BQU57 selectively inhibits Ral over Ras or Rho and suppresses xenograft tumor growth.

HDAC Enzyme Assay: The commercially availablae human recombinant enzyme and fluorogenic HDAC assay kits have used to measure percent inhibition and IC50 values of three HDAC isozymes (HDAC2, HDAC4, HDAC6). Briefly, the inhibitor is added sequentially to a black, flat-bottom 96-well microtiter plate, and the reaction mixture is incubated for 30 min at 37°C. The potent HDAC inhibitor trichostatin A (included in the assay kit) is added to the bifunctional HDAC assay developer at a final reaction concentration of 1 μM to stop deacetylation and initiate the release of the fluorophore. The reaction mixture is further incubated at room temperature for 15 min. Fluorescence is measured on a Spectra Max Gemini XPS using an excitation wavelength of 360 nm and a detection wavelength of 460 nm.

Growth inhibition on human lung cancer cells by the compounds are measured under anchorage-independent conditions in soft agar. Cells are seeded into 6-well plates (coated with a base layer made of 2.0 mL of 1% low-melting-point agarose) at 15,000 cells per well in 3.0 mL of 0.4% low-melting-point agarose containing various concentration of drug. Two to four weeks (depending on cell line) after incubation, cells are stained with 1.0 mg/mL Nitro Blue Tetrazolium and colonies are counted under a microscope. The IC50 values are defined as the concentration of drug that resulted in 50% reduction in colony number compared to DMSO treated control. After 48 hr, cells are subjected to the soft agar colony formation assay. (Only for Reference)