A simple in vitro tumor chemosensitivity assay based on cell penetrating peptide tagged luciferase

The analysis of intracellular ATP can reveal the response of cells to different treatments and is important for individualized medicine. In the present study, we developed a cell penetrating peptides (CPPs) tagged luciferase (TAT-LUC) for tumor chemosensitivity assay. The activity of recombinant TAT-LUC was evaluated using ATP standard solution and tumor cells. This recombinant TAT-LUC was then used for the analysis of sensitivity index (SI) of four strains of tumor cells. The results showed that TAT-LUC could detect less than 10 nM extracellular ATP with a strong correlation between the luminescence intensity and the ATP content (R(2) = 0.994). Without cell lysis, the detection limit for intracellular ATP analysis was 40 tumor cells. Furthermore, chemosensitivity of four strains of tumor cells (Skov-3/DDP, A549/DDP, MDA-MB-231, Huh-7) was determined by this assay successfully. The cell penetration ability of TAT-LUC enables the assay not only to reflect drug resistance of tumor cells real-timely but also to minimize the test time, which can be a valuable aid for personalized cancer chemotherapy.