An optimized screen for mitotic inhibitors using cancer cells synchronized at the G2/M phase border Free

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Mitotic inhibitors represent a major class of chemotherapeutics currently used in the clinical practice of oncology. Many of them have been discovered by cellular screens looking at cell proliferation or viability endpoints. Recently, high throughput imaging techniques have been developed that allow screening for mitotic inhibitors by direct measurement of mitotic cell fractions. However, in a typical mitotic screen, cells are incubated with test compounds for extended periods of time (>24h) and the accuracy of measuring the mitotic index could be adversely affected by mechanistic or off-target toxicities. Here, we describe a screening approach for mitotic inhibitors that uses human cancer cells pre-synchronized at the entry of mitosis by a selective CDK1 inhibitor, RO-3306. This method shortens drug exposure times to 3 hours and helps to separate anti-mitotic activity from toxicity of tested compounds thus increasing the accuracy of detection of mitotic inhibitors.