Evaluation of antiproliferative agents using a cell-culture model

Chinese hamster ovarian (CHO) cells in culture were used to evaluate the relative antiproliferative potential of drugs. These agents have been used to improve the clinical response after glaucoma filtering surgery. The following drugs were evaluated: 5-fluorouracil (5-FU) as the benchmark, 5-fluorouridine (FUR), 5-fluorodeoxyuridine (FUDR), 5'-deoxy-5-fluorouridine (DFUR), bleomycin, and cytarabine (ARA-C). In addition to cell counting, a colorimetric assay based on the tetrazolium salt, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used to follow growth response. The MTT assay was found to be extremely convenient and an indirect measure of cell activity, offering an alternate or addition to a measure of cell number. All agents tested were shown to inhibit cellular proliferation. Dose-response curves for each agent indicate the following absolute potency: FUDR greater than FUR greater than ARA-C greater than 5-FU = bleomycin greater than DFUR. Besides absolute potency, an evaluation of the effects of equivalent inhibitory concentrations of each drug on growth rate was assessed. Several agents affected the proliferation rate patterns differently. Based on these studies, it is suggested that the in vitro model can identify potential agents through an assessment of their overall activity profile in CHO cells, which includes not only their potency based on dose response, but their onset of activity, duration of effect, and potential for toxicity.