A comparison of colorimetric and clonogenic assays for hypoxic-specific toxins with hamster and human cells

The hypoxic cytotoxicities of misonidazole and pimonidazole (Ro 03-8799) towards the human tumor cell lines HT-1080 and LoVo have been compared with those seen with Chinese hamster V79-379A cells. Survival was assayed using two colorimetric assays, either a tetrazolium salt (MTT) or methylene blue, and by conventional colony scoring. The drugs were more cytotoxic towards HT-1080 and LoVo cells than V79 cells. The times taken for 10 mmol dm-3 misonidazole to reduce survival to 0.1 surviving fraction (SF) using colony formation as the end point were 2.6 hr for HT-1080, 2.4 hr for LoVo, and 3.5 hr for V79; using the MTT assay these times were 3.5 hr, 2.1 hr, and 2.9 hr, respectively. The times for 2 mmol dm-3 pimonidazole to reduce survival to 0.1 SF using colony formation as the end point were 2.0 hr for HT-1080, 1.7 hr for LoVo, and 3.7 hr for V79; using the MTT assay these times were 2.5 hr, 1.4 hr, and 2.5 hr, respectively.