PtdIns-(3,4,5)-P3 (PIP3) serves as an anchor for the binding of signal transduction proteins bearing pleckstrin homology (PH) domains such as phosphatidylinositol 3-kinase (PI3K) or PTEN. Protein binding to PIP3 is important for cytoskeletal rearrangement and membrane trafficking and initiates an intricate signaling cascade that has been implicated in cancer. 3,5-dimethyl PIT-1 is a dimethyl analog of PIT-1, the selective inhibitor of PIP3/Akt PH domain binding, that is designed for more favorable solubility in vivo. 3,5-dimethyl PIT-1 inhibits PI3K/Akt signaling (IC50 = 27 μM), suppressing PI3K-PDK1-Akt-dependent phosphorylation, which has been shown to reduce cell viability and induce apoptosis in PTEN-deficient U87MG glioblastoma cells (IC50 = 36 μM). 4T1 breast cancer growth is significantly attenuated in BALB/c mice with a dose of 1 mg/kg of 3,5-dimethyl PIT-1 per day.
