Cyclin-dependent kinase 1 inhibitor RO3306 promotes mitotic slippage in paclitaxel-treated HepG2 cells

Hepatocellular carcinoma (HCC) is the most common primary liver neoplasm and current systemic chemotherapy are mostly ineffective. Paclitaxel (PTX) has a clinically significant effect on many malignant tumors. Cells treated with PTX undergo reversible mitotic arrest and although high doses can cause side effects it may also induce apoptosis. We investigated the effect of a sequential combination of PTX and RO3306, a cyclin-dependent kinase 1 inhibitor, on the hepatocellular carcinoma HepG2 cell line. The sequential drug treatment protocol involved the addition of PTX (0.2 µmol/L) for 18 h followed by RO3306 (2 µmol/L) for a further 6 h. Cell viability and proliferation were measured using tetrazolium dye (MTT) and colony formation assay. Cell cycle profiles were established by flow cytometry. The expression level of protein was examined by immunoblotting. We observed a synergistic effect of PTX and RO3306 treatment on cell growth and proliferation as well as an increased proportion of cells in sub-G1 phase. Expression levels of cyclin B, cyclin E and phosphorylated Histone H3 demonstrated that RO3306 enhanced apoptosis in PTX treated cells by mitotic slippage. Our data suggested that the combination of PTX and RO3306 may be an effective therapeutic combination for the treatment of liver cancer.