Dactolisib (BEZ235)

PI3Kα, β, and δ proteins are composed of the iSH2 domain of p85 NH₂-terminally fused to the full-length protein p110 protein, with the exception of α that also does not contain the last 20 amino acids. PI3Kγ is produced as full-length protein deleted for its first 144 amino acids. All constructs are fused to a COOH-terminal His tag for convenient purification and then cloned into the pBlue-Bac4.5 (for α, β, and δ isoforms) or pVL1393 (for γ isoform) plasmids. The different vectors are then cotransfected with BaculoGold WT genomic DNA using methods recommended by the vendor for production of the respective recombinant baculoviruses and proteins. BEZ235 are tested for their activity against PI3K using a Kinase-Glo assay. The kinase reaction is done in 384-well black plate. Each well is loaded with 50 μL of test items (in 90% DMSO) and 5 μL reaction buffer containing 10 μg/mL PI substrate (l-α-phosphatidylinositol; Avanti Polar Lipids; prepared in 3% octyl-glucoside) and the PI3K proteins (10, 25, 10, and 150 nM of p110α, p110β, p110δ, and p110γ, respectively) are then added to it. The reaction is started by the addition of 5 μL of 1 μM ATP prepared in the reaction buffer and is incubated for either 60 (for p110α, p110β, and p110δ) or 120 min (for p110γ). It is terminated by the addition of 10 μL Kinase-Glo buffer. The plates are then read in a Synergy 2 reader for luminescence detection.

HCT116, DLD-1 and SW480 cells

0-1 μM

48 hours

The human CRC cell lines, HCT116 (PIK3CA mutant; kinase domain at H1047R), DLD-1 (PIK3CA mutant; helical domain at E545K), and SW480 (PIK3CA wild-type) and isogenic DLD-1 PIK3CA mutant as well as wild-type cells are maintained in DMEM with 10% FBS and 1 × Penicillin/Streptomycin. Cells are plated at different initial densities (HCT116: 3 × 10³ cells/well, DLD-1: 5.5 × 10³ cells/well, SW480: 4.5 × 10³ cells/well, DLD-1 PIK3CA mutant: 7 × 10³ cells/well, and DLD-1 PIK3CA wild-type: 9 × 10³ cells/well) to account for differential growth kinetics. After 16 hours, cells are incubated with increasing concentrations of BEZ235, and the drug-containing growth medium is changed every 24 hours. Cell viability is assessed 16 hours after the initial plating and 48 hours after initiation of drug treatment using the colorimetric MTS assay CellTiter 96® AQueous One Solution Cell Proliferation Assay, as per the manufacturer's instructions. Cell viability after drug treatment is normalized to that of untreated cells also grown for 48 hours. For western blot analysis, cells are plated with zero or maximum inhibitory dose (500 nM) BEZ235 for 2, 6, 24, or 48 hours.

Female Harlan athymic nude mice

45 mg/kg

p.o.