Detection of PI3K inhibition in human neuroblastoma using multiplex luminex bead immunoassay: a targeted approach for pathway analysis.

Neuroblastoma (NB) is a common solid tumor in children. Outcomes for advanced stage NB have not improved, at least in part because of multimodality therapy resistance. Better comprehension of novel molecular targets will likely lead to improved therapies with specific cytotoxic agents. For instance, the role of deregulated IGF-1R/AKT/PI3K/mTOR (PI3K) pathway activity has attracted much attention across several tumors, including NB. Thus, modulating this pathway via anti-PI3K drugs has taken center stage in many cancer clinical trials. However, varied clinical effects have hampered the precise application of these agents. Tumor PI3K pathway profiling may reveal a method to enhance the efficacy of these inhibitors. To this end, solid-phase antibody-based array platforms have emerged as a direct, rapid means of profiling intracellular signaling pathways. We tested the efficacy of four PI3K inhibitors against a panel of human NB cell lines using Luminex xMAP bead array technology to establish PI3K phosphoprotein profiles. We demonstrate the utility of the xMAP approach in following intracellular signaling signatures specific for PI3K targeted therapy. Further validation is required before xMAP is used routinely for clinical PI3K pathway evaluation, but this method may eventually be personalized by taking into account each child's basal NB pathway status.