Flow-Based CL-SMIA for the Quantification of Protein Biomarkers from Nasal Secretions in Comparison with Sandwich ELISA.

Protein biomarkers in nasal secretions can be used as a measure to differentiate between allergies, airway diseases and infections for non-invasive diagnostics. The point-of-care quantification of biomarker levels using flow-based microarray facilitates precise and rapid diagnosis and displays the potential for targeted and effective treatment. For the first time, we developed a flow-based chemiluminescence sandwich microarray immunoassay (CL-SMIA) for the quantification of nasal interferon-beta (IFN-ß) on the Microarray Chip Reader-Research (MCR-R). Polycarbonate foils are used as a cost-effective surface for immobilizing capture antibodies. By using a commercially available set of anti-human IFN-ß antibodies, the CL-SMIA can be compared directly to an enzyme-linked immunosorbent assay (ELISA) performed in microtiter plates concerning the bioanalytical performance and economic issues. Pre-incubation of the sample with detection antibodies facilitates the lower consumption of detection antibodies, as this allows for a longer interaction time between the antibody and the biomarker. The direct injection of pre-incubated samples into the microarray chips eliminates the adsorption of proteins in the tubing as well as the contamination of the tubing and valves of the MCR-R with clinical samples. The small flow cell allows for a low sample volume of 50 µL. The limit of detection of 4.53 pg mL-1 was slightly increased compared to a sandwich ELISA performed on microtiter plates which were 1.60 pg mL-1. The possibility to perform the CL-SMIA in a multiplexed mode makes it a promising assay for the rapid and cost-effective non-invasive detection of biomarkers in nasal secretions.

G2-checkpoint targeting and radiosensitization of HPV/p16-positive HNSCC cells through the inhibition of Chk1 and Wee1.

BACKGROUND AND PURPOSE: HPV-positive HNSCC cells are characterized by radiosensitivity, inefficient DNA double-strand break repair and a profound and prolonged arrest in G2. Here we explored the effect of clinically relevant inhibitors of Chk1 and Wee1 to inhibit the radiation-induced G2-arrest in order to achieve further radiosensitization. MATERIAL AND METHODS: Assessment of Chk1 activity by Western blot; assessment of cell cycle distribution by propidium iodide staining and flow cytometry; assessment of cell survival by colony formation assay. HPV+ HNSCC cell lines: UD-SCC-2, UM-SCC-47 and UPCI-SCC-154; Chk1 inhibitors: LY2603618, MK8776; Wee1 inhibitor: AZD1775. RESULTS: Specific Chk1 inhibitors efficiently abrogated the radiation-induced G2-arrest and caused radiosensitization. Wee-inhibition by AZD1775 resulted in the activation of Chk1. This feedback mechanism is likely to counteract some of the effects of Wee1 inhibition but could be antagonized through the combined inhibition of both kinases. Combined inhibition was effective using profoundly reduced concentrations of both inhibitors and resulted in more efficient radiosensitization of the HPV-positive cell lines compared to p53 proficient normal human fibroblasts. CONCLUSIONS: Specific Chk1 inhibitors as well as the combined inhibition of Chk1 and Wee1 radiosensitize HPV-positive HNSCC cells.