Nanoimmunoassay to Detect Responses in Head and Neck Cancer Feasibility in a Mouse Model

ObjectiveTo demonstrate the feasibility of detecting and quantifying extracellular signal-related kinase (ERK) phosphorylation status using nanoimmunoassay (NIA).Study DesignAnalyses using Cal27, SCC25, and OSC19 head and neck squamous carcinoma cell lines in vitro and in a murine xenograft model.Subjects and MethodsNIA and immunoblot were performed on whole-cell lysates, tumor lysates, and fine-needle aspirate biopsies to detect ERK phosphorylation states.ResultsUsing NIA, all 6 isoforms of ERK1/2, including nonphosphorylated, monophosphorylated, and diphosphorylated species, could be reliably detected, distinguished, and quantified in a single assay using a single antibody. In vitro treatment of Cal27 cells with the epidermal growth factor receptor inhibitor gefitinib abolished phospho-ERK detection by immunoblot but resulted in residual detectable species by NIA. Residual phospho-ERK in gefitinib-treated cells could be further reduced by the addition of the insulin-like growth factor 1 receptor inhibit...