Electrochemical antitumor drug sensitivity test for leukemia K562 cells at a carbon-nanotube-modified electrode

The change in electrochemical behavior of tumor cells induced by antitumor drugs was detected by using a multiwall carbon nanotubes (MWNTs)-modified glass carbon electrode (GCE). Based on the changes observed, a simple, in vitro, electrochemical antitumor drug sensitivity test was developed. MWNTs promoted electron transfer between the electroactive centers of cells and the electrode. Leukemia K562 cells exhibited a well-defined anodic peak of guanine at +0.823 V at 50 mV s(-1). HPLC assay with ultraviolet detection was used to elucidate the reactant responsible for the electrochemical response of the tumor cells. The guanine content within the cytoplasm of each K562 cell was detected to be 920 amol. For the drug sensitivity tests, 5-fluorouracil (5-FU) and several clinical antitumor drugs, such as vincristine, adriamycin, and mitomycin C, were added to cell culture medium. As a result, the electrochemical responses of the K562 cells decreased significantly. The cytotoxicity curves and results obtained corresponded well with the results of MTT assays. In comparison to conventional methods, this electrochemical test is highly sensitive, accurate, inexpensive, and simple. The method proposed could be developed as a convenient means to study the sensitivity of tumor cells to antitumor drugs.