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. PIT-1 is a selective nonphosphoinositide inhibitor that specifically disrupts PIP3/Akt PH domain binding with an IC50 value of 31 μM. PIT-1 suppresses PI3K-PDK1-Akt-dependent phosphorylation, which has been shown to reduce cell viability and induce apoptosis in PTEN-deficient U87MG glioblastoma cells (IC50 = 37 μM).
