e separate experiments are shown. Niermann et al. Page 12 Radiat Res. Author manuscript, available in PMC 2012 April 1. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript FIG. 4. AZD1152 results in radiosensitization in PC3 and DU145 prostate BMS-387032 CDK inhibitor cancer cells. Cells were treated with AZD1152 and were then exposed to radiation . After 8 days, colonies were stained and scored. Values shown are the means ± SD of three separate experiments. Radiosensitivity was increased in both cell lines. Niermann et al. Page 13 Radiat Res. Author manuscript, available in PMC 2012 April 1. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript Combining histone deacetylase inhibitor vorinostat with aurora kinase inhibitors enhances lymphoma cell killing with repression of c Myc, hTERT, and micro RNA levels Leo Kretzner1, Anna Scuto2, Pamela M.
Dino5, Claudia M. Kowolik2, Jun Wu1, Patrick ABT-751 141430-65-1 Ventura3, Richard Jove2, Stephen J. Forman4, Yun Yen1, and Mark H. Kirschbaum4,5 1 Department of Translational Research, Clinical and Molecular Pharmacology, City of Hope and Beckman Research Institute, Duarte, CA, USA 2 Department of Molecular Medicine, City of Hope and Beckman Research Institute, Duarte, CA, USA 3 Department of Bio statistics, City of Hope and Beckman Research Institute, Duarte, CA, USA 4 Department of Hematology and Hematopoietic Cell Transplantation, City of Hope and Beckman Research Institute, Duarte, CA, USA 5 Department of Experimental Therapeutics, Nevada Cancer Institute, Las Vegas, NV, USA Abstract MK 0457 and MK 5108 are novel aurora kinase inhibitors leading to G2/M cell cycle arrest.
Growth and survival of multiple lymphoma cell lines were studied with either drug alone or in combination with vorinostat, an HDACi, using MTS and Annexin V assays, followed by molecular studies. Either AKi alone at 100 500 nM resulted in ~50% reduced cell growth and 10% 40% apoptosis. Addition of vorinostat reactivated pro apoptotic genes and enhanced lymphoma cell death. qPCR and immunoblotting revealed that epigenetic and protein acetylation mechanisms were responsible for this activity. The prosurvival genes Bcl XL and hTERT were downregulated 5 fold by combination drug treatment, while the proapoptotic Bad and Bid genes were upregulated 3 fold. The p53 tumor suppressor was stabilized by an increased acetylation in response to vorinostat and a reduced Ser315 phosphorylation in response to aurora kinase A.
Vorinostat or trichostatin A decreased Myc mRNA and protein as well as Myc regulated microRNAs. Myc is a critical gene in these responses, as Myc knock down combined with the expression of the Myc antagonist Mxd1, raised cell sensitivity to the effects of either AKi. Thus, the HDACi vorinostat leads to both transcriptional and post transcriptional changes to create a pro apoptotic milieu, sensitizing cells to mitosis specific agents such as Aki,s. Keywords Vorinostat, Aurora Kinase, Lymphoma, c myc, hTERT, miRNA Corresponding author: Mark H. Kirschbaum, formerly of Department of Hematology/HCT, City of Hope, Duarte, CA. Current contact information: Director, Experimental Therapeutics, Nevada Cancer Institute, Medical Oncology, One Breakthrough Way, Las Vegas NV 89135, Ph: 702.
822.5229 Fax: 702.944.1165, mkirschbaumnvcancer. Conflicts of Interest: Supported in part by a research grant from the Investigator Initiated Studies Program of Merck Sharp & Dohme Corp. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Sharp & Dohme Corp NIH Public Access Author Manuscript Cancer Res. Author manuscript, available in PMC 2012 June 1. Published in final edited form as: Cancer Res. 2011 June 1, 71: 3912 3920. doi:10.1158/0008 5472.CAN 10 2259. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript Introduction The aurora kinases are Ser/Thr protein kinases active during late G2 and M phases of the cell cycle. Aurora Kinases A, B, and C r