Tyrosine Kinase Inhibitor Profiling Using Multiple Forskolin-Responsive Reporter Cells

We have developed a highly sensitive promoter trap vector system using transposons to generate reporter cells with high efficiency. Using an EGFP/luciferase reporter cell clone responsive to forskolin, which is thought to activate adenylate cyclase, isolated from human chronic myelogenous leukemia cell line K562, we found several compounds unexpectedly caused reporter responses. These included tyrosine kinase inhibitors such as dasatinib and cerdulatinib, which were seemingly unrelated to the forskolin-reactive pathway. To investigate whether any other clones of forskolin-responsive cells would show the same response, nine additional forskolin-responsive clones, each with a unique integration site, were generated and quantitatively evaluated by luciferase assay. The results showed that each clone represented different response patterns to the reactive compounds. Also, it became clear that each of the reactive compounds could be profiled as a unique pattern by the 10 reporter clones. When other TKIs, mainly bcr-abl inhibitors, were evaluated using a more focused set of five reporter clones, they also showed unique profiling. Among them, dasatinib and bosutinib, and imatinib and bafetinib showed homologous profiling. The tyrosine kinase inhibitors mentioned above are approved as anticancer agents, and the system could be used for similarity evaluation, efficacy prediction, etc., in the development of new anticancer agents.

Isolation of Reporter Cells That Respond to Vitamin A and/or D Using a piggyBac Transposon Promoter-Trapping Vector System

Previously, we established a highly sensitive promoter-trapping vector system using the piggyBac transposon for the efficient isolation of reporter cells. Herein, we examine whether this screening system can be applied to obtain vitamin-responsive cells. As a result, one and two reporter cells that responded to bexarotene (vitamin A) and calcitriol (vitamin D), respectively, were isolated from 4.7 × 106 seeded HeLaS3 cells. 5' RACE analyses identified the well-known CYP24A1 gene as a calcitriol-responsive gene, as well as two new bexarotene- or calcitriol-responsive genes, BDKRB2 and TSKU, respectively. TSKU, interestingly, also responded to bexarotene. Endogenous levels of the TSKU and BDKRB2 transcripts displayed only slight changes and were not detected in the comprehensive analyses performed to date. Dose-response analyses of BDKRB2 and TSKU reporter cells in parallel revealed a differential profile in response to each vitamin A agonist, suggesting a bioanalyzer. The present study demonstrates that producing multiple reporter cells by a type of random screening can efficiently identify novel genes with unusual characteristics and be used for the profiling of the properties of vitamin compounds. Similar approaches to the method shown here may be useful for identifying new markers and for the analysis or diagnosis of nutrients, toxins, metabolites, etc.