3,5-dimethyl PIT-1

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.

A cell-permeable benzoylthiourea compound that is shown to compete against PIP3 (Cat. No. 524615) for binding PH domains of Akt1 (IC₅₀ ≥31 μM), ARNO, GRP1, and PKD1. Effectively blocks PIP3-dependent cellular PI3K-PDK1-Akt signaling pathway activation in U87MG (25 to 100 μM for 3 d) and PDGF-induced Akt and GRP membrane translocation in serum-starved SUM159 cells (1 h 100 μM pretreatment), while being inactive against PDGF-induced Btk translocation or PMA-induced PLC-δ and TAPP1/2 translocations. Although DM-PIT-1 can be administered as a DMSO stock for effective culture treatments, incorporating DM-PIT-1 into PEG-PE mixed micelles enhances its solubility (up to 1 mM) and i.v. dosing limit for more effective in vivo administrations (5% vs. 41% of control 4T1 tumor size in mice via 1 mg/kg micelles-formulated or 0.4 mg/kg free drug daily i.v., respectively).