Quisinostat (JNJ-26481585) 2HCl

JNJ-26481585 exhibits broad spectrum antiproliferative activity in solid and hematologic cancer cell lines, such as all lung, breast, colon, prostate, brain, and ovarian tumor cell lines, with IC50 ranging from 3.1-246 nM, which is more potent than R306465, CRA-24781, or mocetinostat in various human cancer cell lines tested. ^[1] A recent study shows that JNJ-26481585 promotes myeloma cell death at low nanomolar concentrations by resulting in Mcl-1 depletion and Hsp72 induction. ^[2]

In an HDAC1-responsive A2780 ovarian tumor screening model, JNJ-26481585 dosing at its maximal tolerated dose (10 mg/kg i.p. and 40 mg/kg p.o.) for 3 days leads to an HDAC1-regulated fluorescence , which predicts tumor growth inhibition. Furthermore, JNJ-26481585 also shows more potent inhibitory effects on the growth of C170HM2 colorectal liver metastases. ^[1]

• HDAC activity assays

  In all cases, full-length HDAC proteins are expressed using baculovirus-infected Sf9 cells. In addition, HDAC3 is coexpressed as a complex with human NCOR2. For assessing activity of HDAC1-containing cellular complexes, immunoprecipitated HDAC1 complexes are incubated with an [³H]acetyl- labeled fragment of histone H4 peptide [biotin-(6-aminohexanoic)Gly-Ala-(acetyl[3H])Lys-Arg-His-Arg-Lys-Val-NH2] in a total volume of 50μL enzyme assay buffer (25mM HEPES (pH 7.4), 1 M sucrose, 0.1 mg/mL BSA and 0.01% (v/v) Triton X-100). Incubation is performed for 45 minutes at 37 °C (immunoprecipitates) or 30 min at room temperature. Before addition of substrate, HDAC inhibitors are added at increasing concentrations and preincubated for 10 minutes at room temperature. After incubation, the reaction is quenched with 35μL stop buffer (1 M HCl and 0.4 M acetic acid). Released [³H]acetic acid is extracted with 800μL ethyl acetate and quantified by scintillation counting. Equal amounts of HDAC1 are immunoprecipitated as indicated by Western blot analysis. HDAC1 activity results are presented as mean ± SD of three independent experiments on a single lysate.

• Cell lines

  NCL-H2106, Colo699 and LNCAP cells

• Concentrations

  0-300 nM

• Incubation Time

  24 hours

• Method

  All cell lines are obtained from American Type Culture Collection and cultured according to instructions. The effect of HDAC inhibitors on cell proliferation is measured using an MTT. Proliferation of non–small cell lung carcinoma (NSCLC) cell lines is assessed using an Alamar Blue–based assay. For proliferation of hematologic cell lines, cells are incubated for 72 hours and the cytotoxic activity is evaluated by MTS assay. Data are presented as mean IC50 or IC40 ± SD of at least three independent experiments.

• Animal Models

  HCT116 human colon carcinoma cells are injected s.c. into the inguinal region of athymic male NMRI nu/nu mice, C170HM2 cell suspensions are injected into the peritoneal cavity of male MFI nude mice.

• Dosages

  ≤10 mg/kg

• Administration

  Administered via both p.o. and i.p.