A robust strategy for proteomic identification of biomarkers of invasive phenotype complexed with extracellular heat shock proteins.

As an extension of their orchestration of intracellular pathways, secretion of extracellular heat shock proteins (HSPs) is an emerging paradigm of homeostasis imperative to multicellular organization. Extracellular HSP is axiomatic to the survival of cells during tumorigenesis; proportional representation of specific HSP family members is indicative of invasive potential and prognosis. Further significance has been added by the knowledge that all cancer-derived exosomes have surface-exposed HSPs that reflect the membrane topology of cells that secrete them. Extracellular HSPs are also characteristic of chronic inflammation and sepsis. Accordingly, interrogation of extracellular HSPs secreted from cell culture models may represent a facile means of identifying translational biomarker signatures for targeting in situ. In the current study, we evaluated a simple peptide-based multivalent HSP affinity approach using the Vn96 peptide for low speed pelleting of HSP complexes from bioreactor cultures of cell lines with varying invasive phenotype in xenotransplant models: U87 (glioblastoma multiforme; invasive); HELA (choriocarcinoma; minimally invasive); HEK293T (virally transformed immortalized; embryonic). Proteomic profiling by bottom-up mass spectrometry revealed a comprehensive range of candidate biomarkers including primary HSP ligands. HSP complexes were associated with additional chaperones of prognostic significance such as protein disulfide isomerases, as well as pleiotropic metabolic enzymes, established as proportionally reflective of invasive phenotype. Biomarkers of inflammatory and mechanotransductive phenotype were restricted to the most invasive cell model U87, including chitinase CHI3L1, lamin C, amyloid derivatives, and histone isoforms.

Measurement of prostate-specific antigen by use of a novel blood collection and analytical system.

BACKGROUND: Prostate-specific antigen (PSA) is widely used in the detection and monitoring of prostate cancer. We developed a system for the self-collection and transport of capillary whole blood for PSA analysis, with the goal of reducing phlebotomy visits and, thus, increasing the access and utilization of PSA in prostate cancer screening and monitoring. METHODS: The blood collection device [BIOSAFE Blood Transport System (BTS] collects 70 microL of blood through a heparin-coated material into 200 microL of stabilizing solution. The diluted whole blood is used for measurement of PSA by a modified version of the Hybritech Tandem-MP PSA Assay. Results were compared for matched samples of professionally and self-collected BTS blood and for matched BTS samples sera from blood collected by venipuncture. Imprecision for the whole-blood PSA measurement was estimated from analysis of whole-blood controls in duplicate, twice per day, over 20 days. RESULTS: BTS samples (n = 140) collected by a qualified healthcare professional compared with serum samples yielded the regression equation: y =1.02x + 0.04 (S(yx) = 0.35; r = 0.99). Comparison of the results for samples (n = 128) collected by the patient without professional assistance with serum samples yielded: y = 1.08x + 0.02 (S(yx) = 0.31; r = 0.99). The between-run CVs at 0.069, 0.53, 2.9, and 10.7 microg/L were 21%, 6.0%, 3.5%, and 3.8%, respectively. PSA was stable in BTS samples stored for 21 days at 18-24 degrees C and for 7 days at 37 degrees C. CONCLUSION: The BIOSAFE BTS system allows accurate and convenient measurement of circulating PSA by a precise method for diluted whole blood.