In vitro activity: AG-1024 blocks the IGF-1 receptor and IR autophosphorylation with IC50 of 7 μM and 57 μM, respectively. AG-1024 also inhibits the receptor tyrosine kinase activity towards exogenous substrates (TKA) with IC50 values of 18 μM and 80 μM, respectively. AG-1024 (10 μM) inhibits cell proliferation in a time-dependent manner, and induces apoptosis in MCF-7 cells at 48 hours by 20.1% and>40% when combined with irradiation (10 Gy), more potently than that of irradiation (10 Gy) alone by 11.8%, which is associated with a down-regulation of phospho-Akt1 and bcl-2, and up-regulation of Bax, p53 and p21. AG-1024 significantly inhibits melanoma cell proliferation with an IC50 of<50 nM in the absence of serum, by blocking MAPK/ERK2 signaling, subsequently rapidly inducing pRb dephosphorylation and activation, and eventually the formation of growth suppressive pRb-E2F complexes. AG-1024 treatment down-regulates the expression of Bcr-Abl and P-Akt, and up-regulates DNA-PKcs expression in UT7-9 and Ba/F3-p210 cells, leading to decreased clonogenic survival and proliferation. AG-1024 also significantly inhibits the proliferation of cells resistant to the BCR-ABL inhibitor STI571, which correlates with a dose-dependent decrease in Bcr-Abl protein expression.

Kinase Assay: NIH-3T3 cells overexpressing IGF-1 or insulin receptors are plated on 96-well plates (2,000-5,000 cells/well) and maintained overnight in complete medium. Cells are then changed to DMEM containing 1% FBS in the presence of 10 nM IGF-1 or insulin and various concentrations of AG-1024 for 120 hours. Medium is replaced every 48 hours. At the indicated periods of time, the medium is aspirated from the wells and 100 μL MTT is added to each well. The cells are then incubated for 4 hours at 37 °C and lysed by addition of 100 μL isoamylic alcohol and shaking for 20 minutes. The plate is then read in the ELISA reader at 570 and 690 nm. The IC50 value is calculated at the 120-hour time point.

Cell Assay: Cells are exposed to AG-1024 for 24, 48 or 72 hours. For the determination of proliferation, cells are harvested and counted with trypan blue dye exclusion. Apoptosis is evaluated by dual staining of MCF-7 with fluoresceine anti-digoxigenin and propidium iodide. Briefly, fixed cells are washed with PBS, suspended in TdT buffer with TdT enzyme and Dig-dUTP for 60 minutes, and suspended in FITC blocking solution with anti-Dig-Fluorescein for 30 minutes at room temperature and kept in a dark place. Cells are then rinsed in buffer and resuspended in propidium iodide/RNase A solution for 30 minutes then analyzed by flow cytometry. For the assessment of phospho-Akt1, Bax, p53, bcl-2 and p21, cells are lysed and analyzed by western blot.

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