Integrated Microfluidic and Imaging Platform for a Kinase Activity Radioassay to Analyze Minute Patient Cancer Samples

Abstract

Oncogenic kinase activity and the resulting aberrant growth and survival signaling are a common driving force of cancer. Accordingly, many successful molecularly targeted anticancer therapeutics are directed at inhibiting kinase activity. To assess kinase activity in minute patient samples, we have developed an immunocapture-based in vitro kinase assay on an integrated polydimethylsiloxane microfluidics platform that can reproducibly measure kinase activity from as few as 3,000 cells. For this platform, we adopted the standard radiometric (32)P-ATP-labeled phosphate transfer assay. Implementation on a microfluidic device required us to develop methods for repeated trapping and mixing of solid-phase affinity microbeads. We also developed a solid-state beta-particle camera imbedded directly below the microfluidic device for real-time quantitative detection of the signal from this and other microfluidic radiobioassays. We show that the resulting integrated device can measure ABL kinase activity from BCR-ABL-positive leukemia patient samples. The low sample input requirement of the device creates new potential for direct kinase activity experimentation and diagnostics on patient blood, bone marrow, and needle biopsy samples.