-up approach. Progastrin releasing peptide (ProGRP), a low abundant and clinically sensitive biomarker for small cell lung cancer (SCLC), was used to exemplify the mSPE platform. Four different mMIPs were synthesized, and an mSPE method was developed and optimized for the extraction of low concentrations of tryptic peptides from human serum. The mSPE method enabled the selective extraction of the ProGRP signature peptide, the nonapeptide NLLGLIEAK, prior to quantification of the target via LC-MS/MS. Overall, the mSPE method demonstrated its potential as a low cost, rapid, and straightforward sample preparation method, with demonstrably strong binding, acceptable recoveries, and good compatibility with MS. mMIPs are a potential low-cost alternative to current clinical methods for biomarker analysis.

Automated Protein Biomarker Analysis: on-line extraction of clinical samples by Molecularly Imprinted Polymers

Robust biomarker quantification is essential for the accurate diagnosis of diseases and is of great value in cancer management. In this paper, an innovative diagnostic platform is presented which provides automated molecularly imprinted solid-phase extraction (MISPE) followed by liquid chromatography-mass spectrometry (LC-MS) for biomarker determination using ProGastrin Releasing Peptide (ProGRP), a highly sensitive biomarker for Small Cell Lung Cancer, as a model. Molecularly imprinted polymer microspheres were synthesized by precipitation polymerization and analytical optimization of the most promising material led to the development of an automated quantification method for ProGRP. The method enabled analysis of patient serum samples with elevated ProGRP levels. Particularly low sample volumes were permitted using the automated extraction within a method which was time-efficient, thereby demonstrating the potential of such a strategy in a clinical setting.

Digging deeper into the field of the small cell lung cancer tumor marker ProGRP: a method for differentiation of its isoforms

In this paper, we have used a newly developed immunocapture and LC-MS method to demonstrate for the first time the presence of protein isoforms 1 and 3 of the small cell lung cancer (SCLC) marker progastrin-releasing peptide (ProGRP) in sera. In addition, the method allows for indirect determination of the relative presence of the other known isoform of ProGRP, also known as ProGRP isoform 2. This new method is able to determine total ProGRP as a marker in sera at clinically relevant levels and to differentiate between isoforms at the low-pM level through combining selective sample preparation by immunoextraction, tryptic digestion, and separation followed by detection with LC-SRM-MS of the signature peptides, NLLGLIEAK (total ProGRP), LSAPGSQR (ProGRP isoform 1), and DLVDSLLQVLNVK (ProGRP isoform 3), with accuracies ≤ 25% for lower limit of quantification (LLOQ) and precisions ≤ 33%. By analyzing serum samples from four patients diagnosed with SCLC using the here described new and fully validated method, the ability is shown to both determine total ProGRP concentration and to differentiate between ProGRP isoforms 1 and 3 in one single run. Quantification of various ProGRP isoforms in one single run may be helpful for further understanding of the underlying biochemical processes in SCLC and differentiation of small cell lung cancer.

Study on biodistribution and radioimmunoimaging of (131)iodine-labeled monoclonal antibody D-D3 against progastrin-releasing peptide31-98 in tumor-bearing mouse

This study was aimed at investigating the biodistribution and radioimmunoimaging of (131)I-D-D3 in nude mice bearing different types of tumor xenografts. Radioiodination of the D-D3 antibody was performed with the chloramine-T method. The radiochemical purity was determined through thin-layer chromotography. (131)I-D-D3 was injected into healthy Kunming mice via a tail vein, and the %ID/g for various organs was obtained. Similarly, the %ID/g and tumor/nontumor tissue ratio of (131)I-D-D3 in nude mice bearing small cell lung cancer (SCLC) xenografts were obtained. Planar images of (131)I-D-D3 in tumor-bearing nude mice were acquired at different times after injection. The (131)I-D-D3 labeling rate was 86.56%  ± 3.8%. The radiochemical purity of (131)I-D-D3 was 99.27%  ± 0.6%. After 12 hours of incubation in 37°C water bath, the radiochemical purity was 97.64%  ±  0.5% and remained at 88.38% ± 0.4% after 48 hours. After being mixed with healthy human serum for 24 hours, the radiochemical purity was more than 64%. The metabolism of (131)I-D-D3 in healthy Kunming mice was consistent with a two-compartment model with first-order absorption; T(1/2α) and T(1/2β) were 0.25 and 37.89 hours, respectively. The %ID/g of (131)I-D-D3 in SCLC xenografts was much higher than those of other tissues at 48 hours after injection, and the tumor/nontumor tissue ratio also gradually increased with time. After 24 hours of injection, planar imaging was obtained, which clearly showed a contrasting tumor on the right armpit of nude mice bearing SCLC with high concentrations of radioactivity. Also, nude mice bearing gastric cancer showed similar results as that of the SCLC with a lower radioactivity level. No observable accumulation was observed in nude mice bearing pancreatic cancer or lung adenocarcinoma. The labeling rate and radiochemical purity of (131)I-D-D3 were high and stable. (131)I-D-D3 selectively accumulated at tumors that highly expressed progastrin-releasing peptide; therefore, it is a promising radioimmunoimaging reagent for SCLC.

Restricted-access media supports for direct high-throughput analysis of biological fluid samples: review of recent applications

This review presents an update on the use of restricted-access materials (RAMs) for direct injection of biological samples. The fundamental improvements in the preparation of tailored RAMs and the diversity of applications with these phases are presented. Insights into diminishing the matrix effect by the use of RAM supports in methods by LC–MS and into the low number of methods for enantiomeric separations by direct injections of biological samples are addressed. The diversity of systems that incorporate RAMs for selective sample clean-up or fractionation in proteome and peptidome analysis is also covered.