[PubMed] [Google Scholar] 6. of dinaciclib with cisplatin synergistically promoted cell cycle arrest and apoptosis, and inhibited the subcutaneous xenograft growth of ovarian cancer in nude mice. Altogether, dinaciclib potently synergizes with cisplatin in preclinical models of ovarian cancer, indicating this beneficial combinational therapy may be a promising strategy for treatment of ovarian cancer. <1, respectively) than flavopiridol, the first CDKs inhibitor to enter the clinic trail [15]. Preclinical data have demonstrated that dinaciclib is active against a broad spectrum of human cancer cell lines with median IC50 of 11 nM by inducing cell cycle arrest and apoptosis [15]. The phase I clinical studies showed that dinaciclib administered at a dose of 0.33 mg/m2 as a 2-hour intravenous infusion on days 1, 8, 15 of a 28-day cycle was generally safe and well tolerated with the common adverse events including nausea, decreased appetite, anemia and fatigue [16]. The results of phase II study demonstrated that dinaciclib administered Rabbit polyclonal to PDCD4 intravenous at the 50 mg/m2 dose was well tolerated, but without antitumor activity as monotherapy in patients with non-small cell lung cancer [17]. In addition, another phase II trial illustrated that dinaciclib at 50 mg/m2 administered as a 2-hour infusion every 21 days displayed some antitumor activity and was generally tolerated in patients with advanced breast cancer, but efficacy was not superior to capecitabine at 1250 mg/m2 administered orally twice daily in 21-day cycles [18]. Furthermore, dinaciclib administered at doses of 30-50 mg/m2 on day 1 of a 21-day cycle exhibited EG01377 TFA encouraging single-agent antitumor activity in patients with relapsed multiple myeloma [19]. Evaluation of dinaciclib in combination with other chemotherapeutical drugs for multiple types of cancers currently is in progress. In this study, we investigated that anticancer effects and mechanisms of dinaciclib alone or combined with cisplatin in preclinical models of ovarian cancer. RESULTS Dinaciclib inhibited the growth of ovarian cancer cells < 0.05 and **< 0.01 corresponding control. Dinaciclib induced apoptosis in ovarian cancer cells To determine whether the growth inhibition of ovarian cancer cells by dinaciclib is also due to apoptosis, cell apoptosis was assessed after dinaciclib treatment. A2780 and OVCAR3 cells were treated with dinaciclib (0.003, 0.01, 0.03 and 0.1 M) for 48h, stained with Annexin V/PI and examined by FCM. As shown in Figure ?Figure3A3A and ?and3B,3B, dinaciclib dose-dependently induced early apoptosis (Annexin V+/PI-) and late apoptosis (Annexin V+/PI+) in both cells. Futhermore, the apoptotic related proteins were detected EG01377 TFA by Western blot to investigate the molecular mechanism of cell apoptosis by dinaciclib. After treatment with EG01377 TFA dinaciclib, the cleaved PARP, which is the marker of apoptosis, was time- and dose-dependently generated in both cells. Furthermore, the protein levels of XIAP, survivin, MDM2, Mcl-1, Raf-1, HSP90 and -catenin were significantly decreased in both cells (Figure ?(Figure3C3C). Open in a separate window Figure 3 Dinaciclib induced apoptosis in ovarian cancer cellsA2780 (A) and OVCAR3 (B) cells were treated with dinaciclib at the indicated time and concentrations. The apoptosis was detected by FCM Annexin V/PI staining. The proportions of Annexin V+/PI? and Annexin V+/PI+ cells indicated the early and late stage of apoptosis. The protein expression was examined by Western blot after lysing cells, and -actin was used as loading control. The representative charts, quantified results and Western blot results (C) of three independent experiments were shown. *< 0.05 and **< 0.01 corresponding control. ROS was critical for the anticancer effect of dinaciclib in ovarian cancer cells ROS plays an important role in tumorigenesis and chemotherapy of most anticancer drugs [20]. To assess the role of ROS in the anticancer effect of dinaciclib in ovarian cancer cells, we used dihydroethidium (DHE) as ROS fluorescent probe, which can be oxidized by ROS to oxide ethidium that binds with DNA to emit the detectable red fluorescence [21], to stain cells treated with dinaciclib. As.