Antibodies against various proteins were from the following sources: topoIIα, BD Transduction (San Diego, CA); topoIIβ, casein kinase (CK)2α, Ets-1, ubiquitin, hemagglutinin, HDAC1, and HDAC6, Santa BGB324 manufacturer Cruz Biologicals (Santa Cruz, CA); Fbw7, Bmi1 and Skp2, Invitrogen; Fbx4, Rockland (Gilbertsville, PA); Fbx7, ProteinTech (Chicago, IL); acetylated lysine, HDAC4, HDAC5 and GSK3β, Cell Signaling Technology (Danvers, MA); Flag,

Sigma-Aldrich; β-actin, MP Biomedicals (Irvine, CA); COP9 signalosome subunit (Csn)5, GeneTex (Irvine, CA); p-Ser/Thr, Abcam (Cambridge, MA); acetyl-histone H3 and HDAC2, Millipore (Billerica, MA). Goat antirabbit and rabbit antimouse immunoglobulin G (IgG)-horseradish peroxidase conjugates were from Jackson Laboratories (West Grove, PA). PLC5 cells were transfected with Lipofectamine 2000 (Life

Technologies, Gaithersburg, MD) according to the manufacturer’s protocol. Plasmids and RNA interference were obtained from the following sources: short-hairpin RNA (shRNA) constructs PD0325901 mouse against HDAC1, HDAC2, HDAC6, and CK2α, and plasmids encoding CK2α and Csn5, Origene (Rockville, MD); small interfering RNAs (siRNAs) against Csn5, HDAC4, and HDAC5, Invitrogen; Fbw7 shRNA and hemagglutinin-GSK3β plasmid, Addgene. Immunoblotting was performed as described.14 Cells were treated with AR42 for 48 hours and lysed by buffer B (5 mM HEPES, 1.5 mM MgCl2, 0.2 mM EDTA, 0.5 mM DTT, 26% glycerol [v/v], 300 mM NaCl, pH 7.9) on ice for 1 hour. After centrifugation at 13,000g for 20 minutes, one-tenth volume of supernatant was stored at 4°C for use as input and the remainder

was incubated with protein A/G-Sepharose beads for 1 hour to eliminate nonspecific binding. The mixture was centrifuged at 1,000g for 5 minutes and the supernatants were incubated with anti-topoIIα antibodies and protein A/G Sepharose overnight. The immunocomplexes were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and proteins were detected with indicated antibodies. PLC5 cells were treated with AR42 for 36 hours and fixed in 1% formaldehyde for 15 minutes to immobilize histone to DNA. Cross-linking was stopped with 125 mM glycine for 5 minutes. ChIP was performed see more as previously described6 using antibodies against acetyl-histone H3 or Ets-1 with nonspecific rabbit IgG as negative control. Primers spanning the proximal promoter regions of CK2α were used for amplification by reverse-transcription polymerase chain reaction (RT-PCR): 5′-GGGGATTCCTTCCATTTTGC-3′/5′-ATG GAGGAGGAGACACACGG-3′. Total RNA was isolated from drug-treated cells with Trizol reagent (Invitrogen) and chloroform extraction. Aliquots of 2 μg of total RNA were reverse-transcribed to cDNA with the iScript cDNA Synthesis Kit (Bio-Rad Laboratories, Hercules, CA) according to the manufacturer’s instructions. PCR products were resolved by agarose (1.2%) gel electrophoresis and visualized by ethidium bromide staining.