Seven-signal proteomic signature for detection of operable pancreatic ductal adenocarcinoma and their discrimination from autoimmune pancreatitis

Multiparametric plasma EV profiling facilitates diagnosis of pancreatic malignancy

Pancreatic ductal adenocarcinoma (PDAC) is usually detected late in the disease process. Clinical workup through imaging and tissue biopsies is often complex and expensive due to a paucity of reliable biomarkers. We used an advanced multiplexed plasmonic assay to analyze circulating tumor-derived extracellular vesicles (tEVs) in more than 100 clinical populations. Using EV-based protein marker profiling, we identified a signature of five markers (PDACEV signature) for PDAC detection. In our prospective cohort, the accuracy for the PDACEV signature was 84% [95% confidence interval (CI), 69 to 93%] but only 63 to 72% for single-marker screening. One of the best markers, GPC1 alone, had a sensitivity of 82% (CI, 60 to 95%) and a specificity of 52% (CI, 30 to 74%), whereas the PDACEV signature showed a sensitivity of 86% (CI, 65 to 97%) and a specificity of 81% (CI, 58 to 95%). The PDACEV signature of tEVs offered higher sensitivity, specificity, and accuracy than the existing serum marker (CA 19-9) or single-tEV marker analyses. This approach should improve the diagnosis of pancreatic cancer.

Potential prognostic significance of a new proteomic profile in patients with advanced pancreatic adenocarcinoma

OBJECTIVES

Seven-signal proteomic approach has recently been developed as a new proteomic profile measured by matrix-assisted laser desorption/ionization mass spectrometry. The aim of this study was to evaluate prognostic significance of this proteomic value in patients with pancreatic adenocarcinoma.

METHODS

Blood samples from the patients with pancreatic adenocarcinoma were prospectively collected before treatments including surgical resection and systemic chemotherapies. The seven-signal proteomic profiles of the samples were measured, and the prognostic significance of the proteomic value was evaluated through comparison with other existing prognostic markers.

RESULTS

Cut-off value of the proteomic profiles at 52 stratified overall prognosis of the patients (6.5 months vs. 10.9 months with the values ≥52 vs. <52, p = 0.020). In subgroup analyses of inoperable cases with carcinoembryonic antigen level of <5 ng/ml or performance status of 0-1, the proteomic value at 52 stratified their prognosis (p = 0.002 and p = 0.006, respectively).

CONCLUSIONS

The new seven-signal proteomics showed useful prognostic significance for patients with pancreatic adenocarcinoma. Further studies with a large sample size would be required to evaluate whether this proteomic approach possibly complements the existing parameters, such as carcinoembryonic antigen and performance status.

An economical high-throughput protocol for multidimensional fractionation of proteins

A sequential protocol of multidimensional fractionation was optimised to enable the comparative profiling of fractions of proteomes from cultured human cells. Differential detergent fractionation was employed as a first step to obtain fractions enriched for cytosolic, membrane/organelle, nuclear, and cytoskeletal proteins. Following buffer exchange using gel-permeation chromatography, cytosolic proteins were further fractionated by 2-dimensional chromatography employing anion-exchange followed by reversed-phase steps. Chromatographic fractions were shown to be readily compatible with 1- and 2-dimensional gel electrophoresis or with direct analysis by mass spectrometry using linear-MALDI-TOF-MS. Precision of extraction was confirmed by reproducible SDS-PAGE profiles, MALDI-TOF-MS spectra, and quantitation of trypsinolytic peptides using LC-MS/MS (MRM) analyses. Solid phases were immobilised in disposable cartridges and mobile-phase flow was achieved using a combination of centrifugation and vacuum pumping. These approaches yielded parallel sample handling which was limited only by the capacities of the employed devices and which enabled both high-throughput and experimentally precise procedures, as demonstrated by the processing of experimental replicates. Protocols were employed at 10 mg scale of extracted cell protein, but these approaches would be directly applicable to both smaller and larger quantities merely by adjusting the employed solid- and mobile-phase volumes. Additional potential applications of the fractionation protocol are briefly described.