Rigosertib

Kinase experiment:

Recombinant PLK1 (10 ng) is incubated with different concentrations of Rigosertib in a 15 µL reaction mixture (50 mM HEPES, 10 mM MgCl2, 1 mM EDTA, 2 mM Dithiothreitol, 0.01% NP-40 [pH 7.5]) for 30 min at room temperature. Kinase reactions are performed for 20 min at 30°C in a volume of 20 µL (15 µL enzyme + inhibitor, 2 µL 1 mM ATP), 2 µL of γ32P-ATP (40 μCi), and 1 µL of recombinant Cdc25C (100 ng) or casein (1 μg) substrates. Reactions are terminated by boiling for 2 min in 20 µL of 2× Laemmli buffer. Phosphorylated substrates are separated by 18% SDS-PAGE. The gels are dried and exposed to X-ray film for 3-10 min.

Cell experiment:

Tumor cells are plated into six-well dishes at a density of 1×105 cells/mL/well, and Rigosertib is added 24 hours later at various concentrations. Cell counts are determined from duplicate wells after 96-hour of treatment. The total number of viable cells is determined by trypan blue exclusion.

Animal experiment:

Bel-7402 tumor models: twenty female athymic (NCR-nu/nu) nude mice are injected with 1 × 107 Bel-7402 tumor cells subcutaneously, and 10-14 days later, when the tumor volumes reach 200-250 mm, the mice are divided into four groups such that each group harbors tumors of the same volume. Rigosertib (ON01910, 250 mg/kg) dissolved in PBS is administered alone or in combination with NSC 266046 (100 mg/kg) intraperitonially on alternate days. Tumor measurements are done two times/week using traceable digital vernier calipers. Body weight is determined during each measurement. The animals are observed for signs of toxicity[1].

References:

[1]. Xu F, et al. Rigosertib as a selective anti-tumor agent can ameliorate multiple dysregulated signalingtransduction pathways in high-grade myelodysplastic syndrome. Sci Rep. 2014 Dec 4;4:7310.
[2]. Hyoda T, et al. Rigosertib induces cell death of a myelodysplastic syndrome-derived cell line by DNA damage-induced G2/M arrest. Cancer Sci. 2015 Mar;106(3):287-93.
[3]. Gumireddy K, et al. ON01910, a non-ATP-competitive small molecule inhibitor of Plk1, is a potent anticancer agent. Cancer Cell. 2005 Mar;7(3):275-86.
[4]. Reddy MV, et al. Discovery of a clinical stage multi-kinase inhibitor sodium (E)-2-{2-methoxy-5-[(2',4',6'-trimethoxystyrylsulfonyl)methyl]phenylamino}acetate (ON 01910.Na): synthesis, structure-activity relationship, and biological activity. J Med Chem. 2011 Sep 22;54(18):6254-76.
[5]. Chapman CM, et al. ON 01910.Na is selectively cytotoxic for chronic lymphocytic leukemia cells through a dual mechanism of action involving PI3K/AKT inhibition and induction of oxidative stress. Clin Cancer Res. 2012 Apr 1;18(7):1979-91