Comparison of cell-based assays to quantify treatment effects of anticancer drugs identifies a new application for Bodipy-L-cystine to measure apoptosis

Cell-based assays that measure anticancer drug effects are essential for evaluating chemotherapeutic agents. Many assays targeting various cellular mechanisms are available, leading to inconsistent results when using different techniques. We critically compared six common assays, as well as a new assay using Bodipy.FL.L-cystine (BFC), to identify the most accurate and reproducible in measuring anticancer drug effects. We tested three common chemotherapies (methotrexate, paclitaxel, and etoposide) in two cell lines (Ln229 and MDA-MB231). Spectroscopic assays such as Cell Titer Blue, and 2′,7′-dichlorofluorescin diacetate (DCFDA) yielded a strong drug dose response, especially for paclitaxel and etoposide (R(2) = 0.9). MTT and Calcein-AM fluorescent dye-based assays were less consistent in that regard. Among three flow cytometry assays, Propidium Iodide (PI)-based DNA content analysis and a new BFC-based glutathione-redox (GSH) assay produced drug dose dependent results. Compared to PI, BFC showed a better correlation (R(2) = 0.7–0.9) in depicting live and apoptotic cells. We found that the combination of Cell Titer Blue spectroscopy and BFC flow cytometry assays were most accurate in assessing anticancer drug effects by clear distinction between live and apoptotic cells, independent of drug mechanism of action. We present a new application of BFC as an agent for measuring cellular apoptosis.