HDACi have demon strated potent activity against colon cancer cell lines in vitro and in xenograft models with little or no cytotoxicity reported against normal cells and clinical evaluations thus far have demonstrated favorable toxicity profiles. Several studies to date have demonstrated that HDACi induce alterations in the expression of multiple drug tar gets and/or metabolic pathways www.selleckchem.com/products/INCB18424.html that are critical molecular determinants for cancer therapeutics. Importantly combi nation treatment with additional agents targeting these modulated pathways has resulted in synergistic growth inhibitory effects on cancer cells in vitro and in vivo. It has been recently reported that HDACi synergize with 5 FU in vitro and in vivo in colon cancer cell line models through HDACi induced downregulation of the 5 FU target enzyme thymidylate synthase, providing a mechanis tic basis for the drug synergy.
The HDACi vorino stat is also reported to acetylate and markedly reduce the chaperone activity of HSP90 in T cell lymphoma models resulting in a synergistic interaction with the HSP90 inhibitor bortezomib. This combination was subse quently extended to colon cancer cell lines with similar synergistic anti proliferative effects. In addition, the HDACi vorinostat was demonstrated to induce tumor cell selective expression of the TRAIL death receptors 4 and 5 sensitizing breast cancer xenografts to the effects of a TRAIL agonistic antibody, an observation which is currently being clinically evaluated in lymphoma patients.
More recently, HDACi were also reported to enhance the apoptotic effects of EGFR inhibitors in lung cancer models and clinical evaluation of this is ongoing. Therefore, the identification of novel genes modulated by HDACi in colon cancer cells may provide pathway driven rationale for novel and urgently needed efficacious drug combinations. This study was designed to determine the effects of two clinically relevant HDACi, vorinostat and LBH589 on the growth characteristics of two cytogenetically distinct colon cancer cell line models HCT116 and HT29. In addi tion, HDACi induced alterations in global gene expres sion were analyzed using the Illumina Human 6 V2 BeachChip arrays and Ingenuity Pathway Analysis. Methods Compounds and Reagents LBH589 was provided by Novartis Pharmaceuticals. Vorinostat was provided by Merck and Co,Inc. and the National Cancer Institute.
CellTiter96 AQueous MTS rea gent was purchased from Promega. Cell Lines HCT116 AV-951 colon cancer cells were a generous gift of Prof. Bert Vogelstein and HT29 colon cancer cells were purchased from selleck compound ATCC. HCT116 and HT29 cell lines were maintained in McCoys 5A medium, supplemented with 10% fetal bovine serum, penicillin/streptomycin and sodium pyruvate. Cells were maintained in a humidi fied Hepa Class100 Incubator at 37 C and 5% CO2. Cell lines were routinely screened for mycoplasma using the MycoALERT Detection kit.